5.3 on 15psi 718 hp
12-22-2013, 09:16 PM
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5.3 on 15psi 718 hp We had the car on the dyno trying to go 20plus psi but the motor does not make power pass 15psi car has a 4500 stall is a bone stock 5.3 with cam and springs only turbo is a borgwarner 75mm with 132 back housing car is running 1600 pound in injectors Weldon pump and e85 timing is at 17-18 degrees and there is no boost Leak I did notice higher oil pressure after the cam swap under wot . So on higher boost level I lose power don't know we're to start
12-22-2013, 10:02 PM
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12-23-2013, 09:36 AM
#10
Thats a pretty wide LSA, thats like 10.5 degrees of overlap? Not too bad. I can't imagine there is much back pressure on a 1.32 AR and only 15psi. Is that the larger S475 96mm wheel version as well?
I thought most of the big baddie turbo racers used monster cams with very little back pressure. I have no personal experience with them, but if you can do 1:1 or better on back pressure you shouldn't get alot of reversion with the high overlap/duration cams.
I didn't even know you could run a 650 lift cam on a 5.3 without special pistons or fly cutting. Doubt the OEM heads/intake would pick up any gain from going with that large of a cam.
I thought most of the big baddie turbo racers used monster cams with very little back pressure. I have no personal experience with them, but if you can do 1:1 or better on back pressure you shouldn't get alot of reversion with the high overlap/duration cams.
I didn't even know you could run a 650 lift cam on a 5.3 without special pistons or fly cutting. Doubt the OEM heads/intake would pick up any gain from going with that large of a cam.
Last edited by Forcefed86; 12-23-2013 at 09:56 AM.
12-23-2013, 11:34 AM
#15
If it came to be 850 HP at the crank and you were doing that with a 75 MM turbo...Id say your out of compressor wheel at that point...but I am not an expert.....you would need to read a compressor map for that wheel to see if you have maxed it out.
Last edited by Chicago TDP; 12-23-2013 at 11:55 AM.
12-23-2013, 11:40 AM
#16
I was still making power at 24psi with the baby t4, 1.10AR (83mm wheel) S475 on my 8.6:1 5.3 with 317 heads. I'd bet that funky cam has something to do with it. Haven't seen Any "stock" 5.3 builds with a huge cam like that. Just isn't necessary...
What is it running for Down pipe/exhaust?
12-23-2013, 05:56 PM
#17
That's actually not bad power at all for a 5.3/75mm. Some of these high dyno numbers people post are just not accurate info IMO. When you check the power the cars are showing they just don't add up. From what I have seen the bigger cams/smaller turbos will make a lot of pk power on low boost then max out the turbo early. I think some of has to do with the larger cam not being happy with higher back psi, as well as turbo flowing less air at a lower pressure ratio. As power is made at higher rpm the turbo, ignition, fuel system valvetrain etc all have to work harder to keep up.
