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

 

cam specs?

 

Which cam and springs. Higher boost could mean more valve float.

 

subbed

 

241-248 650 117 springs 660 titanium retainers

 

75 comp. which wheel cast or billet? Race cover

Could be running out of wheel.
715 to the ground? Isn't bad.

 

Im gonna guess with that much duration your blowing air and fuel out the exhaust port during overlap as to why your not making more power at higher boost.

 

^^^^^^^^^^ What he said.
Check your back psi.

 

what was the thought process behind that cam?

 

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.

 

Good HP for low boost!

 

It tuff to gauge real power on the dyno with a loose converter. How much fuel are you using right now? What is the base fuel pressure and duty cycle on the injectors?

 

Nice numbers!

 

That's some nice numbers for only 15psi should be fun.

 

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.

 

Shouldn't be out of turbo with a BW 75 (esp with a 1.32AR and 96mm exh wheel) on a "bone stock" 5.3.

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?

 

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.

 

This thing rocks for a 5.3/75 that's great power great job

 

ding ding, we have a winner

 

Subscribed, good info here.