What really limits our engines to rev higher

[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:


(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.

IMG_5654.jpeg

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?

Anderson Comp Coupe Final Graph-2022-03-02-08-27-19.jpgAnderson Comp Coupe Final Graph-2022-03-02-08-27-19.jpg

[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.