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5.7 swap to 6.5 turbo diesel
- Thread starter DeckerZ71
- Start date
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Ha ha! Got a crystal ball? No, seriously though, pick a number out of a hat is as good a way of telling as any other.
That motor could go 5 miles after you finish the conversion or go another 150K. It's a crapshoot with a used, cracked block.
The biggest factor is that the bottom ends on these motors aren't balanced very well from the factory and that causes much of the stresses that crack main webs and shears crank shafts. The biggest thing you can do to ensure any sort of longevity for a 6.5 bottom end, web cracks or intact block, is to replace the harmonic balancer every 100k miles or at the first signs of it delaminating.
For about $120 it is cheap insurance, just use ONLY a new OEM GM/ACDelco and NOT a Dorman or any other aftermarket junk (they only last about 30k miles, if that, before delaminating and falling apart). The ONLY exception is dropping the big bucks (~$400) for a Fluidamper balancer which will most likely outlast the motor.
Ultimately, the decision is up to you as to what to do with that motor.
That motor could go 5 miles after you finish the conversion or go another 150K. It's a crapshoot with a used, cracked block.
The biggest factor is that the bottom ends on these motors aren't balanced very well from the factory and that causes much of the stresses that crack main webs and shears crank shafts. The biggest thing you can do to ensure any sort of longevity for a 6.5 bottom end, web cracks or intact block, is to replace the harmonic balancer every 100k miles or at the first signs of it delaminating.
For about $120 it is cheap insurance, just use ONLY a new OEM GM/ACDelco and NOT a Dorman or any other aftermarket junk (they only last about 30k miles, if that, before delaminating and falling apart). The ONLY exception is dropping the big bucks (~$400) for a Fluidamper balancer which will most likely outlast the motor.
Ultimately, the decision is up to you as to what to do with that motor.
Will L.
Well-Known Member
Adding studs will help it run longer is the theory. Others figure dont add another penny as it has a short life left anyways.
My theory is: if you have to tear it apart, add studs because they can be reused in the next engine, provided you plan to stay with the 6.2/6.5 long term.
Look at the mileage he got and his engine started smacking valves at 4200 rpm. The lower you keep rpm down the better.
The mains crack because of multiple factors. Unbalanced crank/rod/piston assemblies. Bad harmonic balancers. Uneven injector outputs. Unequal compression ratios. Crankshaft deflection. Overly advanced timing.
Yes extra cost, but much better results from engine rebuilds. Which results in better power, better fuel mileage, and longer engine life. Gotta pay to play, and the more you pay, the more you can play.
So this is where what current budget is and how much gamble you prefer comes in.
Leave everything alkne and just run it is cheapest today. How long depends on your luck and how hard you run it. Putting around empty and 10 mph under the speed limit will last longer than daily loads of 1500lbs, being first off the green light and doing 90 on the freeway.
Balance the rotating assembly is $300 depending on your area. New balancer AC Delco $100/ fluidampr is$425. Scat crank is about 575-600 (however My personal belief is GEP is buying scat cranks so cheaper option that way?). But when the mains finally break free- IF you dont get a different block rebuilt before she scatters- all that is wasted- you dont rerun any of that stuff after it happens.
So that becomes a big gamble.
The $360 for studs, you might loose half of the studs to damage. Most of the time they are all reusable except the first main that lets go-so only $30-$40 lost.
Many say you can rerun studs after a bottom end blow out, many say not worth the risk. I can tell you one week I broke the front four maincaps completely out once, we reran those studs the next week at the track and they stayed in and we blew 1/2” holes in the top of 6 pistons and 1” holes in the other two and the studs held just fine. Infact we ran that set through 2 or 3 more engines before threads were damaged from bottom end destruction. Keep in mind the free GM engines were required to run to destruction so we got a couple good runs then broke something finding limits on purpose every track day.
Turns out breaking toys is fun when you don’t have to buy the new toys- haha.
How much does studs help? We had an engine that we ran bolts on start cracking.- complete tear downs between runs. We added studs hoping to see cylinder wall failure first that week testing low coolant runs. First tear down 2 cracks one side 1 on the other all about 3/4” long. Next run with new bolts: 3 mains cracked on both sides. About 1” each. No balancing done btw. We added the studs and the cracking did not get any worse the next two runs. Cylinders 7&8 did the linear crack as expected and we ran till hydrolock, bending rod 7 loosing 1/2 it’s compression. That was all done with transmission replaced by load drive (like a long brake drum and shoes) in the truck. The cracks still did not progress.
That is when determined unless block integrity was required tests- all subsequent builds began with studs.
