60-1 is plenty, my 60-1 with a gt wheel supported 10 Psi on my lq4

 

just shooting ideas. i would have to say leak also then.

 

How close is the tune when you guys jump to a ls6 cam?
Did you go with longer pushrods?


i need to get off my but and put mine in.

 

I started working with my tune this evening and it is off a lot more than I thought it would be. It runs fine on low boost but it is way off on high boost. Oh well, it's not something that a little time won't fix.

I didn't go with longer pushrods. Kbracing has been running his stock pushrods for quite a while so I just followed his lead.

 

the waste gate isn't exact. on some set ups a 7psi spring is more like 10psi, other set ups it might be only 5psi. a 7psi spring will actualy start to open at 5 or 6 psi on the bench but on the truck there is exhaust presure pushing on the valve and it might actualy start to open even sooner. the psi when it equalizes varys with every set up.

a cam change and loss of 1psi doesn't seem un usual to me. i bet it is making a lot more power even at that lower boost.

 

The weird thing is that is goes right to 5.5psi which is the wastegate spring and holds it until about 4,500rpms. At 4,500 it starts dropping and is down to about 4-4.5psi at the shift points.

By seat of the pants it still feels faster even with the lower boost and my maf reading went from 11,400 to 12,000 on the low boost setting. The maf flow is as high now at 5.5psi than it was at 8psi before the cam.

 

Parish hits on the one thing I didn't think about, Exaust back pressure...

The exhaust pressure has increased trying to meet the demand for more air. The high exhaust pressure on the waste gate, assisted the spring in opening sooner. I bet if you got a bigger exhaust housing your back pressure would drop and your missing boost would come back. or just turn the **** on the boost controler for high boost, and live with the low boost. 1 psi isnt anything to worry about imo...

 

I can tell you I lost 2PSI after I ported my heads. Turbo maxed out @6000' elevation made 16PSI before, and will only make 14PSI now, wastegate completly shut. Im thinking about removing the wastegate and blocking it off. The waste gate still bypasses exhaust even when shut.

 

what turbo?