Tahoe Motor Is Blown Up

[6.2 turbo]

I will lower the compression,but not sure how far. I'm going to check if the pistons may have hit the heads ? I know they were pretty close. So far it is obvious that they were bent for a while,#8 piston was rubbing the crank. Also it had a knock when cold,even before I gave it more fuel. The first I heard the noise it was just idleling. It could be that at high rpms,everything stretched enough to let the pistons hit the heads ? When I replaced the head gaskets every thing looked fine,and the new gasket was thicker,but may have compressed to thinner than the copper gaskets.

 

[DZZ71]

Could always have the rods shot peened. That may give the you a better shot of it staying together. Along with going to like 18-19:1?

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Agreed 18-19:1 would hold boost numbers that high alot better over the stock comp. I have mid to high 17 compression on my "built" engine and love it. The other one with the twin turbos is even lower then that and I still
Have no complaints on it at all.

 

[6.2 turbo]

I finally got the engine out,and we took it completely apart. Two pistons are broke,camshaft is bent,cam key was sheared,cam retainer broke. All the rods are bent and #8 exploded,the center section is gone. There is a good sized chunk broken out of the bottom of #7 and#8 cyl wall. The head gaskets look like brand new,and apparently held lots of psi with orings and stock bolts. I think it bent the rods from shear pressure, or from carbon build up. Regardless the compression will be lowered ,not sure how much. There is a fair amount of carbon buildup,and it looks smashed. I should of had water injection. The only thing is,the rods,especially #8 were bent farther than carbon buildup,so it must have been the high compression,and boost,and a fair amount of fuel combined ? I think the only reason it works for Bill,is because he has less fuel,or the water injection. I'm not convinced enough to try it again,and just ad water.

 

[NVW]

Well you definitely know how to stress an engine. Good luck on the next build.

 

[3500GMC]

Oh man do I ever want to see all the twisted mangled parts. Pics?

Morbid curiosity, that's all.

And a lesson on what 'not' to do..

 

[turbonator]

I finally got the engine out,and we took it completely apart. Two pistons are broke,camshaft is bent,cam key was sheared,cam retainer broke. All the rods are bent and #8 exploded,the center section is gone. There is a good sized chunk broken out of the bottom of #7 and#8 cyl wall. The head gaskets look like brand new,and apparently held lots of psi with orings and stock bolts. I think it bent the rods from shear pressure, or from carbon build up. Regardless the compression will be lowered ,not sure how much. There is a fair amount of carbon buildup,and it looks smashed. I should of had water injection. The only thing is,the rods,especially #8 were bent farther than carbon buildup,so it must have been the high compression,and boost,and a fair amount of fuel combined ? I think the only reason it works for Bill,is because he has less fuel,or the water injection. I'm not convinced enough to try it again,and just ad water.

cool... so is the block going to be able to be re-used or are the broken chunks going to mean it is scrap? did the pistons hit the head? do you think that having the cement in the block kept the damage to a minimum? well, maybe a little bit more than the minimum...LOL... so, whats the plan here, 6.2? have you thought about using the ol 6.2l in there, or are you going to source another 6.5l? sounds like you are going lower compression again.... but how much? your 6.2l was down to 16:5 right?... to bad about your motor, but its been along time since i seen carnage like that, so from both of us here we give you a salute and a big thumbs up...

KBC

Hey man, not even sure what your name is, but you are an inspiration for my bro and I !!! When I think of how many 6.2/6.5L owners quote Heath for this and that, us included...LOL. You are on the same track, maybe a little extreme, but you push the envelope. I am sure Bill Heath has had carnage too, and not just the ones we always hear about and discuss, but many ,many motors blown. This is just part of the game. If not for people pushing the limits, we would never know the actual capabilities of a system.

Keep up the good work, and for the betterment of all of us....continue sharing your knowledge and experience. Beauty with you is...."no top secret here", you share openly good and bad. F*%k the naysayers.

 

[btfarm]

Good job! :thumbsup: If youy're gonna scatter it, might as well do a good job of it. :hihi:

J/K (sort of). Pretty expensive lesson though.

Hope you can re-use the externals.

 

[turbonator]

Good job! :thumbsup: If youy're gonna scatter it, might as well do a good job of it. :hihi:

J/K (sort of). Pretty expensive lesson though.

