1991 Cummins Suburban

[UrbanCummin]

Vulcan looks like they make some good products. I think I'll probably just keep the stock one for now. At some point, I'd like to upgrade the whole fuel system: new sending unit, new fuel lines, FASS separator, rebuild the IP or replace the VE with a P pump. All that plus a new turbo, more agressive fuel pin, and, and, and.

What kinda hp are you shooting for?, the VE ip is a very reliable injection pump, unless your shooting for over 400hp I would stay with the VE. Keep in mind that really high hp diesels are not well suited to long distance expedition style trips while going slow off-road. I will elaborate more if you want me to, but it's time to go to sleep.

 

[DEEZLPWR]

Pretty sure your talking about the lift pump not the sending unit. The sending unit is for the fuel level guage, the lift pump sends fuel to the injection pump. Best bet is to replace the crappy in tank lift pump with a Walbro FRB5. By far the best impeovement I made for my 6.5 Blazer. It's a inline, high flow, flow on fail (A VERY IMPORTANT FEATURE!!!) lift pump. The reason the flow on fail is important is that should the pump fail, the injection pump can still pull fuel, although at a much reduced rate and not burn up the injection pump due to lack of lubrication. Remember diesel fuel lubes and cools the injection pump as well as powers the engine.
Just gut the stock unit of its pump and attach a suction tube where the old pump was and install the Walbro in line with a pre-filter in between the tank and lift pump that is at least 50% coarser than your pre-injection pump filter. In other words if your engine filter is 5 micron then your prefilter should be 10 micron. Makes things much happier and longer lasting. The engine filter last longer because it only has to filter 10 micron or less particles and the Walbro will last longer because it isn't pumping crap along with the fuel. If you want to get real trick plumb some vacum switch sending units and idiots lights in to tell you when to change your filters. That way you only change them when the pumps are seeing a vacum and trip the light indicating the filter is clogged and needs to be replaced.

be careful with this notation as when the lift pump fails the psi will drop to nothing and no matter what the injection pump WILL fail. this is the problem with the 2nd gen dodges, there is a diaphram in the vp44 that will burst when there is less than 4psi delivered to the injection pump. That is why it is good measure to instead have a fuel pressure gauge reading whats going into the vp44. If it should fall off stop the engine ASAP and find the issue or replace the lift pump. But its your choice if you want to drive on a failed lift pump and ruin the injection pump $1200+

 

[UrbanCummin]

be careful with this notation as when the lift pump fails the psi will drop to nothing and no matter what the injection pump WILL fail. this is the problem with the 2nd gen dodges, there is a diaphram in the vp44 that will burst when there is less than 4psi delivered to the injection pump. That is why it is good measure to instead have a fuel pressure gauge reading whats going into the vp44. If it should fall off stop the engine ASAP and find the issue or replace the lift pump. But its your choice if you want to drive on a failed lift pump and ruin the injection pump $1200+

Certain IP handle lower pressure much better, Bosch VE pumps and the Stanadyne DB2 style found on gm 6.2s and early 6.5s and ford 6.9/7.3 (pre powerstroke) run a lot less lift pump pressure. Most of these pumps will only put out 2-5psi. Can't remember the pressure for the VE lift pump of the top of my head, will look it up at work.

 

[Spur]

What kinda hp are you shooting for?, the VE ip is a very reliable injection pump, unless your shooting for over 400hp I would stay with the VE. Keep in mind that really high hp diesels are not well suited to long distance expedition style trips while going slow off-road. I will elaborate more if you want me to, but it's time to go to sleep.

Really? I thought the VE pump was only good for 300-350 HP? That's about the range I'm shooting for eventually. Right now I'm just doing two mods. I'm installing a smaller turbo housing for quicker spooling and I'm installing the 3200 governor spring. I want to drive the vehicle for a while before I start stacking on the HP.

 

[Spur]

Pretty sure your talking about the lift pump not the sending unit. The sending unit is for the fuel level guage, the lift pump sends fuel to the injection pump. Best bet is to replace the crappy in tank lift pump with a Walbro FRB5. By far the best impeovement I made for my 6.5 Blazer. It's a inline, high flow, flow on fail (A VERY IMPORTANT FEATURE!!!) lift pump. The reason the flow on fail is important is that should the pump fail, the injection pump can still pull fuel, although at a much reduced rate and not burn up the injection pump due to lack of lubrication. Remember diesel fuel lubes and cools the injection pump as well as powers the engine.
Just gut the stock unit of its pump and attach a suction tube where the old pump was and install the Walbro in line with a pre-filter in between the tank and lift pump that is at least 50% coarser than your pre-injection pump filter. In other words if your engine filter is 5 micron then your prefilter should be 10 micron. Makes things much happier and longer lasting. The engine filter last longer because it only has to filter 10 micron or less particles and the Walbro will last longer because it isn't pumping crap along with the fuel. If you want to get real trick plumb some vacum switch sending units and idiots lights in to tell you when to change your filters. That way you only change them when the pumps are seeing a vacum and trip the light indicating the filter is clogged and needs to be replaced.

You're right. I got my terms confused. Thanks for clearing that up.

 

[Spur]

Your welcome. I would still open up the solenoid and check the contacts, and also put on the diode for safe messure.

http://www.fostertruck.com/sol-saverdiode.htm

http://www.fostertruck.com/dodge/default.htm

I emailed Foster. The diode is actually only for 2nd Gen trucks. The solenoid on an 89-93 doesn't have the problem.

 

[Metcalf]

Few things....

-Change the lift pump over to the low-pressure piston unit. You get a little more flow and a lot more durable pump.

-If your going to be building an exhaust anyways you might as well go to 4" to support any further power needs.

