93 corvette twin turbo boost problem
 

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

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.

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.

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.

93 corvette
 

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.

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?

they are t04e turbos i think 63mm ar50 trim

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?

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

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.

yes on the bottom port. i thought that putting that small of a pipe would cause more backpressure and more velosity and heat. i have wrapped the exhaust wouldn't that help. i am grasping at straws here.

thanks for the info.

yes. making the pipe smaller will increase the velocity but its not going to do as much as you want it to do. your talking about creating enough flow to eliminate 2000-3000 rpm of lag in first gear. the smaller inlet pipe is just not going to do that. wrapping it will help but again its not going to make that much of a difference. im assuming the kit is designed for the corvette so with those turbos your not going to get any spool in first gear no matter what you do. in my opinion, boosting in first gear is rather useless anyway as its just going to burn up the tires. second gear spool up is a lot better. i wouldnt change a thing and just enjoy it. wish i had my corvette so i could turbo it. im so damn jelous. what did the kit come with as far as tuning?

nothing. i had to build everything. even an accell dfi system. all i got with the kit that i could use was the turbos and wastegates everything else i made.i will try to post some pics.

do you think it will help at all with boost with the smaller pipe? i am not neccesarily lokking for boost in first gear. it is that i only get about 2-3 lbs of boost in second and about 5-6 in third gear. will that help some.

it may help a little but not much. you may want to try some better flowing headers. that definitely may help quite a bit.

i have a set of hooker full length headers already. there has to be something i can do to improve boost a little more.

i think your at the maximum flow your going to get without choking out the engine with a smaller exhaust

how come on the c6 corvettes remote turbo system they dont have any problems with boost.

is there anything at all you can think of that would help me?

im out of ideas. did you ever check your wastegates? make sure there not leaking or not adjusted correctly. since there are two of them there difficult to get in sync with each other.

i checked them and a friend put his hand in front the exit side when i was revving it up and he said it was leaking a little.

that would make sense. if there leaking its going to increase lag. each wastegate should have a sealing ring that mounts under the wastegate plunger. if this sealing ring is missing they will not seal at all.

can i put in an h pipe and use just one wastegate. i figured out that only one was leaking

It would probably be cheaper and easier to just fix the wastegate thats leaking.

what is the trim on the turbos?

are you using an intercooler/s?

please post pics

it has been my understanding if you were to use a 50 shot of juice it will not only help you out of the hole but it will help you spool up faster.you only need to back off 2* of timing per 50 shot of nitrous ( it will help a lot)

thanks alot gives me something to think about

get a free photobucket account and post pics, full details of setup helps too.