low comp pistons needed-where can i find them?

no_doz · April 23, 2009, 02:12:19 AM

im looking to do a 3400 top swap on my 3.1 & am looking for the lowest compression pistons i can find that are decently priced-can someone please help me?

90grandprixstet · April 23, 2009, 08:06:44 AM

good luck... most of the time these arent just laying around, i have some 3100 pistons that are 9.5:1 comp if you want those, but thats not very low.

id say your only chances are going with a custom made set, id recomend ross pistons, they were a big help when i was looking for pistons, i was going to get some from them a swell, but i found a great deal on the exact pistons i was going to buy.

z284pwr · April 23, 2009, 02:08:39 PM

Why do you need such low comp pistons? Our good engine was running 9.5 pistons and a GT3076R turbo at 10 PSI with 0 knocking at a whole lot more timing than stock.

TGed · April 23, 2009, 05:05:04 PM

Stock is 8.8:1 iirc you don't need to go any lower. Nothing wrong with 10:1 cr. All about the tune and fuel.

flybynite · April 23, 2009, 09:47:50 PM

Quote from: TGed on April 23, 2009, 05:05:04 PMNothing wrong with 10:1 cr. All about the tune and fuel.

x2

no_doz · April 24, 2009, 12:06:56 AM

yea but the 11:1 compression that my engine will have with the 3400 heads cant be smart/make as much power on 93 pumpgas can it...without injecting shit & all that

90grandprixstet · April 24, 2009, 05:52:18 AM

ummm... yes you can...

you can run any comp ratio with boost, all that matters is the ammount of boost you plan to run and what kind of lb injectors you have...

you sound like u just want to throw something together and make it fast without the long work of tuning, upgrading fuel system, or anything like that... if this is the case, lowering the comp ratio alone is only going to make you slower...

heres where you can calculate compression ratios with boost
http://www.rbracing-rsr.com/compression.htm

no_doz · April 24, 2009, 01:33:13 PM

i am looking to throw something together fast but im counting a lot on flybynights chip for that, so im going to make sure i have detailed every part & such so he knows & can program accordingly, then i do intend to tune it as i go, but for now im looking for 300 on sc in a pretty small timeframe (50 days).

GhrarhG · April 24, 2009, 01:57:12 PM

Are you running a fwd 3.1 or a rwd 3.1? Running a 3400 top end on a fwd 3.1 actually drops the compression ratio. The combustion chamber volume in the gen 2 alum heads is 26.4cc where the 3100/3400 is 28.6cc. Only if you're running rwd pistions do you get over 11:1 compression ratio since they have very little dish to them 12cc vs ~26cc that the fwd have.

no_doz · April 25, 2009, 12:10:59 AM

lmao oh thats right! i forgot the info i was using was for the camaros topend swap that i probably will not end up doing since im going to sell it and put the money into either my 92 lumina euro 2dr or a sunbird, im betting on the sunbird due to cost effectiveness-sell the lumina for 1k, sell the camaro for 1500, buy a sunbird for 300 bucks that needs a trans or headgasket (hopefully its a bad auto trans-these come up cheap as hell or get scrapped ALL the time) & spend 1200 of the remaining on the sunbird while me & my gf pay up all our debts & our first months rent with the lumina money-also we get paid on off weeks & both work full time during the same 6-7 hours (she works 4-11 & i work 5 to 11 but i can come in as early as id like and stay as long as id like-as long as i dont get OT :D.

also what compression ratio would 3400 heads & a tgp head gasket give me?

GhrarhG · April 25, 2009, 01:16:28 PM

great tool:

http://60degreev6.com/content/CR_Calculator

Looks like 8.67:1

no_doz · April 25, 2009, 11:50:36 PM

i dont know how to use that... but thank you! :)