I have installed 99 spec turbos on my 93 Touring. The boost will hold at 10 PSI but not higher. Am trying to get 400 at the wheel but it seems that the boost drops ~3 psi after a few minutes with boost higher than 10 PSI . Any suggestions?

TIA
Thanks.

 

Do you have a boost controller? and these turbos drop off to around 8 psi in the high rpm range...

 

Also, FYI, no way in hell you're getting to 400 wheel HP with twins. About 350-380 is as high as you can get with twins.

+1 on what boost controller. Also, what other mods are done to the car?

Dale

 

Sorry it took so long to reply but was at Duke visiting mother. I have jetcoated downpipe, Greddy SMIC, upgraded fuel system to include 1600 secondary injectors cold air intake, PFC with Commander, and a Stage 1 motor build by Brian at RotorSports Racing, in Kannapolis. they are using two stage Greddy solenoid controlled boost controller and it appears to be in the plumbing. It just does not want to hold the higher PSI, but will hold 10 PSI.

As for the HP claim, I can only say that dynos are different and produce different numbers. I had the car listed as 350 at one shop prior to a Steve Khan tuning. I told him the number and he said it wasn't possible. He tuned it to 300 with the original 93 turbos on a different dyno. Plenty fast for me. The numbers are that just numbers; 300 or 350, or maybe close to 400, I will never use that much power.

TIA for any help. If there are questions I cannot answer I will pass then on to the mechanic.

Charles

 

What is the exact name of the Greddy boost controller you are using?

 

400 on twins is possible, not many people have done it tho, mostly because its just better to go single at that power level.

most who have done 400 on twins, did it with BNR stage 3s. i think only less than a handful actually did it on stock twins and lived to tell the tale

 

Chagar- Something does not sound right. I have a RotorSports engine( stage II) from Brian and twins that have been blueprinted, ceramic coated and massaged by Pettit. I routinely run 14 psi and set them at 17 psi for a couple days, just to see what it was like ( then set back to 14 psi before self-destruct program kicked in). Your J-spec turbos should support more than 10 psi. Can you hear leaking air pressure?

 

I will have to check on the model tomorrow and let you know. To my knowledge they are not hearing air leakage, but it is on the dyno so they would probaly not hear it.

 

If you have not done so already, I would suggest replacing every piece of rubber from the air intake to the turbos, turbos to the intercooler and intercooler to intake manifold with hard pipe. Air flow is better and the risk of a leak decreases. You probably have already checked, but if you are still using the stock BOV's they may be leaking pressure. I had a sluggish charge control valve that stuck open and leaked about 30% of the boost until it would kick over to support the secondary turbo. Lots of places in the complicated plumbing that have to work perfectly to get full boost. Hope you find what is the problem.