What really limits our engines to rev higher

[Aevus]

Since I'm rebuilding one of my engines, I was looking for ways to get higher RPM limits in order to get both the typical screaming sound of high rev engines and more horsepower (while keeping it N/A)...

Basically, the pushrod Viper engine is limited by:

- Valvetrain stability (it's a pushrod)
- Long stroke
- Oiling system (especially gen 1-2-3 and no dry sump for gen 4/5)
- Air flow (2-valves, heads limitations, etc..)

The ''theorical'' limit for mean piston speed is 25 m/s or 4900 ft per minute, but that's open for debate since some will say 4000 fpm is the maximum ''safe'' limit while others says a race engine can be pushed as far as 5500-6000 fpm. Many factors to consider here...

But basically a Viper's 3.96'' stroke would be at the 4900fpm limit around 7,400 rpm, which is already a lot. I've seen destroked Viper on youtube going to 8,000rpm and also few others in the 7,xxx range.

But other than destroking, what is the path to get that huge engine rev higher? Super lightweight and stable valvetrain is probably mandatory, then you need sufficient air flow (ported heads, high duration camshaft, excellent intake/exhaust systems, etc..) and obviously the oiling and cooling systems that will keep that high rev engine from blowing apart...

But what else?

Is super lightweight pistons/rods that important, or it's better to focus on parts strenght?
Same for push rods, is it better to have heavier oversized but very stiff and stable ones?
Extemely stiff valve springs? at the cost of losing efficiency


Some interesting stuff here on the subject:

https://www.motortrend.com/how-to/1111chp-how-to-increase-engine-rpm/

...but probably some tips do not apply for a 7-8000 rev engine.

[Steve M]

I can't really comment due to a lack of knowledge/experience, but two things stuck out to me:

1. Dailey Engineering makes dry sumps for Gen 2-5 Vipers - you can even retain your A/C for Gen 3-5 (https://www.daileyengineering.com/dodgechrysler/)

2. In the article linked, this statement immediately stood out:


In just about every racing class in existence that limits maximum displacement, the quest to turn more rpm than the next guy rules the day.

For a street/occasional track car without maximum displacement limits, it doesn't make much sense to me. Yeah, high RPMs sound cool, but if you end up having to lose displacement to get there, you are also going to lose torque.

I don't think you'd even necessarily have to give up displacement. Arizona Vipers spins his 9L up to 7,000 RPMs all the time. That's obviously at the low end of your 7-8,000 RPM range, but still qualifies as high RPMs in my book.

Maybe I'm just getting too old and need to take a nap...it just sounds like an expensive science project that won't really do much beyond what you already have other than make a lot of noise.

[Aevus]

I don't think you'd even necessarily have to give up displacement. Arizona Vipers spins his 9L up to 7,000 RPMs all the time. That's obviously at the low end of your 7-8,000 RPM range, but still qualifies as high RPMs in my book.



Very impressive to get 7,000rpm from a 9L stroker indeed

[Aevus]

Maybe I'm just getting too old and need to take a nap...it just sounds like an expensive science project that won't really do much beyond what you already have other than make a lot of noise.

Just a very different character engine, that's all. Even 7,200rpm would be plenty of fun, best of both world: a relatively high revving engine + large displacement.

Sure is an expensive science project but far less than a 11,200rpm LS7 engine (!)

[Aevus]

Valvetrain/Oiling/Cooling is more about reliability but can it get there?

The air flow is the key to just be able to rev high. So I believe anything less than ported gen4 heads won't cut it, for anything north of 7,000rpm

Here is some flow numbers:

http://www.speedstore.ca/VP4_flow_sheet.html

Without going too crazy on the lift, you can get 360 cfm on the intake and 260 on the exhaust, and I heard the porting can be made even better (Greg Good ?) close to 390 cfm, I'm not sure if that's true...

Then, how big of durations can you push it until it becomes impossible to tune

[TKO MOTORSPORTS TEAM]

They are hydraulic motors

[Aevus]

Listen to the sound of a high rev gen2, built by Calvo

https://youtu.be/_0LD6Ty-nxQ?t=85

[TKO MOTORSPORTS TEAM]

You cant keep the lifter pumped up at high RPM on hyd motor. The lifter passes by oiling hole so quickly at high RPM it wont stay pumped up, then all kinds of problems happen. High RPM motor you just go solid and problem is solved. Then onto factory manifold problem

[Aevus]

That's interesting.

And what is ''high RPM'', exactly?

By using the gen 1/2 Mopar slow bleed lifters, what would be the upper limit, 6,500-7,000rpm?


Found this:

https://www.motortrend.com/how-to/mopp-0312-solid-vs-hydraulic-lifters/



At what point can instability with a hydraulic lifter begin to hinder performance? The answer, unfortunately, is combination specific. Valvetrain weight and geometry, pushrod deflection, preload adjustment, spring load, and the cam profile's smoothness and intensity are some of the factors, along with rpm, that can upset a hydraulic lifter's ability to maintain valve control. Even oil viscosity and temperature have been reported to make a difference.

Though there are too many variables to pinpoint the rpm capability of a hydraulic-lifter camshaft, extensive experience in the use of hydraulic cams can suggest basic guidelines. Depending upon the camshaft/valvetrain/spring combination, standard hydraulic lifters can operate effectively in the 5,500-6,000-rpm range. Typically, anti-pump-up lifters can raise the rpm potential by 500-1,000 rpm more. Certainly, some have far exceeded these numbers, while other combinations experience problems at even more conservative levels.





The solid cranked 550 hp at 5,800 rpm, and 559 lb-ft of torque at 3,900. Interestingly, the torque levels were quite close at peak, and below at the low-to-middle of the rpm curve. At higher rpm-about 5,200 and above-the solid cam walked away from the hydraulic, pulling cleanly to 6,300 rpm, at which we limited our test. The solid cam's power curve was nicely shaped, exactly what we like to see.

We had a 30hp gain, with the same "size" camshaft, with the peak horsepower coming in a good 400 rpm higher. There was no part of the curve where the hydraulic showed a clear advantage. Seeing is believing-when it comes to spinning it up, a solid flat-tappet cam does have the edge.

[Old School]

By using the gen 1/2 Mopar slow bleed lifters, what would be the upper limit, 6,500-7,000rpm?

Slow bleed lifters are actually just the normal lifter used in everything from mini-vans to pickup trucks and early Vipers. The fast bleed ones are the weird (and expensive) ones used for emissions reasons.

[Aevus]

https://www.hagerty.com/media/maintenance-and-tech/big-camshaft-street-manners-anti-pump-up-lifters/

[Aevus]

https://www.youtube.com/watch?v=GZTdo2-cGCM



On this episode of Engine Masters, the comparison features 100-percent more hydraulic cam! Last round we compared hydraulic and solid roller lifters on hydraulic and solid cams, respectively. But we have more questions! For instance, can you actually run solid roller lifters on a hydraulic cam? Why would you? And, if you do, will they make more power? How long will they survive?

[TKO MOTORSPORTS TEAM]

That's interesting.

And what is ''high RPM'', exactly?

By using the gen 1/2 Mopar slow bleed lifters, what would be the upper limit, 6,500-7,000rpm?


