GTA42 experts, please

CTD2500

CTD2500

Brown Between the Cheeks
Joined
Aug 3, 2013
Messages
454
Hi, I just got a used GTA4202 in the mail today. It was a $175 ebay find.

Anyway, I tore it down. Other than having some fairly bad corrosion, the bearings were pretty tight. It turned fine. Wastegate actuator was rotted out, a few small cracks in the turbine housing. (1.15 gated)

Anyway, to the point. When I pulled the compressor cover off, this is what the wheel looked like:

IMG_0151_zps8zpkpv59.jpg


Obvious machine marks of a billet wheel...? My other GTA4202 and 4294 are cast as seen here:

02 left, 94 right
GEDC0179_zps405ddb73.jpg


I was unaware that Garrett offered the GTA4202 in a billet version. From my memory and photos, it *looks* pretty much identical in design. Can anyone confirm this? Is it an aftermarket wheel? On the back, there is a number stamped in it: GTA8059

The Detroit Diesel part number on the tag is: R423528059
I Googled that part number just now with no results.

The main question I have is:
Is this billet wheel better than the cast wheel? Does it flow more?
The cast 4202 is currently installed in my truck, is it worth the trouble of swapping it out for the billet?

Thanks guys
 
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Its Identical aero to the cast wheel. Good find! Probably not worth swapping out unless the other charger is getting tired.
 
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Thanks!

What about weight differences or strength? Pretty negligible, I assume.
I noticed it felt light when I was holding it. I thought I remembered the cast one feeling pretty bulky, but that was about 6 months ago and my memory might be playing tricks on me.

The other one in the truck started out as a fresh 4294 last summer, then I bough a used 4202 over the winter to try, but the turbine wheel was toast so I just swapped the compressor wheel, housing and back plate (and balanced it). Since then, I've been looking for another good used one or even just a turbine wheel build a 4294 with the compressor I took off so I have both ready to run and easily swap-able.
 
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Lol, this is the first 4202 I got...found some valve chunks in the housing.

GEDC0178_zpse587bf0c.jpg
 
I wonder if that wheel is out of the vgt garret off of the egr 60 series. I know they had a 71mm version of it like the 4294 had. I can go look at the one I have and measure. I dont recall that turbo im referencing being boreless though.


How do you like the 4294? I have some 71mm detroit and c12 67mm versions. Always been tempted to try one on my truck. Haven't read much on guys running them though.

Sent from my SM-T110 using Tapatalk
 
I loved the 4294, it had such fast spool and was awesome driving around town. Only problem was I lost noticeable top end with it.
That's why I tried the 4202, but it has a lot more lag which is a bummer.

I forgot to mention, I measured this billet wheel I got today, it was 74/102mm.
 
When you were running the 351/4294 do you have any dyno or track numbers? Also drive and boost numbers? Were both the turbos completely stock or did you open up the waste gates? Spring gate or factory gate on the 351?

Sorry for all the random questions but I just happen to have both of those turbos laying around.
 
I actually just installed the 351 last Wednesday so I never drove it with the 4294. I ran an older BW 59/65/12 from a CAT with the 4294.
I leave the gates stock on the GT42s, they seem to be big enough as is. I port all my secondaries as much as I can though.
As for actuators, I have a spring gate on the GT42 and so I used it's actuator on the 351, since it's gate was missing when I got it. I made a bracket that bolts to the T3 flange studs instead of the compressor housing to allow the 351 to be clocked how I wanted. I tested it with compressed air and the actuator and linkage move smoothly, but I haven't driven it much yet because this used 351 leaks oil bad out the back so I have new seals on order.

Looks like this:
IMG_0142_zpsz23zcvmy.jpg


I have no drag strip or dyno numbers, the truck is basically a hobby. 60psi total (before the 351 install), 25 primary is about all I can tell you.

If you have a 351 and 4294, I'd say try them. I'm not sure what you're after, but I think they'd be hard to beat for towing.
 
CTD2500 said:
Thanks!

What about weight differences or strength? Pretty negligible, I assume.
I noticed it felt light when I was holding it. I thought I remembered the cast one feeling pretty bulky, but that was about 6 months ago and my memory might be playing tricks on me.

The other one in the truck started out as a fresh 4294 last summer, then I bough a used 4202 over the winter to try, but the turbine wheel was toast so I just swapped the compressor wheel, housing and back plate (and balanced it). Since then, I've been looking for another good used one or even just a turbine wheel build a 4294 with the compressor I took off so I have both ready to run and easily swap-able.
Click to expand...

