Author Topic: Stage 1 T3 turbo (Read 2471 times)

Rabbit TD · « **on:** March 26, 2009, 05:47:08 pm »

When I was building my 1.6 T/D engine this winter I got a rebuilt by MJMturbos Garrett t3 converted to what they call a Stage 1 having a bigger compressor wheel on it. It is identical to the stock turbo otherwise but I didn't know much about turbo's at the time, {now either as far as that goes} and told them I would like to get something for just a little more power than stock. They said they could put a little bigger compressor wheel on and machne the case for it and I agreed. It has all new Garrett parts, doesn't leak a drop of oil but I haven't seen over about 6 psi boost yet even with the T/D pump and the EGT's would climb to about 1350 running it through the gears. The engine was timed to 1.0 and ran perfect other than the pump leaked and caused long cranking times but with the N/A pump on it now {waiting on the reamers and bushings to do a re-bush and re-seal} I'm still only seeing about 5-6 psi but myEGT's have come way down. Could it be that this turbo is actualy too big compressorwise. I don't know actualy how much bigger the compressor wheel is but looking at it compared to the old turbo it looks definately bigger. Does anyone know what they commonly call a Stage 1 upgrade or did I just get something too damn big. I didn't even think at the time to ask what size wheel it was going to be and really don't know what it could be really. Any thoughts on this would be appreciated.

subsonic · « **Reply #1 on:** March 26, 2009, 06:12:28 pm »

Ask them for the specs on the wheel. What are the exact demensions, trim. There are also variations of the same wheel, a-b-c etc.. All are different. Also find out what the new, if changed, A/R ratio of your compressor housing is now. Have them send you a turbo map of the new wheel.

jtanguay · « **Reply #2 on:** March 26, 2009, 06:19:55 pm »

getting 6 psi boost with 1300F or so out of a T3 turbo isn't normal. i think either they didn't machine the housing properly and so the turbo is losing pressure from the wheel (too much of a gap) or you have a boost leak somewhere in the system. it could also be a wastegate related issue, but if they rebuilt it, and did it correctly, there shouldn't be a problem.

do you have an intercooler hooked up? hows the exhaust? the muffler can actually get plugged up causing considerable backpressure and so you would see high egt with low pressure. its unlikely, but it still does happen.

Rabbit TD · « **Reply #3 on:** March 26, 2009, 06:56:45 pm »

Quote from: "jtanguay"

getting 6 psi boost with 1300F or so out of a T3 turbo isn't normal. i think either they didn't machine the housing properly and so the turbo is losing pressure from the wheel (too much of a gap) or you have a boost leak somewhere in the system. it could also be a wastegate related issue, but if they rebuilt it, and did it correctly, there shouldn't be a problem.

do you have an intercooler hooked up? hows the exhaust? the muffler can actually get plugged up causing considerable backpressure and so you would see high egt with low pressure. its unlikely, but it still does happen.

It's just the basic 2 in. exhaust with the down pipe from the 83 Jetta and a straight through Magnaflow muffler. I dont think the wastegate is actualy bleeding off boost, but I'm not so sure the diaphram is good to actualy let it bleed if it has to. I had to put my N/A pump back on while I'm waiting to get the T/D one re-sealed and without the extra fuel being injected the EGT's don't get past about 1,100 even on the mountain pulls. The motor makes absolutely no smoke that I can see with this pump and it had just the faintest amount visable with the T/D pump on it trying to see if it would smoke. I hate to think I got a screwed up turbo but I have a feeling I might have but I don't know what the stock one I have would do as I never tried it since it had so many miles on the car it came out of {432,000} and I don't know what a good stock one should do either as I've never dealt with turbos till this project. I still have it and am considering changing the compressor secton on it to the new one but then I have to get it balanced I guess. The motor had lots of power with the N/A pump on it though and ran great other than the long cranking because of the leak. I don't know anything about MJMturbos as far as their reputation but I have a feeling it's just too big to spool up on this stock engine. Where is a good place to get a turbo balanced if I go the compressor change route? And I forgot to add that I don't have an intercooler yet, I didn't think with that low of a boost it would be worth the effort yet. Oh one other thing, if a wastegate actuator itself leaks wouldn't it just not let the turbo bleed boost and not actualy bleed it otherwise? And I haven't disconnected the hoses from it yet to test in that manner and also I do still have the factory blow off valve on the motor also right now.

Rabbit TD · « **Reply #4 on:** March 26, 2009, 07:26:57 pm »

Quote from: "subsonic"

Ask them for the specs on the wheel. What are the exact demensions, trim. There are also variations of the same wheel, a-b-c etc.. All are different. Also find out what the new, if changed, A/R ratio of your compressor housing is now. Have them send you a turbo map of the new wheel.

I really don't want to deal with them aymore as I think I might have just gotten something that is just a peace of crap and they knew it. But it is solid and doesn't leak a drop of oil or let any pass through it. I just wish I'd have had a little more knowledge about turbo's and the pros and cons of big versus small when I got this thing. I had just started reading he Forum here at the time and just knew I needed a new turbo. I know it is a new wheel though as it did have the new numbers stamped or sprayed on it however it's done but I didn't even think at the time to write them down for future reference. It is a good bit bigger though just looking at it. Is the next size bigger compressor wheel really much bigger to actualy notice by just looing at it as compared to the stock 83 jetta one from Garrett? I was very specific though when I ordered it stating that I didn't want to make gobs of power and mess up my mileage and all, just a little more than stock power and he said their Stage 1 would be just right for this, but really I don't even know what it is componen wise.

vanbcguy · « **Reply #5 on:** March 28, 2009, 08:12:07 am »

Probably should do some troubleshooting before condemning them... If you think your wastegate might be dodgy then make sure it's not a problem, make sure you don't have any boost leaks, etc...

Seems to me that a shop that is familiar enough with turbos to be offering services like that to their customers should know a thing or two about what they're doing - have you gone back and talked with them at all about your concerns? The fact that they're willing to do custom machine work on turbos implies a certain level of knowledge that your "average" place doesn't have.