High Comp RS Spec

[1972_911T]

In Waynes rebuild book it gives an example of a RS-High comp engine with 9.8:1 compression compared to the 8.5 for the standard RS-spec. How much horse power would this engine produce comapred to the standard RS? Also is twin pluggin essential/adviasable with this motor to use pump gas?

Steve

[MBEngineering]

HI Steve do not forget to tell them it has MFI from a???, cam's???, exhaust, std/converted K-jet heads, and a distributor from a????, with all that on it , it should make around 230-240BHP?

regards mike

[1972_911T]

Originally posted by MBEngineering
HI Steve do not forget to tell them it has MFI from a???, cam's???, exhaust, std/converted K-jet heads, and a distributor from a????, with all that on it , it should make around 230-240BHP?

regards mike

911 E MFI intakes bored to RS spec, converted 911t pump, probably S cams, converted CIS heads and possibly distributor-less ignition if I go with twin plug.

Whats your thoughts on the twin plug mike is it needed with the high comp spec or not worthwhile?

Steve

[MBEngineering]

HI depends on the pistons you select/use.

regards mike

[andyjboy]

I have a high compression 2.7 RS-spec engine in my 911R-inspired car (about to be swapped to my 2.8 twin-plug).

Started off as a 2.4 mfi 911E & was rebuilt using 9.8:1 JE 90mm pistons/Nicasil cylinders & modified mfi (to RS specs), RS distributor, etc.

Twin-plugging is not usually deemed necessary unless your compression ratio is ~ 10.5:1 or higher.

Mine is dynoed at 230bhp & runs fine on pump gas.

[kenikh]

My recollection is that twin plugs are a good idea at anything higher than 9.8:1, not 10.5:1.

By extrapolating from the 170 HP made by a 2 liter MFI S, you can assume that a 2.7 on S cams at the same 9.8:1 should make 229.5, which is exactly what Andy is making! If you want more power, consider a Mod-S or DC44 cam.