my NA Project 800 hp 7000 rpm roadster

[Aevus]

Before anything else, I'll start to work on the breathing part of the car:

- Throttle body (single blade?)
- Bigger/more efficient air filters (if any)
- Intake manifold porting

Then, maybe the bottleneck comes from the exhaust...

Finally, it may be the camshaft itself. Advanced 4deg vs retarded 4deg that's 400 rpm right there

[Old School]

You can log your MAP reading vs RPM to see if there is a pressure drop at higher RPM. This would indicate a restriction in the air filter or throttle body.

[heath1225]

Before anything else, I'll start to work on the breathing part of the car:

- Throttle body (single blade?)
- Bigger/more efficient air filters (if any)
- Intake manifold porting

Then, maybe the bottleneck comes from the exhaust...

Finally, it may be the camshaft itself. Advanced 4deg vs retarded 4deg that's 400 rpm right there

Maybe the Gen 3 heads could factor into it?

[13COBRA]

Here's my dyno... solid line was baseline, and dotted line was after cam, ported heads and throttle body...on pump gas.

Anderson Comp Coupe Compare Graph-2022-03-02-08-36-19.jpg

On 100 octane and after break-in (slightly warmer weather too...about 15 degrees.:

259713 (1).jpg


Cam specs:

188313.jpeg

[T/A KID]

just calculated 60-130

3,900rpm 3rd gear @ 60mph
6,516 rpm 4th gear @ 130mph

Should work very well

They mean how fast it does 60-130 lol

[Aevus]

They mean how fast it does 60-130 lol

LOL

I know that T/A kid, just meant I'm right in the powerband and my valvetrain can take the beating of 6500rpm

:-)


also means only 1 shift.
remember I have 4.10 gears, shifting comes pretty often

[Aevus]

Here's my dyno... solid line was baseline, and dotted line was after cam, ported heads and throttle body...on pump gas.

Anderson Comp Coupe Compare Graph-2022-03-02-08-36-19.jpg

On 100 octane and after break-in (slightly warmer weather too...about 15 degrees.:

259713 (1).jpg


Cam specs:

188313.jpeg

13COBRA, thanks for the info

yeah, that's the kind of dyno I would expect from a 11.5 deg overlap like you have

[Old School]

On 100 octane and after break-in (slightly warmer weather too...about 15 degrees.:

259713 (1).jpg

The graph on this one looks like max RPM was ~5800?

[13COBRA]

The graph on this one looks like max RPM was ~5800?

He didn't send me the full print out, just stopped where it was the maximum. At this one, we weren't tuning it..but were tuning the paddle shifters, and I asked him to give it one rip.

[Aevus]

13COBRA, can you share more details on your build?

[13COBRA]

13COBRA, can you share more details on your build?

Just a 8.3L with the above cam, ported heads/intake and a Roe throttle body.

[Aevus]

thats very good numbers, congrats

I'm starting to wonder if my 4.10 gears are not distorting my dyno numbers a bit more than the 3-4% they say


edit: Roe TB is the single blade, right? That and the ported intake... Uhmm food for thoughts. Maybe that's exactly what my recipe is missing

[Aevus]

Maybe the easiest way to nail down the problem I have is to make some tests with ethanol, simply because there is 35% oxygen content in it. In theory, if my car doesnt breath enough, ethanol should help that.

If it doesnt help, then it's the camshaft.

[13COBRA]

thats very good numbers, congrats

I'm starting to wonder if my 4.10 gears are not distorting my dyno numbers a bit more than the 3-4% they say


edit: Roe TB is the single blade, right? That and the ported intake... Uhmm food for thoughts. Maybe that's exactly what my recipe is missing

It is a single blade.

[heath1225]

Was the baseline stock?

[13COBRA]

Was the baseline stock?

Yes. Sealed World Challenge motor.

EDIT: I say stock... but it has the optional VCC headers.

EDIT: The car has always ran strong. When I first got it, it was about 50 rwhp than I was expecting.

20200722_122005.jpg

[Old School]

thats very good numbers, congrats

I'm starting to wonder if my 4.10 gears are not distorting my dyno numbers a bit more than the 3-4% they say


edit: Roe TB is the single blade, right? That and the ported intake... Uhmm food for thoughts. Maybe that's exactly what my recipe is missing

What was your AFR on the dyno?

