These things are very expensive to have rebuilt. I have handled them and I cannot see what is so complicated. All I see is a shaft, a couple impellers some bearings and some seals. Apparently, all those things get pressed together on a shaft with the proper spacing and order,,,,order is important also.
Recently I had the opportunity to look at a 8V92 Turbocharger. I found that the turbo compressor shaft would move in and out 20 or 40 thousandths.....guessing there but it moved enuf to clunk. I figured it was completely shot but the board corrected me and it turned out to be very serviceable. I guess how much play and in which axis is different for each design and I am sure that must be written down. When I first started reading about turbines it was in the Air Force and their tolerances for gap separation from fins to wall was measured in thousandths of an inch and the thrust was not in the "clunk" neighborhood. I know I can have my parts balanced and then I can have them balanced to turbo spec and I thought that was much closer. I got it done for free so I never questioned anything.
Anybody know? Is it so difficult that I would only want to deal with certain "known" shops?
Thanks,
John
One needs to consider the cost of failure when looking to cut costs. If the compressor side were to fail & come apart, you'll probably loose the rest of the engine.
The biggest issue with turbos is the speed at which they turn - in the 100,000+ rpm range.
The clearances may be measured in thousandths, but the runout & balance are much more critical (meaning a much smaller number).
I'm sure the handling of the bearings is important too, lots easier to damage a small ball bearing than most think. Bearing life is measured by revolutions - at speeds of 100,000 rpm, the revolutions add up quickly!
I'm sure lots have had success doing it on the cheap.
As for me, I'll stick with a reputable rebuilder with experience & the proper fixtures for the turbo I need.
John, I'm a little confused with your post???
Do you have a turbo that needs rebuilt?
You wrote> I know I can have my parts balanced and then I can have them balanced to turbo spec and I thought that was much closer. I got it done for free so I never questioned anything.
The turbine wheel and compressor wheel are balanced seperately. Then once assembled they are balanced as a complete assy. This is either done or it is not done.. You got the turbo balanced for free or you got the rebuild done for free??
If the turbo went clunk/clunk that usually means that the thrust is pounded out. This will usually wipe out the backplate, which will eventually leed to wheel rub..
Part on these turbochargers add up very quickly $$$ You typically cannot cut corners with these animals, or you will paying to have it repaired again the second time around :(
JohnEd,I will go any place on and engine even the injectors but the turbo is one place I don't go it is a lot more to rebuilding that one would think as Kevin said parts are hi dollar just price a center section for one
.Don and I use a shop in Lake Havasu Tom has been rebuilding turbo for years he started the turbo rebuilding program for DD in Utah and with all the years behind him I have had one of his fail.
A good turbo rebuilder is worth the price to me if Kevin wasn't so far from me I would give him a try and so would Don
good luck
Kyle,
All solid advice. Truly! Solid advice that i would expect from a knowledgeable Knut. And, I thank you.
For clarification: I am one of the worlds biggest believers in "Qualified Experts" and I place the greatest value and respect on "experience". I also confirm that almost anybodies skills and profession are seen as simplistic by lots of folk but their own as really complicated, full of innuendo and hard fought skills and richly deserved/earned. I can not remember ever not having this respect for my elders, superiors, craftsmen and professionals. Someone long ago made an impression and taught me an important lesson at a young age. I am not offering this as a defense or anything as I don't think any has attacked me, but it is background.
The consequence of a failure is the determining factor in how much will be spent to assure success. NASA spends like a drunken sailor if the item is a "single point of failure" for the space mission. And that last few percentage points for confidence usually cost much much more than all the funds used to get to 97% probability of success. I would not risk a $18K overhaul on saving $500 or so on "unqualified source" workmanship. I surely might do so on "personal challenge", however. Might was the operative word there.
In general, I agree with all you said about it being complicated. With all the cautions I hear, however, I doubt that "lots have had success doing it on the cheap". That I truly doubt. And there is little chance I won't follow your lead and buy, instead of rebuild, any turbos I might need in the future.
I thank you for your comments,
John
John Ed,
Well said,
John
Quote from: JohnEd on December 03, 2009, 02:36:05 PM
I doubt that "lots have had success doing it on the cheap". That I truly doubt.
I doubt it too, seems my sarcasm needs some work . . . ;)
if you do try it, add an aftercooler(intercooler) in case it needs to filter some parts for ya, if it don't then you have cooler intake air :)
Kyle,
By definition, "sarcasm" is the wit of the master. Nice work. ;D
New Bee,
I have pondered that a lot myself. The intercooler is sooooo prooooven. Why aren't more people modifying their 2 stroke config to include one? They prevent power drop off and add efficiency. Beats me. Your right about them catching the debris from a desintergrated turbo. Either one of those, by themselves, would justify the cost of the intercooler. Just to make sure we are both on the same page: aftercooler comes "after" the roots compressor/blower and "intercooler" comes after the turbo. I'll bet that isn't written down in DD lit.
