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Discussion Starter #1
So the last month or so I've been plagued with a rather annoying issue. The HX35 in my set of compounds develops a boost leak between the compressor housing and center section. I've cleaned the two surfaces and reassembled them and it never fails eventually it will start leaking again. The snap ring is a PITA and I know there are issues with it blowing off when under pressure from the primary charger...the fix being 3 machine screws tapped into the housing to cage the snap ring in place. So who else has experienced this and what did you do about it other than the obvious...change turbos. I know the H1C's have an O ring, but all the 35's I've had apart just relied on the machined surface for a seal.

The leak becomes pronounced once boost pressure reaches about 40 or so total and keep right on going to 70. I have yet to blow off the snap ring, but was wondering if a thin gasket would help...something on the order of a thou or two. Any more than that and clearances for the wheel will be altered too much I know. So yeah, has anyone else had this pesky prob with their 35 as a secondary?

When I come up with a viable fix I'll post it if no one else speaks up.

Chris
 

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TIG it together!
 

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oldsmokey94 said:
what exactly causes the turbo to squeal instead of whistle at very high boost?? drive pressures, bearings???
It's not squealing. As more boost applied it sounds like......well make the "f" sound with your mouth, that's the sound. IT makes that sound, as the leak becomes more pronounced with higher boost pressures. Everything is still working just not efficiently because his secondary can't take the pressures anymore for what ever reason. I hooked him up yesterday with a GT4288 yesterday so once he figures out the turbine hsg he's in fat city!
 

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Discussion Starter #6
yeah baby! The compressor map is nice and fat and it has a high pressure ratio capability. Like 'Slope said though it
s all about finding the right T-housing for it. It has a 1.22 A/R on it now which is just too big. I'd like to be able to get down around .90-1.0 non gated. We'll see. The compressor is sealed now....a thin bead of high temp sili worked nicely once allowed to cure overnight. I now have a merge collector gasket leak. Fixing that tonight with some steel cored high temp gasket material. Note to self.....standard exhaust gasket material does NOT hold up. It gets brittle and shrinks to cause a leak and then crumbles. The drive pressure is the killer. It can take the heat, but not the pressure.

Chris
 

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Got the axle joint done, did you bag anything this weekend?
 

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Discussion Starter #8
Yes and no...long story. The short version is 2700 vertical feet and dragging deer at midnight don't mix!! I'll tell ya bout it later

Chris
 

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Discussion Starter #10
no pics yet...but here's a tidbit.

The compressor housing is the same size as the HX35 dimensionally. It's a .72 A/R compressor which utilizes a 64mm/88mm inducer/exducer wheel. The map is huge, makes air well down on the low rpm side, but can withstand a high pressure ratio and make good air on the upper rpm side as well. The catch is that it has a big turbine/wheel on it that just won't do for a secondary charger. So Garrett is crunching some numbers for me. I've told them the HP estimate, engine size, rpm, the numbers on my primary charger, and what my existing secondary is. Hopefully they will give me a part number for a small enough exhaust housing and wheel to make it work well. We'll see in a few days when I hear back from them.

Chris
 

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I was going to use a GT37R (the new BB design for diesels) over my GT45R as twins...but I've heard that the BB version on top wouldn't like that (haven't called Garrett yet, though;))

If I can't make that work, I'll probably use a GT4088 up top, with the GT45R on bottom! Should spool awesome for their size...GT45R is gonna be 102mm+ with a 1.01 housing:D

I'll be watching how yours works!!!
Chris
 

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Discussion Starter #13
It's tough comparing Holset's exhaust sizing with Garretts. The A/R compared to a critical area square sometimes is apples and oranges. Even though The Holset I have on top uses a 12cm2, the porting I have done to the critical area just might make it more like a 14 or 16 or even bigger. I know I can get the 1.01 A/R turbine for the GT4288, but compared to about a .80 conversion for the Holset, I worry it will be laggy. And you know as well as I do that when you're fabbing your own stuff, redoing things gets time consuming if you guess wrong!! I do know this....the 64/88 .72 compressor I REALLY like. It's just if I can get below a 1.01 housing. I'll know in a day or two when Garrett gets back with me. He was thinking the 1.01 might be the smallest, which I still think might be big for a secondary.

Chris
 

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I'm with you...that 1.01 might be a bit big for a secondary. A buddy of mine is running a 68mm (Precision) Garrett with a .81 housing and it's REALLY laggy, but that 68mm wheel is HUGE, and very aggressive!

I would shoot for a .80 or so housing from Garret, or maybe look into having something made to fit. Maybe call Precision Turbo or Forced Induction and see if they could help you??

Chris
 

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Discussion Starter #15 (Edited)
Thanks for the input Chris. .80 was what I was thinking as well. I might go to a few more extremes on this turbo becasue of the potential it has with the very aggressive compressor. The exhaust wheel is an 84 trim (68/82) and I've also requested of garrett to see if another wheel would open up some possibles for housings as well. I'm checking to see if a housing off of a 40 or 37 could be machined to fit this sucker too. Glad to see someone else on board playing with the GT's. Let's definitely keep comparing notes eh?

'Slope...be sure and let me know of any "new" developments from your end as well.

Chris
 

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Discussion Starter #16
here's an update on the GT4288. I've decided to use the 1.22 A/R exhaust housing....but with a twist. I'm gonna modify the housing so that only one volute of the scroll (the forward one) sees exhaust initially. I'll do this with a butterfly built into an adapter block between the manifold and turbo inlet controlled by a wastegate actuator that will block the rear volute under low boost. Just tune the actuator with boost to keep drive pressures where I want them and keep the GT spooled, yet have lots of flow potential...kind of a built in wastegate. I'll keep you all posted on the progress.

Chris
 

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got...DIESEL? said:
here's an update on the GT4288. I've decided to use the 1.22 A/R exhaust housing....but with a twist. I'm gonna modify the housing so that only one volute of the scroll (the forward one) sees exhaust initially. I'll do this with a butterfly built into an adapter block between the manifold and turbo inlet controlled by a wastegate actuator that will block the rear volute under low boost. Just tune the actuator with boost to keep drive pressures where I want them and keep the GT spooled, yet have lots of flow potential...kind of a built in wastegate. I'll keep you all posted on the progress.

Chris
Do you work for ATS???:lol3:
Actually, that should work SWEET if you can get it dialed in and working right...but I'm sure you will;)

I'll definately be keeping an eye on this one now:D
Chris:peelout
 

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Discussion Starter #19
ah yeah, didn't even make the connection!! I forgot ATS was R&D'ing a "multi-staged turbine". Well that solves half of the equation, if they are doing it it must be worth pursuing. Mine will be a little different design though. It'll be pretty straight forward. Just gonna be a matter of matching the actuator leverage ratio to the opening curve that doesn't make any drastic changes in turbine trim too soon. Then getting the actuator signal right. I think I'll make the bellcrank for the butterfly adjustable as far as the ratio is concerned, this will prolly aid in tuning for a final apply ratio.

Chris
 
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