[Aevus]

What was your AFR on the dyno?

the dyno guy had problems with SCT that day, I'm trying to get the info

[Aevus]

Discussed with few people about the dyno numbers I got and the build in general, and I had various answers:

- ported heads maxed out
- throttle body maxed out
- intake manifold maxed out
- cam timing way too advanced

Can't do much about the heads, unless I put a shaft mount rockers with different ratio to get more lift but that would be downright stupid if I'm already 800rpm away of any valve float issues... Not to mention I'm less than 10 CFM of the max

Cam timing is a hell of a job, for an engine we just installed...

So what's left is TB and manifold.

Also, maybe the breathing problem comes (as well) from the exhaust system.

[13COBRA]

Throttle body and intake is a no-brainer.

[Aevus]

Throttle body and intake is a no-brainer.

yeah I'll start with that. Hopefully I'll be able to get a Roe single blade TB, because they're bankrupted...

[Aevus]

it seems like I'm complaining about my car, not doing high RPM as I wished, but really the car is a blast to drive. Pure joy from A to Z. Penske double + Hyperco springs make the whole thing even better, I'm very happy.

In fact, I cannot imagine being able to sell that car.
Yes, there is tons of ''better'' cars out there; Porsches, Mclaren, etc... Engineering gems, no doubt (and I do love that), but that gen 3 heavily modified Viper roadster is the car that gave me the most thrill and general enjoyment in my life. It's fun on idle, it's fune cruising it on the highway, it's fun with the top up or down, it's fun on straight acceleration, it's fun in twisty roads...

So yeah, the high-RPM thing won't stop me sleeping at night.

That being said, I'll try to fix it anyway. That's part of the fun as well, isnt it?

[J TNT]

I Think it's awesome that you wrench on and drive your car , I've always found doing both to be a Zen for myself .
Well Done !

it seems like I'm complaining about my car, not doing high RPM as I wished, but really the car is a blast to drive. Pure joy from A to Z. Penske double + Hyperco springs make the whole thing even better, I'm very happy.

In fact, I cannot imagine being able to sell that car.
Yes, there is tons of ''better'' cars out there; Porsches, Mclaren, etc... Engineering gems, no doubt (and I do love that), but that gen 3 heavily modified Viper roadster is the car that gave me the most thrill and general enjoyment in my life. It's fun on idle, it's fune cruising it on the highway, it's fun with the top up or down, it's fun on straight acceleration, it's fun in twisty roads...

So yeah, the high-RPM thing won't stop me sleeping at night.

That being said, I'll try to fix it anyway. That's part of the fun as well, isnt it?

[Aevus]

I Think it's awesome that you wrench on and drive your car , I've always found doing both to be a Zen for myself .
Well Done !

Thanks!

[Aevus]

After few days and 500 miles, here are my observations:


- My new engine will run on alcohol. Too late now, the snake tasted it and liked it. How much? We'll see. E30 probably, but E45 tune is coming...

- The camshaft makes the car sluggish between idle and about 2,200 rpm. Normal for a big cam and not a big deal, except for one thing that I forgot: cruising on the highway in 6th gear. Fortunately, I have 4.10 gears. Otherwise, I would only use the 5th. Maybe a tune will help, maybe higher % of ethanol will help too. But the thing is, I probably can't think of retarding the cam timing until I fix that problem.

- Everything points out to breathing beeing the bottleneck on my project, so next mods will look like: (ported) single blade TB, (ported) intake manifold, spacers on both TB and manifold. Also I'll try to find some improvement for the air filters...

- Next, maybe a new exhaust system. 3.25'' diameter (or back to 3.5'') with 5.5'' or 6'' muffler can, as long as possible (32-36''), with better packing. Basically: more flow without being louder than it is now. And while at it, probably all made in Titanium to save weight.

- Then, if breathing and exhaust potential are maxed out, then I'll order a lightweight shaft mount rockers with ratios as high as possible to get the last few CFMs I can from my heads...

- Finally, if the car's not sluggish anymore at low rpm, I'll retard the cam 4 or 6 degrees.


That's basically all I can think of at the moment. Hopefully all that can bring the engine to 670-680 whp