pistons for forced induction

[firebirdv6 3.4]

what is the best piston for forced induction flat, dish, or domed top

[Turbo V6 Camaro]

umm ross dish top for you motor if its a street and dome if it's a track only car.... flat if its both

we need more info on your goals to help you

[firebirdv6 3.4]

Originally posted by viper04af:
umm ross dish top for you motor if its a street and dome if it's a track only car.... flat if its both

we need more info on your goals to help you

which one would make the most power with a fff turbo kit

[phoenix64]

Domed are to increase compression with oversized combustion chambers. They have no place on a FI engine.

I don't think anyone here knows enough about the combustion chambers on a 3.4 to say which makes the most power.

[Turbo V6 Camaro]

Originally posted by phoenix64:
Domed are to increase compression with oversized combustion chambers. They have no place on a FI engine.

I don't think anyone here knows enough about the combustion chambers on a 3.4 to say which makes the most power.

high c/r +turbo + alot of octane = POWER [img]smile.gif[/img]

thats why i said track only car

[RicE-ter]

Originally posted by viper04af:
</font><blockquote>quote:</font><hr />Originally posted by phoenix64:
Domed are to increase compression with oversized combustion chambers. They have no place on a FI engine.

I don't think anyone here knows enough about the combustion chambers on a 3.4 to say which makes the most power.

high c/r +turbo + alot of octane = POWER [img]smile.gif[/img]

thats why i said track only car </font>[/QUOTE]and if u can just point me to a gas station that has 104+ octane racing fuel please ;)

i thot low compression pistions were better for forced induction?

[Turbo V6 Camaro]

Originally posted by RicE-ter:
</font><blockquote>quote:</font><hr />Originally posted by viper04af:
</font><blockquote>quote:</font><hr />Originally posted by phoenix64:
Domed are to increase compression with oversized combustion chambers. They have no place on a FI engine.

I don't think anyone here knows enough about the combustion chambers on a 3.4 to say which makes the most power.

high c/r +turbo + alot of octane = POWER [img]smile.gif[/img]

thats why i said track only car </font>[/QUOTE]and if u can just point me to a gas station that has 104+ octane racing fuel please ;)

i thot low compression pistions were better for forced induction? </font>[/QUOTE]most gas staions in ohio in my area have 110

it is better cuase you need lower octane and can make more power, but a higer C/r will always make more power if you have the fuel to back it up

[phoenix64]

Not true. 110 octane will support a given actual cylinder pressure. You can get there with 10psi and 11:1 C/R or 20psi and 8:1 C/R. The 8:1 will make WAY more power, and live longer.

Also domed pistons tend to cause detonation.

[98Camaro3.8]

Originally posted by phoenix64:
Not true. 110 octane will support a given actual cylinder pressure. You can get there with 10psi and 11:1 C/R or 20psi and 8:1 C/R. The 8:1 will make WAY more power, and live longer.

Just curious here, as I don't know much about FI....

Why does it matter what the C/R is? If you take 10 psi and compress it 10 times (10:1), you get 100 psi when compressed. Take 12.5 psi and compress it 8 times (for 8:1), you still end up with 100 psi at TDC. What's the difference? Is it the mass of the air/fuel charge entering the cylinder?

[RicE-ter]

around here the highest octane is maybe 92 :( - i heard of a place a lil up north of SD that has 98 or sumtin

from my understanding NA engines do well with high octane and increased compression- since higher octane has a longer burn and push, it would seem beneficial to increase the throw of the piston since there is no added pressure from a supercharger/turbo

FI alows for more fuel do to the added air thus increasing pressure, sort of increasing compression but mostly for harder push from more fuel. NOS increases compression also, the nos gas molecules take up space in the combustion chamber

what i "know" is mostly here-say so corrections are welcome

[jaberocs]

crap...im plannin to turbo and highest ive seen here (in san francisco) around my area is 91 octane

[Turbo V6 Camaro]

Originally posted by phoenix64:
Not true. 110 octane will support a given actual cylinder pressure. You can get there with 10psi and 11:1 C/R or 20psi and 8:1 C/R. The 8:1 will make WAY more power, and live longer.

Also domed pistons tend to cause detonation.

bye accual you mean the "final" c/r when the boost in there? or the th ratio that it is N/A....

I need to know good facts now cuase if i'm wrong i have been misinformed

Boost and Altitude Correction to Compression

You are running 10 PSI of boost at an altitude of 0 feet. Your motor's static compression is 8.5 :1. At this boost level and altitude your effective compression ratio is -14.28 :1, and without altitude correction your compression ratio would be 14.28 :1

Boost and Altitude Correction to Compression

You are running 10 PSI of boost at an altitude of 0 feet. Your motor's static compression is 12 :1. At this boost level and altitude your effective compression ratio is -20.16 :1, and without altitude correction your compression ratio would be 20.16 :1.

diff page http://www.supermotors.org/vehicles/...ted_horsepower

8.5 cr with 10 psi will be 14.28
12 cr with 10 psi will be 20.16

[Turbo V6 Camaro]

Originally posted by 98Camaro3.8:
</font><blockquote>quote:</font><hr />Originally posted by phoenix64:
Not true. 110 octane will support a given actual cylinder pressure. You can get there with 10psi and 11:1 C/R or 20psi and 8:1 C/R. The 8:1 will make WAY more power, and live longer.

Just curious here, as I don't know much about FI....

Why does it matter what the C/R is? If you take 10 psi and compress it 10 times (10:1), you get 100 psi when compressed. Take 12.5 psi and compress it 8 times (for 8:1), you still end up with 100 psi at TDC. What's the difference? Is it the mass of the air/fuel charge entering the cylinder? </font>[/QUOTE]after think about the 8:1 has more "room" for air there is acualy more space..... not alot but there is more....

any physics majors?

[phoenix64]

Originally posted by 98Camaro3.8:
</font><blockquote>quote:</font><hr />Originally posted by phoenix64:
Not true. 110 octane will support a given actual cylinder pressure. You can get there with 10psi and 11:1 C/R or 20psi and 8:1 C/R. The 8:1 will make WAY more power, and live longer.

Just curious here, as I don't know much about FI....

Why does it matter what the C/R is? If you take 10 psi and compress it 10 times (10:1), you get 100 psi when compressed. Take 12.5 psi and compress it 8 times (for 8:1), you still end up with 100 psi at TDC. What's the difference? Is it the mass of the air/fuel charge entering the cylinder? </font>[/QUOTE]Yep with the higher boost you get the same pressure, but more air and fuel. Hence more power.

[nocutt]

There is a difference in ideal and reality...
Ideally meaning in theory...if you can keep detonation away by design of engine and tunning and we have enough octane (we do) then a high Compression engine will ALWAYS beat a similar engine with LC pistons...ALWAYS...
The reality is few have the means, few have the resources...go to the race track you will see all sort of combinations, but with the advent of newer compressors, more info on EFI...engine design etc a lot off people are running higher compression pistons...I am not talking 12:1 here but the OLD 8:1 crap are for those who don't a) want to deal with octane (understandably) or b)those who don't want to tune...
take a look at porshe's design they run higher compression pistons and moderate timing...and before someone says apples to oranges...pls save it...engines might be different...not the burn, combustion is combustion...
remember if you are building a drag car...don't compare to a street car...I am strictly speaking of the later...

[ June 06, 2005, 01:27 AM: Message edited by: nocutt ]