turbo experts needed!
 

How can I tell the differance between an s4 and an s5 turbo? I think I might have an s5 that is bolted to and s4 manifold witch I believe is hindering me from getting any boost! If this was the case would and s4 manifold on an s5 turbo prevent boost? Thanks.

they won't bolt up. They have a slightly different bolt pattern. S5 is perfect rectangle. S4 has an offset on the top bolt towards the front of the car. (if i am recalling from memory correctly). s5 also has a bigger wastegate and a double flapper door.

Do you have an shaft play? does it spin freely? how do you know you're not getting any boost?

Step awake from the crack pipe... :smoker:


-Ted

S5 turbos are on 89-91s ;)

I know what years s5's are and no I'm not smoking any crack! I bought a turbo from a guy a long time ago, bolted it up and never got any boost from it. I know it is good because there is absolutly no shaft play and it spins freely! I was just woundering if the s4 manifold could bolt up to an s5 turbo incase the guy sold me an s5 turbo. I had a mechanic put it on and there is no telling what he did. THere is just no boost. Also I have a greddy turbo boost guage that has a vacuum at first and when reved goes up to 0 and thats it. Thanks.

wastegate stuck open??? I don't even think putting a s5 turbo on a s4 mani is possible.

yeah check the wastegate, it could be wide open. i've seen where the clip that holds the actuator rod on can break and it's wide open and it's hard to build boost

ok I'm going to jack the car up today and work on that. I'll send a reply when I find out. Thanks.

Your are going to build very little boost with no load. What happens when you floor it ?

James

I get no pressure if I rev it hard enough i can barley hear it spin. Hey I'm checking if my wastegate is open right now and I don't know how to tell if its in the open or closed possistion, does anyone know how to tell? Thanks.

Could be your boost controller is not fuctioning right, wg stuck open, cracked turbine housing or exhaust manifold, bad bearings, or low compression..

I tried a manual boost guage and my electric one and both did the same thing. Low compression what? I just drove it today and it is as strong as when I first bought it. today I got up under the car and looked at the wastegate actuator and found that the rod on the actutor was sticking out about 2 to 3 inches. so I tried pushing on it or pulling and I was unable to move that rod. Can you normally move that rod with your hands or do you usually need like a bike air pump? I put everything back together and still same thing happens. Its like I'm getting a little boost but not much and still my boost guage doesn't read much past 0 if any at all.

So on the road, in 3rd gear at say 4000rpm, the aftermarket gauge reads zero? Are you sure you have the gauge connected correctly? What line did you tee into?

If your turbo bolted staight to the manifold, then it's an S4 one. Is the twin-scroll actuator still working? Are you mistaking the twin-scroll actuator for the wastegate actuator?

That canister on the turbo that has a banjo bolt with a thin pipe on it.......is the switching actuator. It gets vacuum from the switching solenoid. That vacuum pulls the rod into the canister, under 2800 rpm, and operates the lever/flap on the other end of that rod. Put a piece of vacuum hose on that thin pipe and suck on it. The rod will retract into the canister and pull the lever on the opposite end. That switching actuator fails to the wide open position, so it should not keep the engine from making boost. The waste gate actuator is that other lever on the turbo.

See here is the thing. Everything was fine with the old turbo it actually spooled up great, good boost, through you back in your seat etc... however the new turbo that was put in by the mechanic was just directly put in just like the old one. so unless they did something not right in hooking it up it should work just the same but with more boost.

How do you know that?

So what are the answers to my questions? Gauge hook-up? Twin-scroll?

I think you need to go back to the mechanic.

I think your right!