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6.2/6.5 turbo hybrid questions

T

TheMacster777

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Hey guys, I have been poking around here and some other sites for a while now trying to gather up some info on a build I'm doing for my gf. The truck its going in is a 86 K20 currently a 350/TH400 and I have a 12" spring lift for it so most clearance problems wont be an issue.

From what I have read so far the 6.2 with the 1 piece RMS is the short block that I should look for I think, my main question is with the heads. The J code heads have the bigger valves but all the 6.2s have the smaller precups, but the 6.5s heads with the diamond precups (code F?) make more power right? Could I just run diamond precups (or hog the 6.2s out) in a J code head and have the best of both worlds or is there other differences in the heads that I am completely missing. I remember reading something about the injector line angles, does that mean the injector spray pattern anles are different too?

On the pump side I understand that the 6.5 mech IP is better than the 6.2 IP so is that the one I want? I don't know much about these pumps beside that when I was in the Marines I'd crank a screw on them 1/4 turn and they run like hell for a couple thousand miles and then blow up.

If all this stuff has already been covered I apologize but I couldn't seem to find an answer and if any of the stuff I said is incorrect let me know. Any help would be great. Thanks
 
6.2 heads have bigger valves, which theoretically would flow more, and are more prone to cracking between the valves. if your going to use the 6.2 heads with a turbo you should seriously consider the diamond precups. as far as inj line angles the issue is clearance with the turbo exhaust manifold. can be done with extra gaskets but it is tight. as far as pumps go your looking for bigger plungers in the pump and the 4911 mech pump has the biggest.
 
So J code heads with diamond precups is my best option then? There are no other advantages of the 6.5 heads? And for the lines can I just run 6.5 lines or am I missing what you are saying?
 
You might describe your project a little more. Replacing the engine? Going turbo and with what parts?

The precups come out easy. You can drop diamond precups in 6.2 heads. The 6.5 injectors are shorter although the thread is the same. So using 6.2 lines on 6.5 injectors requires a little line bending.

All parts are interchangeable. Using 6.2 heads will give you clearance issues on 6.5 manifolds on the passenger side although this is not a show stopper. (assuming using the shorter 6.5 injectors as 6.2 injectors do not clear a 6.5 manifold.) The 6.5 manifold also has issues with the AC box in the old 80's body style. The manifold just has to come off to change injectors in the future. Maybe you are using the banks manifold?

Keep in mind the MPG drop going turbo. You loose about 1/4 of your MPG. If you are staying NA - keep the NA cups and the 6.2 pump. More fuel NA the engine can't burn.

I have used 2 6.2 long blocks to replace 6.5's. The precups are critical to change for turbo application. Otherwise they smoke a lot...

Injector angle is an unknown factor. With the camshaft and restrictive exhaust the bigger valves haven't done anything for me. My biggest improvement was using a non-factory turbo like the A Team Turbo or HX40II.
 
The project is an 86 K20 12" lift D60 front/14FF rear 4.10s and the biggest tires I can cram under it without having to cut the cab

Yes I am replacing the engine, it has a SBC 350 now, as for a turbo I was leaning towards one off a cummins (H1C,HX30,HY30) not sure which yet, haven't got that far or even a HX40 or compounds. So why couldn't I run 6.5 injectors and lines into my 6.2 heads so I don't have to do any bending or is that what you are saying I do? The A/C box isn't an issues, all its going to have is an alternator and P/S and I will have to swap to hydro boost obviously for the brakes.

I have no concern for MPG as its going to be a mud truck

As for the pump can't I swap some of the guts out of a 7.3 IDI into our DB2s? I found a write up somewhere but my computer crapped out and I can't find it again. Or maybe a DB4 out of a John Deere or something.
 
Look up moose pumps, conestogadiesel.com, for a wicked DB2 IP or 4 plunger marine. Although off road I would think you would want low end power so a boost valve for a larger turbo is the way to get low end and have you top end cake too. Plenty of turbo info on here to wade through. A 6.2 pump runs out of fuel for larger turbo's.

You need to use the short 6.5 injectors for 6.5 turbo manifolds. The banks manifold will clear the taller 6.2 injectors. 6.2 or 6.5 lines will work just bend to the injectors. The 6.2 vs 6.5 heads also has you bending lines. Don't hurt them any to bend them. IMO it is easiest to use 6.5 lines on 6.5 injectors regardless of heads.

I have DS4 6.5 injector lines on 6.2 heads with 6.5 injectors.
 
I would rather find a couple used DB2s and pull em apart and tinker with them and build my own that shell out almost a grand for a pump. Thats why I want to find some more info on them and the ones used in other applications like Ford or John Deere, I'm not sure what else they came in or what the differences are in the actual pumps from application to application.
 
You can buy brand new DB4 831 5722 pumps through a Stanadyne dealers.. you would be further ahead with something like that then trying to piece one together.. You could also check with Unique diesel, they modify DB series pumps for the GM diesels
 
I appreciate the info on where to get new ones and all but I personally would rather find out exactly how they work and mod it myself, i really wish i could find that info about using 7.3 parts
 
You're not going to gain anything from 7.3 parts.. there already HO injection pumps for the GM platform.. there already is a DB4 mechanical 4 plunger for GM's.. there already is a DB2 .330" 2 plunger for GM's.. The ford 7.3's never had a HO pump. The ford guys you are referring to had used some of the HO internals that were available for the GM's for their 7.3 pumps.

The one thing I know that the 7.3's had, was a nose cone that had a 3/8" inlet vs. the 1/4" that GM used.
 
Ok so I'm picking up a 97 F code 6.5 this week for 100 bucks minus the ds4 pump. The guy blew a HG and swapped in a 12v. So I'm now in the market for a pump. Do all the 4911 pumps have the .310 plungers or do some have the .290? Where do I find the 8XX numbers on the pump?
 
You will want to check the heads for cracks and the mains as well before spending too much money... The IP will will have a Stanadyne manufacture / ID tag right on it will have the DB2 831 4911 numbers or what ever the pump numbers are...
 
I found one on ebay but it just says DB2/4911, no 8XX though. Seems sketchy. My buddy is a supply sergeant, I'm gonna see if he can snag me a HMMWV one. Should work since they never went to the DS series.

This is what I found:

2910-01-434-8597 DB2831-5079 6.5 Turbo (1996 &1997) 4L80-E M1113/14

2910-01-326-9221 DB2829-4879 6.2 after 1990 3L80 Basic HMMWV

2910-01-199-2355 DB2829-4523 6.2 before 1990 3L80 Basic HMMWV

2910-01-414-1272 DB2831-5149 6.5 NA (1996 &1997) 4L80-E A2s

Pending NSN DB2831-5209 6.5 Detuned (1996 &1997) 3L80 Basic HMMWV
 
They all look pretty much the same inside. The newer ones will have a different rotor,and possibly a steel advance sleeve.
 
Well I just picked up a recently rebuilt 4911 with lines and a GM3 turbo for 150 bucks. This seems to be the pump to hot rod and now that I have an extra turbo I might just have to run compounds. No good to me sitting on the shop floor.
 
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