What is the maximum boost you can get out of a 6.5 with the gm-8 turbo? I am shopping around for guages and am curious to how big of one I need to get.

12psi maximun useable boost - a 20 psi gage is satisfactory.


JCWHITNEY.com has combo 30"vac\20psi Boost gage for about 20 bucks.


Simple matter to switch line to vacuum pump or wastegate solenoid for system testing

My vac at the WG in stock form bounces alto, 16 to 19. I put on the boost control and it will stay at 20.5, solid, no movement. I can turn down the boost control and it will bounce again. I have do boost gauge. What's going on?

sorry, I have no boost gauge. http://www.dieselplace.com/forum/smileys/Clown.gif

btw, I have replaced turbo wg solenoid, and checked the vac. line from wg to solenoid, it held 22 for 1 minute with no movement

Get a boost gauge first. The ECM changes vacuum to the wastegate to control boost. It may be working ok.


I would go for a 20 or 30 PSI gauge. Even though you probably won't ever run more than 12 to 14 PSI, it still spikes up a lot higher.

What is the importance of the vaccum reading on the gauge? I hadn't planned on buying a gauge with both the pressure and vaccum but if it is needed then I will do so. That gauge on jcwhitney is pretty nice for the price.

The Vacuum-Boost gage is not necessarily needed, but I use it as a very handy system status tool.


Boost is function of PCM-controlled vacuum on wastegate servo.


When having Boost failure problems, first thing to check is vacuum on wg servo @ ~15", then vacuum at pump @ ~25".


Manifold pressure at idle is Baro, or 0 Boost pressure - if air filter becomes wet, or extremely dirty, Vacuum Gage will indicate where problem exists as air flow is reduced by faulty filter.


This can cause black smoke, no power, just like losing vacuum at wastegate servo results in no Boost, with black smoke, no power.

if i buy one of bill's turbomaster, i won't need to check the vaccum right? Aren't the vaccum pump and the solenoid and all that bypassed with the turbomaster? Edited by: steiner43511

Correct

if i buy one of bill's turbomaster, i won't need to check the vaccum right? Aren't the vaccum pump and the solenoid and all that bypassed with the turbomaster?


Yupp in fact I removed vaccum pump and put a '93 belt on so no chance of pump seizing and burning up belt.

if i buy one of bill's turbomaster, i won't need to check the vaccum right? Aren't the vaccum pump and the solenoid and all that bypassed with the turbomaster?


Yupp in fact I removed vaccum pump and put a '93 belt on so no chance of pump seizing and burning up belt.





Isn't the vac pump needed for the brakes? Aren't the brakes boosted by vacuum?





T

they are boosted by the power steering pump hydraulics. so no.

Don't you need vacuum for the heater/air controls in the dash?

Vaccum ONLY runs Waste Gate and EGR sensor. EVERYTHING on my truck works after taking out pump. BRAKES work, Heater & AC work Power steering works, radio works, doors locks work. transsmission works, Cruise control didn't work before still don't. Trace the lines for yourself if you don't believe me and Bill Heath. If you put the Turbo Master you don't need the vaccum pump. '92&93's never had a Vaccum pump because it had a manual waste gate controller. Edited by: 16gaSxS