I would guess the billet wheel as a touch heavier. It would also take more abuse. Turbo resource would be my first call if I were looking for a replacement stub shaft gt42 exhaust wheel.
 
I'm running a 351/4202 setup, I'm extremely impressed with how well it spools, and it pulls almost as hard at 70psi as the old 351/78 setup did at 100psi. No numbers or times for it yet though.
 
madmikeismad said:
I'm running a 351/4202 setup, I'm extremely impressed with how well it spools, and it pulls almost as hard at 70psi as the old 351/78 setup did at 100psi. No numbers or times for it yet though.
Click to expand...

Good to hear, I'm itching to drive mine! I wish those seals would hurry up and get here.

Are you running the 2 stage a/w coolers again?
 
CurtisEmery said:
I would guess the billet wheel as a touch heavier. It would also take more abuse. Turbo resource would be my first call if I were looking for a replacement stub shaft gt42 exhaust wheel.
Click to expand...

I should look into Turbo Resource. If I get my hands on another turbine shaft, I could put together all 3 turbos complete and sell one of the 4202s.
 
CurtisEmery said:
I would guess the billet wheel as a touch heavier. It would also take more abuse. Turbo resource would be my first call if I were looking for a replacement stub shaft gt42 exhaust wheel.
Click to expand...

What abuse does a compressor wheel see that a cast wheel wouldn't last as long against? Dirt? Always wondered that.

CTD2500 said:
Good to hear, I'm itching to drive mine! I wish those seals would hurry up and get here.

Are you running the 2 stage a/w coolers again?
Click to expand...

Just the cooler between the secondary and intake. I removed the interstage cooler to simplify the plumbing a little bit, free up some room under the hood, and free up A LOT of the work load on the single water pump I was running. Plus, it fit perfect, no modification needed, in the volkswagen lol. Win/Win.
 
madmikeismad said:
What abuse does a compressor wheel see that a cast wheel wouldn't last as long against? Dirt? Always wondered that.
Click to expand...

I would think billets can handle higher P/R and RPM...just guessing though.
I saw in your other thread that your GT42 is ball bearing, do you find it makes a difference in spool? Is it a GTX?


On a side note, I just spent about 10 minutes with some varsol and a brush...

IMG_0154_zpsjawquyab.jpg


IMG_0157_zpsbgtlmdap.jpg


It doesn't seem like this turbo had a lot of miles on it, but it does look like it sat out in the weather for a long time.
 
Just a gtx. I've never used or been in anything with a journal bearing 4202, so I can't say for sure. What I can say is it spools almost so fast, I think it might spool as fast as the he351. It literally starts making boost at the same time, but just doesn't climb quite as fast. I wonder if it's just the secondary slowing it down lol
 
Just a GTX...lol, aren't those like $2000?
Sounds pretty impressive though.

The journal 4202 spools OK, a tad slower than the K31 I ran before. But the 4294 (which was journal) spooled pretty damn good. It would maintain 2-4psi while cruising on the highway.

I've only ran Detroit 60 Series turbos as primaries, I've never tried an S400 so I can't compare to the standard S475/96/1.32, etc. I've always had a preference for a wastegate on both turbos.
 
CTD2500 said:
Just a GTX...lol, aren't those like $2000?
Sounds pretty impressive though.

The journal 4202 spools OK, a tad slower than the K31 I ran before. But the 4294 (which was journal) spooled pretty damn good. It would maintain 2-4psi while cruising on the highway.

I've only ran Detroit 60 Series turbos as primaries, I've never tried an S400 so I can't compare to the standard S475/96/1.32, etc. I've always had a preference for a wastegate on both turbos.
Click to expand...

Holy crap that's an expensive typo. I meant just a GT4202R. I must have been reading your post while typing and subconsciously typed the "X" LOL

I have the gates cranked shut on both chargers for now until I see temps get crazy. Might open up the secondary a little to see if it'll help the garrett spool faster, since it seems to want to run as a single already lol. Maintains about 5psi just cruising, and 10 psi total at the head.
 
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madmikeismad said:
What abuse does a compressor wheel see that a cast wheel wouldn't last as long against? Dirt? Always wondered that.



Just the cooler between the secondary and intake. I removed the interstage cooler to simplify the plumbing a little bit, free up some room under the hood, and free up A LOT of the work load on the single water pump I was running. Plus, it fit perfect, no modification needed, in the volkswagen lol. Win/Win.
Click to expand...

The billet wheel has a higher density/ tighter more consistent grain structure making it stronger. Most of the oems use billets for added durability in high cycle apps like garbage trucks that see constant idle to wide open throttle cycles.
 
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