Suggestions for a Dual Purpose Race Engine DE/AX

[nine14cats]

I would like suggested engine configurations that would yield the most power per dollar while providing reliability, let's say 150 -200 hours without a catastrophic failure. This would be a dual purpose engine Driver's Ed/PCA Time Trials and Autocross. This engine is for track use only. No street use.

I have noticed that most people suggest giving as much information as possible to help with suggestions. Here is some background:

I have owned a 914-6 track only car with canti slicks setup up with a 2.7L motor. Motor had head work, reconditioned cylinders, 10.5:1 JE pistons, single plug, Weber 40 IDA's, MSD 6AL, Webcam 120/104's, 1.5 inch headers and phase 9's. 7200RPM redline. With this motor I could run in my local PCA regions and win TTOD at an AX and with the same car go to Buttonwillow and set a Time Trial class lap record. This car has since been sold.

I also own a 911 with Getty 993 bodywork and a 1995 3.6 mated to a G50. Track only again and fast.

I have another 914-6 tub semi-tube frame with Sheridan kit that needs a motor. I am curious about some combo's that I could try.

Here are my specs:

1. Budget = $10K for motor. This includes purchasing a motor as I don't have any core.
2. Induction can be carbs or EFI. What carb size? What Cams?
3. Can be high compression. Will run 100 Octane gas.
4. Open to any displacement but prefer 2.7 through 3.6.
5. Dual Purpose Track and AutoX.
6. Dual Driver. My wife shares my hobby. She can finish top 10 in an AX and also owns a regional Time Trial class lap record. We don't baby the car. It gets used. Hard.
7. Car weighs 2000lbs wet. Don't worry about class. The local PCA region uses a point system. Wherever we end up in points will be our competition. We don't care.
8. Power band can be anywere. We can adapt driving style and regear our transaxles. Just keep in mind dual purpose car DE/AX.
9. 150 to 200 hours of use assuming 2 drivers at events. (Typically 2.5 hours of total runtime during a given day....i.e. five 20 minute sessions per driver times 2 drivers.
10. Car will be running slicks ~23.5x11.5x16 Hoosiers

As a data point, I spent $10K on my 2.7 which included purchase and assembly. It had ~150 hours on it when I sold it.

Thanks in advance for your suggestions.

Bill P.

[nine14cats]

Bump....

[kenikh]

Originally posted by nine14cats
I have owned a 914-6 track only car with canti slicks setup up with a 2.7L motor. Motor had head work, reconditioned cylinders, 10.5:1 JE pistons, single plug, Weber 40 IDA's, MSD 6AL, Webcam 120/104's, 1.5 inch headers and phase 9's. 7200RPM redline. With this motor I could run in my local PCA regions and win TTOD at an AX and with the same car go to Buttonwillow and set a Time Trial class lap record. This car has since been sold. [/B]

With twin plugs and 7R case, this is a street motor that will run a lot longer than 120 hours. Why not build the same motor again on DC40 cams? On 100 octane and single plugs, it should purr for a long time and since 2.7 parts are very common, building one should be one of the cheaper options you could choose. Building the car on Webers will be cheapest, but not the best option for the track and MFI weighs and costs a lot more than Webers. Perhaps PMOs or EFI? All of that said, I'd wait for someone to sell a fully rebuilt 3.2SS if dispalcement isn't an issue.

[Steve@Rennsport]

Bill:

A few thoughts,....

I cannot see how anyone can build a reliable 3.2 race-type motor (or larger) with $10K. IMHO, those terms are mutually exclusive given the need to address certain issues indigenous to those engines.

If thats your budget (including aquisition costs), I'd stick to a good 2.8 or 3.0 and configure it as you did previously. A bigger budget would permit EFI with an ITB intake.

Ultimately, the long-term durability is going to depend on how you drive it,...

[nine14cats]

Thanks guys. This is the type of feedback I am looking for.

I have a question on the DC40 cams. What type of power range characteristics do they have compared to the Webcam 120/104's that I am familiar with?

And no problem with the Weber 40's on a 3.0 liter dual purpose car?

[nine14cats]

another bump....

Will the Weber 40's I have be sufficient for a 2.8 or 3.0 motor?

Thanks,

Bill P.

[Steve@Rennsport]

Bill:

40mm Webers will work just fine on a mild 2.8 to 3.0 depending on what camshaft (RPM range) you choose. If you use something like the DC-40's, you'll be OK.

"S" cams or bigger are happier with 46mm carbs.

[nine14cats]

Hi Steve,

Thanks for the answer, I appreciate it!

Bill P.