Thanks for your comments,
John
I think the reason the intercooler isn't as common with DD two strokes, particularly the V series, is packaging and cost. An intercooler isn't particularly cheap, it needs air flow to work, and you need to plumb from the turbo to the intercooler and back. The length of that introduces turbo lag as well. For marine installations that don't use radiators, it's just so easy to pop the turbo up on top of or right behind the engine, direct shot from the exhausts and into the blower intake, aftercool the air charge in a controlled fashion, and bob's your uncle, done. Here is a cool twin turbo 8V-71, imagine trying to complicate that with intercoolers and how much more difficult it would be to package: http://www.powerlinecomponents.com/literature/detroit_diesel/ddc_drawings/70837699ID.pdf (http://www.powerlinecomponents.com/literature/detroit_diesel/ddc_drawings/70837699ID.pdf)
for bus applications, particularly where there are side rads or you are re-engineering the cooling system anyway, designing an intercooler is very easy and just part of the project. Air to Air also removes the additive heat load that would be driven into the cooling system of the engine install, another bonus when you are already trying to remove additional heat from a power boost in your application.
BTW, to the original topic, my DD V series manual has detailed instructions on how to rebuild a turbo, and complete exploded diagrams. a lot of "internet" rebuilders just seem to replace the seals and clean it good. Not sure that's what I would consider a "rebuild".
Brian
Guys there are a lot of buses out there with 8v92 engines that have intercoolers it was always a option even on the trucks with 92 series.
DD was the first to use the intercooler
In fact I am stopping over in Albuquerque next week to install new injectors and a turbo for Jim who is installing one on his bus.
The intercooler has been in use for a 2 stroke for a very long time
You remove the aftercooler and install a air deflector in its place and the deflector is getting hard to find now days.
JohnEd it is in the book along with the water cooled intercooler for marine use
good luck
Brian,
Thank you. It all sounded good till Cliff's post. Everything you said was so true.
Cliff,
Thanks. Doesn't seem that that was all that common pf knowledge. You the MAN!
John
to further explain what Clifford said is that I rebuild most of the turbo we use, I use Tom when I don't have a core or I am buys and can't get to it. I have had some of Tom's turbos faill just like from time to time mine will go south on me. You can't do any kind of work for a linght of time and never have a bad day, ( just ask BK ) LOL HA HA
Don
Cliff,
I am confused as to what the logic might be in removing the "aftercooler" in a turbo upgrade? The after cooler does a good job, I assume, in reducing the temp of the air after the blower increases that temp but the aftercooler can only drop the airtemp to 180 degrees, engine coolant temp, because it is coolant to air. I can intuit that the air temp after the compressor stage is above 180. After the "intercooler" the temp must be something above ambient and I suspect it is a lot. So now the compressor is ingesting hotter air than a N engine and it should profit from the aftercooler even more. Why delete it?
Thanks,
John
The two area's that will haunt any turbo builder is the turbine wheel seal ring grooves and the bearing housing seal bore.. The 100% method is to replace the bearing housing and turbine wheel. The 85% method is to cut the groove width .005" oversized, and cut the seal bore out of the bearing housing and CNC a new insert/seal and install and hone to std/std...
Tearing a worn turbocharger apart and installing new bearings and new turbine side seals will normally result in a 100% failure. The reason is these units have already had the text book rebuild done 600,000 miles previous.. I see bearing housings with .040 over.
For my personal engines and recommendations to friends and family, I strongly recommend buying a new bearing housing at a minimum. Grinding a turbine wheel that does not have FOD damage to the blade tips is acceptable. But with our 2 cycles wiped out turbine wheels is a common thing..
Most "new" TV series bearing housings will run you between $245 to 285.00 Genuine Garrett. The days of slapping in std seal rings and bearing are far and few between due to the fact that Garrett is NOT manufacturing new turbochargers for these engines.
JohnEd, they will not lower the temps that much they are better than nothing the problem I have with the aftercoolers they restrick the air flow and they are only 4 inches wide and 11 inches long no bigger than a auto heater core.
The air going into blower from the turbo is about 600 to 800 degrees and the aftercooler sits under the blower.
Air to air is a lot cooler buy the time it leaves the intercooler back to the blower diesels love cool air to make power.
I think and other do also that a aftercooler will add heat to a 8v92 and other engines like Cat and Cummins.
I do know that 8v92 will run cooler without a aftercooler for a fact and DD tells to remove it when using a intercooler clear huh
good luck
Cliff,
What you have said seems clear enuf. It only makes sense to me if there is no aftercooler on the "N" version. True? I think I remember a NA version. Happy to be wrong tough.
Thanks for all the info Cliff....I hope I am not the only one getting something out of your comments.
John
Guys, This thread is very helpful and full of interesting facts. I don't have a turbo, but I' m learning something just in case. ;)
Great Thread!
Paul
JohnEd, the N/A had no turbo the 8v71T and other 71T models used a turbo with no kind of a cooler they used that set up for years still a lot of 2 strokes in use today with no cooler only the turbo.
