gharris4000

i got a twin turbo universal system for my 93 corvette. the problem is boost i cant get any boost in first gear. it only starts building boost at about 4000 rpms in second gear. i wrapped the pipes. one pipe per turbo and they are remote mounted.the blow off valve is good i dont know about the waste gates.would a insert or resonator in the tailpipe help the turbo pressure? please help

busa4

awesome. post some pics. ive wanted to do a twin turbo build on a corvette for a while.

turbos generate boost dependant on load. since this is remote mount system your going to have more lag than usual. your engine doesnt produce enough exhaust flow in first gear to spin the turbo. when you get to second gear the engine load(exhaust flow) is greater so it spools up the turbos. there is two ways to fix this: smaller diameter pipe going into the turbos and/or smaller turbos.

gharris4000

what if i replaced part of the pipe with smaller pipe at the turbo from 2.5 to 2" or 1.75. how about that? would that make a diferance. kind of like an air nozzle on an air line. goes from 3/8 to pin hole size. it increases pressure.

busa4

it may help but it would be more of a trial and error. by the time the exhaust gas gets to the turbos in the back, the exhaust gas has cooled to a point where it loses most of its velocity. have you checked your wastegates? make sure there sealing and make sure there connected correctly.

gharris4000

wouldn't a 1.75 pipe build more pressure and increase the heat at the turbos if the 1.75 pipe is mounted in between the 2.5 pipe and the turbo flange with the pipes wrapped.

busa4

a smaller turbo inlet pipe will increase exhaust speed but it will not increase heat. the heat/velocity is lost the farther away from the cylinder head. theres no way to get the heat back. try it and see what happens. it may help a little but i dont think it will help you spool in first gear. your first gear is not producing enough engine load to spin the turbos. most of these rear mounted turbo kits use small turbos for this reason. what turbos are you using?

gharris4000

they are t04e turbos i think 63mm ar50 trim

busa4

That appears to be the perfect size turbo. You may want to check your wastegates. How did you run the boost reference vacuum line to the wastegates?

gharris4000

i run it to a t from the waste gates and to the boost controller then to a vacuum port on intake

busa4

did you use the bottom port of the wastegates? there are two ports on the wastegate: the lower one is the port you need to use. the top port is a vent.