Wondering if anyone has any good or bad experiences building a 5.2/6.5 hybrid motor, best parts combinations or any tips you might have. I am building a motor for my 85 k10 half ton with 140,000 kms. Motor in it right now burns about a liter of oil every 300-500kms so it is in desperate need of a rebuild.

 

You may want to talk with CVolia he did a 6.2/6.5 combo recently and as far as I know he loves it

 

I did a 6.2/6.5 hybrid. I love it. depending on if you want power or MPG's decides whether to use the 6.2 pre chambers or the 6.5's. i am running the 6.2l prechambers and im gettin 28mpg with 4.10, 33x12.50 BFG All-Terrains, and the NV4500. all depends on what you want

 

thanks mayhem!
I did a 6.2/6.5 hybrid. Its in my 6200lb CCLB Dually and its a mean b*tch. The 6.2 bottom end is a lot stouter than the 6.5 mainly due to cylinder bore. a the 6.2 heads are also a lot stouter than the 6.5 heads. This is partly due to the intake valve size difference. The larger 6.5 intake valve leaves less material between intake and exhaust valves. This coupled with a design flaw makes the 6.5 heads crack prone. The difference between the intake valves is minute, and not noticeable when making it turboed. (Which is what I did).

The 6.5 injection pump has a slightly bigger bore than the 6.2 pump, giving it the ability to fuel the engine sufficiently for the adding of the Turbo. The 6.5 pump also operates at approximately 2100psi (200-300psi higher than the 6.2 IP). Using the 6 t pump doesn't require the use of 6.5 injectors but I advise to use them because not only are the nozzles slightly larger but they are calibrated to the same pop pressure as the pump.

I used my 6.5 intake and exhaust manifolds to accommodate the use of a new GM8 Turbo. I currently have it set up with a homemade turbomaster and set to 12.5 lbs of boost.

Also with the information I have found about the stock camshafts used with the standard and military 6.2s and the mechanically injected 6.5, the military 6.2 (140hp) and the 6.5 (185hp) seem to have to about the same specs. When I rebuild my engine, If I don't get a regrind, I will use the 6.5 cam.

I also have the dual thermostat housing from the later 90's 6.5s. I'm not sure how well the single thermostat housing works(my truck had the dual when I bought it) but the dual works great. Its never overheated when pulling and when not pulling, it doesn't go above 160.

 

no one else to comment? I know I'm not the only one to do this.....

 

It is very common to use a 6.2 short block and add 6.5 aftermarket cylinder heads(Clearwater cylinder heads) with the remaining parts being 6.5.

A Tee must be made at the OPS port on the block to supply pressurized oil to the turbo and still have OPS function.

It is also a good idea to use the 6.5 94+ timing set and balancer so that the reluctor is in place if ever an electronic IP is used.

 

That is exactly what I did. I tee'd off the OPS oil feed and used 1/8" brass pipe and fittings to bring the hook up to near stock 6.5 turbo oil feed location. That way I could use my stock oil feed flex line.

 

So 6.2 prechambers can be swped out with 6.5? and thier is an associated MPG gain???