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The mkiv Supra Owners Club

External Wastegate Question


Marty

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Bit of an afterthought this..

Ive got an external wastegate on my supe, apparently it has a 1.1bar wastegate spring in it, now, i am planning on running my setup at 1bar for now, being controlled by an apexi avcr.

Can i do this.

Whats the crack with the whole wastegate spring thing when a boost controller is controlling the boost? Or should it be removed if running a boost controller? hmm

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that seems a bit high..i think my spring opens at 0.5 bar

 

Cheers

 

G

think yours is too low mate, it should be close to what you want your turbo boosting at... i found this from a good search.....

 

Inside the wastegate is a diaphragm which creates a seal, and a spring which holds the wastegate closed. Spring rates vary depending on the amount of boost you want to run, typically they are given in a "bar" value for example 1 bar would be 14.7psi. This would mean that in order to open the wastegate you would need to excerpt a greater pressure than the 14.7psi spring holding the wastegate closed. In order for the wastegate to work you must have the compressor reference port hooked up to the compressor side of the turbo, if you don't have this vacuum line attached than the boost pressure will not be limited to the set spring pressure; it will build unlimited boost pressure until your engine is destroyed.

 

Normally pressure from a spooling turbo pushes against the diaphragm (though the vacuum line attached to the compressor reference port) which in turn pushes against the wastegate spring. When the pressure from the spooling turbo exceeds the spring pressure the wastegate's plunger opens releasing the excess pressure through the dump tube into the exhaust after the turbo or to open atmosphere. Typically, if you use the wastegate to control your boost levels you will experience a decrease in power and spool times. Why? Although the spring fully opens at its set spring pressure it tends to begin opening before reaching the set spring pressure. This "pre-opening" leaks boost pressure through the dump tube before max boost pressure is reached resulting in a decrease in power mostly toward the top end. This can be corrected by using a boost controller.

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hmm, so do you guys think im going to see problems trying to limit my boost to 1.1bar odd with this spring?

Its a hks 50mm wastegate if that makes any difference.

The whole reason i dont want to run high boost is im planning on running on my 550cc injectors for a few months and i dont want to put any strain on them, or damaging my engine, by turning the boost up to much.

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XS power wastegate working fine??? did u have to do any modification on it?

 

There's a significant number of people using them without issues, though most have the 50mm version. I've been here a while but there's no record of a failure or problem with this wastegate. If you have experienced a problem please post up details!

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There's a significant number of people using them without issues, though most have the 50mm version. I've been here a while but there's no record of a failure or problem with this wastegate. If you have experienced a problem please post up details!

the only issue i heard of was they are prone to seizing up, but if you open them up, and put a nice bit of high temp lube in there, they work perfect

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Out of the box as it came from XS Pooer? Or has it been taken apart and re-engineered so that it doesn't jam shut like some of the other XSP ones have done?

 

Jake, do you have any more info on that?

 

Edit - genuine question, as you may have seen i'm about to fit one tomorrow!

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Jake, do you have any more info on that?
Only what I read on SF when I was considering a budget single for my grey Supe. It was some time ago though TBH. I almost never visit SF since they introduced that ghey advert-hyperlink-in-posts thing. I do remember that one thread was written by the guy SupraDibbs bought his Garrett turbo from. He showed how to mod the XSP wastegates and everything. I don't recall the guy's name - sorry.

 

 

I can't say I've known anyone who it's jammed open on.
Jammed open would maybe be an acceptable risk. OTOH jammed closed for as little as a few secs could be fatal for your engine.

I think I would strip it down and check it out, just to be on the safe side.

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Only what I read on SF when I was considering a budget single for my grey Supe. It was some time ago though TBH. I almost never visit SF since they introduced that ghey advert-hyperlink-in-posts thing. One thing I do remember is that the thread I was reading was written by the guy SupraDibbs bought his Garrett turbo from. He showed how to mod them and everything. I don't recall the guy's name - sorry.

 

I remember some of the post, though it was filled full of crap by the some of the US tuners with scare stories (none of which we've seen here.... so far ;) )

 

IIRC the problem was with the old 46mm wastegate they no longer supply. The 50mm wg I had was packed full of lube and moves freely once pressure is applied. If it does get stuck it's easy enough to back off the throttle though, considering it costs around £50 its a disposable part IMO - same as the manifold.

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quote ...

 

Your wastegate will problably get stuck the first time you hit more than 10 psi (happend to a few people already), you will need to open up the wastegate and grind down the valve it seems like with the heat it expands and it gets stuck, would be a good idea to do it before hand.

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