C5natie

iTrader: (1)

Recently that Ive been in the middle of a high compression LS6 build Ive been trying to find info on anyone else doing a similar build but have been coming up empty. Seems that no one else is really doing it. I google or look up "high compression LS1"... etc, but no luck. It seems that everyone refers to 11.1:1 as high compression but Im talking 12:1+ cr. Anyone out there near this number, or that isnt just going FI like most guys? I love high compression engines for their high revs and sound. I like refering to them as "real" engines since its an application where its entirely up to the powerplant to produce all its power and not dependant on a power adder. It also makes every engine part/piece that much critical.(I love blowers and nitrous too so dont hate, just a humorous remark to mess with the FI and sprayer guys) Please let me know if you have a 12:1cr engine or higher (GenIII or IV if possible) and what route you took on your build, engine characteristics, street only, track only, fuel octane... etc. Thnx.

ericg69ss

I have a couple of high compression motors. One is a first gen SBC and the other is a Gen III C5R. The C5R is 13.5-1 and it runs Nitrous as well. It was build for drag racing only but I don't mind running VP C12 on the street so it has seen some light street duty. Anyway I'm getting ready to start a new LSx engine that will also be an all out high compression, solid roller, nitrous eating bitch. PM me if you have any questions.

C5natie

iTrader: (1)

Thnx. Those motors sound like some beasts. My compression will be around 12.3:1 and I'll be running a pump/race fuel mix, even though we might have a street tune for 91oct and a race tune for 100oct. Im also looking at some meth injection kits. My plan is to take the car to HPDE events and road coarse while keeping it mostly for street. Thnx on the info, I'll be sure to pm you any questions that come up and keep us posted on that next build.

Ryne @ CMS

iTrader: (10)

i have built a few high compression motors for myself and customers, i have built 2 12.5:1 402's, my 438 in my gto was 12.5:1, the 451 going into my drag formula is 15.1:1 compression (N/A build), and i am currently building a 12.7:1 445 stroker for another customer..... so to answer your question the ls motor isnt any different then any other motor, increased compression will increase cylinder pressure therefore increasing power if the fuel/tuning allows it...

Ryne @ CMS

iTrader: (10)

i think your on the right track with having two different tunes for your vehicle, i would also run a big or maybe a few coolers for your trans if your going to run the yank 3600 stall converter on the road course, because heat is going to be a bitch for you

C5natie

iTrader: (1)

Im thinking of getting a second cooler even though I already have a pretty big one. I know there isnt too much difference in the build compared to a regular motor but you just dont see much info on these builds. I know a guy with a 2006 Z06 and a 12:1 LS7 that hauls ***. Just wondering though, did most of you guys go with domed pistons or just smaller combustion chambers? Trying to see if anyone makes domed pistons for TFS heads. BTW, thnx for the input Ryne.

383lt1impala

iTrader: (33)

My 383 ls1 has 12.56:1 compression and I plan to boost about 7-10psi on c16 fuel with twin turbos and a carburator. Its going to be a drag only set up. I'm going to change out the cam,block, pistons when I can to boost more.

Ryne @ CMS

iTrader: (10)

i like to try and get the most compression possible without going to a dome piston.... i just feel the chance of knock is minimized when running a flat top piston, but if your shooting all out compression then go obviously a dome piston is needed

C5natie

iTrader: (1)

So Im guessing you went with smaller combution chambers and flat tops with big reliefs on them?

$O$OE

iTrader: (14)

I wish I had more CR I feel like 10.3:1 is not enough

Ryne @ CMS

iTrader: (10)

well i run it that way unless i need more compression.... for example my gto had a flat top pistons, milled heads and a relatively thin cometic

Wicked94Z

iTrader: (26)

im not sure how much your pistons are out of the hole on your average lsx build, but id say thinner than the standard .050 head gaskets would be a given for a high compression build. you need to get that quench tight to avoid detonation. im .007 out of the hole with .040 gaskets and i feel relatively comfortable at 12.5 static. easier to run higher CR on ltx though.

A20SVT00

iTrader: (13)

whats the most highest compression can a motor run with pump gas that you all guys have seen or have

C5natie

iTrader: (1)

12:1 can run on pump gas but without meth injection youll probably have to take out a lot of timing.

MrElectric03

iTrader: (71)

My motor is running about 11.5:1 compression, built by CMS. Runs on pump gas with no problems. Ryne did all the tuning, it runs awesome, actually better than it did with my smaller cam. The torque is pretty nice as well.