alright so i am going through doing port and polished head oversized valves. 2.3 springs. secret cams. already have header cat back and intake. lightweight crank pulleys. all the motor mounts .stage 2 clutch and lightweight flywheel,arp head studs,cometic head gasket, and i plan on doing the supercharger on my ld9 after i do all this motor work. and i read not to lower compression on the gm sc kit because it maxes out at 10 psi. but i wanna do forged pistons and rodsso i dont detonate my pistons. and i will obviously do main and rod bearings . but what do you guys think about raising the compression because of my limits with the gm sc. or just getting the the stock compression with forged internals? i will really appreciate the help on this not my special area. i deal with the top ends not the bottoms.
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I hope you do not think that the pistons and rods will keep you from detonating. All they will do is make your engine more likely to survive a minor detonation problem. To keep detonation at bay you need to run 91 or better fuel and if you plan on pushing the charger to the max you need alky injection.
To answer your ? I am sure you will be fine with 10:1 compression provided you are not running lean. I doubt you will be able to tell the difference between 9.7:1 compression you have now and 10.1. It is not a bad idea just don't expect a huge performance gain from it.
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If you were to advance the ignition timing, or retard the cam timing, you could also keep yourself from detonating. One thing to keep in mind is that aluminum dissipates heat quicker than cast iron. which is a plus for anyone wanting to run a higher compression with boost! with a timing change too, you'll keep from expanding the cylinder walls too much and sabotaging the rings as well!
Project Resurrection is in full swing!
what's the highest compression ratio pistons that are safe to use with a supercharger for the 2.4?? I've seen a few people who's builts included 9.5:1 pistons.. but has anyone used 10:1 or 10.5:1 pistons???
When I step on the gas, I want people to think the world is coming to an end! - Homer J. Simpson
i'm going to be using 9:1 compression with je aluminum forged pistons .020 over, h-beam eagle rods, secret cam swap ,arp studs and cometic headgasket, +1mm stainless steel lifters (thanks to wade jarvis for the info), with stock springs, and i have the m45 supercharger kit, rebuild will be done in 3 weeks, but i did this so if i decide to go with more boost or switch to a turbo i have the lower compression, it's so little you won't really know the difference from what i have been told....as for going higher i would really stick to stock compression if your only doing the gm supercharger kit.....
"If you have no clue what's going on... STFU!"
Golden Trojan wrote:what's the highest compression ratio pistons that are safe to use with a supercharger for the 2.4?? I've seen a few people who's builts included 9.5:1 pistons.. but has anyone used 10:1 or 10.5:1 pistons???
10:1 would be fine. It was what I was going to go with until I was told wiseco only makes 9.5:1
FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!
Quote:
10:1 would be fine. It was what I was going to go with until I was told wiseco only makes 9.5:1
Karo told me he could get me a set of 10:1 pistons. I am just waiting to sell my 9.5:1 pistons first
Jason
99 Z24 Supercharged
157hp/171tq - NA
LD9 for Life
I know that adding a S/C would up compression within the cylinder. Using the 10.5:1 pistons could someone add a supercharger and NOT blow head gaskets daily! haha.. also wondering if you could get by with using 93 octane or would you need it higher (if it is possible)
When I step on the gas, I want people to think the world is coming to an end! - Homer J. Simpson
If you had alky injection that would help greatly with detonation assuming you already had a good afr.
FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!
Wade Jarvis wrote:Golden Trojan wrote:what's the highest compression ratio pistons that are safe to use with a supercharger for the 2.4?? I've seen a few people who's builts included 9.5:1 pistons.. but has anyone used 10:1 or 10.5:1 pistons???
10:1 would be fine. It was what I was going to go with until I was told wiseco only makes 9.5:1
Nevermind my previous statement. Wiseco standard pistons are 9:1 You can get 9.5:1 or 10:1 but they are a custom order there are also several other compression ratios that can be custom ordered.
FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!
you can call Karo at carcustoms and he can have a set of 10:1 comp pistons made for the 2.4L from Wiseco.
as far as would it be ok yes, with supporting conditions...meaning 93 octane at the very least. Even if you dont have the S/C on yet, and have the 10:1 pistons in run 93 octane....it will help with keeping the cylinder temp down and in turn prevent detonation...an alky kit wouldnt be a bad idea, as it not only improves safety by lowering temps but it also provides more power from cooling the air as it enters the cylinder.
some other things to keep in mind:
1. piston rings have a specific gap for S/C applications....make sure to gap correct.
2. S/C love high compression, but require high octane to run safe....
3. as soon as the high compression pistons go in, use 93 octane. (even if the s/c isnt on)
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i ran 13.9's with the 9:1CR setup and 14.1's before..........
Tha01cav wrote:you can call Karo at carcustoms and he can have a set of 10:1 comp pistons made for the 2.4L from Wiseco.
as far as would it be ok yes, with supporting conditions...meaning 93 octane at the very least. Even if you dont have the S/C on yet, and have the 10:1 pistons in run 93 octane....it will help with keeping the cylinder temp down and in turn prevent detonation...an alky kit wouldnt be a bad idea, as it not only improves safety by lowering temps but it also provides more power from cooling the air as it enters the cylinder.
some other things to keep in mind:
1. piston rings have a specific gap for S/C applications....make sure to gap correct.
2. S/C love high compression, but require high octane to run safe....
3. as soon as the high compression pistons go in, use 93 octane. (even if the s/c isnt on)
Stock SCR is 9.7:1, so why would he need higher octane? 10:1 isn't a huge jump in compression. I run 10.7:1 on 87 octane. Higher octane prevents detonation because it requires a higher activation energy to ignite the fuel, not because it decreases cylinder temps. Increasing AFR's, intercooling/aftercooling, manifold/head design, alky/water injection, etc. are all methods of decreasing cylinder temps. If you are recieving "0" knock, then increasing the octane of the fuel without increasing timing will only lead to poor performance, because higher octane fuel contains less internal energy than fuel of the same type of a lower octane and you're not going to get a complete burn of the fuel.
Edited 1 time(s). Last edited Saturday, January 12, 2008 4:24 PM
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"Youth in Asia"...I don't see anything wrong with that.
yes i ran 13.9 @ 103.5 with everything except meth injection and the 2.6 pulley, my cars down right now or i would have a updated 1/4 mile time.
There is nothing wrong w/ high compression and boost. It only makes tuning slightly more difficult as the tune has to be pretty close, and you will need more fuel because of the high compression as well.
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4 Cams...32 Valves...5 Liters...This Could Get Fun!
anywho i am doing everything now 10:1 pistons 0.20 overbore,eagle rods,clevitte bearings main and rod,balancing crank shaft,port and polished head,bronze valve guides,oversized valves,three angle valve job,arp main and head studs,secret cams,light weight crank and alt pulley,rsm 62 mm tb, 95 2.3 springs only a lil stiffer,cometic head gasket,dc sport header,magnaflow cat back,aem intake gonna be made to fit the ,gm super charger sent out to steigmier for port and polish,2.6 inch pulley after broken in,snow performance meth kit,accel afpr,venom fuel rail,ttr upper engine mount,dog bone lower mounnt,poly transmission bushings,melling oil pump,perma cool oil cooler,light weight flywheel and stage 2 + clutch. think that is all of them but now i would like to know what you guys think i should run for injectors?
http://www.cardomain.com/ride/2623318
10:1
HO cams
OBX 4-1
60mm 2.3 TB
ported head
GMPP S/C with 2.4" pulley (7.5 PSI)
"stock" 310cc injectors
226.5 HP at rev limit.
Ran just fine until i pulled the S/C off in favor of a turbo.
Blwn LD9 wrote:Quote:
10:1 would be fine. It was what I was going to go with until I was told wiseco only makes 9.5:1
Karo told me he could get me a set of 10:1 pistons. I am just waiting to sell my 9.5:1 pistons first
all this higher compression with the m45 talk, im running 9:1 CR hmmmmm
well do not expect just because someone has this and that mod and ran this and that time to do the same. EVERY motor is different even bone stock ones to built ones. You'll find out sure enough because theres only a handful of m45 guys getting low 14's, everyone else is stuck at super high 14's or 15's.
I ran 310cc just fine while making over 200 HP
