Engine/Transmission (1994 - 1998) Adjustable wastegate elbow or not?

[QWaller]

I have a slightly modified 98 with only a BHAF and 10 plate at somewhere between stock location and full forward. Star adjusted to where it has tolerable smoke. I was running with the air line to the waste gate plugged in the middle. Actually really liked this for power/smoke etc. I decided to put an adjustable elbow to keep the turbo pressure down. I would get anywhere from 35-40 PSI and now I max at 28ish. Also power and throttle response low end don't seem as strong. Also my EGT's hit 1250 (higher if I stay in it) quite a bit quicker. Should I just leave with plugged up and manually keep my boost down or keep the safety elbow in place? What do you guys think?

 

[Lil' Dog]

The safe level would be 35 psi range for the stock turbo. Most plate kits come with the boost elbow already preset for that pressure. 28 psi is low.

 

[QWaller]

I felt 28 was low as well, What is the ill effect of running with the line plugged other than the 40PSI potential?

 

[Lil' Dog]

The effect is really up to the driver. The turbo (HX35) starts to run out of its efficiency range above the 35-38 psi mark and its basically just making hot air. The amount of drive pressure on the exhaust side starts to become higher than the boost and essentially all that happens is the boost gauge looks cool at 40 psi, but there is no benefit. If you can turn up the boost elbow to the 35 mark and then forget it, that would be less to worry about. But if you are fine using your right foot to control that level, thats fine too.

The higher boost level also indicates higher turbo speed that could cause problems with wear to the bearings and possible balance issues. That may lead to an early failure, though many tout years of that boost with no ill effects.

 

[kenny61]

From what I understand anything over 35 psi on the HX35 is just hot air and you are possibly over speeding the turbo

 

[QWaller]

I will just go ahead and unhook it. I only see 40 PSI if conditions are right and I am in it hard anyway amybe 3 seconds at a time at the most. I can control it anyway. Maybe there is something wrong with my elbow.

 

[kenny61]

I will just go ahead and unhook it. I only see 40 PSI if conditions are right and I am in it hard anyway amybe 3 seconds at a time at the most. I can control it anyway. Maybe there is something wrong with my elbow.

That may not be so far off with your mods. I believe mine was similar. I have mine set to about 30 max but it is hard to get it there for more than a few seconds. I think that basically by the time the engine is fuelling enough to make more than 30psi the rpms are up and are already pulling back the gov. No Fuel =No Boost