A boost question

[thumpertrev]

Hope you guys can help. What I have is an old,rebuilt BAE turbo kit.I'm only getting about 4 psi boost unless I take it past my rpm comfort zone (no tach yet). I know that I don't have any exhaust or pressure leaks. I assume this was simply a low pressure kit. The only thing I can tell you about the turbo is that its a t4 on center Rotomaster with a A/R .85 compressor housing. My question is what do I need to change to achieve about 8-10 or so psi.Also, motor is otherwise untouched. I haven't even turned up the pump yet. EGTs' are at about 450 on a level cruise. Also, this is a non wastegated turbo. The motor's not a smoker and I get plenty of whistle so I know things are functioning,just not as much as I would like. I know that turbos spool from exhaust heat as much as flow so,would turning up the pump have any noticable ( seat of the pants) improvement? Thanks in advance.

[Busted]

It's in an S-10, there's nothing there to make the turbo work hard. Try a brakestand and see if that pushes boost up ;)

[thumpertrev]

Truck weighs 4100# has 33's and 3.31 gears. If has plenty to push. Also not gonna brakestand with new tires. :D
Ithink I'm looking for an excuse to buy a different turbo, Maybe mine to large? Should I be wastegated? My setup uses a centered t4 turbine and I haven't found any on the web with a wastegate. I know a gate only limits boost, but all the newer tech turbos use them. I've only seen non wastegates in the larger trucks. This is what makes me think mines too big.

[thumpertrev]

Anyone????

[DmaxMaverick]

It's real hard to get boost out of an unloaded truck. A "brake stand" does not mean burn the tires. Hold the brakes and let the torque converter soak up the HP (not too long, or your tranny will overheat). If your RPM's don't come up enough to increase boost, you are short on fuel and/or timing. And, if you can't hold the tires still, you need better brakes, or don't worry about more boost (you already have more HP than you need).

[JohnC]

If you have a decent amount of HP, the rear brakes alone won't cut it. If it's 4WD, engage it and all 4 brakes should hold it fine.

[thumpertrev]

Will try it in 4wd and get back to ya.

[thumpertrev]

Heres what I found. My automatic advance was way out of adjustment. I also expanded my mechanical comfort level and turned up my pump about 1/5 turn. It only makes about 1psi more than i had,but it feels like a whole new truck.:D

[Patrick m.]

the T-4 non-waste-gated exhaust housing is probably very big, and not going to spin the turbine very fast.
Those housings are available in different sizes, with different outlet mounting arrangements.

If you want more boost with that turbo, get a smaller turbine housing, or a smaller housing and a more aggressive turbine wheel to speed things up