3.6RSR Build / Design by Drive One Motors Progress Images

[Driveonemotors]

3.6RSR Build / Design by CarlosDaSilva Progress Images. My build is coming to a close, here are some progress images and specs.

Original LB '90 964 as shown when purchased.
Modifications included:

11.5:1 JE Pistons

RSR Sprint Cams:
Duration @ 1mm =278/267
Duration @ .50”=272/262
Valve Lift=470” / 450”
Lope Separation Angle= 101
Overlap Setting=6.2mm

APR Rodbolts, J&R Springs
993 Crankshaft
Rothsport Racing Low Butterfly ITB's 47MM
Clewett Crank Pulley with Magnetic Sensor (COP)
Megasquirt 3x ECU with custom harness
COP, 12 Coils
Headers 1.75' by Knight Racing
Patrick Motorsports Lightweight flywheel
Sachs Power Clutch
GT3 Supersprint Stainless Muffler

Special Thanks to a few 911 friends,

Dave @ TRE for the beautiful engine shroud kit
William @ Knight Racing for the ITB Hookup, trick headers and consultation
Paul @ Rothsport for the sweet billet machined linkage and horns to finish it off
Al @ X-Factory for getting it on the stand for tuning and wiring up the harness

[winders]

Cool build…

Street car? Is that compression a bit high for pump gas?

What kind of power are you getting?

[Driveonemotors]

Thanks. Yes, street Hotrod. No dyno yet but the power should come in at between 330-350hp at crank. Will need some additive at full up with 92 octane. Carlos

[Helix8]

Knock sensor?

[Driveonemotors]

Yes.

[mikedsilva]

Awesome. Can't wait to see a video of it running

[Driveonemotors]

Thanks Michael, HNY!!

[stanglife]

So is it desirable to run that high of compression IF you have the ability to control timing via knock sensors or is it better to run lower compression and then raising timing up to threshold? I'm in between 2 piston choices right now...JE 11.5 and Mahle 10.5 for a 3.8

[Driveonemotors]

Your actual compression will depend on some calculations at assembly. Clipped from another build thread.

JE Pistons Nominal Compression Ratio Calculation

If anyone is curious how JE comes up with their nominal compression ratio - the following example should provide a good feel for it.

JE Piston specs from their website (PORSCHE - PORSCHE 911 (Sport Compact Section) - JE Pistons)



Using the info off of this chart - you can plug the #'s into a compression ratio calculator such as this one: Engine Compression Ratio (CR) Calculator

JE assumes a standard 3.2L engine with the following:

- 95mm bore
- 74.4mm stroke length
- 90cc combustion chamber volume
- .040in / 1.016mm deck height (deck clearance)
- 0mm base gasket (really this is part of the deck height)
- 35.1cc piston dome volume (JE's spec for this piston)

If you plug the above #'s into the calculator - you come up with 9.5 to 1 compression ratio.

Obviously if any of your engine's measurements vary (deck height, combustion chamber volume etc.) - then you will come up with a different compression ratio.

Just tossing this

[stanglife]

Originally Posted by Driveonemotors

Your actual compression will depend on some calculations at assembly. Clipped from another build thread.

JE Pistons Nominal Compression Ratio Calculation

If an

Absolutely. - I've seen that one and a few others. Sorry to derail this otherwise cool build thread Just curious on the compression...as most of the aftermarket 3.8 kits I've come across seem to be 11.4+ - just curious how most people are living with these. Through horse trading and buying deals, I've ended up with most of the stuff I need for a 3.8...but also 11.5 compression. Living in FL, ambient gets really hot. In a previous life, I did a lot of Ford engines and the OEM (especially in the 90s) leaves a lot on the table and going from 8.5 to 9.5 compression was never really a problem. If that's the case with the 3.6 - 3.8 and 10.7 to 11.4 - then maybe this is a non issue. I have 93 here.

PS @driveonemotors - Those numbers are pretty reliable from what I've seen. The constants being stock stroke, known combustion chamber volume of 90cc (964), known bore diameter, known proper deck height of 1mm...of course, these are all "should bes" and need to be confirmed. Dome volume is a big deal and seems to be the biggest variable. If you have ported heads, perhaps another cc will reduce compression .15ish (calculated for 100mm).