Compression Ratio Question

Boss_232

Registered User
I am assembling a n/a 3.8L engine to put into my son's 85 Mustang (building to '95 EFI specs) and have '93 SC rods and pistons to put in. My question is:

Is the lower Compression Ratio in Super Coupes a design of the SC pistons or a design of the SC heads?

How can I figure the compression ratio of the combination of '98 Mustang heads with '93 SC pistons and rods?

I'd like to go ahead and use the SC pistons in case of future forced induction (which will not be a concern of mine. I just want to get this thing assembled as strongly as possible with cost a large consideration. Future mods will be done by sonny boy when he gets his own job!) but I am concerned about the power output while it remains N/A.
 
Is the lower Compression Ratio in Super Coupes a design of the SC pistons or a design of the SC heads?

The SC pistons will yield a noticably lower compression ratio and it will certainly be felt for the time the engine is normally aspirated. Remember, the SC pistons are not forged they are Hyperutectic <~~~spelling. The later pistons (94-95) are slightly higher compression ratio than the early units, but still notably lower than you will desire. I do not recall if they are still available, however I would consider looking into some TRW forged slugs as an economical solution for your needs. You may need to have some of the piston machined down to achieve the proper installed deck height, but will still be ahead of the game money wise.
If you have a bit of a budget (relative term), then consider a different router all together and go for some H beam rods with forged custom slugs like those which will be available in an upcoming group buy beginning this weekend. Watch the Group purchase forum for details.

How can I figure the compression ratio of the combination of '98 Mustang heads with '93 SC pistons and rods?
The following link should aid you in your calculation needs:
http://www.virtualengine2000.com/VirtualEngineCalculatorTour.htm

Paul
 
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