1992 964 Engine rebuild - reasonable approach?

[Sboxin]

Hi all, RE: 1992 Porsche 964 Engine Rebuild

Considering we are not looking for high horse power or spending a lot of money, What input would you offer for our project?

Background:
We are in the process of rebuilding a 1992 964 3.6L engine for my son's 1978 911 race car. The car has been running a 3.2L Aase built stock spec engine for about 5 years - it is still very strong and a class winner for 2 years. But, we need more torque and minor HP increase to still be competitive within the NASA PTA Class. Based on our weight HP is limited to 248 RWHP and torque lower than HP.

Findings:
We purchased a used 3.6L and have disassembled it to inspect and measure. The engine had a known leak down test indicating rings - but we also found valve issues in #5 & 6 and #5 rod bearing excess wear. Cylinders are out of tolerance spec also.

Approach:
After discussing the issues with our local Porsche Indi shop and Don at EBS(and researching the Forums) we have decided to:
1. send the cylinders to EBS for refinishing and increase to 102MM
2. send heads to local racing engine machine shop for reconditioning-guides,grind,etc.
3. send crankshaft and rods to machine shop for reconditioning and microfinishing
4. send cams to Webcams for regrind to 20/21 - and maybe rockers for recondition
5. replace with JE 12.5CR 102MM piston set
6. replace with ARP rod bolts
7. replace with EBS racing valve springs
8. replace head studs
9. replace rod, main and IS bearings
10. replace flywheel with Patrick 964/915 custom conversion
11. replace front pulley with single belt
12. clean and flush case and valve carrier oil passages
13. reassemble by Porsche Indi shop
14. wiring conversion by Indi shop
15. use existing 915 custom built and geared transmission - rebuilt last year
16. use existing custom 1.75" header system
17. use 964 stock intake and DME
18. when conversion to 3.6 is complete take car to Steve Wong for dyno custom chips

I will be posting this thread on several different places for feedback.

Thank you for your time to respond.

Sincerely,
Roy Turner
Phoenix, AZ

A picture of the UPS brown Porsche race car ---

[Sboxin]

We are moving onward with the rebuild - here is one of the other threads describing our progress...

1992 964 Engine rebuild - reasonable approach?

It is now time to assemble the 964 with a few new and reconditioned parts -- and bump to a 3.8L in the process...

And, a little teaser of the new pistons...102MM JE 12.5CR..



and a crankshaft with rods bolted onto it...
magnafluxed and polished crank -- reconditioned and balanced(with crank and pistons) rods with ARP bolts



Now, I think I would like to have a true 964 -- maybe RA...anyone got a roller?

Regards,

[Sboxin]

We have finished with the 1992 964 engine rebuild and installation into my Son's 1978 911 SC race car.

The following thread tells the story and has the photos and end result Dyno graphs.
The 964 engine has so far proven to be a very good engine.
We towed the car to California to Sergio Nardi's shop - Game-Face Motorsports in La Habra -- where Steve Wong worked for 5 hours on the Dyno Tune (we had an issue with the throttle cable adjusting nut coming loose and changing the WOT switch activation.
Steve spends a lot of time smoothing the A/F ratio -- there were 28 Dyno runs total.

The bottom line is 270 RWHP and 250+ RWT with JE 102MM 12.5 CR pistons, Webcams 20/21 cams, custom headers and stock 964 intake.

1992 964 Engine rebuild - reasonable approach?

A Photo of the completed engine before installing into the car (Laguna muffler in pic)



Regards,

[gduke2010]

Good job, would like to do my 1985 with 1995 e.6 some day.

Did you replace the valve guides.?

[Sboxin]

Originally Posted by gduke2010

Good job, would like to do my 1985 with 1995 e.6 some day.

Did you replace the valve guides.?

Thanks gduke2010,

Yes, we replaced the valve guides...
The heads went to a machine shop where they replaced the valve guides and recut the valve seats.
Roland, the engine builder, installed all new valves, EBS race springs with TI retainers.

Two things we learned during this process - find a really good engine to do the conversion
(one you don't have to rebuild) and remember what Steve W says...need more
cooling capacity for the 3.6L

[gduke2010]

My engine runs great. Howe er, after 10 years , I'd love to add more power and shorter trans. gearing.. Your heads look great.,