So I blew my front twin turbo yesterday at the drag strip, see pics attached and youtube video here.

The nut and the end of the shaft broke off somehow.., question is where did it go?? There is no oil or metal shavings found at the top of my ypipe. There is oil and metal shavings in the inlet side of the front turbo and in the inlet intake elbow. I just took off the inlet elbow and ypipe crossover pipe. shaft play feels not good but not the worse I've felt before. I haven't checked the rear turbo yet. I know I beat the crap out of these turbos and boost them much more than most recommend, but this seems weird to me to see that happen.

I shifted into 3rd gear, hit the gas and the car had no power, I looked behind me and seen the smoke. I reviewed the FC datalog from the run and boost held fine through 2nd gear and then it didn't boost after I shifted to 3rd. Boost was holding around 18 psi till I shifted, peaks at around 21 when the boost hits then falls off some. Also there was no high knock or anything out of the ordinary when looking at all the datalogging and afr when this happened.

Engine still didn't shut off, and sounded all good at idle and reving up some, but it was smoking some. I was able to drive it home, just smoked a little especially if I put more load on it, looks like light blue smoke when driving. I just cruised home, didn't try to boost it or put too much load on it, and it drove fine.

This was on my first run since the last time I was at the track when I got the 10.87 @ 128.9 with a 1.57 60 ft. This run I hooked up great at 14 psi in the tires and got a 1.48 60 ft, my best ever. And I had been tuning my car alot in the past few weeks and got it tuned much better, it was too rich at 6k rpms before which you can see from my dyno graph in my last thread it didn't make as much power there.

First two pics attached are the blown turbo, look at the fin damage and nut/shaft broken off. 3rd pic is a old turbo with nut attached, what that part should look like.

So what the heck happened.

 

Assuming that is the hot side of the turbo it looks like the shaft sheared was ingested by the turbo (hence the fin damage) and probably made it's way into your cat. If you have cats it will be there otherwise it might be trapped in a muffler.

 

That is the cold side. I did some searching on this problem that has happened to others too, and I found two cases where the nut was found in the air box, I'll check my air filter after work and hopefully find it there. But still something must have also happened on the hot side because of the smoke. And oil is in the turbo inlet elbow but not in the ypipe or Ic pipe, seems strange but good.

 

what is your plan - buy another set of stock twins (new or used), BNRs?

 

Are you running a BOV?

 

I think compressor surge could have caused this when I let off to shift into 3rd gear cause it felt good and boost did not drop off in 2nd gear, then it never boosted in 3rd gear. A month or two ago I eliminated the other stock blow off valve and my greddy bov has been rather quiet, not very loud, the stock bov vented to the atmosphere was much louder. So maybe its all related..

 

My Greddy BOV is LOUD. I hate it.

 

I will probably start looking for a great set of used stock turbos with low miles. With The power and results I've had with them, I can't justify the cost of bnr's. Big single turbo would be nice but I can't afford it right now. I still want to set a better record at the drag strip with The stock twin turbos cause my car wasn't actually tuned great and didn't have a great start when I did 10.87

 

man that suks, hope you find the nut! car looked like it was running good until it went... was the vac line on the back of the greddy BOV in good condition? Mine is loud and blows off at any slight throttle lift? something for me to pay attention to I guess if it starts getting quiet! Hope just a new turbo takes care of everything!

 

I would assume compressor surge coupled with over spinning the turbos which is necessary(i think) to make the boost you are making.

 

BOV vacuum line is new, should be good, it's attached good. The bov worked but maybe it didn't work good or good enough. I also tightened it some, to harden it up, when ever I removed the old stock secondary bov, so maybe that didn't help. Ya I'm sure spinning them so fast to produce the high boost contributed to this happening. But this has also happened on stock turbos that were at 15 psi or less.

 

I found the nut and what looks like a piece of the compressor blades, many of the blades look like a little piece is missing or bent. See pic attached. Also there is about 1 mm of in and out shaft play that I just realized. I'll pull the turbos out of the car in the next day or two to inspect everything.

