External wastegate Q

[Sydneykid]

Hi SydneyKid

sorry for the delay been to busy.

1) straight connection to wastegate ie no boost controller involved the wastegate dosent just snap open at exactly 7psi it actually creaps open could be causing the smaller wastegate to be fully opening/closing all the time where as a larger diam wastegate would only for instance need to be opened halfway. Back to your theory on causing damage to the diaphram from opening/closing to much if you look at it that way actually reverses what you was saying.

As for your 35mm wastegate theory there I have to say that we have a 38ml on this car I told you about and it wont hold boost fullstop. There is just to much exhaust velocity to stop the turbo from spooling with that small a wastegate on this application, your theory did not work on that car.

BR,

JH

Well 35 mm worked on 8 other engines, so there must be another reason, what do you think it is?

Sorry I don't understand your point #1, if I have 1 wastegate actuator and swap it from a 35 mm wastegate to a 45 mm wastegate, they will both open the same amount at the same time in response to the same boost pressure.

But the 45mm wastegate will flow 65% more exhaust for the same opening. If that 65% more flow is too much (ie; boost drops) then the wastegate will close. Then it will open, then it will close etc.

If the 35mm wastegate is the right size, then it won't do this open/closed stuff.

Hope that clarifies:cheers:

[japsky33]

Any number of reasons which i pointed out in the other posts, ie exhaust design and manifold/ tune/motor/ turbo blah blah blah.. This bullshit about oh im using that wastegate on a 9million kw motor so there must be something else wrong crap is just that utter shit. Ive said my argument on that to many times Ill post you the dyno read outs for this car monday, Ive never ran into a incorrectly sized wastegate by it being to large I have seen issues with large wastegates and fluctuation caused my manifold design. :rave:

As I said they will both creap open wether that be at the same time or not?!?!?! I was talking about this inital creap your wastegate is semi opened before it hits your desired boost they dont just snap open and shut.

Br,

JH

Well 35 mm worked on 8 other engines, so there must be another reason, what do you think it is?

Sorry I don't understand your point #1, if I have 1 wastegate actuator and swap  it from a 35 mm wastegate to a 45 mm wastegate, they will both open the same amount at the same time in response to the same boost pressure.

But the 45mm wastegate will flow 65% more exhaust for the same opening.  If that 65% more flow is too much (ie; boost drops) then the wastegate will close.  Then it will open, then it will close etc.

If the 35mm wastegate is the right size, then it won't do this open/closed stuff.

Hope that clarifies:cheers:

[Sydneykid]

As I said they will both creap open wether that be at the same time or not?!?!?! I was talking about this inital creap your wastegate is semi opened before it hits your desired boost they dont just snap open and shut.

Br,

JH

Sorry, I still don't understand, help me out here.

But first let's get the crap out of the way, this is not a discussion about the turbo being too big or too small, or the manifold being crap or the intercooler might be blocked etc. It is a discussion about whether a wastegate can be too big. I am sorry if I gave the impression otherwise. So to the subject at hand....

If the 45mm wastegate "creaps open" (your words, not mine) it will flow 65% more exhaust than the 35mm wastegate. If that is too much turbine bypass (boost goes below target) it will close (maybe not completely shut). If that's not enough turbine bypass it will open (maybe not fully, just a bit). etc etc

Maybe the problem is when I say "open" I don't necessarily mean FULLY open. When I say "close" I don't necessarily mean FULLY closed.

So I can not see any way that TOO large a wastegate won't open and close more than a wastegate that is the right size. If I put my dial gauge on the diaphram of the too large wastegate, it will move more often than the wastegate of the right size. Or have a I missed something?