Compression ratio for 94 octane ported Steggy

[Oiljunkie]

CR and Boost Ported Eaton 94 octane
Have a question for you boys.

Im in the process of building the engine and car in my Sig. The machine shop told me the other day that the std bore pistons i ordered won't work as the bores need to be cleaned up, and ill have to go with a .020+ piston.

Now i recently found out that i have 94 octane readily available where i drive. Im now contemplating ordering the -5.2 cc diamond pistons instead of going with the -11.5cc pistons. This would put me at roughly 9.4:1CR

However i still need to be able to run 91 octane as a back up, and torco because 94 isn't readily available if i leave the Calgary area.

My pulleys are a 4# lower and I'm trying to trade my 2.76 for a 2.93

thanks Jay

 

[Oiljunkie]

I posted this in the blower bistro but it wasn't getting much action. Just looking to maximize the eaton set up

 

[Wicked46]

You can get away with the CR but you'll need to back off on the timing a bit. You wont maximize that setup on 94 octane. Also, with a -5.2cc dish on a .020 over bore, you should be higher then 9.4:1... My pistons are -6.5cc dish on a .20 over bore and im right at 9.8:1

 

[Oiljunkie]

You can get away with the CR but you'll need to back off on the timing a bit. You wont maximize that setup on 94 octane. Also, with a -5.2cc dish on a .020 over bore, you should be higher then 9.4:1... My pistons are -6.5cc dish on a .20 over bore and im right at 9.8:1

Thanks.
I'm running 01 cobra heads. Compression will be lower then 03/04 cobra heads

 

[Ourobos]

-10.5cc is 9.5:1 FYI, that's what I'm going with.. I'll be running 93 and a tune.. You can get away with whatever compression you want with a good time (which will pull timing as needed).

 

[Oiljunkie]

-10.5cc is 9.5:1 FYI, that's what I'm going with.. I'll be running 93 and a tune.. You can get away with whatever compression you want with a good time (which will pull timing as needed).

Whats your deck height and Top ring dimension.

Right from the Diamond website is says 8.8or 8.7 for 55cc chambers, 01 heads are 54cc