Possible Blown Turbo - Couple questions - R32 GTR

[SGT Grumbles]

Hey all, so from what I've read in old posts I'm pretty confident I blew one or both of the stock turbo exhaust wheels last night. Car was on boost at WOT, then I shifted (around 6500/7000) heard a loud noise car juddered and rattled and no more boost. What I wasn't able to find searching and has me worried were some of the other symptoms I had. I don't remember if I let off right when it happened or not, but shortly after the pop I pulled up to a red light. It made some horrible rattles noises, sounded almost like my front pipe came off, idled horribly going from too low to too high, but then rattles went away and it settled down. I didn't notice any smoke out the back but to be honest wasn't looking back there. After the engine settled down there was still a spiny rattle noise that's particularly noticeable when near the exhaust tip, idles normally, and drives normally off boost. I limped it the 2 miles home and it drove ok but couldn't build up boost. Oil pressure, oil temp, and water temp all remained normal; even when the engine was acting up. Haven't started it up since.

For reference I have a decat pipe, tomei equal length downpipes, and a cat back muffler. Rest of the car is stock. I noticed the day of that the car was making a bit more boost than usual but I never turned it up myself and had been running stock boost until then.

Planning to take off the down pipe, endo-scope up the rear of the turbos, compression test, and endo-scope through the sparkplugs for any noticeable damage. If I don't find anything doing that I'll start checking intake/intercooler piping and get the stuff for a leak-down test. Again, pretty sure this is a blown stock turbo exhaust wheel, but I'm wondering if anyone has any other ideas for what to check and if my symptoms indicate something catastrophic. Should I start budgeting for a new/rebuilt short block?

Also side question, assuming the engine isn't boned, can I run -5's on stock boost with a stock ECU/fuel system? Not sure I have the funds to do everything at once and was hoping to get it back on the road this summer.

[Duncan]

It sure sounds like a lost turbo wheel if it idles and drives OK off boost but won't make boost. As you don't have a cat you are unlikely to ever find the missing wheel. 

Having an intercooler pipe blow off or split is another potential cause and can sound terrible, but the car almost always won't start or idle in this case.  Best to carefully check each large intake pipe before you start pulling turbos off, as well as obvious failures like pipes not being connected there can be harder to identify issues like splits under hose clamps for example.

Least likely but still possible is you've had an engine problem at the same time, eg broken ring lands. A compression test will tell you if there is a problem but again this is unlikely if it starts and idles OK.

If it is a turbo wheel coming off I have heard of engine damaging resulting but have never seen it personally. Apparently ceramic from the turbo wheel have more velocity than exhaust gases and can travel through the open exhaust valve into a cylinder, scoring it badly enough to require on oversize piston rebuild.

[SGT Grumbles]

Thanks Duncan. Have you heard of a lost wheel causing a rough idle and sputtering for 30 seconds to a minute after it happens? That's what has me worried I may be one of the unlucky few that had ceramic backflow into the cylinder. I've also heard of the ceramic damaging the internals but wasn't sure how common it was. I have a borescope so hopefully that should be good enough to see any damage that might have been caused.

And that's a good idea, I'll check all the intercooler pipes closely. It's all original and almost 30 years old so definitely a possibility. What I could see without diving to much into it last night looked like everything was connected still at least.

[r32-25t]

I would check your intercooler hoses first and then check the rear wheel on the rear turbo with your camera 

[Dose Pipe Sutututu]

Then I would go order a twin scroll single turbo manifold, a twin scroll turbo, and two gates. Don't replace shitty twins with another pair of shitty twins.

I know Americans love their "twin turbos" but seen any fast reliable Supra with twin turbos? They all go sex spec single.

[Stixbnr32]

When i lost my turbo wheels at WOT i just lost boost but never had splutters etc.  Although i was on the highway so didnt slow down much.

 

I did eventually have an engine failure but I did a rain launch for a laugh so i think it was just a stock pump failure.