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 --- DONE
2. send heads to local racing engine machine shop for reconditioning-guides,grind,etc. --- DONE
3. send crankshaft and rods to machine shop for reconditioning and microfinishing --- DONE
4. send cams to Webcams for regrind to 20/21 - and maybe rockers for recondition --- DONE (rockers OK replaced 1)
5. replace with JE 12.5CR 102MM piston set ---- DONE
6. replace with ARP rod bolts ----DONE
7. replace with EBS racing valve springs --- DONE
8. replace head studs ----DONE
9. replace rod, main and IS bearings --- DONE
10. replace flywheel with Patrick 964/915 custom conversion ---DONE
11. replace front pulley with single belt --- DONE
12. clean and flush case and valve carrier oil passages ----DONE
13. reassemble by Porsche Indi shop --- doing
14. wiring conversion by Indi shop --- DONE
15. use existing 915 custom built and geared transmission - rebuilt last year -- DONE but changed 5th to 0.82 Stock
16. use existing custom 1.75" header system ---DONE
17. use 964 stock intake and DME --- Replaced Intake manifolds x6 --- DONE
18. when conversion to 3.6 is complete take car to Steve Wong for dyno custom chips --- NEXT

I will be posting this thread on several different places for feedback.
Here: https://rennlist.com/forums/racing-a...-approach.html

Thank you for your time to respond.

Sincerely,
Roy Turner
Phoenix, AZ

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

Steve Weiner-Rennsport Systems

Roy,

Don't forget to add an additional oil cooler, given your climate. For maximum durability & performance, you really want to maintain 185 deg F oil temps.

More power = more heat.

Marc Shaw

What about ARP headstuds and a GT3 oil pump for reliabilty?

Marc

Sboxin

Marc,

Thank you for your input.

Head Studs:

Yes, we plan to replace the head studs, but haven't decided on which ones yet.
Because this is a race engine it may see several rebuilds and the ARP may be well worth the investment.

Oil pump:
I have read the switch to a GT3 pump would be helpful -- but that is big bucks.
The 993 pump is a step up because of the pressure needed for the lifters and that may be an option. But, I have also read that the 964 actually puts out a good flow and pressure for the 3.6 engine. It is still possible the an oil flow/high temp situation may have caused the #5 rod bearing excess wear -- but, it is more likely looking at the general condition of this engine that poor maintenance or rough driving is more likely the cause.

We do have a separate race oil cooler on the UPS race car to handle the 3.6 needs.

Thanks again for your help,
Regards

Sboxin

Steve,

Thank you for your input.

Yes, we have an existing front oil cooler and the 3.2 stays very cool -- even in the 100 degree temps we have here in Arizona (although we really don't race in the mid day summer heat and only very short sprints in the morning).

An upgrade to a GT3 or 993 oil pump is still on the list of unanswered questions --- what do you think for <6500RPM and mild cams and 12.5CR pistons?? I think we are border line on this upgrade -- however, we do use Amsoil race oil and change regularly with very little degradation.

Thanks again,
Regards,

Steve Weiner-Rennsport Systems

You are quite welcome.

Don't forget, a 12.5:1 3.6 runs considerable hotter than a 3.2 so keep a close eye on running temps.

A 993 pump is the same as the 964 one, but a GT-3R one is a nice upgrade. They differ in scavenge capacity and thats something that helps keep the engine cooler when continuously running above 6K RPM.

mfyoung1086

Is the car even driven in the summer months? Road racing season in AZ usually ends what April, May? Ambient temps usually in the 90's by the last races of the season I would believe

Sboxin

EDIT/UPDATE: Not racing on June 3 ---too close to Grandbaby due date...
You are almost correct --- we will be racing at 0825 on June 3 at Firebird East track in a 30 minute sprint -- then there is a lay off until August which is a night event...the main thing is to not idle the race car on grid...and make sure the Cool Shirt box is ice cold and make sure the friend with the RV and AC is at the track for personal comfort...

This is the NASA event info -- stop by the trailer and say Hi
http://forums.nasaaz.com/showthread.php?t=5062

I am thinking now would be a good time to refresh or upgrade the front racing oil cooler...all good things to consider

Thanks

Sboxin

6-13-2012 Progress report

Cylinders back from EBS along with new JE 102MM 12.5:1 pistons , rings & light weight pins, ARP rod bolts, steel head studs, and EBS race valve springs

Cams sent to Webcams for 20-21 grind and cut off power steering piece (?)

Parts to local speed engine machine shop: recondition heads with new exhaust valve guides and 3 cut valve seats, recondition rods, check and polish crank; balance crank, rods and pistons.

Thanks to Don Jackson Enterprise in Phoenix for the Excellent technical assistance and future engine assembly.

Thanks to Don at EBS for your excellent service!

This is a slow process -- but we have plenty of time -- Granddaughter born this past Monday so driver will be out of the car for a bit...

VR6-er

Looking good Roy, what BHP do you think you'll get from this? If you don't mind me asking, what was the cost of the cylinders refinishing and pistons?

Sboxin

VR6-er

Thanks -- we are looking at 248RWHP to stay in NASA PTA class
We need the torque to be up around 230+
When we have Steve Wong do a dyno tune later this year we'll see what the maximum HP might be.
Cylinders and pistons ~ 2K (the cylinders were out of spec anyway)

Regards,

FeralComprehension

Wow, that seems really reasonable.

Sboxin

7-05-2012 Progress Report

Heads, rods and crankshaft done and balanced.

However, there is a very, very small pothole on the #5 rod journal in the center near the oil hole - it is about half a pin head in size. This is the rod bearing that had the damage. The journals measure spec -- no wear.

We have about decided to not turn the crank and run as is. I don't have a picture - but it is so small I'm not sure you can see it anyway. As insurance we can send oil to the lab and keep an eye on the bearing wear.

This will be a race engine - but limited to 6200-6500RPM with most running between 3K and 6K.

Your feedback on this crankshaft issue is appreciated.

Regards,
_________

Sboxin

7-21-2012 Status Update

Parts cleaning and starting assembly - thanks to the Don Jackson Enterprise Porsche shop in Phoenix - and Roland doing the work.
http://www.donjacksonent.com/

A few pics to help see what is being done...
Reconditioned Rods on polished and magnafluxed crankshaft (all balanced) --
New valves and EBS racing springs in reconditioned heads and cam carrier on heads --
Clean cases --

Regards,

Rocket Rob

I'm in the middle of rebuilding my engine. Loving the discussion and photos. Please keep them coming. Thx.