real quick compression question

[bloodhound248]

hey guys, im currently building a motor and i need to know whats the highest compression ratio i will be able to run on pump gas? thanks alot

 

[BuckChoklit]

Depending on ambient temperature/intake temperatures...I'd say 12-14:1.

 

[28]

14:1 is kinda steep isn't it?I mean if it's a gonna be a daily driver anyway...Isn't it?

 

[Jman20427]

I wouldnt go higher then 11:1, mine is 10.5:1 and runs perfect on 93. You might be able to get away with 11:1 if you guys have sunoco 94.

 

[octane]

It depends on several factors. I normally try to run 10.5 - 11 with aluminum heads and about 1/2 a point lower with iron heads. It also depends on your camshaft specs. You are after "cranking pressure", which will depend on how long the valves are open and when they are open. Hope this helps.

 

[DropTopFord 5 0]

I wouldnt go higher then 11:1, mine is 10.5:1 and runs perfect on 93. You might be able to get away with 11:1 if you guys have sunoco 94.

I thought they stopped making SUNOCO 94...? at least in Mass, i loved that stuff until about 6 months ago, now we only have 93, at the same price as 94... also, we're just assuming this is N/A right, dont forget about any boost you might ever want to run... which is often a big no-no w/ high compression... :nono:

 

[EvergreenSVT]

Well, the new Z06 runs 11:1 on 91. Sport bikes and direct injection BMW engines also run 12:1 or more on 91. I don't know what a Ford engine can do though.

 

[cobraracer46]

AloT of 96 and later 4v dohc cobras are running 11:5 compression on the street without any problems.

 

[Jman20427]

I thought they stopped making SUNOCO 94...? at least in Mass, i loved that stuff until about 6 months ago, now we only have 93, at the same price as 94... also, we're just assuming this is N/A right, dont forget about any boost you might ever want to run... which is often a big no-no w/ high compression... :nono:

I dont know where he lives, I know were still have some stations in CT that have it. and a little nitrous didnt hurt anyone :rolling: