fastjweb

iTrader: (2)

I have an 03 4.8 silverado. It has a small ht1 cam, dual valvesprings, and a 4" MBRP exhaust. I originally had the Magnum 70mm that came with my trick kit, That turbo lasted 300 miles, before the compressor started rubbing the cover. I cant explain why, but I think i got a bad unit. Anyways, I needed a turbo to replace it and in a hurry, so I through on a used turbonetics 62-1, and kept my .96 ar exhaust housing from the magnum. I have been running this turbo for 7000 miles and has been just fine. Boost is currently at 9.5lbs. The truck seems to run good, but I feel the turbo is too small. I really only want to run a max of 12lbs, i have a built trans, 3600 converter, and 3.42s will be replaced with 3.90s. I realize the the 62-1 is only a 62mm compressor and 65mm exhaust wheel, but what would be a good size to go with for only 10-12lbs? Am I right to say that this turbo is probably out of steam where im at now? I have spare Garrett gt4088 with the 65mm compressor, 68mm exhaust wheel, or should I get something in the 72mm/ 68mm exhaust wheel area? Thanks for your time. This a single cab/step side, 2wd. 450 to 500 rear wheel is the goal. I feel its over 400 rear wheel now, but I think it falls off in the top end.

TrickTurbo

iTrader: (12)

Couple of questions.
Did you contact magnum about replacing that unit under warranty ?
The compressor wheel touching/ how bad? A little kiss no big deal. And bad dig and not turning. Very bad.

The exhaust housing more then likely will not swap across the turbos.
Differently mfg. possible different profile in the wheel.
Even tnetics old design to newer stuff won't just swap out.

The current turbo is small bit turned up will still get you to 500.
That 65wheel
Is great for street spooling but looses top end breathing.

70/72/76 compressor will all feed that engine your power level goal.
The exhaust side.
65/68/75 will all do it. But the larger wheels will get there with room to spare.

fastjweb

iTrader: (2)

Thanks for the advice Rick. Actually, I had sent you pics of the damage, and you told me that it looked like something got in there. After I first heard the noise, I pulled the filter and could not see any damage. So i had a buddy slowly rev it up while I watched. Above 3000 rpm, the compressor would come forward a rub the case pretty good, then any rpm above that, the compressor would suck back in and be fine. I thought right away that the thrust bearing was bad, so I took it apart to check. The journal bearings were fine, shaft was clean, clean oil, the actual thrust bearing was good, but the thrust collar in front of the bearing was damaged on the compressor cover backing plate side? When I had sent you the pics, I just figured you would be able to give some idea besides telling me that something got in there. Nothing was in there, and the compressor had a butter knife effect going on where it rubbed. I didnt know what to do regards to the warranty, for all I knew by the time I installed it it was too late, and you did not mention the steps we could possibly take. I didnt blame anybody, I just needed it back on the road. The only thing I can think of is that it had too much back pressure with the stock exhaust I had at the time, but I was only running 4.5lbs when it happened. I realize the components between the turbos wont interchange, I was just mentioning i had a good gt40 laying around, and wondered if it would be any better than the 62-1. I can tell you that the 70mm at 4.5lbs hit harder then the 62-1 at 9.5lbs.

TrickTurbo

iTrader: (12)

Should be a card inside the turbo box talks about warranty.
You should be able to send it back in and have them check it out.
I talk to lots of people and sorry if I didn't mention the warranty through magnum. Most turbo mfg offer some type of warranty except eBay co.
What's the date on the ticket I will get ahold of magnum and see what can be done on that unit.
No promises but will try.
Just pm me the info. Name date etc.

TrickTurbo

iTrader: (12)

Gt40 is gonna take some modding to the down pipe.
Not a good exact replace set up.

fastjweb

iTrader: (2)

Ok, sounds good Rick, I will check for that card, and yes your right, looks like the Vband is larger then the exhaust housing for the Magnum. Thanks again.

Show-n-go5.3

Ive recently been doing some research lately and came across some good info. A guy did a back pressure test with his 4.8 MP t76 AR.96. he had a 3:1 back pressure ratio from 5psi to 15 psi of boost. A 2:1 ratio is considered max on most setups. Ive been suggested to go with either a 76/83 or 76/87 with a AR1.0 min. I kinda wish id never bought the mp T76. If u did go with a bigger turbo hot side, you would have to upgrade to a 4" down pipe. Its not going to be instant response but less heat, more power and u could crank the boost into the 20psi range and not be bottle necked. Check this video out https://www.youtube.com/watch?v=qDE0...kUKmRZGCXlJwiw

TrickTurbo

iTrader: (12)

3.5" down pipe work on the Borg. T4 stuff nicely.

Interesting vid.

Choda

iTrader: (1)

Was that foose? I wonder what exhaust he was running and how it vs open dp would have effected the pressures.

oakley6575

iTrader: (5)

Yes that was foose's truck. Pretty interesting vid.