6.2 vs 6.5 swap into my 84 Sub

[coxfmly]

Hello again, I currently have an 84 Sub, 6.2 and Banks set up.
My truck runs great with the 6.2 and has only 143K.
If I installed a new 6.5, would I have an increase in power?
The reason I ask is my brother has just picked up a 91 Sub with a 454.
He is going to get rid of his 85 which has a new 6.5 n/a. It looks like I will be able to buy his older rig and pull off the items that I want. His 85 is a horror show subject to the new 6.5 engine. Since the 6.5 has less than 20K, I want to put it into my truck some day. What issues will I have when I switch motors? Will the turbo system cause any problems since his motor was purchased as a N/A unit.
I would take his engine and upgrade it for the future, girdle kit, gear drive etc. I'm sure I have quite a few years left on my 6.2 but would change it over if I could get some more power for towing. I tried to find HP/Torque numbers for the 6.2 vs. 6.5 but was unable to find any. I'm not too sure of the differences between the motors. Subject to the lower miles, should I push the swap? Thanks

[More Power]

If I remember correctly, the highest rated 6.5L N/A was 160 hp and 290 lb-ft of torque. This is a little higher than the highest rated 6.2L.

Would help to know exactly what 6.5 was installed in the '85 Sub. There's a genuine N/A version (which is more rare) as well as the more common TD versions. Either will run fine N/A, but the genuine N/A version will likely produce better fuel economy - due to some specific head design differences.

You'll need the newer fuel injector lines for the 6.5. Your 6.2 lines won't work without bending them (not recommended). Otherwise, it'll bolt in just like the 6.2. All of the 6.2 accessories will bolt right on - including the 6.2L V-belt style water pump and backing plate. You can't use the 6.5 water pump cuz it spins opposite to the V-belt version.

Jim

[coxfmly]

Thanks for the info Jim,
My brothers truck has V belts just like mine. The rotation is the same, is the water pump different? As far as the engine, It has a sticker on the valve cover that says "Genuine GM" or something like that.
The engine was purchased direct from the dealer as a long block. The gentleman who installed it never could start the engine. He used starter fluid to start it which didn't work. It was sitting in a field ready for the junk yard when my brother rescued it. He replaced the glow plugs and fired it up.
Its been running great for the last year or so. It pulls very hard even without a turbo.
My engine has 6.5 injectors and a new I.P. I'm not planning to switch it out anytime soon, I just want it in the wings just in case.
Should I be concerned with the 6.5 block? Should I install a web support or?

Thanks, Paul

[john8662]

Either way, I'd pick up the '85 to keep the engine as a spare for yours.

The highest rated N/A 6.2 was:

155 HP @ 3600 RPM
250 ft. lb. TQ @ 2000 RPM

As mentioned the 6.5 N/A wasn't much different.

I think if you swapped everything you probably wouldn't notice too much seat of the pants difference, other than a fresher engine.

I'll bet the valve cover says GM Goodwrench, if it's a crate engine replacement.

Get the engine and keep it for when your brother mentions a swap to remove that gas hungry 454 from his 91, hold him ransom!

J

[coxfmly]

John, Would you know the main reason GM went to the 6.5? If it didn't offer any better performance then? As a matter of fact the valve cover says "GM Goodwrench". Fortunately my brothers company picks up the gas for his rig so the 454 will not hit him that hard. I would be cool to hold him hostage :)

I have a 53 F-100 that has been in the family for over 30 yrs which is going on it's 3rd rebuild. We built a 454/T400 set up which is sitting next to it. We need to install the beast after we beef up the frame. We talked about stripping the Sub and shortening the frame for the 53. It would definately be a different ride.

Thanks for the info, Paul

[john8662]

The larger bore of the 6.5 does make a difference in power. I was told by Peninsular, that on the dyno, the 6.5 will make 10-15 more HP than a 6.2 with the same equipment bolted on it.

The key to the 6.5 is in the heads. The heads have a different injector angle which some say produces more power. I say that it helps aide in starting.

The later 6.2 heads (91ish ) also incorporate this design and start better in cold weather.

The other difference in the 6.5 is that they were designed with a turbo in mind, which includes things like larger pre-cups to allow more fuel into the chamber and pistons that are annodized (sp?) to reflect some of the heat away from the core of the piston.

GM went the way of the 6.5 for more power, buy there just isn't that much difference in RWHP from the 6.2 it replaced.

[snoman87]

The later 6.2 heads (91ish ) also incorporate this design and start better in cold weather.

Wouldn't happen to know what the casting number of these heads where by any chance?


I am picking up a 90's block and heads ... it would be good to know if I have the good ones