boost

[piersbc]

I was monitoring/testing my boost yesterday and under full acceleration (3500rpm) my boost climbed to 8 lbs then it dropped off rapidly. Then the tranny shifted and as the rpms got back up to 3300 the boost only was at 6 lbs. Then at 2000 rpms curising the boost maintained 2-3 lbs. So my question is...is this normal specs for the stock engine?

Also, is there any reflashing/reprogramming of my truck's computer? Any updated versions? Are my only options a chip and boost controller?

[More Power]

Your experience with boost pressure is all perfectly normal. GM designed the system that way to allow the engine to produce max torque at about 1800-2000 rpm. Think of boost pressure a torque indicator.

The various chips available for the 1994-95 models usually raise boost pressure somewhat. Either a JK electrical boost device or a Heathdiesel.com Turbo-Master allow you more control over boost pressure. Still, boost will decrease as engine rpms increase, though not quite as much. It's simply a matter of exhaust backpressure overpowering the wastegate actuator (which is either spring tension or vacuum).

If they were a little less expensive (to use as an experiment), I've thought that an adjustable Banks Big Head wastegate actuator made for the LB7 Duramax might work to manage the 6.5 turbo wastegate as a function of manifold pressure. This would give a more constant boost pressure across the rpm range - certainly up to 2800 or possibly 3000 rpm. A constant boost pressure across the rpm range is why the Duramax produces a nearly flat torque curve up to ~3K.

Personally, I'd stick with no more than 10 psi without an intercooler or 12-14 with.

Jim

[a5150nut]

It's some of that old "Idiot Proofing" to protect us from ourselves. Talk to Heath, he has a chip that will adjust boost, fuel, ect. He gives a real good explanation as to how it all works. I used an Eprom my boost sensor and see 10/11 lbs at fullthrottle but it still starts backing down about 2800rpm. At cruise on highway I run 3 lbs boost. Any higher and I would need an intercooler.

[bbudus]

Mine will jump to about 18-19 under hard acceleration, exhaust temps don't climb much over 550-600f. When I am cruzing I am sitting at about 5-8 depending on how fast I decide to go that day. Usually running exhaust temps around 400-500f. I don't pull as much as I used to, but I do punish my leafs with the loads of wood I put on the back, and I am happy to report, no change.

Bbudus