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Tahoe Motor Is Blown Up

littleboy said:
From real world experience i have never seen a set of compound turbos get anywhere close to a 1-1 drive ratio. They end up closer to 2-1 drive ratio than they are 1-1. Your science and math have nothing on real world experience.
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And the knowledge in your experience may not be the kind I care about. All the stuff you talk about pushes for the extreme performance. You have to know where the turbos are most efficient and make sure they are in that range. Are you even measuring drive pressure, do you have some data to provide? The compound setup will be more efficient than a single, so if your compound is 2-1, then your single was probably 3-1 at the same boost. But as of now, at the boost levels most of us run on a 6.5, our single turbos are already in the 1.1-1 to 1.2-1 region, because we dont overspeed them. The small GM turbo you could get to 2-1. So take two turbos that are operating in their 1.1-1 ratios and you will end up even more efficient.

Its kind of like the real world guy thinking the pressure at TDC was just the pressure at BDC multiplied by the CR. Im sure there a many expert machinists and technicians out there that do think that. There are a lot of little misunderstandings like that in the real world. There is a difference between expert technician and design engineer. The technician will understand practical things better from experience, doesnt mean they understand what is happening from following the instructions they have. The engineer usually lacks some practical knowledge on what trial and error has taught the technician.
 
Are you serious......?

So.... according to wat you are saying, 6.2turbo should take and put a huge big turbo after the 52 and that would lower his boost and drive pressures?
 
I can't see how compounds could be good for 6.2 or 6.5,except with very low compression ,because it would probably make 80 psi boost.
 
littleboy said:
Are you serious......?

So.... according to wat you are saying, 6.2turbo should take and put a huge big turbo after the 52 and that would lower his boost and drive pressures?
Click to expand...

Thats not at all what I said, you dont understand. You dont have a grasp on the concept, so I'll just leave it at that. You cannot even provide details of your own stuff.

You dont need to make the compounds go to 80psi, you have to size and gate them to prevent that. If you push 40psi with one turbo vice 40psi with the combining of two, the two will be more efficient than the 1. If you just compound to reach higher boost then its not helping. Compounding to gain efficiency vice compounding to make more boost.
 
buddy said:
Thats not at all what I said, you dont understand. You dont have a grasp on the concept, so I'll just leave it at that. You cannot even provide details of your own stuff.

You dont need to make the compounds go to 80psi, you have to size and gate them to prevent that. If you push 40psi with one turbo vice 40psi with the combining of two, the two will be more efficient than the 1. If you just compound to reach higher boost then its not helping. Compounding to gain efficiency vice compounding to make more boost.
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Personal attacks aside... you don't seem to understand how compound turbos work! They compound everything. Even if you gate the small turbo and the big one you will compound the boost and drive pressures. Now... if you want efficiency you would need to do twin turbos. How do you think i know? I am not pulling facts out of my head! This is all stuff i learned from personal experience. The 6.5 world is looking like the cummins world did 10 years ago and there was folks like you running around spouting off ideas just like you . We have learned so much in the last 10 years and i only share wat i have learned the hard way! Too bad you can't do the same.
 
Buddy, you seem to keep referring to "other" engines, and how things work on "other" things.

I have a vehicle for you to plug into your science.
3.9 liter engine (cummins)
181/210 108lsa cam
stock valve size
17.5:1 compression
5x13 155 spray angle injectors
60/64/12 over gt4202r (1.08)
at full throttle I'm seeing over 60psi boost. Each turbo is doing exactly half the complete boost number.
Edit: there is a 7/8inch wastegate between the 2 turbos that opens at 20psi.

Compound turbos are a crappy way of gaining horsepower. They COMPOUND the pressures. A large single will ALWAYS be more efficient.
 
buddy said:
You guys dont understand, Im not going to explain it.
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This is the best you can do when faced with real world scenario?
Btw sir, my engine is governed at 3250rpm, and made 360hp/680tq and gets 25mpg. I have tried low pressure compounds, high pressure compounds, different wastegates and settings, and all sorts of crap that I won't explain here.
I look at what 6.2turbo is doing, and I see a man defying alot of theories and myths...
 
Cumminsfever said:
Compound turbos are a crappy way of gaining horsepower. They COMPOUND the pressures. A large single will ALWAYS be more efficient.
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This says enough of your understanding.

Now try reading a few articles on the subject.

