6.5 or 6.2?

[Chevypoor]

Here is were I am at.

Pulled the motor out of the 95 K2500 GMC and the block is a good well seasoned 929 with no cracks. Pistons and rods are in great shape. Heads are in good shape except for two small cracks in one head in the bridge between the valves. They are not leaking coolant yet. I need lifters, a cam, bearings and a crank. Maybe heads as who knows when they will start leaking unless I have machine shop band aid them with a valve guide liner.

I have a 93 Vin J 6.2 599 motor that was running when pulled. Had zero blowby when cold and only a small amount when hot. The engine has 245k on it. I am going to assume since it had good oil pressure that all the internals are solid.

As you can see from my signature below what has been done to the 95 K2500 GMC as far as mods and general setup. I hit 24psi of boost with the ATT when the 6.5 collapsed/ destroyed lifters and spun five main bearings. I am trying to keep the rebuild cost under or around $1500 if at all possible.

What I am thinking is pulling the 6.2 apart for inspection. Hopefully the crank, rods, and cam are good. Then doing a simple re ring with studs on the bottom and top. Use the 6.2 heads with the 6.5 pre cups and 6.5 head gaskets.

Question is will the 6.2 pistons handle that kind of boost?

Or am better off with a Scat crank, maybe 6.2 heads and cam and re build the 6.5.

Or should I run the ATT on my 95 Chevy ( the tranny is very healthy, the GMCs is on Lucas ) and run the GM-5 with the turbomaster on the 6.2 and save even more money and not use studs. If I do that should have a have studs on the Chevy? She has 172K and runs strong with a fair amount of blowby.

I was not expecting the boost I got from the ATT. The GM-5 on the GMC was blowing oil into the motor and the wheel squeaked/ dragged when you spun it by hand with the motor off and I was not putting money into a stock GM turbo.

In a perfect world I would love to run the Heath cam but studs on the top and bottom eat up the budget quickly.

Looking for you guys thoughts as I am not sure were to head from hear.

 

[Chevypoor]

I forgot to mention the truck is an auto, it will be asked to tow anywhere from 2000-12000k maybe as much as 6-8 times a year. It will primarily be used for running into town for groceries or a Walmart run, taking the wife out to dinner, picking a round bale or too, picking up feed and fencing supplies at the store, just general truck uses. It is not a street princess. She will be worked but taken good care.

 

[tanman_2006]

I would leave the ATT on the tow rig. GM5 would be ok on 1500 truck w/ 3.42's on grocery runs.

The 6.2L interals will hold up to the turbo, look at warwagon, it has been tested extensively. Your 599 6.2L heads should be similar to 6.5L heads (precup changing needed). If the 6.5L looks ok then I would keep running it unless you have a good reason not to.

As far as the cam check out delta, they have a cam that should increase bottom end torque and let the top end breath a bit better.

 

[6.2 turbo]

I would go with the 6.2 ,they can take more cyl pressure.

 

[WarWagon]

I have run the 6.2 longblocks up to 24 PSI on the HX40II and 18 PSI on the ATT. (I have a boost gauge now but may have run over this number when we pegged the engine sensor at 17 PSI.) EGT's nearly off the scale.

I would run the parts that are in the best shape. 6.2 or 6.5 only difference that matters is precups. 6.2 heads just take creative injection line routing bending and clearance is tight to the manifold. Nothing like being on a budget that make 6.2 heads work on a 6.5 turbo setup.

:idea: Come to think of it I blew up the 6.5's not the 6.2's yet.

You will need to toss the oil pump and oil cooler after that engine failure. Use studs. I didn't blow a head gasket even while eating valves and that worm clamp. The one thing I have not had is a head gasket failure with the studs and the extreme stuff I have done.

 

[Chevypoor]

Thanks for all the advice guys. I have decided to run the 6.2 with a pair of the best heads, weather that is 1 6.2 and 1 6.5 we will see once I disassemble the 6.2. I plan on using 6.5 injectors, pre cups, and head gaskets. I am going to run head studs. I have decided to leave the cam alone for the moment in the interest of keeping cost down. Plus this truck will probably only see 4-6K a year. The real mileage is on the 95 Chevy which sees around 45-50K a year. I am going to take the 6.5 929 block and start a slow build to have a motor waiting for the 95 chevy which has some blowby and pushes the dipstick out ( still runs and passed the water test, suspect a broken ring in one cylinder :dunno: ).