We still broke mains- but nothing you would ever produce in normal power applications.
Some of our crazy power runs, we did jb weld studs. It would rip the entire bottom of the engine off in one piece, but the mains didn’t have the vertical cracks- just horizontally broken. They paid for xray of one set. It showed zero cracking. The nitropropane content was so high we think 3 cylinders fired at same time. The rear assemby broke clear up by the cam- that back end never fails.
So if you want to “throw away” at best survival chance-
I would balance the injectors because they can always be reused. No fancy stuff on pistons or rings. Balane rotating assembly. New Delco balancer&pulley. Main studs. Gm crank. Keep the boost low. And become a grandma driver with it.
Start the quest for towards a takeout optimizer and build it proper for the 400,000 hard working mile version.
My theory is: if you have to tear it apart, add studs because they can be reused in the next engine, provided you plan to stay with the 6.2/6.5 long term.
Look at the mileage he got and his engine started smacking valves at 4200 rpm. The lower you keep rpm down the better.
The mains crack because of multiple factors. Unbalanced crank/rod/piston assemblies. Bad harmonic balancers. Uneven injector outputs. Unequal compression ratios. Crankshaft deflection. Overly advanced timing.
Yes extra cost, but much better results from engine rebuilds. Which results in better power, better fuel mileage, and longer engine life. Gotta pay to play, and the more you pay, the more you can play.
So this is where what current budget is and how much gamble you prefer comes in.
Leave everything alkne and just run it is cheapest today. How long depends on your luck and how hard you run it. Putting around empty and 10 mph under the speed limit will last longer than daily loads of 1500lbs, being first off the green light and doing 90 on the freeway.
Balance the rotating assembly is $300 depending on your area. New balancer AC Delco $100/ fluidampr is$425. Scat crank is about 575-600 (however My personal belief is GEP is buying scat cranks so cheaper option that way?). But when the mains finally break free- IF you dont get a different block rebuilt before she scatters- all that is wasted- you dont rerun any of that stuff after it happens.
So that becomes a big gamble.
The $360 for studs, you might loose half of the studs to damage. Most of the time they are all reusable except the first main that lets go-so only $30-$40 lost.
Many say you can rerun studs after a bottom end blow out, many say not worth the risk. I can tell you one week I broke the front four maincaps completely out once, we reran those studs the next week at the track and they stayed in and we blew 1/2” holes in the top of 6 pistons and 1” holes in the other two and the studs held just fine. Infact we ran that set through 2 or 3 more engines before threads were damaged from bottom end destruction. Keep in mind the free GM engines were required to run to destruction so we got a couple good runs then broke something finding limits on purpose every track day.
Turns out breaking toys is fun when you don’t have to buy the new toys- haha.
How much does studs help? We had an engine that we ran bolts on start cracking.- complete tear downs between runs. We added studs hoping to see cylinder wall failure first that week testing low coolant runs. First tear down 2 cracks one side 1 on the other all about 3/4” long. Next run with new bolts: 3 mains cracked on both sides. About 1” each. No balancing done btw. We added the studs and the cracking did not get any worse the next two runs. Cylinders 7&8 did the linear crack as expected and we ran till hydrolock, bending rod 7 loosing 1/2 it’s compression. That was all done with transmission replaced by load drive (like a long brake drum and shoes) in the truck. The cracks still did not progress.
That is when determined unless block integrity was required tests- all subsequent builds began with studs.
We still broke mains- but nothing you would ever produce in normal power applications.
Some of our crazy power runs, we did jb weld studs. It would rip the entire bottom of the engine off in one piece, but the mains didn’t have the vertical cracks- just horizontally broken. They paid for xray of one set. It showed zero cracking. The nitropropane content was so high we think 3 cylinders fired at same time. The rear assemby broke clear up by the cam- that back end never fails.
So if you want to “throw away” at best survival chance-
I would balance the injectors because they can always be reused. No fancy stuff on pistons or rings. Balane rotating assembly. New Delco balancer&pulley. Main studs. Gm crank. Keep the boost low. And become a grandma driver with it.
Start the quest for towards a takeout optimizer and build it proper for the 400,000 hard working mile version.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Thus ends Chapter One of War and Pieces by @Will L. LOL! The short version, how much time and money do you want to put into a block that is eventually going to fail? You can delay the inevitable for a fairly long time at stock power and load levels by studding the mains and having a healthy harmonic balancer. Everything else he outlined to increase longevity requires an ever increasing investment in time, money and parts of which you will recover nothing on your investment when the engine does fail beyond the rebuilt and balanced injectors. Roll the dice.
Will L.
Well-Known Member