TAI Dreams going up in BOOST

[blackgn1]

Well here we go again. Everytime a Buick meet comes around i start having problems. Just installed a new Single shot exhaust and now I'm having over boost problems. Did no work under the hood. I have 27psi of boost with 02's 791 with zero knock. I have always had the car at 18psi of boost. RJC boost controller. Downpipe puck is not stuck. I can't tune what I can't control. When I ran the car with just the downpipe boost went to 20psi. Put on 3" exhaust and now got 27psi+. Check all the normal culprits.

 

[blackgn1]

Found a possible very very small dry rotting crack in the rubber nipple that connect the hard line from the three bar sensor to the metal hard lines. Could I be that lucky? I think probaly not.

 

[johnplogii]

You'll need the 27psi to be competetive in TAI anyway

Could very easily be a boost line going to the wastegate.

 

[jasjamz]

^^^True!^^^
You tried turning the boost down? I'd just make the adjustment, make sure its steady, and start tuning.

 

[blackgn1]

I agree with the boost need to be 27psi plus. TAI guys are running in the 9's all day long. I really can't tune the car without everything working correctly. I need to be able to start with low boost and work my way up slowly. I can run in the 10's on about 18psi. I'm looking to run a conservative tune and see how far I can go this year. Out of time. Full work load next week so the clock is ticking. Seems like I may have lost 2psi of vacuum on the gauge. Hope it's a leak!

 

[jasjamz]

Check'em all real good(hoses) Wastegate isn't sticking is it? I lost like 2.5 in of vac without reason too. Turns out its my Autometer Z series starting to give up. Its like two psi off(low) on boost when compared to the powerlogger reading. Best of luck in BG!

 

[blackgn1]

Hoses looking good. Help me out guys.

 

[WSLN 6]

Just goes to show how crappy your old exhaust system was. I gained almost 4psi boost when I changed to a 3" single.
How big is your wastegate hole?

 

[blackgn1]

Yes the prior exhaust was very restricted. Waste gate hole is still precision factory size. I really thought I could still control the boost with the RJC but it isn't looking that way. Going to put the powerlogger to it tonight to verify the boost. I could track it down eventually but I'm out of time. Work until I leave for the big BG

 

[bad V6]

I think that you will find that you'll have to port the wastegate hole of the turbo. I had the a boost creep issue until we got the wastegate hole the proper size.

A free flowing exhaust will magnify the problem. The turbo will spool faster, moving a larger volume of air, however the unported exhaust housing will not be able to relieve the pressure of the new found volume of air.

 

[blackgn1]

I think you may be right. Sounds like I have a project to try to fit in this weekend. I have always been able to put the boost anywhere I wanted it. Hard to believe that the wastegate hole has finally showed its presents.

 

[WSLN 6]

I agree, will be worth your time. My wastegate puck on my Mease 3" pipe was 1.44" but I don't think many are quite that big anymore. Makes a big difference over .9 or so. Be prepared to tighten up your wastegate after as well.

 

[blackgn1]

Looks like the only way to do this the right way is to remove the Turbo. Then remove the housing and grind it with it seperated from the Turbo. I don't want metal to get into the Turbo nor in the engine. Looks like a job for Superman! No not really. I may be in the hotel parking lot with an extension cord running out of the room and out in the parking lot. I have done that before.

 

[Slow91z]

27 psi 791 and zero knock...What's the problem??? Maybe turn up the fuel a touch.

 

[blackgn1]

If I had made adjustments and got these numbers I would have been satisfied. This was a short street run and the possibility of boost creep is a problem. The car tuned itself. I didn't make any adjustments. It just ran some good numbers on the 02's and zero knock. I now know I can run up to 27psi and have no knock but I need to find a route to get there.

 

[Slow91z]

Just FYI, that was about 80% a Joke

 

[blackgn1]

Oh I know. I just a little aggrevated. I have worked on this car to the wee hours of the morning for days to try to run Bowling Green. Get it done and everything perfect to get knock out another year because of this. If I had just another few days(work is not going to let that happen). Reynolds was a broken motor mount.....BG last year transmission.......Going to do the wastegate hole this weekend if that fails I'm out of the running for BG this year. It's the price to pay for having a street/race car. Still going to take the car just no racing!:biggrin:

 

[JDEstill]

What turbine housing size do you have? If it is a 0.63, then moving up to a 0.85 housing will help in a couple of ways. First, the bigger housing has to flow more to produce the same boost level, which means it has to wastegate less. So it helps relieve the wastegate restriction, since less wastegate flow is needed. Second, the bigger housing will reduce the pressure in the headers for a given boost level. Lower header pressure, which is the backpressure that the engine actually sees, means more power at the same boost level. In other words, you'll make more power at 20 psi with a 0.85 housing than you will at 20 psi with a 0.63 housing, because of the reduced backpressure. And if you are spooling real good now (which I imagine you are), the bigger housing shouldn't hurt that part of things too bad.

Of course if you already have a bigger housing now, then never mind

John

 

[blackgn1]

I have the .85 housing. I went ahead and pulled the turbo and removed the housing and ported the wastegate hole. Got everything back together and now have a solid 22psi without boost creep. I believe thats as low as I'm going to get with an HD accuator.:biggrin: Going to head for Bowling Green and get on the track and see what kind of times I can lay down. My car has always been consistant on times. Good for our local bracket racing in the 1/8. I just want to run for fun.:biggrin: I'll let the "BIG DOGS" fight it out.

 

[jasjamz]

Glad to hear you got it fixed. How do you like the exhaust? Too loud? What muffler?