Found this:

https://www.motortrend.com/how-to/mopp-0312-solid-vs-hydraulic-lifters/

There really is no need to spin any motor past where it makes peak power. 7k on built hydraulic viper motor is very dicey. 6600-6800rpm is a safer bet
Solid viper motor 7500-8K reliably is not a problem but to take full advantage of 8K RPM you need to improve other aspects of the motor.

[Aevus]

There really is no need to spin any motor past where it makes peak power. 7k on built hydraulic viper motor is very dicey. 6600-6800rpm is a safer bet
Solid viper motor 7500-8K reliably is not a problem but to take full advantage of 8K RPM you need to improve other aspects of the motor.

Ain't easy to find information on solid lifters (and solid cam) for the Viper, probably not a common conversion at all for the snake. Maybe Jesel can make solid lifters for it, but then again will it work with a big hydraulic camshaft or a custom solid roller cam will be needed

[Aevus]

Forget about those lame wives tales about solid lifters always going out of adjustment! That's just not true! We're not in the damn 60's and 70's anymore! The ONLY way the adjustment (lash) can change is if something is either wearing out or going bad, period. If a rocker stud starts pulling out, the lash will increase. If the tip of the valve is getting hammered or mushroomed, the lash will increase. That's what hardened lash caps were made for before we had better material to make valves out of. If the tip, or the cup, of the rocker arm starts to wear out, the lash will increase. If a push rod bends or wears out one (or both) of the tips, the lash will increase. If the lifter is getting cupped or the cam is going flat, the lash will increase. If a valve seat "sinks" or recesses, then the valve is actually lifting or sitting higher, which means the lash will decrease. No matter how you slice it, if a solid lifter cam keeps going out of adjustment, something is seriously wrong or isn't up to par! If nothing is wearing, bending, pulling, mushrooming, backing-off, or getting longer or shorter, then there is zero reason for the valve to go out of adjustment. Guys that say solids will go out of adjustment when using modern components, such as stainless steel valves, screw-in studs, roller rockers with tool steel cups and rollers, hard valve seats, chrome moly push rods, etc, then it's just a wives tale being spread by people who have probably never even ran a solid lifter cam in a real engine before. If you're talking about an era engine with era components in it, well then you just might have to do some adjusting from time to time, but not when you have a modern performance engine, or a 1st generation engine with modernized components in it.


https://www.badasscars.com/index.cfm/page/ptype=product/product_id=67/category_id=58/mode=prod/prd67.htm


I realler wonder why the solid lifter thing is not among the top modifications to be done on the Viper engine if that is so obviously better (no adjustement really needed + a bit noisier but on a noisy car anyway...)

According to the motortrend dyno test, it delivers same or better torque/HP all the way... and you gain 500-1000rpm potential.

So, what's the drawback?

[Aevus]

Technology and metallurgy are changing. It use to be that a hydraulic cam wouldn't be very good for a hot street or a mild race engine when in fact, they perform very well. As long as good matching valve springs are used with a set of good quality, light weight lifters, there's no reason a hydraulic cam can't do well on the street, or on the track, and if someone tells you different, have them tell that to the guys running hydraulic cams at well over 7000 RPM in 11 and 12 second street cars.

Solid lifter cams can be a good choice for a hot street or race engine. They usually have faster ramps (lobes) than hydraulic cams, but not as fast as roller cams. They also need stouter springs than a hydraulic cam, but not nearly as stiff as a roller cam. They're kind of the middle of the road between the hydraulic flat tappet and roller cams.


So maybe the solution to reach the 7,000rpm mark all hyd is with good springs + lightweight lifters.

[TKO MOTORSPORTS TEAM]

So maybe the solution to reach the 7,000rpm mark all hyd is with good springs + lightweight lifters.

I probably should have clarified "road course" or long duration high rpm use. 11-12 second daily driven drag cars probably ok going hyd since its short runs and motors are pretty mild; and there is no doubt hyd motors are less maintenance and great for more everyday street use. Yes for sure materials have gotten better and machining processes have gotten alot better which has benefited all of us you can see this everyday. But better design, materials and machining processes cant fix the laws of physics and fluid dynamics that we all have to work with or but heads with on a daily basis.

[Aevus]

But better design, materials and machining processes cant fix the laws of physics and fluid dynamics that we all have to work with or but heads with on a daily basis.

Agreed.

After some research, I think the best route to take to play in the 6,900-7,500 is a combination of: shaft mount rockers (Jesel Pro series?) + oversized pushrods 3/8 or even 7/16 + lightweight valves, springs, retainers and finally solid rollers on a big agressive hydraulic cam, the solid rollers would make the hyd cam ''smaller'' by roughly 10 degrees if I understood correctly (because of the lash needed on the solid rollers -which is pretty big because of the aluminum Viper engine-)

If that all makes sense, the only thing left is to find the most suitable solid rollers that would fit*.

P.S. and again, if I understood correctly, at high RPM the weight is not as important as avoiding any deflection on the lifter/pushrod side of the rocker. So big pushrod + lifter that will bring stability.

[SRT_BluByU]

The main answer to the original question is , money. Anything is possible

[Aevus]

Had a discussion with Dale from Prefix, which was very helpful since they have a lot of experience with gen3 and gen4... Well, to sum it up, I'm pretty much back to square 1 because the very limitation is the air flow. While the gen 4's head can flow enough to create enough power up to 7,000rpm and beyond, the gen 3 can't. I mistakenly tought I could avoid that limitation with all the bolts-ons; 67mm TB or single blade + K&N + Headers and also a custom race exhaust + a big camshaft and obviously getting the head ported...but even with a good porting job, the gen 3's head is limited. Will see later on the dyno, but I can expect somewhere around 6,500rpm would be the max useable limit.

So, what that means exactly is it makes any extreme valvetrain modifications pointless. Including solid lifters, shaft mount rockers, titanium valves, etc... The bottleneck is elsewhere. It just won't rev that high with power to justify it.

Also, the oiling system is the other limitation. Again, gen 4's system would be needed (swing arm oil pan + machined crank for better oiling alone won't cut it for higher rpm) maybe with Prefix's oversize oil pump rotor but to what extent? For street use it may be okay, but I wouldnt feel comfortable bringing the car to the track, even for just few sessions, which is a shame...

In conclusion, I will do what I can to get the most from that engine within a ''reasonnable'' budget, and I will post the dyno results as soon as I have them, but yes, as SRT_BlueByU pointing out: with money anything is possible, and it sure takes a LOT of money and work to make a Viper engine run above 7,000rpm.

No wonder why forced induction is the numero uno solution for big HP.

[Aevus]

There really is no need to spin any motor past where it makes peak power. 7k on built hydraulic viper motor is very dicey. 6600-6800rpm is a safer bet

From what I understand now, even with all the possible bolts-ons, camshaft and porting, using the gen 3's head would make that 6600-6800rpm very difficult to reach. I hope I'm wrong but if the peak power I finally get is anything north of 6,500rpm I will open a bottle of Champagne.

[Aevus]

Very interesting article:

https://www.motortrend.com/how-to/adjusting-hydraulic-lifters-for-more-top-end-rpm/



Adjusting hydraulic lifters for minimum preload (less turns after hitting the initial "zero" lash setting) can extend maximum engine speed by several hundred rpm.



