Boost leak in turbo? Any suggestions?

[boogyman]

Hi all~...

I drive a 2003 Tiburon 2.7, turboed with a Garrett GT30R turbo, with a 38mm TiAL wastegate.

The turbo was installed a little over a year ago, putting out 310 WHP at 0.75 BAR of boost (about 10~11 psi) on premium gas. The wastegate has a 0.6 bar spring, which I raise using a manual boost controller. At this setting, full boost was reached at around 3600 RPM.

A few months ago, boost started going up slower, and not reaching full boost until over 5000 RPM.

It's a big job to take everything out, because of the cramped engine bay, so I just drove the car easy for a few months, until last week, when I had to replace my clutch.

I decided to get to the bottom of the problem while I was replacing my clutch.

I found some exhaust leaks, which I thought was the root of the problem, fixed them, and assumed the car would be okay.

Well, it's not. Right now, at 4000 RPM, the car is only reaching around 0.3 BAR of boost, which is about 4~5 PSI, and to even get to 0.5 BAR, I have to go above 5000 RPM.

I thought that the boost controller may be the problem, taking it out, so that I could get 0.6 bar of boost from the wastegate, but this is not the issue.

I'm at a loss as to where to look for possible boost, vacuum, and/or exhaust leaks.

Can anyone give me some pointers on what may be the issue?

I'm thinking the turbine may be blown, but when I spin it by hand, it spins freely, with no noticeable shaft play, and there's no smoke coming out of my exhaust.

 

[patprimmer]

The OP does not specify mechanical or hydraulic cam. Neither does the engine specifications I could easily find.

I never said the valves would be open, I said ensure they are not. I stick by that comment.

On another note, I read your post in the link you provided above. If you google search this site on burn rate, octane rating, flame propagation, flame travel etc, you might find what you find illuminating.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[thruthefence]

We do it on small aircraft all the time. A shop vac builds up plenty of pressure to find leaks with a plant mister filled with a soapy solution. Works on the intake as well as the exaust. I dont think these aircraft run as high boost pressures as cars...typical example Cessna 421C runs 39" hg MAP at talkoff, thats about 9" over ambient. What's that 4.5 psig, .3 bar? .

 

[Ralf24]

Boogyman, as previously mentioned by others, the three most likely causes would be a boost leak, a faulty wastegate and a partially blocked exhaust. A boost leak IMO is the most likely and probably cause with the faulty wastegate a close second. Even if a boost leak isn’t the cause of this problem, I would definitely start there. A pressure test is not just a simple easy test only capable of finding easy problems. As Vernon mentioned in his link, this test is an extremely valuable procedure to ensure you’re getting the most out of your setup, and if you’re using a MAF will enable you to maintain a reliable tune. If you do decide to make an adapter for a full pressure test, please ensure that it’s well made with a nice bead to prevent it from slipping out of the hose coupler. At 4” diameter, it doesn’t take much pressure to add up to a couple hundred pounds of force trying to pop that thing off. I don’t know if you’ve put it back on, but I would keep the manually boost controller off the car for now, until you find the problem. It’s just one more variable you won’t need to worry about, and the bleed hole in it will be a source of boost leak (nothing you can do about that one)

Checking the external wastegate while it’s removed from the car is definitely the way to go. Make sure it’s not stuck open, and that the spring closes the valve against the valve seat securely. (I’m guessing that’s what you did from your previous post?). You can also pressurize the bottom port to ensure that the valve opens and closes smoothly at or around .6 bar. If all these things check out, then it’s probably not the wastegate.

FoMoCoMoFo, I was referring to intake and exhaust valves within the same cylinder.

Best of luck

 

[Lou Scannon]

Another wastegate check... (simple & obvious kind - sorry if too much so)
With the engine static & cold, check visually and/or by feel that the wastegate valve is fully closed & seated. If this seems OK, next, locate the hose going to the wastegate canister. Rig up an air pressure source with a pressure gauge so you can pressurize the canister and see the pressure. Begin pressurizing, and note the pressure at which the actuator begins to move. This should be very close to the 0.6 bar you quoted in the OP. If not, there's your problem.

 

[robinairtechsupport]

WELL, JUST A LITTLE INPUT, WHEN I NEED TO PRESSURE TEST A COOLANT SYSTEM, EXHAUST SYSTEM, OR INTAKE, A SIMPLE ADAPTER CAN BE MADE FROM AN APROPRIATELY SIZED INNER-TUBE. WORKS PRETTY GOOD ON RADIATORS. IT HAS A BUILT IN SCHRADER VALVE, SO YOU CAN USE AN AIR CHUCK AND AN AIR PRESSURE GUAGE. JUST CUT THE TUBE, AND CLAMP IT ON. ONLY THING, WITH THIS BIG OF A BOOST LEAK(OBVIOUSLY) YOU MIGHT NEED TO REMOVE THE VALVE CORE TO GET THE AIR IN QUICK ENOUGH. BTW, UNLESS A WELD BROKE ON A CHARGE PIPE, I'D CHECK THE INTERCOOLER, OTHER THAN THAT, THE TURBO ITSELF. THERES A LOT OF AIR FLYING THROUGH THAT ENGINE @ 5 GRAND, SO THE LEAK HAS TO BE HUGE.


A GREAT MAN ONCE SAID: "CHEAP, FAST, RELIABLE, PICK TWO."

-A. D. IADANZA

 

[kilrbee]

boogeyman

is it possible you have damaged the turbine?

If this problem showed up gradually over time, perhaps you have gradually rounded over your turbine blades.

 

[kenre]

Have you checked the induction side before the turbo?

dirty air filter etc, ive seen a plastic shopping bag restrict intake systems more than once!

http://www.retallickeng.com.au

Was told it couldnt be done, so
i went and did it!

 

[Warmington]

Boogeyman,

Did you ever diagnose the problem?