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Tahoe Motor Is Blown Up

Dood,

Do you have previous build threads? What is this engine in (vehicle wise)?

Do you just street it or is this your "puller"

You're getting me damn excited about my dern truck again... Carefull with the boost 30psi is at the danger zone for stock spring pressure. I have pictures of valves marks upon piston tops in an 18:1 engine (yeah they're in the hole .025" and they hit). We shimmed the springs enough to not have coil binding issues and get enough pressure to hold 70psi drive pressure and 55psi boost pressure (exhaust valve is smaller, same pressure for both springs).

Haven't really run it since then though.
 
chevydiesel said:
Dood,

Do you have previous build threads? What is this engine in (vehicle wise)?

Do you just street it or is this your "puller"

You're getting me damn excited about my dern truck again... Carefull with the boost 30psi is at the danger zone for stock spring pressure. I have pictures of valves marks upon piston tops in an 18:1 engine (yeah they're in the hole .025" and they hit). We shimmed the springs enough to not have coil binding issues and get enough pressure to hold 70psi drive pressure and 55psi boost pressure (exhaust valve is smaller, same pressure for both springs).

Haven't really run it since then though.
Click to expand...
he built up a 6.2l last year and was boosting 60 psi... heres a link....http://www.thetruckstop.us/forum/sh...2-turbo-diesel&p=232613&viewfull=1#post232613
 
I got the valves adjusted,to no more than .035 preload. Not sure why every time this motor gets assembled I have to grind more off of the valves. It seems like every part in this motor is a different size . I picked up two Military motors the other day. One blown 506 GEP,and a fair ? condition 660 6.2. The 506 needs a sleeve, two rods ,one piston,and an exhaust valve or head. Still not bad for $280 for the pair. It was the first time I bought any thing through Gov Liquidation. It went very well,and I didn't need to fill out any ECU release forms.
 
Have you pulled the pan on the GEP yet? You had mentioned the cylinder and what-not that was damaged, just curious about the main webs and the deck problems......do you see major casting or design differences.

The $280.00 is a good price for two motors.......keep us all posted.:agreed:
 
It has metric bell housing,and motor mount bolt holes. The main webs look thicker ? And they are not cracked. Looks like they took a brand new motor,and bent two rods,but kept driving, until it hammered one piston to nothing . I am seriously starting to worry about 6.5 rods,this is the third engine with bent rods now. Two were like that when I got them. After seeing 11 bent rods I suspect they are fairly weak ? Would it work to fill the sides of the rods with spray welding ? This is a powder metal,used with a torch,and the rod would have to get red hot. My 6.2 was always started with lots of ether plus glow plugs,and injectors that didn't quite seal plus 60 psi boost,the rods didn't even bend. I estimated compression to be 16-1,but probably was closer to 14-1. It looks like a 6.2 is stronger,but I think its because of the small diameter pistons,the force on the rods will not be as great,if every thing else is the same. I can't figure out for sure what bent my rods,so I'm going to put it all together with lower compression,beat the crap out of it,and pull the oil pan back off. Real world testing,only thing that works [or breaks] for me.
 
From what we have been seeing and reading, no two rods are the same. They are interchangable, but center to center can be different as much as .020".

We have started to think about an aftermarket rod, either a Carrillo, or an X-beam rod. This combined with a better piston (Ross racing pistons, does any custom forged diesel piston) and crank will solve any potential problem in the rotating assembly. Costs $$$$ though.....

Keep up the good work..... we really want to see a GEP finally put through its paces and stressed a bit.... no , stressed a lot....LOL.
 
One thought I had in the past was modding some Dmax pistons and rods to fit into a 6.5. Other than piston design, the measurements are similar as far as bore and center of bottom ring to piston top. The piston is a bowl though, lower compression because of it. Its been a long time since I looked into that, but it seemed possible with a little machining. I even have a used set of rods and pistons from a DMax in my garage, and dont think I'll ever use them.
 
Some of my pistons were cracked,and slightly bubbly,pitted looking. Also the precups were cracked almost to the fire ring. It looks like it was too hot and lean ? Egts never went very high,maybe 1100 or 1200 . Would a pyrometer probe survive in a glow plug hole ? I'm working on the injectors now,it's going to be a combination of modified Delphi tips,and at least one china marine tip. So many that I have leak,that I can't build a matched set. So far I pieced together four that don't leak or pee. Pop pressure so far ranges from 2400-2600 psi,I'm adding .010 to the shims. If any one has Military surplus injectors for sale,send me a PM. Any ideas on how to get a longer duration slightly cooler explosion in the cyls ? Retarded timing,lower compression,less boost ? Quite a bit more fuel ? For some reason I'm stuck on the too lean idea.
 
Why a longer duration burn? That usually just heats up the pistons more. I would try to get a faster burn... higher pop pressures on your injectors will help you! More air volume ..... less pressure .
 
A longer burn might have less of a sledge hammer affect to the pistons and rods. If the air fuel mixture is richer exhaust temps will be higher,but cyl temps might be lower ? I also think retarded timing can increase egt's and lower cyl temps. Advanced timing will give you lower egts,but higher cyl temps. ? All this stuff is probably more important when power is a fair amount above stock . My 6.2 had egts over 1600 and the pistons always looked brand new. This motor was ran very rich,like a pulling truck.
 
I dont think the slower burn will help, the amount of fuel you are pushing its hard to burn it all as is. Small precups would have that affect and then limit your power though. Water injection could delay combustion from longer ignition delay and may qulech the intial blast. Although I believe the solution to the "lean" condition is to lower the boost, not change the combustion. The way your fuel transfer pump pressure on the IP is set up it could be constantly over advacning the injection, so retarding the pump might not be a bad thing.
 
I might lower the boost. I will probably retard timing some,but it wasn't over advanced before. With lowered compression, ignition timing will probably retard on its own. I think the leaking injectors helped bend the rods,uneven power. Also this engine had severe harmonics about 1800 rpms,you could even hear it.
 
I had the motor running with no turbo and some iffy injectors. Seems to run on all 8,but the timing is way retarded ,from the lowered compression. Lots of white smoke. Oil psi was good. :thumbsup:
 
are you gonna try that cat turbo this time? i have been thinking quite a bit about that one... if you want, send it up this way and we will do some testing with it...LOL...:thumbsup:
 
I would like to try the Cat turbo. Only thing is,since it has a waste gate ,the exhaust housing is fairly long. I know its been argued before that psi is psi,and I used to think that way also. But if 40 psi with a big turbo is actually more air, than say a HX 35 at 40 psi,it would explain the bent rods ?
 
6.2 turbo said:
I would like to try the Cat turbo. Only thing is,since it has a waste gate ,the exhaust housing is fairly long. I know its been argued before that psi is psi,and I used to think that way also. But if 40 psi with a big turbo is actually more air, than say a HX 35 at 40 psi,it would explain the bent rods ?
Click to expand...

When looking at the turbo maps, and seeing the limits of the different turbos, I believe it is more the bigger turbo is freer
flowing air, with less drive/back pressure. This drive pressure could be a reason rods bent, and never bent with your big-un on the 6.2L.

We did more research on using a D-max c-rod, would either need a custom bearing or be machined down to the size of our journals. Did not have one in hand, but just the look of the transition point in photo, seems it might be too much for a stock rod, and still maintain enough strength to be a viable upgrade.
 
I put the same stock size 2 plunger pump back on. I want to see how much difference lower compression does by itself.
 
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