MPR

Just like the tittle says...

To make a long story short, couple friends and I have been working very hard on our autocross race car, an 87 MKI MR2 supercharged (see sig) for the past 2 months.

1st race of the season I finished 2nd in class and with the 3rd fastest time of the day. That was with not running 100%, bucking and sputtering all day.

Soon after that we found the supercharger clutch was not functioning properly. Since we are already near the limit of power we could make with the sc, we decided to go ahead and remove the sc and change it to turbo.

We removed the intake mani and swapped with one from an NA 4age, and swapped the exhaust mani with a log type home-made turbo mani we got for dirt cheap. After countless hours of fitting and fabbing and welding and cutting, we finally had it running and out on the street last friday night.

It ran great for about a 1/2 hour, when suddenly, no boost, no spooling. Only massive clouds of white and blue smoke out the tail pipe. YIKES.

Today we pulled the turbo out and to our surpise the turbine wheel was GONE! Not a trace! Nothing! The shaft and compressor wheel were undamaged and in place. Crazy!

The turbo we were using was from a skyline R32 GTS-T with the RB20DET engine. A not so good trait of this turbo was the use of a ceramic turbine wheel. When these wheels are spun too fast, they grenade and shatter! Thus, what happened to ours when we tried to run 14psi boost. But MAN it was fast for that few seconds! LOL.


Anyways just thought I'd share this interesting story...PICS TO COME!!! Be patient!

Polkaroo Killa

WHOA!!! I want to see pics of this...hahaha.
That's the same snail I had on my car when it was turbocharged.

MPR

Yeah, I've taken appart, rebuilt many turbos over the years but I have never seen anything like this.

The only trace you can see of any trouble in the turbine side is a little scoring on the inside face of the turbine housing as thousands of tiny bits of ceramic blades flew every which way when it let go.

We have been in contact with a good local turbo shop and there might be a steel replacement turbine wheel for these turbos....I hope...

fingers crossed...

pics to come later tonight!

Polkaroo Killa

Well at least they might have a steel replacement turbine wheel, so that's a good thing. I found the Skyline snail to be a very reliable one, and it would suck if it went to waste.

MPR

No kidding...

I had to make a one-off custom down pipe for this turbo, not to mention many other turbo-specific modifications to make it fit the MR2 perfectly. So we really hope to make this turbo work.

When it was working, it was fully spooled by 3000-3500rpm and when compairing to when we ran the sc, it showed the same, if not, slightly better acceleration with the turbo running 6psi boost as it did with the sc running 11-12psi boost.

MPR

Ok, here are pics as promised:

Before the teardown:





This is what we saw when we looked in the exhaust exit....no turbine wheel. Gone!



Lots of oil because the seals went...but everything else was still in good condition. You'll also notice the entire turbine wheel end of the shaft is missing as well, I'm guessing it is joined with the main shaft via some kind of epoxy from the factory or...?





Bearings were in pretty good shape too. Little bit of scoring, but otherwise, not too bad.




Below you can see some scoring and gouges on the inside face of the housing where the tiny bits of the shattered turbine wheel decided to try depart at over 100,000 rpm...lol.




And just for kicks, here's our entire exhaust system with home made custom down pipe (MR2 in the back-ground);

MPR

We just heard back from the turbo shop, it's not rebuildable for anything less than about $750.

So if anyone has or knows someone with a t3 flanged t3/t4 type turbo in good condition for sale for a reasonable price, please PM me!

Thanks.

Polkaroo Killa

^^^ Holy cow!!! It just disinegrated.....unbelievable. I love how the reminants of the turbine wheel left scars on the housing of the turbo.

I wonder if all those pieces of the turbine wheel shot out of your tailpipe, assuming your cat is hollowed out....hahaha.

$750 to rebuild? Ouch!! That sucks.

MPR

^^LOL what cat?

Yeah all the pieces most likely blew out the exhaust. Though I'm sure there are a few pieces stuck in the muffler.

We may have a new turbo, from a 300zx, that will bolt right on to our setup....pending a response from the seller....fingers crossed.

Polkaroo Killa

Hahahaha oh yeah, I should have known about the cat. I'm talking to MPR here........Mr. Straightpipe...LOL

Are the turbos from the 300zx and Skyline comparable when it comes to size/specs?

MPR

Well, specifically we used a turbo from the R32 skyline GTS-T which is the RB20DET engine. And they used pretty much the same turbo on the 80's 300zx turbo, but we're looking for a turbo off an 85-87 300zx turbo to be specific because those turbo's were identical to the one's used on the RB20DET engine but used a steel turbine wheel...

MPR

[QUOTE=Polkaroo Killa;1411255]Hahahaha oh yeah, I should have known about the cat. I'm talking to MPR here........Mr. Straightpipe...LOL
QUOTE]

lol....

We are actually going to put a cat on it for legal reasons. The car is still driven on the street and since it had a cat from factory, best to avoid any trouble and keep it all legal.

Probably just throw and high-flow spun cat on which does squat for emission anyways...lol. There is absolutely NO emissions control equipment on the car as well...haha. It's all useless now anyways.

MPR

WE FOUND IT!!!!!

The supposed "vaporized" turbine wheel fell out of the muffler as we went to reinstall it back on the car this evening...lol

Couldn't believe it! I lifted up the muffler and something was rattling inside, so I shook the item out which turned out to be the missing turbine wheel from the turbo. It's pretty bad looking, all the blades are broken off etc..



Pics to come...

ton1c

iTrader: (1)

That is impressive and disheartening.

At least you guys found a new unit Try not to vaporize anymore with that mr2

MPR

Well we know now to stay away from any turbo's with ceramic turbine wheels. Kinda funny that a 1.6L broke a turbo meant for a 2.0L...lol.

The new turbo we just installed has a steel wheel and it's a bit bigger (60 trim, the other was a 50). The efficiency map showed it should give us 14psi from 3500 to 8000rpm, within it's peak range for our little 1.6L...so fingers crossed.

Will be running today, we'll see how it well it works. More pics to come...