Hope you can re-use the externals.

i dont think that he had a whole bunch of cash wrapped up in this build.... if i had to guess, i think he had less than $1200.00 into it.... that is money for sure but not a huge loss.... it could be worse, if he had $10,000 into it it might be crying time..LOL

 

[6.2 turbo]

The cranking pressure was 500 psi,on this motor. I should probably try for around 300 psi. The block can be reused,but would rather find one in better shape. The concrete did not seem to cause any problems,and there is still only one crack in the mains that still looks excactly the same. I believe a 6.2 can handle more cyl pressure,because the piston is smaller in diameter. The factory cam must be billit steel,since it bent.

 

[WarWagon]

Doesn't take much for damage to show up during an engine blow up. Not sure the #8 was bent for a long time. A few seconds at 3600 RPM is a long time...

Your sheared camshaft key would hit every piston to a valve. Your valves and pushrods are now suspect junk - bent from piston strikes. The rods can also bend from valve strikes.

High engine RPM will stretch rods and cause pistons to hit the heads. High boost would tend to cushion and stop the piston on the compression and power stroke.

Are you running a CDR to the turbo or a road draft tube? Bill said the CDR dumped enough oil to hydro his 6.2 and bend all the rods. Maybe he hit the limit of the rods instead?

I would guess you broke a piston and everything else followed. Loose rod bent the cam... Pistons hitting carbon or the heads would cause failure after time.

 

[6.2 turbo]

I just have a push in breather. I think #8 was bent for a while ,since it had a noise when cold,and it was with piston speed. For sure the rod bent the cam. I quess the valves could have bent the rest of the rods. It also crossed my mind that my ip turned so hard that the cam key sheared,and caused the valves to hit. The valves hit so hard,that it broke two of the rocker arm shafts.

 

[NVW]

Not unlike the old toy "Mouse Trap"

 

[HELLER]

man that sucks! that was a nice build! trial and error is how you figure things out, instead of basing everything off of theory.

 

[6.2 turbo]

I'm getting the pistons shaved .045 thousands. They are all getting reused,except 2 are from a parts motor . So far I collected 6 straight rods,but will have to pull 2 more from another one of my blown 6.5's. I discovered that 6.5 rods are ofset,the flat sides go against each other. I should be close to 18-1 with stock thicknes head gaskets ,and .010 decked block. Pistons should end up about .030 below the deck. That would give me .075 squish. I didn't break any rings, so I plan on reusing them. Not sure about the rod bearings,I might just flip them. One or two of the main bearings show some slight grooves of copper. I will look into some bi metal bearings,instead of tri metal.

 

[3500GMC]

I discovered that 6.5 rods are ofset,the flat sides go against each other.

It's that way in 99% of 'V' engines. Has to do with the radii (fillet) of the crankshaft rod journals.

Get out the plastigauge for the bearings. Good stuff and a good 'go/no go' indicator.

Once rings 'take a seat' from new, it's usually not a good thing to re-use them unless you can re-install them exactly the direction as they were into the same block. It would get quite nettlesome..

Just some thoughts....

 

[littleboy]

I once had a customer who wanted me to reuse his old pistons an rings. It had a slight bit more blowby than normal but i was very suprised at how good they actually sealed!

 

[turbonator]

We changed out two pistons in this motor almost 4 years ago. We kept the original rod bearings from the crank, but the pistons, rods and rings were all from parts bin. Quick hone, then warmed up. Compression was still well over 325psi. We worked this truck since that time, many times with 14,000lbs hooked to its pintle. We are sure that you can re-use pieces from one to another. This vid is after 50,000miles of said work (700 cords of firewood one summer).:thumbsup::agreed:

Go man Go.....

http://youtu.be/3jGXIK2vmQ4

 

[crash2win64]

Ideally for longevity you would want everything balanced...
Not saying it won't work or anything and cobbling stuff together can work and work good for a long long time. I'm just saying in a perfect world lol...

 

[turbonator]

Perfect world.....LOL.....we are usually so pressed for time, or more often than not almost flat broke....we cobble good. real good...LMAO (twice...LOL).

......And 6.2, go for it.... you got our support (tooo broke to send cash though...LOL).

 

[littleboy]

Perfect world.....LOL.....we are usually so pressed for time, or more often than not almost flat broke....we cobble good. real good...LMAO (twice...LOL).

......And 6.2, go for it.... you got our support (tooo broke to send cash though...LOL).

I can relate to this! Seems wen my truck brakes there is never time or money to do wat i wanna do to it so it just gets slapped back together asap an cobbled together...!