Ok the question is i am building my ecotec i have a 2003 cavy and was wondering if i should lower my compression to 8:9 to1 or keep the stock compression but forged pistons i will be running the highest amount i can with the M62 supercharger with the smallest pulley what compression should i run.
i'm running 10:1 and no problems.
id run the stock compression pistons , but forged , then polish the tops of the pistons to make sure there is no sharp edges
then polish the combustion chamber for the same reason
sharp edges creat hot spots , and hot spots are part of a cause for detonation
also smoothing and polishing will drop the compression a little also
how much more boost can you run on a 8.9 piston then you can on a 10.0 both forged??
im planning on boosting 20-25 psi after i build the motor and i was wondering if stock compression forged would sustain that much boost and give me the added power of the higher compression..
|Forged 8.9:1 Wiseco Pistons|Forged Eagle Rods|HPTuners|60trim|Tial Wastegate|
|Precision Intercooler|2.5" Exhaust|2.5" Charge Pipes|630CC Mototron Injectors|
|Stock: Fuel Pump, Transmission, Manifold, TB, Head, Head Gasket, Ignition, Suspension...|
You can run 250psi on 15:1 compression.
It's all in the tuning.
Gilles
2.3 Ho
well i am going to run 8:9 to 1 because i am going to run the most boost i can with the supercharger and spray nitrous
screw the nitrous keep your stock compression. dont make the mistake i did.......... the s/cer will create plenty of power then just add a small shot of nitrous 25hp would do it.... trust me
i have a built ld9 with a 2.6 pulley and i just ran a 15.8 at 86mph, granted i need a tune prolly more fuel, alky injection and a exhaust system
Sorry...
You have been banned from posting on this site as of 2005-09-21
00:33:32. This ban will expire 2005-09-28 00:33:32 Pacific Time.
Reason: Comments over the top regarding Jordan Kruger and other members in Versus. Also, if you have a problem with a member e-mailing you, do not bring it into the forums.
If you believe this to be in error, please contact us.
Eric Monroe wrote:well i am going to run 8:9 to 1 because i am going to run the most boost i can with the supercharger and spray nitrous
the max amount of boost you could run from a S/C and some N2O will not warrant going down to 8.9:1 compression.
"i have a built ld9 with a 2.6 pulley and i just ran a 15.8 at 86mph, granted i need a tune prolly more fuel, alky injection and a exhaust system" Sorry but thats slow.... u should be running that with the stock motor.. .if not faster..
01' Z24 5 speed
422whp/400wtq
T4 Turbocharged
Built LD9
HP Tuners
He is an auto and it was very hot out in his defense the humidity was insane. as for lowering the compression he can the eco charger is a completely diffrent beast than the little m45 for the ld9. 3 inch on a m45 is around 4-5 psi an eco m62 is more around 10-14.5 is the highest ive heard with an intercooler. Rember lower compression is just a saftey net for tuneing as said Mfk-223 it is all about the tune.
3" on a M45 would be about 2lbs boost. my stock 2.8 saw 6psi boost. either way it is all about proper tuning. whether your running 12:1 or 8:1, an imporperly tuned motor will eat itself.
oh well i got a guess on the pully sorry
Well still i plan on boosting with the smallest pulley i can which probabaly give 15 psi and spray a direct port 80 shot so i still think i am going with the 8:9 to 1
i am trying to get over 300 whp which wont be that difficult i probabaly be close to that without spray but i still building the motor right and have a great setup.
i def think i am running lean. the car needs a tune depratly... it is getting done in two weeks.
the exhaust goes in friday
alky not shortly after that,
new injectors
then a tune
Sorry...
You have been banned from posting on this site as of 2005-09-21
00:33:32. This ban will expire 2005-09-28 00:33:32 Pacific Time.
Reason: Comments over the top regarding Jordan Kruger and other members in Versus. Also, if you have a problem with a member e-mailing you, do not bring it into the forums.
If you believe this to be in error, please contact us.
As i said before i am trying to get over 300 whp which wont be that difficult i probabaly be close to that without spray but i still building the motor right and have a great setup.
Eco charger with the right setup can pull off that with the 2.8in pully And a good intercooler just get it tuned Run a port and polished head with forged rods and pistons run 10:1 compression Stage two clutch bigger ingectors new fuel pump. This should put you at your goal just warn ya thow i have heard 300 is the magic number for the limit of our half shafts.
If i 'm wrong this just a colabaration of the info i have gained on the org other people can probley break it down better for you.
[quote=97cavie24ls(JDM&00s/c sedans™)]id run the stock compression pistons , but forged , then polish the tops of the pistons to make sure there is no sharp edges
then polish the combustion chamber for the same reason
sharp edges creat hot spots , and hot spots are part of a cause for detonation
also smoothing and polishing will drop the compression a little also
WOOOAH....dont polish the chambers....you need a honed cross hatch to bed the rings. Dont ever polish the chambers, thats the rings job and let them do that. Thats all part of that breaking in the motor thing you always hear about.
Eric Monroe wrote:well i am going to run 8:9 to 1 because i am going to run the most boost i can with the supercharger and spray nitrous
You need to leave your compression alone, just get forged internals. If you lower to 8.9 you will be dumping good money after bad and will never make the power you want. It will be a dog. You only need 8.9 if your running a turbo and throwing 30psi+ at it...and juice isn't going to need that low of compression either.
Dont take this the wrong way but there have been guys like you in the past that go and do something against what was recommended. Then when they finished they complained that gm is crap and that they never should have bought the money trap and there so dissapointed. DO NOT DO 8.9.....no need on an S/C.
Edited 1 time(s). Last edited Friday, July 28, 2006 6:31 AM
He meant the combustion chamber(the head) not the cylinder.
Gilles
2.3 Ho
^^^ good call, i dont know what I was thinking. Sorry 97cavie, I thought you knew better than that, turns out i misunderstood.
Do not lower compression, you are a fool to. With a good tune run stock compression with the right fuel set up and you will be fine.
http://members.cardomain.com/vertz24 1998 Z24 Convertible
if anything raise the comp.
Pat,
when did u pump the compression up? or did u get the head shaved?
Nate
Evolution of Cavyboy-->C22t--> C24na--->c24s/c
1995 Cavalier W/2k1 Engine
GM S/C 13.940@99.78pmh w/2.068 60ft
C24s/c wrote:if anything raise the comp.
Pat,
when did u pump the compression up? or did u get the head shaved?
Nate
when i ported the head a couple months back i also shaved the head very slightly to be sure it was flat for bolting things up. it was CC'd before and after so we could find out the true compression ratio.
purplezed wrote:C24s/c wrote:if anything raise the comp.
Pat,
when did u pump the compression up? or did u get the head shaved?
Nate
when i ported the head a couple months back i also shaved the head very slightly to be sure it was flat for bolting things up. it was CC'd before and after so we could find out the true compression ratio.
?? Ya, decking the head is a must. Granted, they only take off the minimun, thousands of an inch, to ensure its 100% flat. Don't think that would bump up the compresson 1/2 a point. Cause if you were to take off more, i would be nervous that there would be too much slack in the timing chain and skip teeth. (dont remember how much the slack the shoe takes). But if you said it tested before and after...curious of the results. post em? Whats the formula for comp again.
Nate
Evolution of Cavyboy-->C22t--> C24na--->c24s/c
1995 Cavalier W/2k1 Engine
GM S/C 13.940@99.78pmh w/2.068 60ft
No need to CC the head. It's 61CC stock and won't go smaller than 60cc at MOST.
It won't change the compression more than 0.1 : 1
Gilles
2.3 Ho
