as stated whats the highest compression you can run with 93, 11:0 at least I would think lets hear some numbers
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
N/A Integras run like 12:1 I think with 93.
I'm thinking about going all motor just to see how much it can pump out like going .040 to 060 over with 12:1 compression and cams , all new internals and a higher rev limiter
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
you keepin' the charger on top of that ?
15.958 @ 88.201 stock, still getting @!#$ty launches...
If you're stickin with the supercharger then I don't think you can up the compression at all dude...
alot of it depends on the cams , and how you set the spark advance up , the total weight of the car , the trans gearing
ive run 97 in my 68 elco , with close to 11 to 1 , and never had any knock
you want to use the lowest octane you can get away with , cause youll make more power on a lower octane fuel than a higher
keep in mind there is a happy medium
its all about getting good quench, and with high compression and cams that have alot of overlap it makes it seem like your not running as much compression.
_______________________
** Flat Broke Racing Inc.**
Well now where did learn about fuel??? 87 octane is cheaper for a reason considering higher octane increases horsepower why do you think race gas is 104 octane. You shouldn't even be running 91 on any fuel injected car because ur stock fuel injection isn't calibrated to run higher octanes unless you fork out the money to change the calibration but why do you think a newer corvettes run on 91 and no less. So yea your elco might not knock but if u don't have to timing set perfectly you will loose a lot of the horse to detonation which will kill ur engine.
no this is not with a blower
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
I guess it all depends on your dynamic compression then. But I would think that with AL heads you can get away with atleast 10.5:1 and maybe more...
05CavCoupe wrote:Well now where did learn about fuel??? 87 octane is cheaper for a reason considering higher octane increases horsepower why do you think race gas is 104 octane.
higher octane gas does NOT increase your horse power !!!!!!!!!!!
the lower the octane the faster it burns , the higher the octane the slower it burns
for a race motor using 100 or higher , they are doing it for higher compression , and more spark advance , which it turn makes more power
if you were to run 87 octane in a 14 to 1 race motor it would nuke itself , unless you were running the timimng on the retarded side which will make you no power
on my elco i run 36-38 degrees of advance , and no knock , the cam , and the way the advance is set up is what allows me to run the lower octane gas , with no problems and full power
if i wanted to run 100 octane i could jump the timing up to mid 40's , but it wouldnt really gain me any more power
Rodimus Prime wrote:I'm thinking about going all motor just to see how much it can pump out like going .040 to 060 over with 12:1 compression and cams , all new internals and a higher rev limiter
you jsut spent all this money for that charger.
you are a dork
Im a Xbox 360 fanboy...and damn proud of it!!
this is for another car , DORK
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
so for a 2001 cav z24 stock... whats the better ocatine to use?? 87 or 93?????
I thought the mid grade was a good medium for it!!!
"Silver 2001 Cavalier z24 5 speed 2 door sunroof and power everything "
AEM Short Ram Intake
B&M Short Throw Shifter
87 but goddamnit people search !!! and threadjacking is not nice
15.958 @ 88.201 stock, still getting @!#$ty launches...
11.7:1 compression on premium over here
Rodimus Prime wrote:this is for another car , DORK
you never said that, DORK!
Im a Xbox 360 fanboy...and damn proud of it!!
The idea is that im going to try to find another ecotec J for a daily driver and pimp out the motor hard core to see how much I can get out of it
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
go rodimus you're our hero
can't wait to see what you'll achieve by going all motor
15.958 @ 88.201 stock, still getting @!#$ty launches...
Quote:
the lower the octane the faster it burns , the higher the octane the slower it burns
Octane is a measurement of resistance to detonation, not flame speed. Look for Gasoline FAQ on any search engine and you should find some really good reading.
The question was "how much compression" and the answer (as said by a few) is "it depends." There are general guidelines you can follow to run "as much compression as possible" and minimize the chances a problem will occur.
Make sure the cooling system is in good shape. You want to do all that's possible to prevent the formation of any steam pockets or hot spots around the combustion chamber. Water wetter or equivalent coolant additive helps. Make sure there are no sharp edges in the combustion chamber, on the piston tops, or around the cylinder bore. Run the coolest plugs practical. Use an oil cooler, and if you're machining the block and crank discuss using piston oilers (like the 2.0 SC Eco) for cooling with your machinist. Use ceramic thermal barrier coating on piston tops, chambers, and valves. This stuff works! Reduce intake air temps as much as possible. Use a less aggressive spark curve! You get more power by preventing detonation than by reacting to it. Keep quench distances small and try to use a flat top piston rather than a dome for fastest burn. Do not try to "slow down the burn!!!" Rather, do all that you can to make the fuel/ air mix burn quickly and start spark as late as possible in the power stroke while still maintaining power. Cam overlap makes high compression "act" lower by releasing cylinder pressure, especially during low rpm operation, so minimize overlap whenever possible. Choose a cam to provide a high rpm power curve and select final drive gears to use that high rpm power, essentially reducing load on the engine. Use Marvel Mystery Oil in the gas, 4 ozs to 10 gals fuel. MMO also helps valves, injectors, fuel pump, etc. With a small bore engine and the right tuning, I'd suspect 11:0 isn't a problem at all. I run about 10.8:1 in a 350 with iron heads and no problems on 87 octane.
hth
-->Slow
i wish you the best of luck there Rodimus
Im a Xbox 360 fanboy...and damn proud of it!!
Slowolej hit it right on the money!
Some other thing to consider are the combustion chamber design (think GMPP Fast Burn Heads)and (as Slowolej said) piston design. The most efficiant design would be a true spherical combustion space(hemi head and dished piston) with the spark starting in the center of the sphere with no shielding of the flame front, but this would be nearly impossiblre to design. Most manufacturers come close as practical with many of todays engines, which is why the CR's are as high as they are for 87 Oct. gas.
Dynamic cylinder pressure also plays a big part in detonation control. That pressure is affected mostly by static CR and the camshaft phasing, higher static CR and less overlap increase cylinder pressures. Cylinder pressures are also somewhat affected by intake design( ramming effect) and exhaust scavaging(over and under scavaging).
My first recommendation is to talk to some of the cam manufacturers and let them help you make the decision as far as how much compression you can use with different cam profiles. The cams will have more affect than any other part of the engine on the way you engine runs. This will help you find out what RPM range you would be running, then you can design the rest of your engine around that power band.
