Something people do with those T3's is swap compressor wheels. All T3 wheels are the same overall diameter & shaft size. You can replace a 40 trim wheel with a super 60 trim wheel. Of cource the compressor housing would need machined to open up the inlet snout.
I'm not a turbo know-it-all but, I have talked with a lot of rebuilders, some even in person haha. You always hear "if the wheels have so much as tinged the housings, it's shot" Nothing could be as far from the truth!! While visiting a rebuilder shop, an employee walked up to a sandblast cabinet with a bucket full of turbine shafts/wheels and dumped them into the cabinet.
That makes you feel a little odd. At home your so carefull, even setting one down, you lay a cloth on the bench first...
The Hitachi turbo. What I did was nothing new, rebuilders had been mixing & matching parts in them for years. A T2 uses dynamic seals same as the Hitachi. It just so happends the T2's is a little bit thicker and has to be file fit about .004. Zero end gap on dynamic seals is desired. There are two styles of turbo seals. Dynamic, which look like piston rings. And mechanical seals, which look like water pump seals, having carbon/steel seal faces that rub. Sometimes there is no choice which seals to use. Say with a draw-through turbo setup. Once you see a good turbo system, draw-thoughs make you cringe. Never throttle a turbo from the inlet. This is what a draw-through does. Think of putting your hand over the inlet snout of the turbo right after a dyno pull. Get the picture? Sucking oil through the seals is never good.
A compressor bypass on a free blowing turbo really helps. Don't confuse a bypass with a blow-off. Blow-off's are set to release boost at a set pressure. Indy cars used them to regulate horsepower. Drivers said when they popped, it was like putting on the brakes.
Last year I built a big Hitachi for a friend. I used a T3/50 trim compressor wheel. A while back I had a machinist make several backing plates to make swapping wheels in the Hitachi possible. Otherwise installing a Garrett wheel requires reducing the boss on the back of the wheel. (I used an old valve grinder & did it myself) and grinding some of the boss on the front of the wheel so the nut will go on, I bullet shaped that boss while I was at it. A 50 trim wheel takes some horsepower to spin, so the turbine wheel needed some help. I looked around for a suitable turbine but ended up having a local welder, weld up the ends of the exducer fins. I ground the welds myself and made sure the blade thickness was consistant. This sounds easy and it might be but, it took me 16 hours to grind & shape the fins. I did my own clipping. Let me add in here that clipping the exducer fins lower back-pressure and has nothing to do with loosing drive power of the turbine. Anyway, I couldn't machine the radious on the fins myself, nor could I machine out the exhaust housing for this, now larger wheel. And of course balancing the whole assy. I drew up some prints, took pictures & made 8X10 glossy's with circles & arrows and writing on the back, then headed out to a rebuider.
This gets confusing I know. I've had compressor housings machined for larger compressor wheels. It's not that expensive and rebuilders don't seem to mind doing it. The only problem is, remember the remark I made about "even if the wheel slighly touched the housing, it was trash?" Well, after having your compressor machined, it will look like trash. They work, don't get me wrong but, the radious (if you can even call it that) doesn't come close to matching the wheels radious. I used clay to make an impression of a 40 trim wheel. Poured plaster into the clay etc. had a nice plug with the radious needed so the machinist could maybe use a tracer on his CNC lathe. What he did was, bored the inlet hole on the lathe, then sat down with a Dotco and sanded that radious by hand until the wheel stopped rubbing. Sound like precision to you? Like I mentioned prior, it works great, no trouble at all, makes enough boost to scare my friend so he's gone back to a smaller turbo until he's ready for that much power.
Right now I'm at the stage where I want to do my own "everything" Enco has a 12 X 36 lathe I need. Saving up $2100.00 is tough, plus lifting a 1000lb machine into the house.... Always something. I must add Saum Engineering made a wonderfull compressor housing for me. It took a few years off his life getting the .0010 tollerance and he never wants to see another one but, he shows that the radious can be made to match the compressor wheel, same a stock. I've had all kinds of ideas like, making a screw-in adjustable valute (inlet's radious area), adaptable screw in inserts for different inducer widths. Long list...
If anyone wants to talk turbo's probably be better to email me & we can swap phone numbers...
<small>[ February 21, 2004, 02:06 PM: Message edited by: Ryan ]</small>
