Boost with no wastegate?

[Keyser Soze]

What boost pressure would I be likely to see with an 86 SVO if I disconnected the reference to the wastegate so it ran full boost? Are we talking 20 pounds, 25 pounds or some number that is sure to blow things up regardless of octane?

[JonProphet]

At this point I think you really need to do more research on the fundamentals of Turbo/Super charged cars. I honestly believe if you continue w/o knowing how to tune or how to operate boosted cars, you are just wasting your time and your money. Not to be rude, but forced induction cars are a whole new ballgame. I'm not saying I'm an expert but I've been researching modified boosted cars for 4 or 5 years before I got my first stock turbo car.

-JD-

[Keyser Soze]

That being said, I'm still looking for a response to my question. I have built and raced cars for over 15 years so I do have a good understanding of what makes them tick. I have not played with a 2.3L turbo for at least 10 years but still recall a good deal about what makes them work and in the end, the same general principles apply.

[JonProphet]

That being said, I would assume if you permanently closed the waste gate you'll get max boost and max CFM from the stock T3 and you would blow everthing from here to there. I doubt anyone has enough nerve or lack of brains to remove the wga. Remember turbo's are not about boost, its about moving air, CFM. Boost is just a convinient buzz word with the kiddies.

Anyhow, you'll basically tear everything up. I doubt you could make a fuel injection system that would adequately supply enough fuel, ie right fuel management. Not to mention you'll get surge because the turbine wouldn't stop spinning. I'm sure with enough money, you could build a stand alone and use big enough injectors. I'm sure the first time you hit first gear the motor would eat self from lack of proper tuning.

Not to mention when you shift, you'll tear the turbines up from all that air shock being run back and forth on the intake side w/o some sort of BOV or recirc valve. They designed waste gates and BOV/Recirc systems for a reason. Wastegates are an integral part of the turbo systems. You simply cannot eliminate them.

Do me a favor if you do this, record it with a vid cam, I'd like to see what comes out the intake and exhaust. ;-P

-JD-

[SVOeric]

same general principals apply, but he's right, if you had a bit more understanding on turbos and how they work, you would not have asked the question. So the answer you are looking for is --

with the wastegate closed, you will KEEP building boost, up to the point that compressor is maxed out. what that number is depends on a lot of things, which make it impossible to predict.

your comressor wheel is outside it's efficent range, so the air coming out is HOT. which leads to detonation.

with the above in mind, yes, leaving the wastegate unhooked will most likley make somthing go POP.

[Keyser Soze]

Interesting. Thank you for the responses. On my old 87 turbo coupe with the IHI compressor, I disconnected the reference hose to the wastegate and in the upper RPM range it would only make around 20psi of boost. I put a digital air charge temp gauge in and it never went above about 160 under those conditions. If you went WOT in the lower rpm range it would show 24psi or so, obviously because the engine could not move the air out. For what it was, the car was relatively fast (all stock, just retarded cam timing 4 degrees and increased the boost, 3410 pounds with driver, ran 14.80)

My thought was that if the SVO turbo ran like the turbo coupe, I could just remove the reference line and do like I did with the turbo coupe. I am learning that I cannot.

Am I correct, then, in assuming that if I have a manual boost controller, I can remove the boost control solenoid? This tails into another thread I have about hardwiring the computer in premium fuel mode?

Your thoughts continue to be appreciated.

[SVOeric]

yes -- you can yank the stock boost controller at any time. it won't even cause a check engine light.

[JonProphet]

First and most enjoyable thing to do on a turbo is to add an MBC (manual boost controller! I hear once you turn it, you can't stop and the major mods follow. Bigger injectors, big intercooler, porting, new manifolds, lions and tigers and bears! OH MY!

-JD-

[65ShelbyClone]

Something that came to mind is the possibility that running a wastegated turbo at a given psi will actually make more power than a disconnected WG at the same psi. My theory is that the wastegate will maintain the boost pressure while lowering turbine backpressure.

Keyser, the SVOs's T3 is more capable than the Thunderbird IHI. Its wastegate is a safety device; it prevents the boost from going out of control and the engine from running lean. Omitting the wastegate might result in a blown head gasket...... on a good day.