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914World.com _ 914World Garage _ 2056 D Jet Stock cam

Posted by: DavidSweden Jan 5 2021, 04:49 PM

What is the recommended compression ratio for 2056 with D jet & stock cam?

Thanks in advance

Posted by: Mark Henry Jan 6 2021, 09:52 AM

ROW 914 IIRC was 8.0:1CR, I wouldn't run a whole lot higher with a stock cam.
WEB73 some have run as high as 9.0:1CR, but I'd be a bit more conservative say 8.5 to 8.7:1CR.

Big duration cams can run higher CR, but won't work with stock FI.

Posted by: VaccaRabite Jan 6 2021, 03:52 PM

Very much agree with what Mark said. Keep it stock or near stock. A slight bump is fine (say by not using the head gasket) but going above 8.7:1 is going to cause issues.

Zach

Posted by: porschetub Jan 6 2021, 04:24 PM

QUOTE(VaccaRabite @ Jan 7 2021, 10:52 AM)

Very much agree with what Mark said. Keep it stock or near stock. A slight bump is fine (say by not using the head gasket) but going above 8.7:1 is going to cause issues.

Zach

my last build used NOS 411 high comp pistons on carbs I was happy to dial in just over 8:6-1 as a safe margin ,IMO its about keeping max engine temps @ a managed level and that hard with a T4 @ the best of times,higher compression is a trade of for long time reliability unless you run a modern fuel system etc.

Posted by: 914Sixer Jan 7 2021, 02:30 PM

I used a custom grind Elgin 330-1 camshaft Slightly higher than stock for 2056 but good for FI. Kept compression 8 to 1.

Posted by: sjhenry1075 Jul 14 2022, 01:10 PM

QUOTE(914Sixer @ Jan 7 2021, 04:30 PM)

I used a custom grind Elgin 330-1 camshaft Slightly higher than stock for 2056 but good for FI. Kept compression 8 to 1.

What kind of performance gains did you get? Is it noticeable? What was it before?