overboosting.

[bird]

need some help with a freinds 86 gn, 60 turbo 63 exh housing, ported heads, 210/205 cam 3" downpipe, racegate. darn thing overboosts climbes slowly to 15 then jumps to 20 and keeps going. wastegate hole is ported to 32mm can go a little larger to35mm(down pipe opening is 35mm). would this make that much of a difference? tried everthing have the lightest(green) spring in the gate. even tried manually locking the valve open and it still overboosts, car is quick but not that quick that gate should be rated to 900hp. guessing this combo to be around the 500hp mark. were puzzled. please help. another freind suggested going to a bigger 83 housing? i dont think that should make a difference. should it?

 

[TType84]

although i cant tell you what your problem is.. i would say DONT SPEND ANY MORE MONEY.

you are right in the assumption that everything SHOULD work okay.. there is definitely a problem somewhere..

 

[Chris McDade]

If the car is over boosting.. which it sounds like it is. You need to put the heavier spring in the deltagate. You want more tension in the deltagate not less. Try a 18lb spring. That's what I had to use when I had a set up close to yours.

What brand deltagate is it?

 

[bird]

hey chris the gate is a turbonetics racegate. i was under the impression that a lighter spring would open the valve quicker from the boost presure. if the spring is stiffer wouldnt it reqiure higher presure(boost) to open? causing more airflow to the exhaust wheel and making it overboost even more?

 

[Chris McDade]

Bird,
It's just the opposite. The lighter the spring the easier it is for the delta gate to open, therefor over boosting. The stiffer the spring the harder it is to open and therefor you won't over boost. Don't ask me how I know all this...

Hope that helps.

 

[bird]

hey chris now im rely confused! none the less ill try installing a stiffer spring this weekend and ill see how it pans out.

 

[crazygn]

did you ever find the problem with the over boost.

i to have a racegate and with the screw all the way out it hits 20-23 psi, i cant seem to get it any lower, that with the vac line off of the top of the race gate.

 

[bird]

ended up being the bleeder valve was to small, i think. my buddy had so so many problems with boost and other things its hard to keep track. what spring are you running?

 

[WIKEDV6]

make sure he has no Vacuum leaks any where.

Good luck
Prasad

 

[crazygn]

iam not sure what springf is in the racegate, i never opened it, they dont make a 20psi spring do they.

 

[bird]

i dont know what spring options they have. check the turbonetics website i think they list the springs.

 

[WIKEDV6]

I believe the race gates and delta gates are built the same way, if so there is fiber O ring that goes on the gate valve is notorious for going bad and it will create over boosting with a bleeding air effect. amybe he needs that changed or get it rebuild.

HTH
Prasad

 

[crazygn]

ok i pulled it apart and it all looks new, it has a black spring in it also[ what psi is this ?] I still cant get my boost under like 24-25 psi at full thottle, this is with the screw on top all the way out so no pressure is on it.

can some one help me with what chris Mcdade posted here

It's just the opposite. The lighter the spring the easier it is for the delta gate to open, therefor over boosting. The stiffer the spring the harder it is to open and therefor you won't over boost. Don't ask me how I know all this...

i thought if the spring was weaker and opened it would let boost out and not in path with the exhuast wheel, and the more press on the gate the more boost it would run. So if i turned my screw in and put more pressure on the puck it would not open and make me over boost more.

no flame here just not under standing this and i might be missing something that will help me out here.

thanks

 

[bird]

youre right, the lighter the spring the easier it will open the valve letting out more boost = less maximum boost.
make sure you have no vacum leaks , check the valve isnt sticking (might want to bench test it), check with turbonetics for the specs on the spring. might just need a lighter spring. is youre beeder valve functioning properly?