High compression & BOOST
Thread Starter
Teching In
Joined: Dec 2012
Posts: 15
Likes: 0
High compression & BOOST What's the highest compression someone has ran with boost? I've got a forged short block that's 11.5 and was thinking about doing a Procharger or turbo and put 12-15 pounds to it on race gas... Thoughts???
TECH Regular
Joined: Dec 2014
Posts: 484
Likes: 18
From: Emory Texas currently
Way more info to say if that's even remotely something worth trying or not. What is all the details stock block,lsx,rhs block. Stock heads mast heads trickflow heads
cam details. Stock crank eagle crank or callies crank. I'm not saying u could or couldn't until u lay out the motor details intake to oil pan. I run forged bottom end stock block worked stock heads and ls6 intake I'm about 10.2 to 1 around 15lbs I use arp studs for heads mains rods and intake and arp bolts in every other hole just to help me have piece of mind.
cam details. Stock crank eagle crank or callies crank. I'm not saying u could or couldn't until u lay out the motor details intake to oil pan. I run forged bottom end stock block worked stock heads and ls6 intake I'm about 10.2 to 1 around 15lbs I use arp studs for heads mains rods and intake and arp bolts in every other hole just to help me have piece of mind.
Well, if no one else has done it before, does not mean it can be done!
I will tell you this. I have a bunch of Buick V6 buddys and they just started going high compression + boost. One guy went up over 10:1 and was going 3+mph trap speed with 22 pounds of boost as he was with 30 pounds. Not detonation, no issues with the motor.
Basically, if the motor hates the compression and boost, it will let you know. If the timing and fuel are there (the right amount and the right octane that is) there is no reason why you CANT got 12:1 & 10 PSI of boost. Hell, that might be the future of this motorsport for the next 10 years till the next combo comes around.
I will tell you this. I have a bunch of Buick V6 buddys and they just started going high compression + boost. One guy went up over 10:1 and was going 3+mph trap speed with 22 pounds of boost as he was with 30 pounds. Not detonation, no issues with the motor.
Basically, if the motor hates the compression and boost, it will let you know. If the timing and fuel are there (the right amount and the right octane that is) there is no reason why you CANT got 12:1 & 10 PSI of boost. Hell, that might be the future of this motorsport for the next 10 years till the next combo comes around.
I'm running a sbe ls6 with heads/cam/fast and an S-trim on 7psi with 93 and meth. Car made 655/557 on a conservative tune. 11.3-11.4 a/f and 16* of timing. Car has great low end and is extremely responsive. Thats the benefit of the high compression and low boost.
I'd consider e85 over straight race gas for the added cooling affect. Good studs and good head gaskets it will be fine.
I'd consider e85 over straight race gas for the added cooling affect. Good studs and good head gaskets it will be fine.
My buddy has been running a 11:1 cr LS6 with tfs220 heads and FAST102.
ARP Head/main studs.
Forged rotating assembly.
YSi 25+ psi.
E85
6 speed street car. Full weight with AC drive it anywhere type car.
Well over 200 passes on that setup - best of 9.21@158
my new turbo setup will be at least 12:1 on E98.
For a basic street car, I’d be happy with 11:1. And good gas. Just keep timing in check...
ARP Head/main studs.
Forged rotating assembly.
YSi 25+ psi.
E85
6 speed street car. Full weight with AC drive it anywhere type car.
Well over 200 passes on that setup - best of 9.21@158
my new turbo setup will be at least 12:1 on E98.
For a basic street car, I’d be happy with 11:1. And good gas. Just keep timing in check...
Trending Topics
With proper octane it will be fine if the tune is good. I’m putting my sbe 10.7cr LS3 thorough 22psi with a D1X. Whenever I do a build I’m gonna bump cr to the 11’s. I run e85 so that definitely helps but I ran it on 93/meth before just fine.
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
Keep in mind compression is not only determined by the static number but the cam timing. Big benefit going in that direction will be the big loss in turbo lag. Better track numbers, possibly lower peak Hp dyno numbers.
Last edited by handyandy496; Oct 5, 2018 at 11:21 PM.
TECH Apprentice
Joined: Apr 2012
Posts: 333
Likes: 4
From: New Zealand
My LS3 is around 11.1:1 static with a smallish 218/222 cam and very tight quench (about 31 thou). I can run 13.7psi through twin turbos on pump gas (93).
On C16 you'll be fine as long as you don't run some crazy small tight LSA carby style cam in it. Keep dynamic compression under 8.7 and you'll be fine. My cam at 11.5:1 would be right at 8.68:1 DCR so would work great on C16/E85. The bigger cam you go the less issues on cylinder pressure
On C16 you'll be fine as long as you don't run some crazy small tight LSA carby style cam in it. Keep dynamic compression under 8.7 and you'll be fine. My cam at 11.5:1 would be right at 8.68:1 DCR so would work great on C16/E85. The bigger cam you go the less issues on cylinder pressure
My 427” Twin 88mm combo I’m doing has a static compression of 12:1 with a dynamic over 9:1.... Cam is in the 26x/27x range @0.50” I’m dual fueled though, E85 on the street and M5 Alcohol when racing. There’s a lot of preparation that needs to be taken into account when running boost with high compression (Softened combustion chambers/Quench pad, Quench distance, Charge air temp ect) definitely not a cookie cutter decision.
