Thread: Gtir T28 Not Holding Boost?

Wheel to housing clearance issue wouldn't show up in leak test...

^^this is very true too^^

I take it your VE had the softer springs. Still seems odd, could be keeping the valves from closing and sealing all of the way.

I should mention, last time I did a boost leak test, my crank would get pressurized too. This time I made sure to check, and it was not leaking air into the crankcase. My valve seals are leaking, I will be replacing them soon and installing 20ve cams back.



True, though I had pretty similar problem without the O-ring too though.

Wait.... what?

Could still be housing and O-ring made it even worse... ?

Just thinking outside the circle. Butter to be safe than sorry.

Yes exactly, had OEM springs initially and would not hold boost. would hit 15psi and fall to about 10psi. this is with stock cams, if you have sr16's or n1's id imagine it would be worse. stiffer valve springs keep the valves from floating and hold the boost in the combustion chamber..especially with a smaller turbo. if you had a larger turbo like a 2871 or a 30r or somethin of that nature, you wouldn't get as much if any pressure drop.

VE's came with two different valve spring rates. Ones are safe to rev to 7,500 rpm, others start valve floating at 7,200 rpm on stock 20VE cams.



That might explain the instant pressure drop when doing the boost leak test past 10 psi too. Now my manifold is a lot less restrictive then the stock ones, but turbo is still fairly small.

Huh? The pressure is on the face of the valves, pushing them closed, not on the backside, therefore the springs aren't having any load at all imparted on them. No?

C

But what does that have to do with software?

i agree Chriscar, pressure will always be lost somewhere doing a boost pressure leak test (crank case,exhaust) the test is to see if there are any immediate leaks like compressor,charge pipes, fittings you might hear leaking...but dont think theres any engines that would hold pressure 100% for the whole time. i was refering to while the engine is running and under boost from the turbo and pressure drop