Building a 3.4L race motor (starting w/ a 3.6L) - Options?

[jeffstev]

Application: 911 Race Engine rebuild, 3.4L (objective is PCA GT3R race class)
budget: $12,000 (Total)

Starting with:
1996 993 Engine, 3.6L basically stock motor
Bought it with 485 miles on it
Installed Jerry Woods Valve Spring kit, raceware rod bolts
Installed solid rockers in place of hydrolics
motor currently has approx 200 hours on it, and a few overrevs up to about 8000 due to missed shifts so I'm obviously due for a rebuild.

exhaust: headers + phase 9's.
Injection: '92 964 C2 Cup injection w/ Motronic DME, rev limit set at 7500
"The Program" DME piggyback computer system
This injection setup was chosen due to the fact that I had no brain w/ the engine and the VarioRam needed at least a 1996 brain which I could not locate at the time we installed the motor. The system works amazingly well. Jerry Woods installed it, tuned it, and the engine dyno'd at 292hp. I also still have the original VarioRam system which, as it turns out, I could have used with the piggyback unit although the jury is still out on what the benefits would have been had we used that.

Objective is to not go crazy with the rebuild and keept total costs in the $10-12K. Some assumptions I'm making:
- lower the total displacement to 3.4L, increase the hp
- have a solid, reliable at least 50 hour motor
- would like better low-end torque (ie, lower rpm limit)
- I'll be dismantling the motor (as I did previously) and having various jobs farmed out as needed.
- if possible, keep the current injection system. HOWEVER, not sure about the limitations that places on my choice of a decent cam. Significant I suspect.

Lowering the displacement either means new PC's or sleeving the current cylinders and reducing the size of the pistons from 100mm to 97mm. If it's new PC's, my first inclination would be to use a 3.0L crank w/ 70.4 x 100mm JE PC's, carillo rods, new valve springs, flowed heads. doing all that leads me to want a decent cam which points me down the path of a new injection system like 56mm TMWs and an engine mgmt that would serve the purpose like Halltech (sorry, Motec is outside the budget).

so many choices, so little $$!! Any help and advice appreciated in a big way. Oh and any rebuilt 3.4L race motors for sale might even be an option.

Jeff
Bushwacker Racing
http://www.bushwacker-racing.com
jeffs@bushwacker-racing.com

[Brad Roberts]

I thought you where moving ??

I look forward to the PRC party at Thill next weekend.

Sooner or later ScottY will actually introduce us instead of me watching you ride around on your 2 wheel scooter.

I need to show you the POC Orange race group in car video of Scott. I need some outside help with teaching him to pass other cars by setting them up.

B

[Brad Roberts]

Now back to your orginal questions.

Your 70.4 x 100 idea is a great combination based on the 3.6 case, but would require a all new injection setup. This particular combo lends itself to large valves and lots of RPM (which is kinda what you where trying to avoid) GE100 cams and twin plug would make things work nicely. Keep the compression down to 11:1 and the engine will last you the 50 hours your looking for.

The 3.6 case and heads are awesome to start with.

As far as injection goes, there is several "other" computer vendors out there that peform just as well if not better than the Motec. Only problem is: we cant hang out in the pit areas and talk Motec with Walton and gang...LOL

Do a Google search for Autronic. This is the one I plan on using in the silver tube frame 914 next year with the short stroke 3.2 engine. FM wireless tuning (on track) and will handle multiple O2 sensors. Autronic is a company founded by ex Motec employees (literally a town away) Just like the bay area. You will need something that flows some air. Figure on at least 50mm throttle bodies. We have a working prototype for a slide valve injection setup, so... our 50mm complete setup might be available in the next couple of months.

B