Been a bottle fed truck for numerious years but going a new direction. My motor is a hair over 11:1 compression. i know for FI you want considerably lower. how low do i need to be? The motor is already forged and i really dont feel like sending back to cali to be redone. Im running LS3 heads on it right now with 65cc chambers. I was thinking my only option is 317 heads. I just hate to give op the flow of the better heads. Will the long run gain be better and worth it?
Slowest in Oklahoma...
Ideally need about 8:1 - 8.5:1 compression. But there are some guys running higher with rear mounts or smaller front mount turbos. Might wanna pm some members who run turbos. Im lookin to run twins on my truck, soon as I get my $ right to start piecing it together
11:1 is pushing it. Lowering it to 317 heads would be a great move. Don't worry about the flow with FI you are forcing the air through. You could sell your other heads and do just fine.
2006 Superior Blue Trailblazer SS AWD, Stock as a rock
Sold: 2002 GMC Sportside Denali front end with a 2002 LS1, FLT level 5, Yank 2600, Trick Turbo, T76, Nelson intercooler, 60LB injectors, Warbro fuel pump, Eaton locker, Magnaflow, 3.42, Nelson Performance Tuning (speed density).
Sold: 1981 GMC LB RC 1500 2002 4.8L 4L60E 12 bolt 3.73 Richmond Lock Right AC PS Nelson Performance tuning
just because youre pressurizing the intake doesnt mean that head flow isnt important... it might not be quite as critical but it definitely makes a difference!!!!! you will be able to make some power with stock 317s but a good port job would still be highly recommended!!
01 Silverado
speed sometime on ls1tech ive looked this up many times , and looking towards to having a fairly high compression boosted setup probably at end of next year, if i can ever get what i have now off jack stands lol
high compression less boost higher octane.. response is at a drop of a foot !!
Simple: 408 on steroids!
single digits coming soon!
ideally you want, the highest compression you can run without knock so it will spool almost instantly. That all depends on octane, boost and chamber design really. idk if i would go as low as 8.0:1 but i would keep it 9.5 or below. Maybe find a set of 317's for cheap and send them off to get a mild port job and get some bigger valves in there, then sell your ls3 heads and intake to recoup some $
04 RCSB 5.3, Homemade 80mm FM, TU1, TH400
That's actually what iv been talking to a guy about. Leaving compression and running e85. Mines on jackstands to. It's been up there alot lately lolOriginally Posted by skeet
speed sometime on ls1tech ive looked this up many times , and looking towards to having a fairly high compression boosted setup probably at end of next year, if i can ever get what i have now off jack stands lol
high compression less boost higher octane.. response is at a drop of a foot !!
Just because alot of the truck guys go lower compression doesn't mean its the best thing. Most do it because they still want to run 91 octane and not have to worry about it as much. The tuner is able to set the timing low enough that they never really have to worry about it. 11:1 isn't THAT much. 11.5:1, e85 and moderate boost levels is the direction I'm heading right now. Only thing I'll change on my motor is new rings and ls9 head gaskets. May drop the compression to 10.8-11:1...
2007 RCSB|DTR81 built LSx 3xx|PRC|NX|BOGART|MSD|QUICKFUEL 950 E85|4L80|FTI Converters|Smith RaceCraft|Racepak
midweststreetcars.com
What kind of power are you hunting out of that setup? I want 750/800+ or I'm wasting my time.
800-1000...If I can't make more than 800 than there is no point in changing my current setup
2007 RCSB|DTR81 built LSx 3xx|PRC|NX|BOGART|MSD|QUICKFUEL 950 E85|4L80|FTI Converters|Smith RaceCraft|Racepak
midweststreetcars.com
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