Turning the rocker arm adjustment nut a lesser amount after reaching the zero-lash point positions the hydraulic lifter's internal plunger closer to the lifter plunger's snap-ring retainer. At high rpm, this delays hydraulic lifter pump-up because the plunger can't move far enough to interfere with valve closure when hydraulic force overcomes valvespring pressure. In fact, some racers even adjust the nut as close as 1/8 turn or less down from zero lash, which positions the hydraulic lifter plunger practically against the snap ring, effectively causing the hydraulic lifter to act like a mechanical lifter because it can't take up any clearance in the valvetrain. Running tight plunger-to-retainer clearances can be risky if using standard lifters that have a paperclip-type retaining ring because hydraulic pressure may cause the plunger body to pop out of the groove, resulting in catastrophic failure. Lifters with full-contact internal Truarc-style snap rings can better withstand these tight clearances. For long-term street durability with a high-perf cam, adjust lifters with Truarc-type retaining rings 1/4 to 1/2-turn down from zero lash; adjust paperclip retaining-ring lifters 1/2 to 3/4-turn down from zero lash.

I just received my performance lifters with Truarc-type retaining rings, will adjust somewhere between 1/8 and 1/4 turn down from zero lash.

Combined with my conical springs, titanium retainers and 3/8'' 0.135'' pushrods I hope the valvetrain will remain stable above 6,400-6,500 rpm...

[SRT_BluByU]

Had a discussion with Dale from Prefix, which was very helpful since they have a lot of experience with gen3 and gen4... Well, to sum it up, I'm pretty much back to square 1 because the very limitation is the air flow. While the gen 4's head can flow enough to create enough power up to 7,000rpm and beyond, the gen 3 can't. I mistakenly tought I could avoid that limitation with all the bolts-ons; 67mm TB or single blade + K&N + Headers and also a custom race exhaust + a big camshaft and obviously getting the head ported...but even with a good porting job, the gen 3's head is limited. Will see later on the dyno, but I can expect somewhere around 6,500rpm would be the max useable limit.

So, what that means exactly is it makes any extreme valvetrain modifications pointless. Including solid lifters, shaft mount rockers, titanium valves, etc... The bottleneck is elsewhere. It just won't rev that high with power to justify it.

Also, the oiling system is the other limitation. Again, gen 4's system would be needed (swing arm oil pan + machined crank for better oiling alone won't cut it for higher rpm) maybe with Prefix's oversize oil pump rotor but to what extent? For street use it may be okay, but I wouldnt feel comfortable bringing the car to the track, even for just few sessions, which is a shame...

In conclusion, I will do what I can to get the most from that engine within a ''reasonnable'' budget, and I will post the dyno results as soon as I have them, but yes, as SRT_BlueByU pointing out: with money anything is possible, and it sure takes a LOT of money and work to make a Viper engine run above 7,000rpm.

No wonder why forced induction is the numero uno solution for big HP.

There is always the 9.0L option! yum yum

[usmcfieldmp]

Can't the Gen 4 heads be made to work on a Gen 3? I'm pretty sure there's a kit to make them work for Gen 2's ($$$$$). I'm curious as to what all is required; I know the Power Steering is one "concern", but that's an easy fix. Well, having power steering, that is... not sure how easy belt routing is without the PS pump, but I can't imagine it would be that hard to fix.

[Aevus]

Can't the Gen 4 heads be made to work on a Gen 3?

Yes of course.

https://store.prefix.com/products/gen-iii-viper-upgrade-kit

Probably mandatory to get in 7,000rpm territory (enough airflow) but I'm assuming that a decently ported Gen 3 head matched with the proper camshaft will be enough to provide for 6,600-6,800rpm. And that's about the limit of everything, anyway:

Oiling system (with oversized pump rotor + machined crank) and valvetrain stability (see my post above), not to mention fuel and transmission before you need to upgrade that as well.

Short story: 6,700rpm is still a reasonnable target. At the limits of pretty much everything but doable.

7,000-7,200rpm probably is not a ''reasonnable'' target... That may include Gen 4 (ported) head, shaft mount rockers, solid lifters/camshaft, titanium valves, better oiling system and maybe even dry $ump...

I mean, that extra 300-500rpm seems to be very costly and a lot of troubles to go through. The high rev N/A thing is a lot of fun, no doubt, but passed a certain point SC or Turbo makes more sense if more power is what you want.

[Aevus]

... the dyno will tell if that ''reasonnable'' high-rev Gen 3 engine can spin to only 6,400 or as high as 6,800... And then only time will tell if durability is part of the recipe

[usmcfieldmp]

I'm curious as to what needs to be machined for fitment and why the intake manifold is "custom".

[J TNT]

I have a set of Gen 5 heads if you’re looking to upgrade.
Feel free to send me a pm with your cell number if you want more information.
Jay.

[TKO MOTORSPORTS TEAM]

... the dyno will tell if that ''reasonnable'' high-rev Gen 3 engine can spin to only 6,400 or as high as 6,800... And then only time will tell if durability is part of the recipe

Your on a budget with hard earned money why roll the dice on durability????. Motor will stop making power probably around 5200-5500rpm why run it to 6800rpm??

[Aevus]

Your on a budget with hard earned money why roll the dice on durability????. Motor will stop making power probably around 5200-5500rpm why run it to 6800rpm??

With all the mods i'm doing, if it stops making power at 5,500rpm there's a dead squirrel stucked in the headers.

;-)

Viper Speciality with their VS-X700 kit dynoed 613.5 HP at 5950 RPM and Peak Torque at 5100 RPM. That's with a ''torque'' camshaft and non-ported gen 4 head.

I will have a ported gen 3 head with similar flow numbers + a high duration camshaft + 11:1 compression w/94oct dyno tune + 3.5'' straight through exhaust... I'm not too worried that will make some decent peak power north of 6,000rpm, the real challenge is the oil system and especially the valvetrain.

But yeah, obviously, if it doesnt show real power delivery at 6,000rpm I won't push it to 6,800... Would be totally pointless.

[Aevus]

I need to point out that I'm running a tune for nearly a year now with a 6,250rpm rev limit. Stock engine.

Going from 6,250 to 6,800 is not exactly fantastic.

[Aevus]

FYI

Stock Gen 4 Head numbers: Intake 327 CFM / Exhaust 242 CFM (0.600'' lift)

Ported Gen 3 Head numbers: Intake 320 CFM / Exhaust 235 CFM (0.600'' lift)*

* Ported numbers can vary of course, but it gives an idea.



(stock gen 3 head = 265/215 CFM, maxed out much more easily)

[TKO MOTORSPORTS TEAM]

FYI

Stock Gen 4 Head numbers: Intake 327 CFM / Exhaust 242 CFM (0.600'' lift)

Ported Gen 3 Head numbers: Intake 320 CFM / Exhaust 235 CFM (0.600'' lift)*

* Ported numbers can vary of course, but it gives an idea.



