993 Piston upgrade on race car

[rsrdave]

Looks like my standard 993 eninge with standard 993 pistons are worn on my 911SC racec ,running on 50mm PMO's with slightly more aggressive cam you can run with standard pistons .

Question -as I am now facing engine out with the view of new P/C what do you guys believe is a good option ,bearing in mind i am still running 915 close ratio box.

Is is easy to turn into 3.8 ? or can you buy more race style 3.6 pistons ?

look forward to great advice cheers Dave

[BimmerDob]

Check in with the guys at EBC on some options. Also rennlist 993 forum may have more "viewers".

[rsrdave]

thank you for info

[JV911SYDNEY]

Originally Posted by rsrdave

Is is easy to turn into 3.8 ? or can you buy more race style 3.6 pistons ?

Easy? Yes. Cheap? No

3.8 pistons and cylinders start at $5k

The less expensive option is to get higher compression 3.6 pistons i.e. JEs, assuming the cylinders are ok

You might also want to run more aggressive cams, which the new pistons would allow, RS valves, ported heads and have carbs rejetted and tuned.

All depends on your budget, what can be reused and possible racing regulations. Get a good engine builder to put together a package so the new parts compliment each other. You can have all top dollar parts but if they don't work together you won't make the power or have max reliability and drivability

[Sboxin]

Originally Posted by rsrdave

Looks like my standard 993 eninge with standard 993 pistons are worn on my 911SC racec ,running on 50mm PMO's with slightly more aggressive cam you can run with standard pistons .

Question -as I am now facing engine out with the view of new P/C what do you guys believe is a good option ,bearing in mind i am still running 915 close ratio box.

Is is easy to turn into 3.8 ? or can you buy more race style 3.6 pistons ?

look forward to great advice cheers Dave

We did a 3.6 to 3.8 and found EBS Porsche Racing Parts : Engine Performance Parts : Brake Parts : Used Porsche 356 : 911 : 912 : 914 : 944 : Porsche Boxster Parts : EBS Racing Inc. in Nevada to be very helpful.
They reconditioned our cylinders and made them 3.8.
We bought JE 3.8 12.5:1 pistons from them and their own valve springs.
The engine runs great. But . . . we had to do a 915 rebuild shortly after . . . LOL!

You have lots of options . . . and there is plenty of Forum info on this upgrade . . .

Regards,

[txhokie4life]

Quote de rsrdave

Looks like my standard 993 eninge with standard 993 pistons are worn on my 911SC racec ,running on 50mm PMO's with slightly more aggressive cam you can run with standard pistons .



Question -as I am now facing engine out with the view of new P/C what do you guys believe is a good option ,bearing in mind i am still running 915 close ratio box.



Is is easy to turn into 3.8 ? or can you buy more race style 3.6 pistons ?



look forward to great advice cheers Dave

We did a 3.6 to 3.8 and found EBS Porsche Racing Parts : Engine Performance Parts : Brake Parts : Used Porsche 356 : 911 : 912 : 914 : 944 : Porsche Boxster Parts : EBS Racing Inc. in Nevada to be very helpful.

They reconditioned our cylinders and made them 3.8.

We bought JE 3.8 12.5:1 pistons from them and their own valve springs.

The engine runs great. But . . . we had to do a 915 rebuild shortly after . . . LOL!



You have lots of options . . . and there is plenty of Forum info on this upgrade . . .



Regards,

Are you able to run pump gas with the 12.5 CR?
What cams did you use?
Thx,

Mike

[Sboxin]

Originally Posted by txhokie4life

Are you able to run pump gas with the 12.5 CR?
What cams did you use?
Thx,

Mike

Mike,

We have been running 100 unleaded more to cool the heads than for power - same when we had the stock 3.2L in the car. The 3.8 12.5 engine was tuned by Steve Wong
on the dyno while using the 100 -- but the 964 engine does have a knock sensor system also. You might be able to run pump 91 - the 964 stock engine I think has 11.5CR (?)

We had the 964 cams reground by WebCams to 20-21 high torque rather than high HP.
Of course we also have a custom exhaust system.

Regards,

[rsrdave]

Thanks Guys for info on upgrade ,looks like i might need to discuss with EBS

[rsrdave]

Hi Roy ,is yours a race engine and were ther any other major upgrades ,i guess rods,valves etc cheers Dave

[Sboxin]

Originally Posted by rsrdave

Hi Roy ,is yours a race engine and were ther any other major upgrades ,i guess rods,valves etc cheers Dave

Dave,

Yes for racing - - a rebuilt 1992 964 engine --
Heads rebuilt but stock with new valves, guides and EBS valve springs
JE 12.5Cr 3.8L pistons from EBS also
Crank and stock Porsche rods and pistons balanced - ARP rod bolts
rockers reconditioned by WebCams
WebCams 20-21 cams regrind from existing cams
Stock 964 intake system - injectors reconditioned to 100%
Race built headers to single out pipe - loud

This is a thread of our build - and a video of cold idle computer settings that was done by Steve Wong
1992 964 Engine rebuild - reasonable approach?

I wouldn't do the 3.6 to 3.8 upgrade except it cost us zero dollars extra from EBS.
They were reconditioning our cylinders anyway and the pistons were the same price as 3.6L. Don't ask what our final cost was - - just an investment in racing - - but
we did get 6K for the 3.2L . . .

Regards,

[rsrdave]

Hey Roy ,
thank you for replying and love you engine and thread .cheers Dave

[txhokie4life]

Originally Posted by Sboxin

Mike,

We have been running 100 unleaded more to cool the heads than for power - same when we had the stock 3.2L in the car. The 3.8 12.5 engine was tuned by Steve Wong
on the dyno while using the 100 -- but the 964 engine does have a knock sensor system also. You might be able to run pump 91 - the 964 stock engine I think has 11.5CR (?)

We had the 964 cams reground by WebCams to 20-21 high torque rather than high HP.
Of course we also have a custom exhaust system.

Regards,

If I build out my 3.8 -- I might tune it for E85 -- getting both effective high octane and extra fuel flow -- and thus head cooling.

I have a motec 48 system on the race car -- no knock sensors.

Mike