3.2 to 3.4 low on power - help me find the way

[infraredcalvin]

Thank you Neil for taking the time to chime in, I was hoping you would. You've basically hit the nail on the head as to where I'm headed, just taking a bit to sink in...

Had not planned to take it down this far yet, but I get the point in doing so.

I've got the work week to think about it...I'll update where I'm at over next weekend!

[dannobee]

If you know any racing officials in your area, chances are they have access to a Katech "Whistler" that is used to check compression ratio. It's very common in class type oval/road racing. It would save you the hassle of teardown and cc'ing all of the parts. Might be worth a shot if you know some people.

[roblav]

For the 2nd time, your port sizes of 44 and 42mm are way too big, especially with carbs. Those port sizes are bigger than a 962, 934, and 935! FYI, 40/38 is standard 3.2.

That's likely the cause of your HP spike. The mod S cam (I have the webcam version) is not enough cam for those port sizes. Or, better yet, your port sizes are too big for that mod S cam.

The biggest mistake "would be" race engine builders make is enlarging the ports too much. The engine becomes a dog.

My last word on this topic. Good luck.

[infraredcalvin]

Originally Posted by roblav

For the 2nd time, your port sizes of 44 and 42mm are way too big, especially with carbs. Those port sizes are bigger than a 962, 934, and 935! FYI, 40/38 is standard 3.2.

That's likely the cause of your HP spike. The mod S cam (I have the webcam version) is not enough cam for those port sizes. Or, better yet, your port sizes are too big for that mod S cam.

The biggest mistake "would be" race engine builders make is enlarging the ports too much. The engine becomes a dog.

My last word on this topic. Good luck.

Hearing you. Thanks!

[mikedsilva]

Originally Posted by roblav

For the 2nd time, your port sizes of 44 and 42mm are way too big, especially with carbs. Those port sizes are bigger than a 962, 934, and 935! FYI, 40/38 is standard 3.2.

That's likely the cause of your HP spike. The mod S cam (I have the webcam version) is not enough cam for those port sizes. Or, better yet, your port sizes are too big for that mod S cam.

The biggest mistake "would be" race engine builders make is enlarging the ports too much. The engine becomes a dog.

My last word on this topic. Good luck.

What would be the 'fix' in this case? or is the only option to replace the heads with stock?

[winders]

Originally Posted by roblav

The biggest mistake "would be" race engine builders make is enlarging the ports too much. The engine becomes a dog.

So my 3.6L engine with 45mm intake ports is a dog?

[roblav]

Originally Posted by winders

So my 3.6L engine with 45mm intake ports is a dog?

You seem to think I'm talking about your engine?? Where did I allude to that? Your inference uses a 10 year old's logic. Get lost.

The OP has a mismatch between displacement, camshaft, induction type, and port size.
Ciao

[winders]

Well, you said that the 44mm intake ports are bigger than what the 962, 935, and 934 had and that biggest mistake builders make is enlarging the ports too much. I have a lowly 3.6L normally aspirated engine.....so I made an inference.

[Neil Harvey]

Infraredcalvin,

I sent you a PM.

Some have good ideas and advice of what it could be, others are TOTALLY sure they are right. I've been building race engines along time and I don't know unless I check. Nothing in this world is always exact. That I am TOTALLY sure of!!!

[KNIGHTRACE]

I am glad to help if you have not found a solution. It looks pretty easy to me. William Knight 615.969.4917

[winders]

Yeah, call William. His has only built a bunch of engines like this....

[Jeff Alton]

Wow, another bun fight.....

Infraredcalvin, Talk with Neil and talk with William. But do report back. They have plenty of experience. Pay little attention to those interjecting their own builds that have very little (at best) to do with yours.

Cheers

[KNIGHTRACE]

I have done more 3.0 engines with 120/104 than any other combination. I am not a fan of the cam But average HP with big port 3.0 heads, 10.5:1, 46 webber at the wheels is about 271 hp average. The last one I did was for Claus Nielsen for the GT4 TWS annual race. He won GT3 and GT4 with it. This is pretty easy to see what is happening, glad to help if he calls 615.969.4917 William Knight

[Classic 911]

Originally Posted by KNIGHTRACE

I have done more 3.0 engines with 120/104 than any other combination. I am not a fan of the cam But average HP with big port 3.0 heads, 10.5:1, 46 webber at the wheels is about 271 hp average. The last one I did was for Claus Nielsen for the GT4 TWS annual race. He won GT3 and GT4 with it. This is pretty easy to see what is happening, glad to help if he calls 615.969.4917 William Knight

How do you measure the power at the wheels? Tires on rolling road dyno or hub dyno?
A power output like yours, using the 120/104 cam who’s all done around 6600-6700rpm, in a configuration like that seems very optimistic.
More realistic numbers would be 230 - 240hp measured at the hubs.
Cheers

[winders]

I would trust what William says.