(stock gen 3 head = 265/215 CFM, maxed out much more easily)

Factory manifold is where the motor falls on its face for N/A cars, options to fix it aren't real budget friendly. Manifold kinda kills the head work or should say doesnt let you take full advantage of your head work or exhaust. But your running lower RPM so maybe manifold wont impact to much

[Aevus]

Very interesting MT article (yeah I know it's a LS7 engine not Viper's, but still)

https://www.motortrend.com/how-to/1811-build-de-stroked-ls7-for-high-rpm-road-racing/

Very decent 400lbs torque from 3,500rpm while having 8,000rpm capability. Pretty impressive. That thing is probably streetable. But it was clearly designed for road course, sustained high rpm...

[Aevus]

A little update on my high-rpm gen3 engine project:

Since the heads are not yet ready and the season is over, I decided to order a shaft mount rocker arm, which only makes sense at the point where I am now...

My target is still 6,600-6,800+ rpm peak power, hopefully around 650-670 whp. Forged internals, Fidenza flywheel, either 3.73 or 4.10 gears, oversized oil pump rotor, headers, custom exhaust, etc.. But the most important here is the valvetrain upgrades:

- Compcam Conical springs (440lbs rating)
- Titanium retainers
- 3/8 pushrods w/ 0.135'' wall
- Titanium, lightweight SS valves
- Prefix performance lifters (lash adjusted 1/8 turn so act almost as a solid lifter)
- T&D aluminum shaft mount rocker arm w/ spring oil hole option and 1.75 ratio (if it fits and needed)
- around 11.2-11.5:1 compression ratio

With the custom camshaft and 1.75 ratio, it will be 0.621'' intake lift and 0.613'' exhaust + 238/251 duration @ 0.050 and 1.70 (more at 1.75). + 115 LSA.

I'm still waiting for the benchflow numbers of the ported heads to decide between 1.70 and 1.75 ratio, but basically that's the whole recipe, as I cannot think of anything else to help my case on that project (other than destroke)...
Will have to wait 10-12 weeks for T&D but I can't wait to see the results.

[Aevus]

49623

Essentially, the whole idea that all the experts and race gurus are saying for high-rpm:

Make the pushrod's side of the rocker as stiff as possible and make the valve's side of the rocker as lightweight as possible.

That's what I did.

[Aevus]

Few other things that I've learned the past months with this project:

- Stock gen 3 crank is good up to roughly 7,000rpm, especially if properfly balanced and with lightweight forged internals that reduces stress on it. I don't plan to put turbos or SC, so I decided to go with 4032 alloy pistons, which were a bit lighter than 2618 alloy ones.

- Hydraulic lifter is one of the most limitative thing here, but high-rpm still doable on hyd (some even did 7,500rpm+ on other engines) and you keep all the obvious benefits of hyd... Use only lifters with Truarc-type retaining rings, adjusted 1/8 (race setting, becomes a solid lifter more or less..) and 1/4 (street) turn down from zero lash.

- Titanium valvetrain components are great but wears faster than steel so don't expect doing 50,000 miles without replacing valves/retainers (and springs while at it). If you take the steel route it will last longer and cost less but you will most likely lose 200-300rpm (minimum) capability.

- Resonance is a big issue in the valvetrain at high-rpm. Big stiff pushrods and conical (or behive) valve springs, close to coil bind (0.050-0.060'') seems the best methods to reduce resonance, along with shaft mount rocker arm.

- According to everything I've read, it WOULD be possible to make that 8.3 liters engine rev higher than 7,000rpm WITHOUT a destroke, but that would probably require to do very expensive things for a very small benefit: aftermarket crank and/or titanium rods, even bigger cam and maybe higher compression to go along (and E85? adios pump gas), even stiffer valve springs and bigger/stiffer pushrods, maybe ported gen 4 heads if ported gen 3's maxed out... and then of course oiling problems (dry sump), fuel, ignition, computer, transmission, etc... All that for, MAYBE, 7,200 to 7,400rpm peak 700-750whp and weaker avg power and torque curve...

Doable, yeah. Probably a bit crazy though. ;-) At some point destroke or FI makes much more sense.

[TKO MOTORSPORTS TEAM]

De-stroked , solid with good internals and valve train, dry sump .....you will be very happy with the results. If you want to go a bit further add individual throttle bodies

[Aevus]

De-stroked , solid with good internals and valve train, dry sump .....you will be very happy with the results.

Yes but we're talking tens of thousands for such project, just for the destroke and drysump alone... Doesnt make any sense on a vert gen 3, IMO. At some point I have to draw a line. Anything above 7,000 peak power seems to be a worm can.

I'm comfortable with the 6,600-6,800 peak power target, and if for some reasons I'm lucky with the build and it pushes in the 6,900-7,000 zone, i'll just have to tweak the oil system (Accusump or else) on top of my already installed compe coupe pan and Prefix oil pump rotor. OR I'll just don't go there and rev limit the wannabe screamer.. lol

I'm not worried with the crank and even less the valvetrain, but at some point a lot of issues would pop up.

[SRT_BluByU]

if 6600-6800 is your goal why not jsut get a crate Gen V?

[Aevus]

Bytheway, with my 2nd (stock) engine but with all bolt-ons, tune and headers+custom exhaust, I already have 6,050rpm peak power. An extra 600 rpm shouldnt be a problem with that aggressive cam, ported heads and completely upgraded valvetrain, not to mention the forged internals. In fact it's very possible that engine will be 7,000rpm capable, but educated-guesses here of the bottlenecks:

- Oil system = 6,800 rpm max
- Prefix's hydraulic lifters (1/8 turn) = 7,000 rpm max
- Custom cam = 6,900-7,100 rpm max
- Stock crank but machined (oil passage) and balanced = 7,000-7,200 rpm max
- Ported heads = ???
- Fuel system = ???
- All the valvetrain except hyd lifters = 8,000rpm+
- Forged internals = 8,000 rpm+

[Aevus]

if 6600-6800 is your goal why not jsut get a crate Gen V?

did they fix the DBW so it's as fun as my TC ?

;-)

also, still no dry sump.

[USAFPILOT]

https://www.youtube.com/watch?v=_uta6RWwx7s

I know this a Viper Forum, but when wondering how to get Revs up higher, this new engine is certainly relevant. Pretty cool. Just illustrating TKO's point above, the Viper V10 is a hydraulic, cross plane, long stroked lazy beast. It can be made to rev higher though. Have a look over at Nelson Racing engines and the work they do. I know other shops also build some great high revving pushrod motors. But will there be any reliability in those builds?

[TKO MOTORSPORTS TEAM]

Yes but we're talking tens of thousands for such project, just for the destroke and drysump alone... Doesnt make any sense on a vert gen 3, IMO. At some point I have to draw a line. Anything above 7,000 peak power seems to be a worm can.

I'm comfortable with the 6,600-6,800 peak power target, and if for some reasons I'm lucky with the build and it pushes in the 6,900-7,000 zone, i'll just have to tweak the oil system (Accusump or else) on top of my already installed compe coupe pan and Prefix oil pump rotor. OR I'll just don't go there and rev limit the wannabe screamer.. lol

I'm not worried with the crank and even less the valvetrain, but at some point a lot of issues would pop up.

