View Poll Results: what compression ratio are your running with boost?
8:1
8
2.92%
8.5:1
44
16.06%
9:1
55
20.07%
9.5:1
69
25.18%
10:1
66
24.09%
11:1
32
11.68%
Voters: 274. You may not vote on this poll
High static compression and forced induction
I bet it runs great, sucks that you cant run more boost without meth.
my old vortech car with 10:1 compression ran great, great throttle response with boost. I ran 9 psi on the stock bottom end. Went consistent 11.2's full weight with drag radials on the stock rims, and just lca's.
my old vortech car with 10:1 compression ran great, great throttle response with boost. I ran 9 psi on the stock bottom end. Went consistent 11.2's full weight with drag radials on the stock rims, and just lca's.
10.5:1 stock bottom end with 13psi here. 93 octane, but i'm spraying a 50/50 mix of methanol also. 15* timing so far (took 22 max NA), but it seems like I could add a little more.
TECH Resident
Joined: Jan 2007
Posts: 751
Likes: 0
From: Texas
Wow! That meth is really helping out. The ls6 heads make all the difference between our 2 setups though. Even when stock on 93 octane they would only allow for 22-23* timing before pinging.
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Thread Starter
Launching!
Joined: Mar 2005
Posts: 229
Likes: 0
From: cobourg ON
WOW ! 1.5 yrs in the making this post has given me alot to read about hahaha . thanks guys for all the feedback and the numbers I knew this has been a longtime question for many and im sure this will help alot of those guys out there that think they need to run 4:1 compression to run awsome numbers.
as for the original shop iwas working with to start at this thread they became alcohol junkies and now they run something like 15:1 and 25lbs through a BDS LOL but i dont have the 30K they dropped into there engine to put into my street car haha. anyways thanks a million for all the replies really has helped me out with my build that im running 10:1 now on my stock bottom end and 15 lbs with meth. car runs strong never had a dyno or a tune other then the seat of my pants thankfully i havent detonated the pistons through the oil pan so far guess my eyes work well still.. all the best
keep moving forward 1/4 mile at a time!
as for the original shop iwas working with to start at this thread they became alcohol junkies and now they run something like 15:1 and 25lbs through a BDS LOL but i dont have the 30K they dropped into there engine to put into my street car haha. anyways thanks a million for all the replies really has helped me out with my build that im running 10:1 now on my stock bottom end and 15 lbs with meth. car runs strong never had a dyno or a tune other then the seat of my pants thankfully i havent detonated the pistons through the oil pan so far guess my eyes work well still.. all the best
keep moving forward 1/4 mile at a time!
My opinion of course.
No corn out here El Paso, TX!! I was hoping for more power on pump gas since I'm putting down 525 rwhp already? Or at least that's what it said on the dyno sheet I got when I got the car back from the shop I sent it out to. Oh well I'll probably go with meth to get a little more power!!
Last edited by Tirefire; Feb 7, 2011 at 08:05 PM.
I've had someone make 685rwhp through twin intercoolers LS 347ci 10:1, D1SC at 12psi.
That setup did get some detonation on pump fuel, IATs were fine though.
Those numbers are solid with twin intercoolers!! That will give me time to purchase a front mount and meth later down the road. Like KP told me "small steps"!! Hey Fraser so what's my final compression looking like on my block? I was under the impression that it was 9:6:1, I thought those heads were 62 cc.
10.4:1 and boosted I want in on this discussion because I have heard so MANY conflicting stories about my build. Upgrading the Family Truckster (2002 Tahoe)
Here is the down and dirty.
Iron 408cid*, -3cc pistons, WCCH worked LSA heads with 75CC chambers, LS9 gaskets (.051 I hear), TVS2300/jackshaft/cogged rear/10 rib setup/ should easily make @12-15psi.
My cam was spec’d by PatG and the CR’s were:
Static compression: 10.4:1
Dynamic compression 7.50:1
Gas is 92 Octane and meth kit can spray whatever mix deemed necessary. Was thinking 50/50 water and meth but 100% meth is fine too.
So you guys say “No way!” or “Sure, but you’re going to be pulling timing up top”
I'm just asking your thoughts. The engine is built, the blower is ordered. Should be together and on the dyno in March sometime...hopefully.
*(The engine is all forged Eagle crank/rods Aries Pistons, all ARP hardware.)
Here is the down and dirty.
Iron 408cid*, -3cc pistons, WCCH worked LSA heads with 75CC chambers, LS9 gaskets (.051 I hear), TVS2300/jackshaft/cogged rear/10 rib setup/ should easily make @12-15psi.
My cam was spec’d by PatG and the CR’s were:
Static compression: 10.4:1
Dynamic compression 7.50:1
Gas is 92 Octane and meth kit can spray whatever mix deemed necessary. Was thinking 50/50 water and meth but 100% meth is fine too.
So you guys say “No way!” or “Sure, but you’re going to be pulling timing up top”
I'm just asking your thoughts. The engine is built, the blower is ordered. Should be together and on the dyno in March sometime...hopefully.
*(The engine is all forged Eagle crank/rods Aries Pistons, all ARP hardware.)
Teching In
Joined: Apr 2009
Posts: 2
Likes: 0
From: Milford MI
E85 - The Poor Man's Race Fuel Gentleman, I currently work for someone involved in advanced engine developement. Trust me, E85 works well in an 11 to 1 engine with leaner mixtures and more timing than pump gas at high boost levels. It also makes 10 to 15% more power due to the higher cylinder pressure developed by the additional timing and leaner mixture. Plus it's cheeper than regular gas and makes lower emmisions. Why would you want to use premium pump gas anymore???