loudsam

Hi, I'm new here, and I've had the question for several weeks of what would be the advantages, as in horsepower gain, increase or decrease in torque output at what rpm's, and just the overall advantages or disadvantages of increasing compression ratio? You guys on this forum, vs the corvetteforum, seem to talk about head compression more than the corvetteforum. My desire is to get the most midrange, (1500 to 5500 rpm), power and torque without putting in a bigger cam. I would go with headers, and even f.a.s.t. intake, but, I just don't know if I want to mess with the cam.

Thanks in advance,
Loudsam

The Guy in MY 99TA

I think 1 point in compression is equal to a 3 or 4% power increase?

Josh S.

jrp

iTrader: (16)

you'll get more mid range from a cam swap then you will compression. seems like you'll be spending a ton of money and not reaping the full potential. modding works as a system.

FWIW my SCR is 12.02 .

STREET SHARK

Its right at 3% at the rear wheels from 10.1:1 to 11:1 But you should change the cam, its not going to hurt you engine! Researching is the key! Do all the research you can. I paid about $1150 for my cam and heads and gained 93rwhp and 44rwtq I would think you would want a 1500-6200+ rpm powerband When it comes to heads just buy good stage 1 ls1 heads and something like a 222/224 cam with .563/.569 lift on a 114+2 lsa Think about down the road , to avoid changing stuff because you will want more when the bug hits you! And listen to jrp!

STREET SHARK

Hey jrp im running 10.94:1 now! Merry Christmas guys

loudsam

So, on a stock '99 ls1, I could expect about 10 horses for 1 point of compression increase? Is the compression increase good when adding a cam? I think I want exceptional lowend torque, and horsepower. I don't think I'll be doing any real racing with the car. More for showing off at launch, without really exceeding the speed limit, or winding the rpm's up close to redline. Won't a cam give the most horsepower, torque increase in the upper ranges?

jrp

iTrader: (16)

with more compression you can run more cam, that coupled with proper tune, it can be a very driveable setup.

i put together a motor setup for road racing, so i wanted a strong mid range. my whole combo including custom cam reflects that.

im hard pressed to recommend anything to you other then AFR 205's and a ~224* cam. mill them so static CR is 11.1 and i think you'll have more midrange then you know what to do with .

the setup isnt cheap but look at alot of the AFR dyno's and you'll notice the broad tq's they have as well as exceptional hp.

Mike K.

just be careful not to go too high with your compression because you will detonate like a mother f*cker if not using race gas. prob 11.5 to 1 is the highest you wanna go safely if you are using pump gas, now with race gas the sky is the limit.

JZ'sTA

iTrader: (23)

I agree and disagree, it has a lot to do with the tune.
During the hot weather we have here in Florida 11.5 is probally the max. When it's not so hot a 12.1 motor would be fine.

JZ'sTA

iTrader: (23)

I defentially would say a CAM is very necessary.
Go over to the dyno section and find some aftermarket cam vs stock cam dyno's. If you go with the right cam you will completly kill the stock cam's power and torque through the whole entire RPM band.
Were not talking 5-10 HP either, we are talking 20-40 HP and Troque with something like a 224/224 cam.
When you finish doing some searching you will find your goals with be much easier and way cheeper using a cam and leaving the heads stock.
Compression is normally only used by guys and gals that want their cars to be that little bit faster. Your goals sound like you would be much better off using some bolt on's and a cam.

pushinfreight

I would have to agree with Mike. I am at 11.7:1 with my setup and can use 93 pump but this is the limit of what my engine builder and tuner will go with 93 octane. If you have only 91 around I would not go this high.

jrp

iTrader: (16)

whats your DCR and hows the rest of your setup? quench, cooling, chamber design, ect?

pushinfreight

It is a stock bottom end and the head work was done by a local shop. They are massages LS1 heads with ceramic coating. Upgraded the springs to 921's and went with a Revxtreme X4 cam 236/230 .601/.591 114. ARP bolts all around and the standard list of bolt-ons. I am going to be spraying on it once the parts come in and we install the upgraded fuel system. The current setup is pretty much at the limits of being able to be driven every day. Honestly I do not know the exact flow numbers of the heads.