Get where your coming just hate to see spending money and not trying to get the most out of every dollar spent. Better option then accusump is exotic engines external oil pump set up.

[Aevus]

Get where your coming just hate to see spending money and not trying to get the most out of every dollar spent. Better option then accusump is exotic engines external oil pump set up.

I don't plan to track the car, though. That changes everything.

I'm doing that project mainly for the fun of doing it and pushing the limits. That will most likely be the last ''true'' sports car I will ever own (RWD, manual, naturally aspirated) so I might as well enjoy it as a constant work-in-progress project that gets modified and driven/tested as much as possible. In other words, the polar opposite of a garage queen.

I've been very luck so far: every dollar spent on mods are highly appreciated, including TKO's parts :-)

[Aevus]

https://www.youtube.com/watch?v=_uta6RWwx7s

I know this a Viper Forum, but when wondering how to get Revs up higher, this new engine is certainly relevant. Pretty cool.

Yeah, exactly, that new Z06's engine is pure porn. That video/demonstration leaves no doubt about it! Wow, triple-check so no service/valve adjust would be needed ''ever''... (from 3:00 in the video) even though it's not hydraulic.

But that's the thing though. Manufacturers need to deal with reliability, noise and emissions issues. That's another world entirely.

Also, while that engine looks amazing, I'm not overly impressed by the 670bhp @ 8,400rpm and especially 460lbs torque @ 6,300rpm. Would be curious to see the torque curve....

[Aevus]

Just illustrating TKO's point above, the Viper V10 is a hydraulic, cross plane, long stroked lazy beast. It can be made to rev higher though.

6,600-7,000rpm maximum
... or higher with destroked+solid and with few more modifications that goes with that kind of project.

And honestly, a destroked 7.6 liters (Calvo) screaming at 8,000rpm like that:

https://www.youtube.com/watch?v=M2v7QMKF898

...is not THAT tempting for my ears. Great engine for sure, but it doesnt sound as a Viper anymore.

[TKO MOTORSPORTS TEAM]

I don't plan to track the car, though. That changes everything.

I'm doing that project mainly for the fun of doing it and pushing the limits. That will most likely be the last ''true'' sports car I will ever own (RWD, manual, naturally aspirated) so I might as well enjoy it as a constant work-in-progress project that gets modified and driven/tested as much as possible. In other words, the polar opposite of a garage queen.

I've been very luck so far: every dollar spent on mods are highly appreciated, including TKO's parts :-)

"Work in progress", " modified and driven/tested as much as possible". VERY COOL......Its what being a gearhead is all about. Since your a TKO customer if you ever need help, info or questions answered we are always ready to support our customers.

[Aevus]

Very interesting article on Motortrend about valvetrain weight factor in general and valves specifically. Tests were made on a LS7, which is a great comparison basis with our engine.

it clearly shows about the possible bottlenecks of a bad combination, that can force you to rev limit as low as 6,300rpm ... or go as high as 7,800rpm if done properly with the right package.


49663



Katech notes: Nearly twice the bounce by simply changing the valve. This combination is fine for a street car, if the rev limiter is set at 7,000 rpm. In road-racing conditions, we prefer to see a 500-800-rpm safety margin, which would mean a 6,300-6,600-rpm rev limit.


Talk about instability! The severe bounce displayed at comparatively low rpm made it unwise to continue testing up to 7,500 rpm. We flat-out don't recommend this setup.


Minimal bounce at 7,900 rpm! This is an excellent combination all the way to 7,800 rpm—as long as the prep work has been done to the valve stems and bronze guides are used in the head.


The test measured the performance of the stock LS7 valve (74 grams), a REV stainless valve (98 grams) and a titanium valve (66 grams). The heavier stainless valve doesn’t have the separation issue that has occurred with some factory sodium-filled units, but with about a 33 percent increase in weight, it is less stable at high rpm.

It doesnt seem like very much weight, but it adds up very quickly.

Behive and Conical springs seems like the best solutions and since the Viper heads don't benefit more than 0.675'' lift (even 0.625'' or so actually), I would say the conical solution is the best.
Then, titanium or tool steel retainers/locks to go along with the conical's. And finally the valves, either stainless steel hollow stem or titanium or a mix of both, intake/exhaust.

Everything put together, including the shaft mount rocker arm and super stiff pushrods, it should relieve some stress on the hydraulic lifters so they can reach 7,000rpm and even beyond...

The next bottleneck, after that 7,000-ish mark, will then be the oil system... and after that, the crankshaft. Which could benefit from an overbalance, aftermarket swap and/or lighter internals. Just to put a price on things, as of november 2021 of course:

- Titanium valves = more or less 160$ each x 20 = 3,200$
- Aftermarket forged crankshaft = 4,000-8,000$
- Titanium rods = 5,000-7,000$

Not including labor of course.

As for the oiling system, I have no idea about the cost for a gen 3/4. Drysump or less extreme solution but it would be costly for sure.

[Aevus]

... and also, I think Katech's advice for a 500-800rpm safety margin for the racetrack is VERY SMART.

Totally agree with that.

In fact I plan to have a dual tune, one to have fun on the street that would be the most permissive and another one more restrictive for the racetrack (if I ever want to tracktest my car).

[Aevus]

Bytheway, with my 2nd (stock) engine but with all bolt-ons, tune and headers+custom exhaust, I already have 6,050rpm peak power. An extra 600 rpm shouldnt be a problem with that aggressive cam, ported heads and completely upgraded valvetrain, not to mention the forged internals. In fact it's very possible that engine will be 7,000rpm capable, but educated-guesses here of the bottlenecks:

- Oil system = 6,800 rpm max
- Prefix's hydraulic lifters (1/8 turn) = 7,000 rpm max
- Custom cam = 6,900-7,100 rpm max
- Stock crank but machined (oil passage) and balanced = 7,000-7,200 rpm max
- Ported heads = ???
- Fuel system = ???
- All the valvetrain except hyd lifters = 8,000rpm+
- Forged internals = 8,000 rpm+


All educated-guesses because nobody really knows about the real limits of a combination. That makes the engine topic so fascinating!

Take the hydraulic lifters. Nobody in their right mind would dare pushing a hyd above 7krpm, right? WRONG.


and compounded the combination with a set of short-travel hydraulic roller lifters, stud-mounted 1.6:1 ratio roller rockers, titanium retainers, and triple valve springs, and wound the thing up to 7,700 rpm without a hint of valve float.

That wasn't a typo. We revved this thing almost to 8,000 rpm with hydraulic lifters in the block. And it worked.

https://www.motortrend.com/news/rpm-small-block-chevy-with-a-hydraulic-roller-cam/

So maybe my hyd lifters with 1/8 turn adjust will start to do troubles at 6,800, maybe 7,000 or maybe only 7,500... Almost impossible to know without testing it with all the other parts. Maybe the whole valvetrain will not be the bottleneck at all. Maybe it will be the flow of the heads, or even the camshaft, or the crank, or the oil system (most likely)...

What's kind of crazy is: there is almost always a solution to push the limits even farther. Even though it would seem ''impossible'' at first. Someone somewhere did some tests, trial and errors, and found a solution for a particular problem.

