yep, 10.6 is boderline with the cast iron heads. also check out the trick flows 23 degree heads they are aluminum and are affordable.
How much compression on pump gas?
Thread Starter
Instructor
Joined: Nov 2006
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From: Detroit
How much compression on pump gas?
I just got a smoking deal on a 388 stroker from a friend and was planning on putting it in my 86, but I think I may have to swap out the heads. It currently has cast iron vortec heads (64cc) and the compression ratio is 10.6:1 . Is this too much compression for a reliable daily driveable tpi car. The other heads I was looking at were either edelbrock performer rpms (70cc) 9.89:1 comp ration or AFR street 180s (74cc) comp ratio for around 9.51:1 . I am looking at smaller heads because I want to build a killer street engine with tons of low end torque and a max rpm of about 5000. The cam I am planning on using is very mild non roller comp cams #12-239-3 X4262H intake 218 exhaust 226 @.050 and 111° separation. The intake side is now stock tpi that I will eventually have all ported or switch to a super ram and the injectors are 24lb/hr. I am not sure which compression ratio is the best for the street or if any of the heads are much better than the others. This will be a close to daily driver car with a rpm range of about 1000-5000rpm. Thanks
Burning Brakes
Joined: Oct 2006
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The only one that could be a problem is the 10.6 with cast iorn you should be alright but that is about the limit for cast iorn heads. Aluminum disapates heat better and allows for a cooler combustion chamber. I would opt for aluminum heads and bump the compresson to 11.0-11.6
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
If the engine was built with good quench, this will give you more leeway on the CR too. Good quench improves combustion efficiency thus helping to prevent detonation.
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Burning Brakes
Joined: Apr 2006
Posts: 787
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From: Ontario
TOO much compression
. Aluminum disapates heat better and allows for a cooler combustion chamber. I would opt for aluminum heads and bump the compresson to 11.0-11.6[/QUOTE]
NOT!!! That's big numbers to run ON THE STREET. 11.0/1 would be max if you want be able to drive the car EVERYWHERE. Better to stay a little low, (11.6 is fairly radical) for a street car and be able to get gas in the smallest town around without pinging.......
Just my 2 cents worth, been there done that!!
NOT!!! That's big numbers to run ON THE STREET. 11.0/1 would be max if you want be able to drive the car EVERYWHERE. Better to stay a little low, (11.6 is fairly radical) for a street car and be able to get gas in the smallest town around without pinging.......
Just my 2 cents worth, been there done that!!
Thread Starter
Instructor
Joined: Nov 2006
Posts: 197
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From: Detroit
After looking around and talking to other people I feel a little uncomfortable running the cast iron vortecs at that high of compression. So I guess i will be looking for a good set of aluminum heads, I know a smaller port would work best for the kind of rpm and torque I am looking for. Now I am not sure what is an ideal compression ratio for aluminum heads, I know that high usually means more power, but I want something that runs good and is very reliable. I am looking at either edelbrock 170s (9.89:1) or the afr 180s (9.51:1) and I cant descide if the afrs are worth the extra money especially since I am not building a high rpm motor. I want a nice broad torque curve, oh well looks like I may have to break down and get desktop dyno or something.
