6.2 or 6.5 Turbo ???

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Aug 30, 2007
San Antonio Tx
How hard is it to go from a sbc 350 to either a 6.2 or a 6.5 liter diesel. The reason I ask is, We use the 6.2 in our blazers and they look just like the 350. As for the 6.5 I believe it is a 395, is this just a punch out 350 or am I an idiot. I want to convert my 40 over to run on biodiesel. I also want to do this as cheap as possible. I have looked into the 1kzt and 13b as well as the 4BT swap, they are all very nice, but would set me back almost twenty grand. I have found a create 6.5 for 7,000, depending on what else it need it may be possible to keep it under ten grand. Any feedback would be great, as I am don't know much about diesels. Thanks JONNY
Check block numbers carefully! Some of the 6.5's are good but many of the older ones including 6.2's have issues.
I hear the older ones have heating issues with there fuel injectors.... is this right?
Howdy! I have looked at the 6.2/6.5 menu quite a bit. 6.2 will go in pretty easy, but less power than the 6.5. Earlier engines had problems with weak webbing on the mains, tend to crack. If you want mucho power, then go with 6.5, but fitment with turbos and intercooler, plus computer, is much more complicated. Google for the Duramax engine board. More info there than you can shake a stick at. John
The 6.2 has issues with cracks in the BEB webs, overheating and cracking heads and injection pumps failing pre-maturely. There are fixes for some of those issues like web "girdles" and special head bolts and gaskets. The 6.5 has issues with cracking between cylinders I think as well as injection pump issues. I read somewhere that the blocks that came out later (after GM no longer made them) were better but that may be the military version.
I just put a military take-out 6.2 in my 1994 FZJ80. These engines in the early 80's had their problems but by the end of their run they were good strong engines. The IP's typically last about 150,000 miles, bad by many standards but pretty good in my opinion considering they only cost about $300 and are not too difficult to replace. I would say the 6.2 is a great engine for the FJ40, it has more than enough power for the 40, so far is seems to have plenty for the 80 as well. I think the 6.5 turbo in the 40 would be overkill. Also the 6.2 is mechanical and much easier to swap in. (the 6.5 turbo was mechanical in 1993 only) It does use the same mounts as the 350 but is a different block (totally different, built by Detroit Diesel) It was built to bolt into the same vehicles as the SBC so if your 40 is already set up for the 350 it should just bolt in. You only need about 3 wires to get it running. I built my own glow plug harness, pretty easy. I am also planning on WVO for my 6.2 and have set it up to run on it. So far I have about 500 miles on mine and love it. I also have a 78 FJ40 I am going to start restoring this fall and am considering a 6.2 for it as well.
Good luck
I have seen a couple 6.2's in 40's. 6.2's are quite a bit wider than a 350. The biggest obstacle is the steering shaft in the engine compartment. One guy made two part shaft with a center bearing and Ujoints. the other the guy mounted the engine very high for clearance. The valve covers were near the hood. I think an inline engine would be a better fit in a 40.
6.2 Injection pumps are cheap, but i haven't had very good luck with them lasting very long running veggie and biodiesel through them. That is my only gripe.

the best deal is to buy a complete running donor vehicle to pull the 6.2 out of.
You will have lots of parts you would normally have to buy.
Rusty, is $300 for a wrecker injection pump or is that a rebuild? I had a friend with the 6.2 and his pump was in the area of $3000 for a rebuild!

If you're running veggie oil you need different seals (veggie oil destroys the normal rubber seals) so you may want to get your pump rebuilt and tell the shop about your intended use so you get the right seals.
Here in Reno you can get a rebuilt Stanedyne DB2 (I believe that's what I put on my 6.2turbo in my FJ55) for around $350. One local company will charge you $900 if you'll pay it. I'd figure like Rusty about 150000 miles before issues. The pump is cheaper than a new Carter carb. The 6.2 I figure more along the lines of a big block Chevy rather than a 350 for weight and size. With a turbo the shock tower(Passenger side) is the issue. I converted mine to Saginaw power steering and a high cross-over steering arm. What tranny would are you using now?
From what I have heard WVO does not effect the rubber seals but Biodiesel does. I have also done quite a bit of research (last 6 months) and there have been alot of failures with the 6.2 injector pumps and WVO. From what I have found is most pump failures are caused by by not cleaning and dewatering the fuel. Apparently water is the main enemy of the 6.2 pump. There is also some talk about switching fuel too soon (before the engine is warm) in these cases fuel is heated via electric heaters to be switched over earlier but the pump is not as hot as the fuel and it causes the shaft to expand too quickly and it shatters inside the housing. This is just a theory but people have done some research on it. I plan to avoid these potential problems with a centrifuge to clean the WVO. I also plan a blend to thin it out so it will flow when cold. I also have electric injector line heaters to heat the oil (after the IP) before entering the cylinder to prevent coking. I have a coolant heated fuel filter as well as coolant heated fuel lines. I have spoken to several people with similar set-ups and they have driven thousands of trouble free miles. I have been experimenting with several blends (75% WVO/25% stale gas is the way I am leaning) and above 60º they are pretty close to the viscosity of cold diesel, this gives me hope that assuming the WVO is clean and dry there won't be any problems. There are also a few 6.2 owners who are using extremely worn pumps. Their cars would barely run on diesel but with the thicker fuel they work just fine, this may be another trick. I have heard the military 6.2 have a hardened pump to run different fuels, I am hoping this to be true.
I hope to get my Cruiser out of the transmission shop this weekend, get some WVO cleaned and give it the initial test, I will keep everyone posted.
get a milti fuel 6.2 from a gov auction and you can run it on about anything I'm workin on the parts to my brown 60 with a 700r4 and split case you will need a trans with a over drive and new motor mounts but the V8 adapter will work gota search for a flywheel most 6.2 were autos
Mine is a military take-out, the IP's are suppossed to be able to handle most anything, I am hoping that is true. If not I am going to try to find an IP that is worn and doesn't run well on diesel, from what I have read they run great on thicker fuels, it is like a custom made IP for WVO without the expense (you could probably pick one up free)!
From what I have found is most pump failures are caused by by not cleaning and dewatering the fuel. Apparently water is the main enemy of the 6.2 pump.

Water is the enemy of ANY diesel fuel system. That's why many diesel vehicles come factory equipped with water separators to ensure no water makes it to the fuel system. You'll want to make that an ESSENTIAL part of your conversion.
I used to own a GMC Suburban 2500 with a 6.5 diesel. The engines aren't that powerful compared to other truck diesels. But they're not too bad in terms of fuel mileage.
The older 6.5 diesels had problems with the FSD's heating up and failing. Later 6.5's don't have this problem but with age and lot's of mileage the injector pump fails. Mine failed at about 250,000 km's. btw it cost me, with labour, $4,200 to have it replaced!!
In my opinion the 6.5 is garbage......
The 6.5 IP's are expensive to replace. The 6.2's are a mechanical pump and pretty inexpensive and seem to last alot longer. Neither are powerful compared to todays turbo diesels but the 6.2 in my FZJ80 feels very similar to the 1FZE, gets 20 mpg (and hopefully more), is easy to work on, parts are available everywhere and are inexpensive and it can run on WVO. That makes it pretty good to me.
Are the motor mounts on the 6.2 the same as the 350?
The motor mounts are the same, I ordered the 350 mounts from AA for my 80 and they worked fine.

Users who are viewing this thread

Top Bottom