[Aevus]

Made a list of all the potential bottlenecks (for high rev, stock 3.96in stroke) and the crankshaft becomes one of them at a certain point.

Antonio from Calvo Motorsports and Greg Good offered some good advices in that thread:

https://driveviper.com/forums/threads/10578-2003-2004-crankshaft-failures-bearing-setup?p=181668&viewfull=1#post181668

[Aevus]

A little update on my high-rpm gen3 engine project:

Since the heads are not yet ready and the season is over, I decided to order a shaft mount rocker arm, which only makes sense at the point where I am now...

My target is still 6,600-6,800+ rpm peak power, hopefully around 650-670 whp. Forged internals, Fidenza flywheel, either 3.73 or 4.10 gears, oversized oil pump rotor, headers, custom exhaust, etc.. But the most important here is the valvetrain upgrades:

- Compcam Conical springs (440lbs rating)
- Titanium retainers
- 3/8 pushrods w/ 0.135'' wall
- Titanium, lightweight SS valves
- Prefix performance lifters (lash adjusted 1/8 turn so act almost as a solid lifter)
- T&D aluminum shaft mount rocker arm w/ spring oil hole option and 1.75 ratio (if it fits and needed)
- around 11.2-11.5:1 compression ratio

With the custom camshaft and 1.75 ratio, it will be 0.621'' intake lift and 0.613'' exhaust + 238/251 duration @ 0.050 and 1.70 (more at 1.75). + 115 LSA.

I'm still waiting for the benchflow numbers of the ported heads to decide between 1.70 and 1.75 ratio, but basically that's the whole recipe, as I cannot think of anything else to help my case on that project (other than destroke)...
Will have to wait 10-12 weeks for T&D but I can't wait to see the results.



New update FYI

Finally ordered valves from Ferrea Racing.

Lightweight hollow stainless steel stem, custom made for the Viper and my ported heads to allow the very best possible flow with the right angles.

They guarantee 80-85gr weight (exhaust) and 85-90gr. (intake) so roughly 25 grams saving per valve, which is a lot.

Very good option, not too expensive (compared to Titanium) and probably optimal up to 7,500rpm+ Viper engine project.

I'm posting all that info because it's very difficult to get any information regarding valves on Viper. The common solution seems to be Manley race series, but there is Ferrea as well, if you want to get above 6,500 rpm.

[Aevus]

Also, I postponed the shaft mount rocker arm until fall. Will probably have to upgrade the oil system, re-order a more optimal cam or adjust the timing on the actual one for 200-300rpm extra and of course the shaft rocker.

So for now, the target is still 6,600-6,800 rpm. Will see what really happens on the dyno before the next upgrades...

Those upgrades would target the 7,000 rpm mark and up to 7,500rpm if the crankshaft is upgraded as well.

[TKO MOTORSPORTS TEAM]

Also, I postponed the shaft mount rocker arm until fall. Will probably have to upgrade the oil system, re-order a more optimal cam or adjust the timing on the actual one for 200-300rpm extra and of course the shaft rocker.

So for now, the target is still 6,600-6,800 rpm. Will see what really happens on the dyno before the next upgrades...

Those upgrades would target the 7,000 rpm mark and up to 7,500rpm if the crankshaft is upgraded as well.

You will run into block oil galley volume problems running hydraulic lifters when you start edging towards 7000 rpm. Just a heads up

[Aevus]

You will run into block oil galley volume problems running hydraulic lifters when you start edging towards 7000 rpm. Just a heads up

Yes, a lot of problems beyond 7k

[Aevus]

Will have to overbalance my (stock) crankshaft, most probably around 51%.

If you want to read about crank balancing, here is a great article:

https://www.enginebuildermag.com/2020/11/crankshaft-balancing-act/

[Aevus]

You will run into block oil galley volume problems running hydraulic lifters when you start edging towards 7000 rpm. Just a heads up

Upgrades I already have regarding OIL:

- (stock) crankshaft machining to fix the known issues
- oversized oil pump rotor from Prefix
- Competition coupe swing-arm oil pan

Now, I'm not sure if it's the best solution but I was thinking Accusump. I won't track the car, especially not at 6,800-7,000rpm so all I need is some engine protection against short bursts at high-rpm, basically as if it were a strip car.

[TKO MOTORSPORTS TEAM]

Upgrades I already have regarding OIL:

- (stock) crankshaft machining to fix the known issues
- oversized oil pump rotor from Prefix
- Competition coupe swing-arm oil pan

Now, I'm not sure if it's the best solution but I was thinking Accusump. I won't track the car, especially not at 6,800-7,000rpm so all I need is some engine protection against short bursts at high-rpm, basically as if it were a strip car.

If you have a swing pick up oil pan and your not tracking your car on a regular basis you really dont need an accusump. Accusumps are also a little bit of a pain in the ass to work with, take up space in the car and add another layer of complexity. Accusumps are great for classes where dry sump systems are not allowed

[Aevus]

If you have a swing pick up oil pan and your not tracking your car on a regular basis you really dont need an accusump. Accusumps are also a little bit of a pain in the ass to work with, take up space in the car and add another layer of complexity. Accusumps are great for classes where dry sump systems are not allowed

No I'm not planning to track the car and if I do it's gonna be with a tune that is safer.

I'm just a bit worried for issues such as cavitation or anything related to high-RPM, even for street use.

[TKO MOTORSPORTS TEAM]

No I'm not planning to track the car and if I do it's gonna be with a tune that is safer.

I'm just a bit worried for issues such as cavitation or anything related to high-RPM, even for street use.

Your putting together a good combo for street and some track use. Unless your pro driver and really putting the spurs to it you should be fine. There are also plenty of other mods you can do to improve performance and safety that don't involve the motor cost and labor involved are also much less then motor parts.

[Aevus]

Update:

Last piece of the puzzle, the camshaft is ordered:

246/259 @ .050 , lsa 114+4 , .587/.560

Had to reduce the lift on the exhaust side, in order to clear the piston and have min. 0.080'' clearance. My heads are flowing pretty well in the 0.500-0.560'' so it's fine. Also, less stress on the springs and overall valvetrain which is welcome for the high-rpm I'm seeking.

Will have 11.73:1 compression ratio.

I'm hoping (!) for not so much torque below 2,500rpm, because of my 4.10 gears and with 246/259 duration I should be okay....


Can't wait to try that engine :devilish:

[Dan Cragin]

That cam is hard to tune with the factory speed density system and JTEC. Back in the day we had to go with a TPS/RPM Map, vacuum was so low at
lower rpms Map is hard to calibrate.

[Aevus]

That cam is hard to tune with the factory speed density system and JTEC. Back in the day we had to go with a TPS/RPM Map, vacuum was so low at
lower rpms Map is hard to calibrate.

Even with 114 LSA?

I've been told it will be tuneable.

Dyno-tuned by Torrie from Unleashed.

