Bought this truck new, always happy with it did everything I needed, won 50 bucks taking off from a dead stop in 5th gear with out burning the clutch, took a block to do it. Tested the boost one day all I could get 7 pounds , yup 7 pounds, always ran good, pulled good, nice fuel mileage, dependable, just lived with it. A few years later its time to play, retest still 7 pounds,full throttle good , fuel psi good , air cleaner good, boost leaks- hoses and clamps good, charge air cooler not tested but no signs of leaks, ya I know really needs to be tested. Fuel pump mods - a little here, a little here and a little bit more here. Oh yea a k/n filter and some timing almost 1/16, don't forget straight pipe. Ok much better 15 pounds before the governor kicks in. A new day is here and we now have two 5 inch stacks sticking out off the bed, can you see me smiling, love it. Well we are now getting 19 pounds , I can live with it, no I can't , I'm guessing a 91.5 turbo is that sad, any thoughts.

Thanks
Steven M

 

check your lift pump fuel pressure. should be 5-6 lbs idling and around 3 lbs wot. Mine only had 10 psi stock. now with my mods. I get 22-25 if my conv. is in a good mood!!!

 

If you don't want to spend a fortune, I'd look for a 12 of 14 CM housing for your turbo.

Mine boosts to 28-30 PSI.

 

With out tuning the ip I dont think you will see much more boost than that. Have you turned the full power screw yet? Read the sticky about the runaway and pump tuning. Mine will make 44 psi of boost with the stuff in my signature.

 

Adding more fuel will help but the stock turbo isn't the best for high boost, you will start to encounter turbo bark at the 20psi range for example, but you can get much more boost by toying with the full power screw, get gauges first. With the mods in my sig and stock injectors I push 32psi on my 91.5 with the stock auto/converter, though I try to keep it below 20 for fear of killing the tranny early

 

Actually, about 14 - 15 psi is what stock configuration should get--not 7ish.

Steven, you say that you have no boost leaks--how did you determine that? You can't just eyeball the boots and proclaim them good. You want to use compressed air and pressurize the intake up to about 15 - 20 psi. You can find lots of small leaks that way, and those small leaks add up. However, if you still have the stock boots on, you might as well just replace them with a set of much tougher silicone boots. I guarantee you have leaks if those are the stock boots.

The turbo on a 91.5 really isn't that bad. With my 1992, I ditched the stock exhaust housing and replaced it with a non-wastegated 16 cm2 housing. At the time, I considered going with a takeoff wastegated 12 cm2 from a 24 valve truck, but thought EGT might get too high when hauling my loaded camper. It sounds like the wastegated 12 is much more popular today, and with your 5 speed you'd certainly appreciate the much-improved spool-up and throttle response.

 

where do you get these ?

 

PDR used to carry the high quality boots--that's where I got mine for my 1992 truck several years ago. BD would be another place to check, along with Source Automotive. I'm sure there are others.

 

Thank you guys for the response appreciate it. Plans to test for leaks with air pressure is in the works, my quick test I put a little grease at the edge of the boot, quick test drive see if the grease blows out. Right now the best option would probably be the smaller exhaust housing, that will have to wait thou new steering gear box first. The fuel screw is in 3 turns, will keep you all informed.

Steven M

 

I have not touched the injection pump on my 91.5 and can get up to 17psi with the KSB on. The only things I have done is make the stock air box breath better and get rid of the muffler.

Sounds like something just isn't right with your setup... I use soapy water from a spray bottle to test for leaks.