How much compression?

[89stang10sec]

I have an 89 GT and will be pulling the motor soon. I will be putting new pistons in with a basic rebuild and I am going to mill my ported heads for more compression. What is the max compression I can run on the street safely? the heads are iron. I plan on using an X-cam with it. Thanks.

 

[89stang10sec]

10.5 to 1 too much ???

 

[thumper460]

10:1 iron head... 10.5 alum! Also the cam makes a big differance... bigger duration, more compression, closser intake center line ..less compression....blah...blah...

I run a 10.75 on pump and 38* total ign timing..4.11 gears !! just as info...cool??

Just me.......................

Thumper

 

[89stang10sec]

Thanks, the reason I ask is because Central Coast Mustang makes a longblock that has gt40p heads and a FRPP X-cam with 10.5:1 compression that makes 340 hp . I wanted to use my ported E7's with the same cam and compression. What do you guys think, with that cam would 10.5 to 1 be too much?

 

[1BAD89GT]

Ive got stock E7TE heads im running 10.7:1 on 93 octane pump gas and runs great, But she loves 101 octane!But we all know my motor is a fluke of Nature..aint that right thumper lol i mean with me gaining HP and compression with 289 long rods...lets not get those threads started again.

But yeah 10:1-10.5:1 great on the street.and still run pump gas.

 

[89stang10sec]

Ive got stock E7TE heads im running 10.7:1 on 93 octane pump gas and runs great, But she loves 101 octane!But we all know my motor is a fluke of Nature..aint that right thumper lol i mean with me gaining HP and compression with 289 long rods...lets not get those threads started again.

But yeah 10:1-10.5:1 great on the street.and still run pump gas.

In your sig, you say you have yor deck milled so that the piston actually comes up out of the bore. Do i have to make any other mods to do that?
Special head gaskets or head work? just curious- I might need to do that to hit my 10.5:1 goal

 

[1BAD89GT]

Yeah youll have to figure out what rods,pistons and crank you want to run and if your going to modify them in any way once you have that dont you have the block decked accordingly.

Say your going to run stock rods,stock pistons and crank then all you have to do is have a machine shop deck the block to specs But remeber if you ever change anything in the short block better recheck everything.Like if later on you decided to run a longer rod then you would have to flycut the piston to bring everything back into specs or order pistons to fit your setup.