[travix]

Hey guys I'm in process of building a EFI 331 Stroker. Trick Flow Heads with an X303 cam. I am afraid that my compression ratio is way too high. Is this ok for a street motor or can i do something like retard the ignition or cam timing. I'd rather not have to replace my heads or anything expensive. My budget is coming to its end. 12.033 seems a little high. However I see a lot of engines running this with no issues. Please give input.

 

[travix]

Well i just figured out there is a difference between static C/R and Dynamic C/R. I'll post a pic of my dynamic C/R here, 11 still seems high. Will detonation be an issue? Also, correct me if I am wrong, but to my understanding the difference between static and dynamic is that static is with no movement and dynamic is while the engine is running and involves valve overlap and cam timing. Thank you.

 

[KLWorra]

You will need race fuel at that compression. Don't use octane boost. Are you sure your deck is E
Zero? Your dynamic is way high, you should be no higher than 9;1 street.

 

[2Manystangs]

you can get thicker head gaskets to lower the compression, if it's tuned right you can easily run 11:1 with pump gas, many cars are 10.5-11 compression, I think the new 5.0 is about 11

 

[KLWorra]

you can get thicker head gaskets to lower the compression, if it's tuned right you can easily run 11:1 with pump gas, many cars are 10.5-11 compression, I think the new 5.0 is about 11

Don't go thicker than quench around .050 or you will have major problems.

11:1 requires lots to make it work. Cam will have to be designed to overlap to bring dynamic down.

I have piston oilers, electric water pump, aluminum heads and run pretty fat to keep mine ok. I am at 210 psi cranking pressure. I run 93, not 92. It will diesel if I don't let cool down after running. Otherwise I get away with it.

 

[Smurf stang]

Your compression is on the high side but what pistons are you running?

My CR is at 11:1 and I had to keep the timing down and run it a little rich to control her. I think my total timing at the end was 29 and it didn't like much more than that.

 

[YLDPONY]

Okay guys, look at the OP's original picture. I'm pretty sure his calculations are wack to begin with:
1. He said he is building a 331, the stroke he used for the calculation is 3.4", a 347 stroke.
2. He entered "-5cc" for piston head volume. This means (to the calculator) he is running 5cc dome pistons. Something tells me he isn't...

So travix...
Are you building a 331 or a 347 :?: 3.25" or 3.4" stroke :?:
Are you in fact using dome pistons, or flat tops with valve reliefs :?:

Don't go thicker than quench around .050 or you will have major problems.

Thank you! He's 100% correct, if you get your quench too big you will have incurable detonation problems. Using a thicker head gasket is generally a terrible way to reduce static CR. .035" to .040" is ideal quench, so I have been told by much more knowledgeable heads than myself.

 

[86fordmustanggt]

this kinda stuff is why i don't mess with stokers, i just took mine to a 306 lol, but yea, need more info mainly piston info, also did u check the piston ring end cap before u installed them?