too low of compression..7.9 to 1
Thread Starter
TECH Fanatic
iTrader: (37)
Joined: May 2008
Posts: 1,034
Likes: 0
From: ocala,fl--- forest-ocklawaha
too low of compression..7.9 to 1 im not fully sure on the comp yet.. but i have done some research and found out that it will be in between 7.9 - 8.2 /1 ratio.. is that to low ??.. i have a twin turbo set up.. it will have full boost at 2,000 rpm,, kkr330 turbo's.. small.. what psi could i run safely on pump gas,, i will add meth down the road.. thanks..
im not fully sure on the comp yet.. but i have done some research and found out that it will be in between 7.9 - 8.2 /1 ratio.. is that to low ??.. i have a twin turbo set up.. it will have full boost at 2,000 rpm,, kkr330 turbo's.. small.. what psi could i run safely on pump gas,, i will add meth down the road.. thanks..
I am 8.25/1 and twin 20G's with the APS kit, 403 cid and it runs great. I am only running 9 to 10 pounds of boost and I figure about 725 to 750 at the rear tires. I havent figured out an easy to stop the inlets from collapsing or I would run more boost. I think my car drives great. I have been daily driving it for about 2 or 3 months. When I was building the engine people told me it needed more compression but it feels pretty good. Off of boost it feels much stronger than the stock engine felt.
if u have some good rods and crank 800 should not be a problem
im on e85 and my engine runs really nice around town and stays cool 180 190 on 80 90deg day
on e85 u wont have spray anything just cruise
im on e85 and my engine runs really nice around town and stays cool 180 190 on 80 90deg day
on e85 u wont have spray anything just cruise
Thread Starter
TECH Fanatic
iTrader: (37)
Joined: May 2008
Posts: 1,034
Likes: 0
From: ocala,fl--- forest-ocklawaha
yea i already have crower i beam rods 6.125.. i am using stock crank,, now i am looking at a single big turbo.. s400-75 t6-83... my turbo's only support up too 330hp a piece.. so 660 hp maybe 700 hp.. t6-83 support's 950 h.p..
I was 8:1 and I think you could hit 800rwhp on pump gas with careful tuning, but I'd look at what timing you should run down low and in the mid range to minimize lag. I think a big single + 8:1 could get laggy if stock cubes, mine was.
On advice of my engine builder went to 9.5 on my 408. He did recommend that I run full time alc injection which plan on and e85 if we get it down the road.
I think the 9.5 makes it a bit less doggy and pretty sure can run 15psi or so on the alc with good timing and afr. Also more power from the higher compression if you can run the same boost level as the lower compression. I have no interest in running much over 20psi ever and likely should be able to run as said maybe 15psi and hit the hp goals I was looking for. Goals were 800rwhp on auto and 850 rwhp on m6. Still might upgrade the turbos not 100% sure yet. Then likely could hit goals at maybe 12psi or have more power in reserve if change goals.
darren I think you can stent something in there..Or just get the upgraded inlets .we spent this much whats another couple hundred?
I would like to see someone dyno with no inlets on there. it won't hurt for brief dyno runs.
I may try that next season .Would be nice to see just what these smaller aps turbos can do on my 408.Put some theories to the test.
I think the 9.5 makes it a bit less doggy and pretty sure can run 15psi or so on the alc with good timing and afr. Also more power from the higher compression if you can run the same boost level as the lower compression. I have no interest in running much over 20psi ever and likely should be able to run as said maybe 15psi and hit the hp goals I was looking for. Goals were 800rwhp on auto and 850 rwhp on m6. Still might upgrade the turbos not 100% sure yet. Then likely could hit goals at maybe 12psi or have more power in reserve if change goals.
darren I think you can stent something in there..Or just get the upgraded inlets .we spent this much whats another couple hundred?
I would like to see someone dyno with no inlets on there. it won't hurt for brief dyno runs.
I may try that next season .Would be nice to see just what these smaller aps turbos can do on my 408.Put some theories to the test.
Trending Topics
im not fully sure on the comp yet.. but i have done some research and found out that it will be in between 7.9 - 8.2 /1 ratio.. is that to low ??.. i have a twin turbo set up.. it will have full boost at 2,000 rpm,, kkr330 turbo's.. small.. what psi could i run safely on pump gas,, i will add meth down the road.. thanks..
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
I'm running 8.7:1 currently, and it takes the first 5 psi of boost to make up for it... Well almost. I used to make 385 na, and with the low-comp block and the turbo I make 407 at 5 psi. Same heads and cam, same intake and exhaust, only differences are a low-comp block and a turbo in the exhaust stream.
At 11psi I'm making 543.
(those are all rwhp numbers)
At 11psi I'm making 543.
(those are all rwhp numbers)
Last edited by John_D.; Nov 25, 2008 at 03:18 PM. Reason: 8.7 compression not 8.4
Check out this build. http://www.exoticperformanceplus.com...Car.php?car=39
It runs a lot better than I thought it would with this much compression. Bob
It runs a lot better than I thought it would with this much compression. Bob
