boost compression ratio ?

[taank]

is 10.25 to 1 compression and 7-10 psi boost compatible? generally you want a lower compression ratio on a boosted application correct? stock ratio is 9.9 to 1.

[Paul Revere]

Geeze you people and your high compression motors with boost ... why not just drop in some pistons while your already at it?

[Turbohwagon]

I've read about a few builds running 10.5:1 with boost and they worked out pretty good.

[Phillyblunt474]

Many RSX people run upwards of 11 psi on 11:1 compression

[taank]

I've read about a few builds running 10.5:1 with boost and they worked out pretty good.

i guess if you pull alot of timing and run higher octane gas it would be reasonable...

[Paul Revere]

Many RSX people run upwards of 11 psi on 11:1 compression

I don't get this

[taank]

you would obviously want to run a flat top or dished piston?

[Turbohwagon]

Dish

[Shaun]

With that kind of compression you will sacrifice quite a few pounds. What kind of fuel? E-85 will buy you quite a bit if you're able to get away with it.

[bluchev]

i got 9.6 to 1 compression with 6 psi on pump gas.

[gixxer]

Its also worth noting you can change your DCR with careful cam selection.

[289Notch]

running that small of a combustion chamber makes 0 sense. The motor will just be fighting against itself and causing unneeded problems.

also it's been gone over on this site even that boost is not a good measure for HP because it's caused by resistance to flow.

if you force in more fuel+air you need a bigger chamber.

8.0:1 would be nice.

[Scotty07]

Ford's new 5.0 will be running 11:1 compression on 87 octane gas. Be interesting to see how much bewst it will be able to handle.

[289Notch]

additionally, the power in an engine comes from the fuel. we get more fuel into the combustion chamber we get more power.

increased compression and octane alone is typically only responsible for ~5-7% more HP in properly tuned applications.

[orange88]

it really depends on the fuel, cam, pistons, turbo . hell you could run 13-1 with 30psi if you have all your ducks in a row.
my old motor was 8.5-1 with 30psi and worked well, my new motor will be around 10-1 with 30psi.

if its going to be a street car id go less. more room for error with changes in pump gas