So it looks like my 7-8 psi is a little on the low side considering I have the pump turned up a bit and can go more (no black smoke yet) and I have a big intercooler, NPR truck size.
How do I increase the boost? Cheaply.

Thanks
Randy

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I have nothing to add to this other than to see all the cool concentric rectangles. Sorry. <img src="/forums/images/graemlins/smile.gif" alt="" />

You increase the boost by changing the wastegate.

You can either swap the spring (involves opening the can which might not be easy) or adjust the length of the rod.

I have done it by cutting the rod and welding in a threaded adjuster like one end of a turnbuckle. You can also just thread the rod and use a locknut rather than welding and risking cooking the wastegate seals.

Shorter rod = later opening and higher boost.

Or you can do what the riceboys use, two bleed valves in series from the pressure line with the wastegate line tee'd from between them. Adjust the bleed valves to adjust the boost.

An EGT gauge is a great idea if you're playing around with fuel and boost. I fried a turbo on friday, the first warning was the EGT reading 880C. <img src="/forums/images/graemlins/angry.gif" alt="" />

Thanks for the tip. I cut the rod and threaded both halves after shortening the rod 1/2".
I used a coupler nut and two jam nuts to reassemble. Shortened it up by about 1/4" to see what that would do. Looks like it has brought boost up to about 11 PSI.
I'm getting an EGT gauge before turning it up anymore.
Thanks again.

Great.

You'll find that if your intercooler can keep the boost temps under control, that more boost will lower your EGT's.

I have also found that turbo backpressure is roughly double boost, but on a turbo that is too small, your exhaust pressure will skyrocket.
I tried to run a T2 turbine on my 4BD1T in place of the T25, around 3500 rpm the back pressure went to 45psi to provide boost of 15psi.
The T25 would run 30psi to give the same boost almost irrespective of revs.