I have a 3.6L race engine he designed that, on the same dyno the OP used, made 369 HP at the wheels. It made 368 hp while being tuned on a hub dyno in Paso Robles too.

You probably think those numbers are optimistic too…but those guys with big dollar 3.8L and 3.94L race engines my car pulls on straights when my car has more aero drag don’t think so…

William is the real deal and does not need to be optimistic with his numbers…

[Classic 911]

By all means I did not mean any negative, it is just that the 120/104 cam is all done around 6600-6700-6800 (in regards to max hp), and with the large ports heads (unmodified?) from the 3.0(39mm intake, 35mm exhaust) and 46mm carbs it is just so much air one can get into the combustion chambers in a 3.0 NA engine that it is quite optimistic to get actual power beyond 230-240hp at the hubs.
Thats why I asked what kind of dyno that was/is used to measure the power.

We all know that there are large variations from dyno to dyno and even on the same dyno from day to day.

To clarify a little: I have many hours experience with an engine using the 120/104 cam, on a ROTOTEST 1005 hubdyno.

Total enginespec:
3.0SC engine case, boattailed
Large ports 3.0 heads ( unmodified, 39mm intake, 35mm exhaust)
3.2 98mm RSR Mahle Racing piston/cylinder 10.3:1 cr
120/104 camshafts
46mm PMO ITB’s
Full sequential ecu
Twin spark
39mm Eisenmann headers
Eisenmann muffler, specially customized for optimized scavenging

This engine has been dynoed also using smaller headers. That gave a bit less hp (238) and a bit more torque (346,5Nm)

Result: 242,3hp and 285.9Nm at the hubs.

[winders]

William has 30 years of experience building engines, architecting engines, designing cams, etc. He is the real deal. If he says it, you can believe it.

[Classic 911]

Originally Posted by winders

William has 30 years of experience building engines, architecting engines, designing cams, etc. He is the real deal. If he says it, you can believe it.

In light of us only getting 242,3 and 285,9Nm at the hubs on the 3.2 "RSR" I would really like to know what we are doing wrong, compared to that the 3.0 produces 271whp, so that we could get more from our 3.2.

271whp = 318.82bhp given 15% drivetrain loss is almost factory 3.0 RSR territory, and the factory RSR produces 330bhp at 8000rpm.

So when the 120/104 cam produces max hp at 6600-6800, at best at 7000, then there are somethings that not ad up given the physics involved.


But if we say ok it is a fact that the 3.0 really produces 271whp, then our 3.2 should be able to produce 289whp if we compare CC for CC.

100% honest, I would pay a large amount of money if the person that built the 3.0 would send me the data on how to do it.

Here’s a 3.2 "RSR" engine to compare with, 282bhp and 313Nm /231 ft lbf, rebuilt by AASE Motors:

https://bringatrailer.com/listing/1974-porsche-911-35/

[KNIGHTRACE]

Classic 911..... First of all I NEVER said anyone was doing anything wrong. I do not do drama. Claus 3.0 with 120/104 was done at TWS on a mustang dynojet and made 271 hp. at the wheels. back to the subject. A decent pump gas motors should make 100 hp per liter. I usually get 120 hp per liter or more on my race engines. We also should not look at the past as a future guide of what is possible. Winders 3.6 motor makes considerably more power factory 3.8 RSR engine. I have done quite a few CIS 3.0 motors with 9.8:1 pistons and an M1 camshaft that make 230's at the wheels. Obviously there is more in those mid 230 hp than just cams but cams alone usually gets 220's at the wheels. The 3.0 RSR motor actually made about 360 hp when it was reworked with different cams. Also Winders thank you for the support. I sincerely like to help people when I can it is rewarding. William Knight

[infraredcalvin]

I posted this question here to gain a few insights and ideas I hadn't thought of, man you all didn't disappoint! Thanks to all that took their time to help. I had a chance to discuss with both Neil and William, I truly appreciate their willingness to share their expertise with me, I believe they are both true assets to the forum, special thanks.

The biggest culprit here has been the unknown specifications of the original build. While I was hoping to find a simple mistake in timing or tune by the PO, it turns out that I just may have a well running engine with a completely wrong combo of internals (and externals).

I still have a few items you all have suggested I check out, but at this point funds do not allow me to dive further into engine disassembly for some of the more critical measurements, as most likely heads, cams, and/or P&Cs replacements would be necessary to maximize the combo, and I prefer to do that only once, when funds permit.

Until then, she's going back together so I can run her and continue to refine my driving and the car setup. I'm sure there are still some ponies to extract from carb tuning, I'll post the afr logs as I'm working through them.