The nut is by itself, so it seems fair to assume the nut spun itself off first, maybe it then almost got sucked in and it destroyed the compressor blades. Maybe that then messed up the rest of the turbo? Idk. Still some compressor surge/pressure must have been great enough to throw the nut back up through the 2 intake elbows and my custom cold air intake pipes out to my air filter down behind the front bumper. So lots of pressure had to force it out there. There was also dirty oil and some metal shavings all through the intake elbows, and no signs of anything in the ypipe after the turbos so I'm hoping nothing got thrown towards the engine.

No evidence of anything wrong with the rear secondary turbo yet.

 

Looked like a nice launch at least :P

 

Would have been interesting to see what the new time would have been with the 1.4 60 foot.

Throw another set of stockers on it and get after it again.

 

Ya that's what I'm gonna do. I pulled out the turbos today, only took an hour, and pulled out the front turbo. It had some oil all though it, and the exhaust side turbine blades had just a little damage/jagged edges where the exhaust first hits these blades, the part of the blades you can't really see until you pull out the turbo after taking out the 6 10mm bolts. This is concerning.. I'll upload a pic later.

The Rear turbo looks all good and dry. Although I didn't pull it out yet to further inspect the blades.

 

So, my main concern is that your engine ingested pieces of your compressor wheel and spat them back out the exhaust. Compression check?

 

Ya I'll do that soon, gotta get my compression tester back from my brother.

 

hey Tom,

I think a lot of it just comes down to the fact that you are pushing these turbos very very hard. I don't have compressor maps for the HT12 turbos but here are the maps for the 20B twins: HT15 for the primary and HT10 for the secondary (two HT10 are used on the 13B-RE Cosmo engine)

 

I shudder to think what you could lay down with a set of BNR's. Hell, I bet they'd come to you some on the price if you showcased them the way you are the stock twins. They pop up all the time in the FS section, too.

 

Ive even got a set of BNRs I could sell him for a deal . However, I would like to see him run a 10.6X on the stock twins as I believe it is possible. I think that would put the record out of reach for years to come.

 

Check out the pics attached, see the difference between the blown turbo turbine blades and the pic of my secondary turbo that is in good shape, nothing wrong with it, no signs of anything but exhaust hitting the blades. Notice how far sticking out the blown turbo turbine wheel is, the blades had to have hit the turbo manifold and that's why the blades are like grinded down, and must be why they are chipped. There is also little pieces of metal and shavings found in the turbo manifold where the turbine wheel spins. There is no oil or metal shavings in the exhaust manifold bolted to the side of the engine, also no signs of any oil or metal shavings between the ypipe and the throttle body (the crankcase doesn't vent back to the ypipe anymore so no oil gets in there). 4th pic is a old primary turbo that I think was leaking oil and smoking.

I also did a compression check and it seems all good, even bounces on all rotor faces, my little battery was a little low so I didn't get real high numbers, but close to the numbers I got after the rebuilt engine was broken in. Also I didn't think the total compression number would be totally accurate since you are supposed to check it when it's hot/warm so I will do that after I get it all back together with another set of turbos. I do want to get one more perfect run at the track to see what I can get it down to with the stock turbos, 10.6 or 10.7 seems very possible.

I think I will also put that secondary stock bov back on to assist and since I never had this big problem before and compressor surge seems to be one likely cause. I will have to make sure my greddy bov isn't bad or set too hard also.

Thanks guys.

 

Bnr stage 3's are on my mine now, I wouldn't mind making more power and going faster, could also set some new records with those Haha. How much would you let those go for? Thanks

 

Ill pm you your price.

 

This happen to me as well with just a simple highway pull. The rear turbo was shredded. Soon after that I purchase a GT35r single kit and swaped it. Took the car for a spin and pop there goes the motor.. Don't know if the motor had Injested particles from the twins but that's what Happen to me

 

That sucks. I just need to pull out the fmic and see if anything comes out of it. Thx