flier1

Trubo damage FOD
My turbo stopped workin on my 87 rx7 76,000 miles, when I had it opened up on the highway. Lost boost pressure, car still ran ok just no pressure, so drove 80 miles back home, checked all systems to the turbo and they were ok, oil flow ok. No smoke from the engine, no odd noises except if I gave it a lot of gas the turbo wined. Checked the compression of the rotors and they checked out at 90 psi on all faces and both rotors. Engine had been rubuilt 3000 miles ago and broke in right. turbo had never been rebuilt.
When I pulled the turbo off I found about 6 pieces of metal the size of a grain of rice and 10 more like sand in the bottom of the hot side of the turbo when i stood it on end and they fell out. Looked like gravel. The blade tips were shreded and the cold side blades had been rubbing on the housing. The blades would still turn. The metal rice size pieces were almost black color. Checked the air filter and intercooler for metal and found none. I don"t think anything entered the engine.
Could the metal have come from the turbo itself? Or where could it have come from?
I am shipping the tubo to Majestic Turbo to get rebuilt. Turbo is a stock HT 18S.
My question is- is there a upgrade that can be done to increase power when they rebuild it that will keep the same stock manifold and racing beat downpipe I have? Have a fuel cut defensor installed and a cone filter and racing beat exhaust, upgraded fuel pump and stock 550 injectors, no other mods. I do not want to get into upgrading to fuel management system or biger injectors, boots guages ect., just a modest power. preformance increase with out revamping the exhaust system or spending a lot of $ for mods. Anyone have any susgestions for the turbo rebuild.

Falcoms

I'd almost be leaning towards carbon buildup from the engine letting go, if you were running it hard on the highway. I don't see wether or not you premix, so I'm just assuming that you aren't and you had carbon buildup that ate your hot side. Carbon can often be mistaken for "black metal" due to it's hardness after intense exposure to heat.

flier1

No premix, still have the working oil metering pump.

flier1

Any way to decarbonize a engine in place in the car to safeguard against this, or a better gas to use, i am burning preimium?
Don't want to thrash another turbo- I like to go fast

Falcoms

Well, what you could do is spray carb & choke cleaner into a vacuum line that goes into the intake. By doing this, the carbon will become gooey and self clean off the rotor. Then when it hits the hot side of the compressor housing, it should just be flecked off, but instead of taking that chance, I'd say get the engine nice and warm without the turbo on it, then do the above trick I mentioned. Oh, and have somebody keep the engine revved up to about 3500-4000rpm while spraying the stuff in.

Manolis_D

iTrader: (2)

DON'T put anything in the engine! It's just been rebuilt - there's absolutely no way to build up an appreciable amount of carbon in 3000 miles, and dumping carb cleaner into an engine is most definitely not the way to go about things... even if there was carbon in it.

Don't worry about it - just get the turbo rebuilt. The only thing i'd check is to make sure you're getting oil pressure through the turbo's oil feed line. Provided that checks out OK, just put it all back together with the new turbo.

Without any fuel upgrades, it's not a good idea to have the turbo modified. You're already probably pretty close to trouble with exhaust on their by itself.

flier1

The oil feed line to the turbo was free flowing oil when I did the compression check just cranking it over (flowed into a can). Just not checked under pressure. The oil return line is open so I am sure it was getting oil. Small pieces were metal, I don,t think it was carbon- tried to disolve it in carb cleaner and took a hammer and pliers to them- they would not break up.

VietFC

maybe those are pieces of the apex seal from when the engine blew. During break-in you didn't really boost it so the turbo wasn't spinning very fast. Then when you finally opened it up and got the turbo really spinning, that's when the old chunks jammed the turbine wheel. Just a thought.