This setup actually achieves more boost than it does backpressure. Actually more than 100% efficient, talk about high RPM horsepower capability.
http://www.atsdiesel.com/ats2/templates/template_06.asp?p=2029422272&c=36

Here is a typical setup, manages to increase boost while lowering backpressure
http://www.dieselpowersource.com/index.php?route=information/information&information_id=6

Ive read on a Cummins forum a couple people running around 100psi boost with 90psi backpressure. So they were able to achieve greater than 100% efficiency.

To get into higher RPMs for more horsepower you have to free up the exhaust on the 6.5, can do that with twins, or compound. Compound is more efficient in reducing backpressure.
 
No top drag racers, pullers, or engine builders reference ATS, nor do they have anything to do with cumminsforum.

Sounds like 6.2turbo needs compounds. Hmmm... are ya convinced yet 6.2turbo??
 
Hmmm.... better get you some credible sources. Cumminsforum is more widely known for it's tall tales than a credible source of info. There is a reason i refuse to read on that idiot infested site.
 
You guys have got to be kidding. I'm not posting any more sources for you, and not explaining anything for you because you wont understand or believe it.
 
buddy said:
You guys have got to be kidding. I'm not posting any more sources for you, and not explaining anything for you because you wont understand or believe it.
Click to expand...

I like real world experience. When you put an hx35over an hx55 on your own 350-500hp 6.5 and PROVE your theory and science, then and ONLY THEN will I believe. Until then, you may keep racing keyboard, I'll keep the real world going.
 
I've mentioned before that I'm not very diesel experienced, but have wrenched on gas engines all my life both 2 and 4 strokers... I've been following this thread closely for awhile and just had been chewing on these things.

I was slightly under the impression that 6.2's problems "could possibly" be born from clearance issues. I say this because of the pics I had seen of 6.2's carnage.. I have seen that before when I was getting into my project.

Example being, When I tore my buddies engine apart to get my pump, head studs, fluidamper, and gear drive timing set.. what I found was just about every push rod looked like a "Z" rather then an "I", every rocker shaft was broken (I think around the bolt holes), and the cam gear had sheared the cam key (had a bit of a time getting the cam gear off), I did not look close at the bottom end even though the oil pan was off, for bent rods. I wish I would have now though.

Now, after the conversation I had with Bill.. (I realize some of you don't like or care for his claims / products), but that aside, he is no dummy. Anyhow, my convo with him really made me see something... The cams in these 6.5's are the SAME cam that came in the early N/A 6.2, which I just cannot believe would be an optimal design for a boosted 6.2 / 6.5 and not to mention many people are wayyy over revving these engines for the cams design. Bill did mention that the GM-x turbo's are NOT the only choke point on our lovely 6.x series engines, but that the cams were also to blame. Makes a lot of sense to me.

Now, the last time I talked to my buddy about the DB4 I got from him, he did say that he / they fiddled with the pump, have the fueling screws maxed and governor tweaked and had it revving as high as 4,600 - 4,800 rpm's, and he said that when his motor went ker-put that it was at an idle or maybe sitting at a stop sign, something along those lines. I do know he ran the living piss out of the truck though.

I'm kinda leaning towards the "over revving" / possibly valve floating (not much room for error on the piston to valve clearance) side of things to bend all the push rods, breaking all the rocker shafts, shearing the cam gear key and then ultimately spiking really high cylinder pressures....

As with 6.2's engine, possibly the same things happening.. I think could possibly be from bent push rods, broken rocker shafts not allowing proper valve operation, maybe gobs of fuel puddling in the cylinder causing a "hydro-locking" situation while the engine is trying to run, possibly causing rods to bend, possibly adding to the cause of the "galling" on the cylinder walls....

The only times I've seen bent rods on an engine were gas GM's late 90's vortec 4.3 - 5.0 - 5.7's 3800 series II's .... all from intake failures and coolant seepage into the cylinders, or somebody dropping a bolt or nut down an intake port while carelessly wrenching on something.... Either way it was from trying to compress something not designed to be compressed.

Anyhow.. Just thinking out loud.

Mike
 
I'm afraid to but that engine back in. Putting a military 6.2 together instead. I'm pretty sure,the rod broke,then the cam key,there was a piece of rod jammed in the cam.
 
Got my pump tested,160 cc's at 2000 engine rpm. 110 cc's at 4000,and was still fueling at 5000 rpm.
 
I had it set around 125 psi max,the metering valve,governor,camring and charge regulator were modified. None the internal holes were touched.
 
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