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
Originally Posted by Websy21
What about 8:1 with a 408 on 91 pump?
Originally Posted by MIGHTYMOUSE
maybe north of 850.. i don't have direct experience.. but i can assure you that displacement will hurt your mileage more than the compression
I really think this is the way to go, 8.5-9 for turbo's anyways and 9-9.5 for S/C. Done deal, thanks guys! consider how much power you want to make
5-6-700 you can keep highish compression and run around on pump gas without much sweat
8-9-1000 hp and you want to 'enjoy' the car on regular fuel i would def. drop the compression.
5-6-700 you can keep highish compression and run around on pump gas without much sweat
8-9-1000 hp and you want to 'enjoy' the car on regular fuel i would def. drop the compression.
Wow, its so much better when a pro explains it, LOL. That makes so much sense, sacrifice a little down low and maximize power output with pump gas. Lower CR is the way to go unless all out race application, meth/race gas.
Just for curiousity any takers guessing here what someone on average would be leaving on the table motor alone by dropping one point in CR? Obviously it doesn't get out weighed by what extra boost you will be able to run though.
This is a very interesting topic as I always pondered this when I was going to go with a S/c on stock cubes. It didn't make sense to me to run 6.0 heads and drop to 9.5 just to run maybe one or 2 more psi. You're only limited to a certain power level within stock cubes so why go the extra mile for giving up efficiency, etc.
Just for curiousity any takers guessing here what someone on average would be leaving on the table motor alone by dropping one point in CR? Obviously it doesn't get out weighed by what extra boost you will be able to run though.
This is a very interesting topic as I always pondered this when I was going to go with a S/c on stock cubes. It didn't make sense to me to run 6.0 heads and drop to 9.5 just to run maybe one or 2 more psi. You're only limited to a certain power level within stock cubes so why go the extra mile for giving up efficiency, etc.
Thread Starter
Launching!
Joined: Mar 2005
Posts: 229
Likes: 0
From: cobourg ON
well guys looking into my build here a little farther seems like im almost limitied to 9:1 compression unless there are head gaskets out there i can use that will drop a full point for me haha. and with boost it seems like head askets are a problem to start with on a FI gen III but MM you are using the new felpro's correct? buuilt even with the addition for the extra 2 bolts? have you had time to check them out yet and see how they perform? what would be the best bet to deal with high boost numbers so far gasket wise??
I can't speak for the gaskets but I wouldn't worry about running 9:1 CR. You should be fine, I decided to go with 8.5 instead of 9.5 but if 9 was option for me I think I'd do it. Kinda the happy medium so to speak.
Well guys I talked to Tony at AFR and my SCR is not were I want it. I think I would want atleast 9.5 SCR. Here the set-up Ls2 402 with -12dish pistons and heads are AFR 225 72cc. I know I need a gasket size of 4.125 but what thickness do I need. Would 6.0L gaskets work or do I need something else. Thanks. I'll be using 93 oct fuel and it will be a street car. I may drive it about 100 miles a month. I would like about 750+rwhp. Thanks
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
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
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
10 Reasons the LS7 Is GM's Most Extreme Naturally Aspirated V8 Engine Ever
Verdad Gallardo
Originally Posted by KWIKKAR
Well guys I talked to Tony at AFR and my SCR is not were I want it. I think I would want atleast 9.5 SCR. Here the set-up Ls2 402 with -12dish pistons and heads are AFR 225 72cc. I know I need a gasket size of 4.125 but what thickness do I need. Would 6.0L gaskets work or do I need something else. Thanks. I'll be using 93 oct fuel and it will be a street car. I may drive it about 100 miles a month. I would like about 750+rwhp. Thanks
Originally Posted by mahhddgtp
Has anyone swung low 700rwhp with 15psi on a 346ci motor on 93pump? What CR for that? 8.1?
Originally Posted by TAQuickness
You'll need a gasket thickness that give the desired quench. Much better to drop compression by changing the pistons.
Well I can't change the pistons so what gasket would you say I should get.
If one were to run a 347 on 93 fuel with a 10:1 ratio. What would be the advised max boost to run 10 - 12? Also how much would a cam play in this factor. Would you use a EPP blower cam 232/240 or a TR blower cam 214/230 ?
I'd go with the bigger cam and boost less with 10:1 personally. But I think you can get into the low 600's at 10:1, and beyond that it's a matter of tunings and inlet air temps.
Originally Posted by Pro Stock John
I'd go with the bigger cam and boost less with 10:1 personally. But I think you can get into the low 600's at 10:1, and beyond that it's a matter of tunings and inlet air temps.
TECH Apprentice
iTrader: (3)
Joined: Nov 2005
Posts: 387
Likes: 1
From: Tinker till it blows, then back it off a notch, maybe!!
Originally Posted by cablebandit
quit thinking boost and think horsepower. you guys need to consider your dynamic compression as well.
But in that you mentioned it twice in this thread, what do you considerto be the threshold?
thx
bte: Were you happy with your Darts?
