Stock boost

[redhotrod]

How much boost can you get by adjusting the wastegate rod on a stock hotair? For whatever reason, I can only get about 10 psi

 

[Matto]

I can get 20 PSI from my stock turbo

Check for leaks, and problems.

Matt

 

[mycarsucks]

Keep in mind that 20psi is probably considered well beyond effeciency range for our turbos, and about the max range for the 86-87 models.

 

[Matto]

Mine will run around 15 PSI with 93 octane and 20 with some 110 mixed. Turbo seems to like it around there, and everything runs great, but that is just my car.

 

[redhotrod]

15 psi, how long is your wastegate rod now? The stock setting looked like 6 1/2" from the center of the turbo mount to the wastegate plunger, After modification, I turned mine down to 6 1/4" and my boost only shows maybe 9 on the autometer gauge, I run 94 octane, and watch the turbolink, I only get knock during shifts, when the tires bust loose. Should I tighten the rod up some more? Is 15psi with stock chip?

 

[Matto]

my wastegate is completley shut, and the fuel system is way stronger than the turbo.

I have a walbro 340, adjustable fuel regulator with 45LBs of fuel at idle w vaccum line off. This is probably why Im able to get this much boost w/ no knock, I dont know alot about these cars but Ive just messed with mine until I got it right.

Tips Build up your fuel system first, that way everything you do, enough fuel will be there.

Get the correct gauges to do adjustments, fuel pressure, and knock are critical, For what Ive done. Next I would like to get a scanmaster.

Go to a 87 ECM so you can mess with chip configurations, to get correct timing, boost, and tranny function to an extent.

get your turbo to breath with 3in exhaust and ATR muffler, with a DP that is proven.

Im going to run mine at the track on WED I'll post what I ran and stuff.

I just orderd a 3in Integral DP from Mease and recieved some poston headers, so I will post when I run these.

Hope this helped if your just starting out, if you already know this stuff, maybe I said something you forgot. Lee Thompson knows way more than me.

 

[redhotrod]

I'm getting my fuel system together, got a walbro 340 on the way, already have a afpr, got a turbolink, fuel pressure gauge, my pressure is set at 45psi to, and right now running a hypertech chip, I have a Joe Lubrant 93 chip on the way also. But still can't get the boost over 10 psi, would a vacuum leak do this, or a bad solenoid? Also, if your wastegate is completely shut, wouldn't you overboost?

 

[Matto]

Well the stock turbo is a small unit, only 375CFM I think, so Ive got it maxed out. Yes some type of leak would cause boost to be hamperd. exhaust perhaps. Also with a bad exhaust system and small downpipe the turbo will not perform to its potential.

I couldnt hit that kind of boost until I put on a ATR 2.5 DP and a 3 inch single shot exhaust system. Im sure other combos would work as well, but this is mine.

 

[mycarsucks]

Matto do you have some sort of mods on the intake side of things? My 85 would easily hit 15lbs and had more in it had I wanted. This was however controlled by the ecm versus the rod adjustment. Maybe thats the difference.

 

[BLACK Ttype]

Check for a plugged cat. conv. or exh. leaks before the turbo.

 

[redhotrod]

I gutted my cat, but have the stock headers, dp, and stock dual exhaust after the cat, I'm gonna try tightening it up a whole bunch and watch for knock

 

[redhotrod]

Well, today I opened up the air cleaner, I put a cookie can type lid under the stock air filter and removed the lower part of the stock air cleaner housing, That made a big difference in breathing. Then used bug and tar remover to clean out the oil in the hoses to the throttle body. I threw in some new CR43TS spark plugs gapped at .031 then tighted up the wastegate rod to the point where I couldn't pull it any further out of the plunger. Took it for a spin and seemed to run a whole lot faster, but the autometer boost gauge still only peaked at 10 psi! I have it tee'd in with my afpr so it should be getting a good reading. Turbolink still shows no knock. So, now what?

 

[BLACK Ttype]

Have you checked the exhaust fins on the turbo, there might be something wrong w/ them causing them not to catch enough exhaust gasses.

 

[EyeTalk2Trees]

I know its long but it should help...really

I had the same problem you have hotrod, after i got my fuel system figured out it would only do 10#. I had to unbolt the wastegate and thread it about inch (probibly too much) more, and then cut off about .25 of an inch. I'm not exactly sure on the measurements they were ruff estimites at the time. after that I can go up to 15#. I can go more but I'd have to pull it off and cut off another .25 inchor so. Some people go so far as to replace the entire rod with all thread, but I just threaded it, its a really common size (i don't remember) so either way you do it, it will be cheap. Oh and if you haven't replaced all the vaccumn hoses it would help alot, if they are in bad shape. And the guy that had my car before wasn't that great with cars, and he actaully missed some vacuum ports in hard to reach (and see) places. Look all over the turbo and throttle body to see any uncapped ports, there is one big one on the bottom he missed and a smaller one in the back. It took me forever to find my vacuum problem but once i did the car ran much better. It didn't effect boost directly, just doesn't ping when i go over 8# now, I run great at 15# on 91 octane(best in town).

 

[redhotrod]

Thanks
my wastegate rod is cut, threaded with 1/4-28 and I have a 1.5" coupling nut with a locknut on there. What I did was tightened the rod up so much that I can not pull it any further to the turbo. All my vacuum lines are new. I just put this motor together this past fall/winter and spring is finally here so I finally got the licence plates on it. Right now, it seems to run great, just wish i could experience boost over 10psi in my own car.

 

[Matto]

You may want to check the hose that goes to your boost gauge, could have a kink in it making it not read correctly, also see where you gauge is reading from, mine is directly on the intake manifold,(THE most accurate spot), I think.

 

[BLACK Ttype]

Another option that you have is to use a small pressure regulator for an air compressor. Put it inline on the vaccum line that goes to the wastegate from the compressor housing. The regulator will only let a certain amount of pressure to the wastegate therefore not letting it open as soon.
If you need a more detailed explatation,
call me after 5pm. (910)797-7755

 

[redhotrod]

BlackTtype, I understand your concept, but I have that rod so short I don't think it is opening the valve anymore. As soon as i give it gas I hear the turbo wanting to go, even in park, Today I looked over the vacuum lines and noticed that the place where I tee'd the boost gauge at might have been kinked, so I fixed that, but wasn't able to drive it yet cuz the gf accidently blocked me in the garage when she left
I will find out tommorrow. I also changed the trans fluid over to type F and it shifts into gear more solid now, can't wait to drive it!
I got my bro into turbos now, he has a 96 bonne, and he just went out and bought a supercharger for his ride

 

[cool 84]

If you're fairly sure your boost guage is accurate, you can try a test to see if it's physically possible to run more boost. Pull the vacuum lines off the wastegate. Ease into the gas slowly, watching the boost, making sure not to over boost. Without the vacuum lines it should hit well over 20psi on a nearly stock motor.

 

[mycarsucks]

just remember to be really really really careful. Boost won't seem to raise much, but when you get higher in rpms it will come on real fast.