Here you go Paul the hp ratings for a 8v71 without coolers only turbos
308hp with N-65 injectors
335 " N-70 "
350 " N-75 "
Don Grouley has a 8v71T in his Eagle 335 hp no cooler
good luck
Great info, Thanks Clifford, now to learn more!
Paul
CLIFF,
The output orifice on the blower isn't 4 by 11 inches is it?
John
JohnEd, the aftercooler inside the block under the blower on a 8v92 is 4in W and 11in L
good luck
Cliff,
I got that part. How big is the output from the blower that sits over the aftercooler?
Thanks,
John
Depends on which blower you have the 80% bypass blower is 3-7/8 in W and 13-1/2 in L
good luck
Cliff,
Well, so much for that theory. The A has 44 sq inches to pass air and the blower has 52.3 so the A is a choke point clearly. Is the hole that the A sits over only 4 X 11? If that is true then the A doesn't really cost you anything in terms of flow if the path is going to be choked down to 44 sq inches anyway.
This is interesting to me Cliff. Thank you for indulging. Even if Paul has gone to bed already. :D :D
Thanks,
John
John, You can't get rid of me that easy! ;D
I'm just following along trying to uderstand the process. I just need to find a good source of reading material to really grasp all you guys talk about.
Paul
Your questions tell the tale. Ask away. If I can't answer, and that may be probable, Cliff or another will help you and maybe ten others that are stuck on the same point.
Who said you could stay up this late? ::) :P ;D ;D
John
that's eleven right? ;D ;D ;D
Mama said it was OK to stay up and play! ;D
As I have never had a turbo or been around one I want to know how they work, how it mounts, what to look for and one more thing. What is the best setup for an 8v71?
I've done a lot of searches and have found nothing specific, like a build sheet and specifications etc. Even went to the Yahoo DD site and didn't find much there either.
Links man, I need links! ::)
I'm just ignorant when it comes to all this turbo talk. ;)
Paul
Paul, your funny the links are buried inside these old heads links are for the internet mechanics LOL me I am going to do you like I did you on the brakes then you become smarter and wiser just joking tell me what you need or want and I'll try to help you
good luck
We need you to upload your brain that's chock full of informaiton so we can all learn! ;D
I get the point, you have a way with words ya know! ;)
I'll be in touch.
Where are you now?
Paul
Paul,
Cliff has a USB port behind his left ear. :-*
Hows this for an opener: A turbo charged D will have more power and get better MPG than a non turbo model. Now, does that pique your curiosity? Just for openers.
John
John;
That wouldn't be true in Paul's case, he would have an ear to ear grin and his foot would on the floor all the time playing with the four stroke people. LOL
Don
Now that sounds like fun, bring it on! ;D
I'm going to tape all of my conversations with Clifford, so if I miss something I can go back and push play!
Seriously, I have read all kinds of things, like, sure you can add a turbo, but you have to change the pistons, injectors, timing and a whole bunch of other stuff. Then I read, sure you can add a turbo, just slap it on and watch the boost, otherwise you can burn a hole in the top of the piston.
I'm sure with a lot of money anything can be accomplished. In my case it's the lack of, but I'm lookin into it just the same, you never know when I have nothing else to do, I can play Hot Rod!
Paul
Quote from: Dreamscape on December 06, 2009, 01:00:07 PM
Seriously, I have read all kinds of things, like, sure you can add a turbo, but you have to change the pistons, injectors, timing and a whole bunch of other stuff. Then I read, sure you can add a turbo, just slap it on and watch the boost, otherwise you can burn a hole in the top of the piston.
Now, even igorant, I know that both those statements are TRUE. Neither is free or even cheap. What good is power if you can't use it?
There is a third option: smoke turbo It is intended to cut down the smoke you make when you are LUGGING the engine up a hill and more importantly...KEEPING the hp you had at sea level for the entire trip over the mountain. The smoke turbo is the second cheapest alternative as it doesn't include the inframe(min). Of course, the cheapest is to be satisfied......figure the odds. ;D ;D ;D People like Don and Cliff can attach rough order of magnitude numbers to the first three options.
Did I mention that I can answer any question that you might ask to MY satisfaction? ??? ::) ;D
John
Quote from: JohnEd on December 06, 2009, 01:27:22 PM
Did I mention that I can answer any question that you might ask to MY satisfaction? ??? ::) ;D
John
:-*
My ideal dream would be to show up at Cliffords, stay for a couple of months, tear the ole gal down and build her back up with some extra power. But then I realized his shop is always full, so I'm back to square one. :D
or
..................................Nevermind, we never did get our Stimulus Package!...................................................
Paul
Now let's just hold on there,Cliffords shop is empty and your lucky moment is about to unfold ;D ;D.
First off I Had the bird out on the free way today,and you should be here in the months to come to watch from tear down to build up on the new 6V92, gotto get them hands dirty.
Oh by the way the USB port is behind the right ear ;D ;D ;D
Maybe Clifford had plans to get his own bus in there. I suspect he may have intended to use it for that at least occasionally.
Removed
;D ;D ;D LOL