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DB2 information

R

randomid25

Rattle-Trap Cap'n
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Location
East Tennesee
I'm trying to research the db2's and to learn more about them. My pump is maxed out and i still have yet to see more than around 700 degrees egt in 4th gear with the tc locked up accelerating up a hill. That is with my turbomaster set at 8psi peak boost.

I know that the first numbers of the pump

DB = pump model
2 = number of plungers
8 = 8 cylinders
29 = .29 inch plunger diameter

and i also understand that the 6.5 has db2831 pumps which ammount to larger plungers but I am trying to understand the difference between the different models of 2829 and 2831 pumps. There has to be variances in these or else they would all have the same numbers after the first 4 (ex. they would all be db2829-4268 or whatever).

Someone please school me on the differences. I may be looking to go to a bigger IP soon because i feel like i have some more hp to be had from my setup.
 
What I remember reading is that the only db2 pump that has the larger plungers was the 93 for a 6.5 turbo. I'm sure others will chime in here who know more than me. IIRC the # was 4911?
 
yeah, the 4911 had larger plungers but there were some others. Thats not what I'm trying to find out. If the the light duty and heavy duty pumps are all the same plunger size, whats the differences in them? Is it just the factory setting of the fuel pump?
 
The DB2 831-4911 was the factory IP on the '92 and 93 6.5TD's. The 31 on the 831 is .31 plungers, thus more fuel than the 6.2 829 with .29 plungers. I think there was also govenor changes as well for the 4911 IP. My '93 had the 4911 and eventually it had the common hot start issues with excessive head/rotor spacing issues. I replaced that with another DB2 off a military hummer, mfg dated in '07. I turned it up about 1/4 turn and it runs better than the 4911 ever did - although i think the 4911 had seen better days when i got it. lol I think there's a DB2 list here in the FAQ's maybe that has a bunch of info on the DB2 IP's. If you can't find that or want more info, PM me as i've stashed a couple of docs on my home pc about DB2's.
Don
 
Thanks for the replies but PLEASE read my first post. I know all about the 4911 pump. I would like the info you have. I have read the faq several times. It's rather vague. Some HP rating but overall, I consider it an incomplete record. I'm also not convinced that the 4911 pump is the one i want. The faq says its rated at 200hp and I'm shooting for more than that.
 
8 psi of boost probably won't net that high of egts. Try bumping the boost to 12. Bet your egts will go up. Not much more to be had from a DB2 frrom what I have read. Could always try to find the mythical DB4. If I understand things right less boost means the exhaust is being dumped which equals less back pressure. More boost means closing the wastegate and creating more back pressure, more egts. It may not be more fuel you need. I'm not sure.
 
Most pumps with the .290 plungers wont push enough fuel to warm one of these engine up much

You need the .310 plungers to be able to push enough fuel to make any real heat.

Rat Man has a pump with the .290 Plungers in it and he has mentioned that the EGT's just dont come up very much.

The 4911 was one of only a few pumps that will push enough fuel to make a turbo motor go good.

MGW
 
Thanks missy. I am looking at a .31 plunger pump off a humvee on ebay right now. I guess to get the benefit I'm looking for, I'm gonna have to break down and replace the ip. Might play with the timing a little bit when I do. Anyone gonna chime in about the differences in the LD and HD pumps?
 
Acesneights1 said:
8 psi of boost probably won't net that high of egts. Try bumping the boost to 12. Bet your egts will go up. Not much more to be had from a DB2 frrom what I have read. Could always try to find the mythical DB4. If I understand things right less boost means the exhaust is being dumped which equals less back pressure. More boost means closing the wastegate and creating more back pressure, more egts. It may not be more fuel you need. I'm not sure.
Click to expand...

I need more fuel. The more boost i run, the cooler it runs. At 9 psi, it wouldn't go above 550 degrees. I turned down the boost on the turbomaster because there was no point in drive pressure that high no more fuel.
 
Aces

With the Tahoe the DS pump is being controled somewhat by the MAP sensor and the ECM will add more fuel.

The DB2 is only going to feed as much as the mechanical limits will allow based on how the pump is set up from the gitgo.

The 4911 will do all that a DB2 can do unless you use a tweeked up pump.

10 PSI is a good maximum boost for these engines. Turn the fuel up to the point that the EGT are about 1000F in the manifold with maximum boost under full load.

1000F is a good point to stop.
Beyond 1000F gets dicey in a hurry. 1100F can be ok, 1200F is on the edge and beyond that is definately off into the crispy ZONE.

The problem is this, when your running out on the edge, the slight differences in cylinder to cylinder fueling and such can see temperature variations.

You can have a couple cylinders that are running way hot as compared to the others.

The injectors play a big part in this too. A set of used up squirts can cause extreme hot spots especially if they are not popping right and or are peeing a stream.

The system works in harmony to make good reliable power...


Enjoy and dont get caught in the "CRISPY ZONE"

Missy
 
I just bought a DB2 for another project I have in the works, look at the inlet to the DB-2, if anything is in need of a FTB it is the DB-2 IP, that little inlet orifice mite be good for 135 Hp, but no way are you going to get maximum fuel thru that inlet, it's smaller than the opening for the DS-4. The FTB for DS-2 isn't going to be as easy as it was on DS-4, but once I figure it out, I'll be posting the how to do it.
 
Last edited:
Missy Good Wench said:
Aces

With the Tahoe the DS pump is being controled somewhat by the MAP sensor and the ECM will add more fuel.
Click to expand...

Unless relfashed like most of the power junkies have done.


FWIW Bill told me for Bonneville if a DB-2 could out supply a tweaked DS-4 it would be there, it can't so it wasn't on the LSR, after looking at the DB-2 I just bought, I see one of the limitations, that will be rectified in due time.

As for those that contend that the DB2 is more reliable than DS4 well it isn't controlled by trons, but beyond that their mechanical frailties ought to be similar, maybe an edge for the DS-4 as the newer IPs came with "hardened parts", not an option for a MFI 6.2 no puter to run the DS4, now that I have a DB2 project in my head, I'll be looking to improve that IP some.
 
Keep me up to date on that TD. I seem to remember the fitting on the DB2 just being sae no ? I think I changed mine to a barb on my old 83 and ran bigger fuel line. Maybe I'm not rememebering corrctly. I know I have brought this up before but Tim, you thoughts on the mythical DB4 ??? :D
 
I thought I read a post somewhere that the db4 was a reverse rotation and that is what makes it so tough to install.
 
Turbine Doc said:
I just bought a DB2 for another project I have in the works, look at the inlet to the DB-2, if anything is in need of a FTB it is the DB-2 IP, that little inlet orifice mite be good for 135 Hp, but no way are you going to get maximum fuel thru that inlet, it's smaller than the opening for the DS-4. The FTB for DS-2 isn't going to be as easy as it was on DS-4, but once I figure it out, I'll be posting the how to do it.
Click to expand...

It's only a 1/4 inch fuel line running into the supply port on a db2. I have already seen this as a potential speedbump in getting the fuel to my motor. I am not brave enough to drill that out with the ip still on the truck and I'm sure that if i go too deep, it will destroy the pump.
 
randomid25 said:
It's only a 1/4 inch fuel line running into the supply port on a db2. I have already seen this as a potential speedbump in getting the fuel to my motor. I am not brave enough to drill that out with the ip still on the truck and I'm sure that if i go too deep, it will destroy the pump.
Click to expand...

Yup the IP will have to come out to make the modification I'm thinking of.
 
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