[LATAMUD]

I wasn't aiming for 7-8k rpm. I still kept it under 6k. I built a Gen3 with forged internals to run around 15 psi through my Paxton. Greg Good posted heads had heavier springs, intake was cut open and ported, Arrow single blade TB. There's an old school mod to convert hydraulic lifters into solid. I used Crower shaft mounted rockers and 3/8 hardened push rods. I modded a Gen4 swing arm oil pickup to use with the Gen4 pan on the Gen3 engine. My block was an 04 but I still used a 05/06 crank to get the beefier snount and crank bolt.
Comp Cams will grind to whatever you desire. I told them solid lifter, 116 LSA for the supercharger. Ended up with a .637/.637 lift. I ran a slightly lower then stock compression I think my pistons were .005 shorter compression height then stock.
I never got any good dyno numbers, I was aiming for 800 on a Mustang dyno. I could never find a reliable tuner and ended up dropping oil pressure so never drove it hard. Car sitting 30 feet away from my house in the street idling, the windows of my house would rattle.
I'm still solid lifter but recently swapped in a Gen4 engine. This setup I'll max the Procharger out at 5700 RPM, I will likely never take the engine past 5500. Again, needs a tune still. It's over built, I don't think I'm going to enjoy this car on the street. Twin disc cluch and billet TOB, only needs about 1" clutch pedal to engage the clutch but it's like 10x heavier pedal than stock. It's so loud, it's louder than the X. On paper, high rev sounds cool but you're gonna miss practical basic Vipering.

51480


https://youtu.be/_yL8ei5lAZY

[Aevus]

damn Latamud, you strike me as someone who doesnt like very much his car!

Sorry to hear that


On my side, it's a pretty safe bet: I have another cam on-hand that is less agresssive... and I have another (stock) engine in case something goes really bad.
I spent hours and hours in the last year to study that project and I'm finally close to the results. Still aim 6,800rpm peak power, 7,000-ish rev limit, no track just street but as racy of a feel as possible. Superlightweight valvetrain, tricked out hyd lifters, forged internals, high CR, 3.5'' exhaust, headers, upgraded oil system, ported heads, 69lbs injectors, and a cam to extract the best of all that (crosses fingers).

I have at least as much fun working on the project as driving the car ;-)

[LATAMUD]

Sure, this one I don't like as much as the other ones. I've daily driven 3 of the 5. The ACR-X isn't street legal.

[DEMO MAN]

Sure, this one I don't like as much as the other ones. I've daily driven 3 of the 5. The ACR-X isn't street legal.

Well........ street legal is one of those relative terms, I mean I would guess there are those out there who might drive that X right down I-4 :)

[Aevus]

I wasn't aiming for 7-8k rpm. I still kept it under 6k. I built a Gen3 with forged internals to run around 15 psi through my Paxton. Greg Good posted heads had heavier springs, intake was cut open and ported, Arrow single blade TB. There's an old school mod to convert hydraulic lifters into solid. I used Crower shaft mounted rockers and 3/8 hardened push rods. I modded a Gen4 swing arm oil pickup to use with the Gen4 pan on the Gen3 engine. My block was an 04 but I still used a 05/06 crank to get the beefier snount and crank bolt.
Comp Cams will grind to whatever you desire. I told them solid lifter, 116 LSA for the supercharger. Ended up with a .637/.637 lift. I ran a slightly lower then stock compression I think my pistons were .005 shorter compression height then stock.
I never got any good dyno numbers, I was aiming for 800 on a Mustang dyno. I could never find a reliable tuner and ended up dropping oil pressure so never drove it hard. Car sitting 30 feet away from my house in the street idling, the windows of my house would rattle.
I'm still solid lifter but recently swapped in a Gen4 engine. This setup I'll max the Procharger out at 5700 RPM, I will likely never take the engine past 5500. Again, needs a tune still. It's over built, I don't think I'm going to enjoy this car on the street. Twin disc cluch and billet TOB, only needs about 1" clutch pedal to engage the clutch but it's like 10x heavier pedal than stock. It's so loud, it's louder than the X. On paper, high rev sounds cool but you're gonna miss practical basic Vipering.

I'm not familiar at all with supercharged Viper engine and what type of cam they required, but it seems to me that 0.637'' lift for both in/ex might not be optimal and you're running heavier springs than required (even with ported heads)... Also since your engine runs solid lifter, wouldnt be fun to rev it higher a bit? Say peak power @ 6,200-6,300?

Again: not familiar with SC so I might be wrong and maybe it's the best set-up for your Paxton... My engine project is 100% N/A oriented, there is no way I could put turbos or SC, but then again higher rpm is more important to me than max HP. If I get 750 crank horses @ 6,800 I'll be happy.

[Dan Cragin]

With a 114 LSA the cam it should be tuneable with those numbers. We had issues with the 107-110 LSA cams.
I have found, that unless your heads are really flowing well, the bigger cam does not make more power and
driveabilty suffers.

Gen 4 heads on a Gen 3 motor with the dragpack intake, you can make big power.

[13COBRA]

With a 114 LSA the cam it should be tuneable with those numbers. We had issues with the 107-110 LSA cams.
I have found, that unless your heads are really flowing well, the bigger cam does not make more power and
driveabilty suffers.

Gen 4 heads on a Gen 3 motor with the dragpack intake, you can make big power.


What kind of power??

[Dan Cragin]

The Drag Pack cars made 800hp with unported gen 4 heads.

[13COBRA]

The Drag Pack cars made 800hp with unported gen 4 heads.

Where might one find one of the elusive Drag Pack intakes?

[Dan Cragin]

I think Prefix still has some.

[13COBRA]

I think Prefix still has some.

Emailed, thanks!

[Aevus]

The Drag Pack cars made 800hp with unported gen 4 heads.


Unported gen 4 heads with 2.08'' valve = 312 CFM @ 0.500'' lift and 327 CFM @ 0.600'' lift (passed that it drops)

it's not that far from the numbers I have with my ported gen 3 heads and I kept the 2.02'' valve diameter (for few reasons) so I think my target of 750 crank HP is reasonnable


Edit: Sorry I think the numbers here are with stock valves and the ported one with 2.08'':
http://www.speedstore.ca/VP4_flow_sheet.html

[Aevus]

With a 114 LSA the cam it should be tuneable with those numbers. We had issues with the 107-110 LSA cams.
I have found, that unless your heads are really flowing well, the bigger cam does not make more power and
driveabilty suffers.

Gen 4 heads on a Gen 3 motor with the dragpack intake, you can make big power.


In fact, all in all, there is not that much to gain with a N/A engine. It's basically always between 700 and 800hp (more or less 85hp difference at the wheels) from the ''basic'' Roe Racing's 710R kit to the somewhat extreme dragpack w/gen4 heads you mention. No wonder why big N/A projects are not very popular... I'm doing it for fun but frankly speaking if someones is looking for best bang for the bucks, it's not very good.

[Aevus]

With a 114 LSA the cam it should be tuneable with those numbers. We had issues with the 107-110 LSA cams.

Yeah I wouldnt dare going that tight. 710R cam is 14 deg valve overlap, I'm pushing it to 23 deg on mine, and that's only because I'll have 11.7:1 CR to compensate. And that will require 93-94 oct all the time and dyno-tune

[Aevus]

They couldnt grind exactly what I wanted so that's the cam I'll finally get:

246/256 @ .050
.596/.554
114+4

It leaves some room for timing adjustments (retard by few degrees, if needed) and also for future shaft mount rockers upgrade with 1.75 ratio (again, if needed)

Not sure if the shaft rockers would be that important, since the valvetrain is now very light and spring lift moderate. Also not gonna spin the thing to 7,500rpm... But at least, there is a possible upgrade.

