boost leak at wastegate (and throttle body)

[Boosted98gsx]

When static boost leak testing your car, you want to test to whatever PSI your car will see under dynamic conditions PLUS, to make sure there aren't any weak points in your system for couplers to blow off and such.

 

[hopwoodp]

On the subject of boost leak testing: Just curious as to why you came to that conclusion. I've boostleak tested my cars to 25+ psi for years. . .

This was a question I brought up while I was at road race engineering. I asked what pressure I should do a boost leak test at and I was told 20psi. I asked why 20 psi, and was told that doing a static test any higher will blow out your throttle body seals. Also, at that range, you will know of any leaks. They also said, if your couplers blow off, you either have clamps that won't tighten down properly or you don't have beaded pipes.

 

[Boosted98gsx]

This was a question I brought up while I was at road race engineering. I asked what pressure I should do a boost leak test at and I was told 20psi. I asked why 20 psi, and was told that doing a static test any higher will blow out your throttle body seals. Also, at that range, you will know of any leaks. They also said, if your couplers blow off, you either have clamps that won't tighten down properly or you don't have beaded pipes.

That doesn't make any sense. If someone was running 30 psi on the seals dynamically, it would do the same thing. Either way, it's going to happen.

 

[hopwoodp]

I am not too sure about the throttle body seals. I am trying to remember if it has to do with the throttle body being open or what. It was explained to me over 2 years ago and I understood everything but, forgot how to explain it.


I am sure some wisemen can explain this for me. I feel like a jack@ss for forgetting.

 

[Boosted98gsx]

I am not too sure about the throttle body seals. I am trying to remember if it has to do with the throttle body being open or what. It was explained to me over 2 years ago and I understood everything but, forgot how to explain it.


I am sure some wisemen can explain this for me. I feel like a jack@ss for forgetting.

If the valve was open or not, the forces acting on the seals would be the same.

 

[hopwoodp]

No, there was more to it than that.

 

[dsm-onster]

No biggie. I'm jsut wondering what you meant. . . I can see a closed throttle body causing a boost gauge to read lower than what's really in the intercooler pipes. . . I alsways have a friend , so I just hold the throttle to the floor.

 

[assault187]

I read this post the other day and thought to myself, hmmm...Im glad my wastegate doesnt leak! Well did a boost leak test when i got home today and what do you know.....my wastegate leaks!! Its a Tial 40MM. Im thinking this is why my turbo does'nt spool as fast as I've been told. I Guess Its never come up before today because I've always had other leaks that robbed the system. Now that there all fixed it reveals more gremlins.

 

[oldman]

This was a question I brought up while I was at road race engineering. I asked what pressure I should do a boost leak test at and I was told 20psi. I asked why 20 psi, and was told that doing a static test any higher will blow out your throttle body seals. Also, at that range, you will know of any leaks. They also said, if your couplers blow off, you either have clamps that won't tighten down properly or you don't have beaded pipes.

No such thing David, always test at least up to your boost level, if not 5psi above.

I think this would account for a "big boost leak". I do my tests with the engine at ~TDC where all the intake valves are closed the engine NOT running.

TDC is the worst place to be during a boost leak test due to valve overlap, pressure leaking straight out of your exhaust.

 

[hopwoodp]

No such thing David, always test at least up to your boost level, if not 5psi above.


TDC is the worst place to be during a boost leak test due to valve overlap, pressure leaking straight out of your exhaust.

I will keep that in mind. Is there a known limit to what psi you may boost before blowing out the throttle body deals?

What I am trying to figure out is why I was told that. I know that the guys at RRE don't lead people astray but, it may have something to do with old throttle body seals. But, that is just speculation.

I plan to actually run higher than 25psi and I know that you need to be able to test it so it will not leak at that level and also be able to hold boost just in case you have a boost spike.

Of course that won't happen any time soon. But, I know that you are already planning on going past 28 psi and I figure you would be the person to be able to chime in on that.

Please, let me know if any of this sounds wrong.

 

[oldman]

What I am trying to figure out is why I was told that. I know that the guys at RRE don't lead people astray but, it may have something to do with old throttle body seals. But, that is just speculation.

Not purposely I would hope but no one is ever wrong-prove, continuing to push the B&M Comemdflo fpr MODIFIER as an AFPR for example. Honestly, what they said on "20" psi doesn't make any sense, if any part of your car (TB shaft seals included) can't pass a 20psi static pressure test, you have no business running 20psi +, my next BLT goal is 30-35 psi before meth injection, I'm waiting for Link's ver 3 so I can go with MAFT and a Tial BOV.

 

[hopwoodp]

Not purposely I would hope but no one is ever wrong-prove, continuing to push the B&M Comemdflo fpr MODIFIER as an AFPR for example. Honestly, what they said on "20" psi doesn't make any sense, if any part of your car (TB shaft seals included) can't pass a 20psi static pressure test, you have no business running 20psi +, my next BLT goal is 30-35 psi before meth injection, I'm waiting for Link's ver 3 so I can go with MAFT and a Tial BOV.

I got your your saying . I don't think I will be anywhere near 30psi until I rebuild one of my spare motors. Not, to mention that I may be moving to AZ and putting on everything I couldn't in cali (IE, FP3XXX turbo, FP exhaust manifold, etc etc etc etc).

Like you, I can't wait for DSMlink V3 to come out.