[ILLKING]

How does the drag pack intake compare to the Gen 5 intake?

[Dan Cragin]

The drag pack intake works with the Gen 3 throttle controls and engine controller, but allows you to use Gen 4-5 heads. It has a much larger upper plenum than
the factory Gen 3 intake, as well as provisions to get more air to the rear cylinders.

[ILLKING]

Going with Gen 5 heads on a 9L gen 2 block. I do have a gen 5 intake in possession, but wonder if it'd be worth it to go with the drag pak instead. Sorry for going off topic

[Dan Cragin]

I'm doing the same thing on a Gen 2 currently, but we are using electronic throttle bodies and a Motec. Much more complicated.
You can use Mechanical throttle bodies on the Gen 5 intake as well. That would be the best my second choice.

[SRT_BluByU]

Doesnt AZ Viper spin his 9L to 7k?

[TKO MOTORSPORTS TEAM]

ITB is the way to go, unfortunately not cheap, but super easy to work with and pretty dang economical when you calc dollar per HP and reliability gain.

[Cody's Car Conundrum]

Doesnt AZ Viper spin his 9L to 7k?

Indeed he does:

https://youtu.be/D345w6UCCEU?t=520

(if it doesn't skip then go to 8 minutes and 40 seconds)

[Aevus]

A little update on my ''high-rpm'' project:

as mentionned above I went with a cam that is about the maximum possible -just before it makes no sense- and it's a very tight fit:

10.9:1 compression was the max possible with valve clearance.
256 @ 0.050'' exhaust duration is also a challenge for valve clearance.

The somewhat limited exhaust lift (0.554'') for such an agressive cam is actually a bet we did: Less strain on the valvetrain, better clearance for higher compression, lots of duration, all for peak power target between 6,700 and 6,900 rpm.

Luckily, my ported Gen 3 heads flows extremely good on the exhaust side: 241 CFM @ max lift but more importantly, it flows better than a stock Gen 4 heads all across the board. Heat-wrapped headers will probably help the scavenging as well.

On the intake side, they deliver 315 CFM @ max lift (0.596'') which is short of about 10 CFM from stock Gen 4 heads and short of about 15-20CFM from 0.400-0.500'' lift. Not yet sure if the cam will max out the intake flow yet... If so, I always have the possibility to put shaft mount rocker with higher ratio and get 325 CFM with higher lift.

Unsure which bottleneck gonna hit first at high RPM: hyd lifters ? Camshaft ? Intake side flow ? Valvetrain ? Oil system ? (hope not lol) or even gas pump ?

My bet would be the valvetrain (valve float) and not the heads, even less the cam. But I may be wrong, we'll see...


Basically the whole engine is new, with only the stock crank (machined + balanced of course):

- Forged Mahle/Callies pistons and rods (lighter 4032 alloy)
- 69# injectors
- Ferrea valves competition plus
- Conical springs
- Titanium retainers
- 3/8 0.080'' pushrods
- Prefix ceramic hyd lifters w/ tru-arc
- Prefix high-volume oil rotor
- Fidenza aluminum flywheel
- M&M heat wrapped headers
- 3.5'' exhaust
- Hiflow cats

Pretty much the max I could do for a high-rpm non-destroked NA project, besides titanium valves and shaft mount rocker with even bigger pushrods. At some point, you really have to worry about the stock crank, oil system, fueling system, cooling system, transmission, etc.. it never ends and the law of diminishing returns kicks hard. Lots of risks, time and money for few extra HP... Not worth it I think.

52249

I'd like to reach the 800 crank ponies mark but I'd be very happy with anything north of 750 (or 650-ish whp) ... We'll see after the dyno tune! Will have the car fully ready in about a week, after over a year of wait.

[13COBRA]

I feel like that took a lot of time, energy and money for hopefully 650 rwhp.

[Aevus]

I feel like that took a lot of time, energy and money for hopefully 650 rwhp.

That's for sure, no doubt.

For someone who's chasing HP, N/A projects are no good at all.

My end goal was not absolute max HP, obviously (would have taken the FI road) but a combination of engine sound, throttle response, higher rpm feel, etc...

Also, I don't feel that a Viper (without traction control) is a good platform for anything with more that 700whp. Even with all the mods I made in the suspension/chassis.

Bottomline, I probably would not have more fun with a 1000hp gen 3 Viper.


Also, 650whp is the minimum I wish for. But since 700whp is about the maximum possible, we're talking 50whp difference, nothing that will stop me sleeping at night...

[13COBRA]

That's for sure, no doubt.

For someone who's chasing HP, N/A projects are no good at all.

My end goal was not absolute max HP, obviously (would have taken the FI road) but a combination of engine sound, throttle response, higher rpm feel, etc...

Also, I don't feel that a Viper (without traction control) is a good platform for anything with more that 700whp. Even with all the mods I made in the suspension/chassis.

Bottomline, I probably would not have more fun with a 1000hp gen 3 Viper.


Also, 650whp is the minimum I wish for. But since 700whp is about the maximum possible, we're talking 50whp difference, nothing that will stop me sleeping at night...


Yeah I hear you. I did heads, cam, intake, throttle body last winter. Put me at 630/617.

[Aevus]

Put me at 630/617.

peak HP 5,900-6,100rpm?

[13COBRA]

peak HP 5,900-6,100rpm?

5225152251

[Aevus]

Yes exactly what I thought.

I planned something more peaky, that's why I can wish for 700whp.

Already installed 4.10 gears because I know I'll lose low-end torque. In fact I HOPE I'll lose some low-end torque, otherwise I'll be in trouble...

[13COBRA]

Yes exactly what I thought.

I planned something more peaky, that's why I can wish for 700whp.

Already installed 4.10 gears because I know I'll lose low-end torque. In fact I HOPE I'll lose some low-end torque, otherwise I'll be in trouble...

What are you wanting to do with it?

[Aevus]

Street, no track

[Dan Cragin]

Are you tuning the stock JTEC engine controller, if so, what software?

[Aevus]

Are you tuning the stock JTEC engine controller, if so, what software?

Stock, yes. Hopefully it will be enough...

Torrie from Unleashed will do the dyno tune

[Aevus]

I guess the last possible upgrade (summer 2023 maybe) would be:

- Shaft mount rockers
- 3/8 pushrods w/0.130''walls
- tuned custom exhaust for better scavenging
- Accusump system

Right now I wish for at least 520 torque @ 6,600 rpm which equals to 653 whp
if I can spin it to 7,000rpm while keeping the torque at 510, I'll get 680whp.

But then again, which bottleneck will show up first: heads (intake air flow) or worst, the crankshaft...

Just thinking outloud lol

[Aevus]

Not properly tune yet, not enough time before winter, but it gives an idea:

https://www.youtube.com/watch?v=EzaxOlgPFj4

sound from the inside:

https://www.youtube.com/watch?v=iXsvjgdPmKc

It's much much louder in person, obviously.
Videos do not justice of how it feels... I'll have to modify the exhaust, no doubt.