-Instead of doing the turbine housing you might want to look for a HE351cw turbo off an 04.5-07 Cummins 5.9. These are a great upgrade. They will flow more air than your injector pump will support. They are also very cheap as takeoffs from newer trucks. The install is pretty easy.

-The 3200 springs is a good mod but requires getting into the injector pump and re-setting the idle and sometimes indexing the throttle lever.

 

[Spur]

Few things....

-Change the lift pump over to the low-pressure piston unit. You get a little more flow and a lot more durable pump.

-If your going to be building an exhaust anyways you might as well go to 4" to support any further power needs.

-Instead of doing the turbine housing you might want to look for a HE351cw turbo off an 04.5-07 Cummins 5.9. These are a great upgrade. They will flow more air than your injector pump will support. They are also very cheap as takeoffs from newer trucks. The install is pretty easy.

-The 3200 springs is a good mod but requires getting into the injector pump and re-setting the idle and sometimes indexing the throttle lever.

Thanks Metcalf. I did some reading on the lift pump. It looks like what I want. I'll do some reading on that turbo. I'm definitely going with 4" exhaust. It's going to be semi-custom. I'm buying a 4" kit for a 2nd gen truck and then we're going to hack it up and make it fit the Suburban.

 

[ntsqd]

Before you do that I'd suggest looking thru an older Rancho catalog. There is a 7 leaf front spring for the K5's in their numerical listing that is NOT in their applications list. It is an excellent spring to start with. Only potential thing is that I do not know for sure what the lift is. It is the front spring that I have under my '91 Sub and it works fantastic.

Alternately you can find the p/n by searching coloradoK5.com's forum for my posting with the p/n in it. It was supposed to be included in their "CoG" thread on springs, but I don't know that it ever got listed there.

 

[Spur]

Before you do that I'd suggest looking thru an older Rancho catalog. There is a 7 leaf front spring for the K5's in their numerical listing that is NOT in their applications list. It is an excellent spring to start with. Only potential thing is that I do not know for sure what the lift is. It is the front spring that I have under my '91 Sub and it works fantastic.

Alternately you can find the p/n by searching coloradoK5.com's forum for my posting with the p/n in it. It was supposed to be included in their "CoG" thread on springs, but I don't know that it ever got listed there.

I'm not totally following you. I'm using a 4" Tuff Country lift from ORD. It's being installed as we speak. Maybe you saw my previous post about the 4" kit and thought I was talking about a lift kit? I was talking about exhaust.

 

[ntsqd]

That was my confusion.

Places like SPD will sell mandrel bent tube sections. SPD has 4" tube listed in 4" CLR, 6" CLR, and 8"CLR in U-bends (except the 4"CLR), 90's, and 45's. Franklin Truck Parts also sells mandrel bent large OD exhaust tubing, but I think that the smallest that they sell is 4.5"
Simple project to piece together an exhaust system, toughest part in your case would be how the head pipe connects to the turbo. Marmon clamp?

 

[UrbanCummin]

Really? I thought the VE pump was only good for 300-350 HP? That's about the range I'm shooting for eventually. Right now I'm just doing two mods. I'm installing a smaller turbo housing for quicker spooling and I'm installing the 3200 governor spring. I want to drive the vehicle for a while before I start stacking on the HP.

350-400hp seems to be the limit on a stock head/rotor. If your shooting for 400hp give or take that will be a hot engine with a stock turbo with smaller exhaust houseing (12,14 or 16 houseing?), everytime you get your foot into it the EGT's will be very high, probably 1500-1700F. If you put on a bigger turbo to flow the air you will need to burn all that fuel it will be laggy on the bottom.

My 99 cummins is a pain on the trail at times, especially the auto (is your truck a auto or manual?), it is a well built tranny but runs very hot when creeping along trails or in the city.

I used to own a 92 cummins, I had 30hp injectors, 16 houseing, and modded the pump. Probably had it around 200rwhp, it was actually a very responsive and fun truck, EGT's were ok even at WOT and had great bottom end torque. With the current VE dodge I will be building I think I will take it to 225-250hp and leave it there. Should be very reliable and a strong running truck.

 

[DEEZLPWR]

i run a stock vp44, with raptor 150 lift pump and edge juice with attitude monitor, my egts dont go above 1365 as i have it set, but on setting 3 out of 5 they never get above 1250~ stock turbo, stock exhaust. i am happy with the setup.

 

[Spur]

350-400hp seems to be the limit on a stock head/rotor. If your shooting for 400hp give or take that will be a hot engine with a stock turbo with smaller exhaust houseing (12,14 or 16 houseing?), everytime you get your foot into it the EGT's will be very high, probably 1500-1700F. If you put on a bigger turbo to flow the air you will need to burn all that fuel it will be laggy on the bottom.

My 99 cummins is a pain on the trail at times, especially the auto (is your truck a auto or manual?), it is a well built tranny but runs very hot when creeping along trails or in the city.

I used to own a 92 cummins, I had 30hp injectors, 16 houseing, and modded the pump. Probably had it around 200rwhp, it was actually a very responsive and fun truck, EGT's were ok even at WOT and had great bottom end torque. With the current VE dodge I will be building I think I will take it to 225-250hp and leave it there. Should be very reliable and a strong running truck.

nv4500, 4.10's, 35" tires

Main reason I want to mod the engine is to compensate for the weight. Fully loaded, I expect the Suburban to be in the 9000 lb range, possibly even 10,000. The stock engine was really great in my 2wd single-cab 250. Even with the getrag, it had a lot of get up and go. I'm not looking for gobs of horsepower, but I imagine that it will feel underpowered once it's all said and done.

I don't think I was clear in what I said. I wouldn't want more than 300-350 horsepower. For right now, I'm just shooting for a 75 hp bump with a few easy mods. Then I want to drive it for a while and see how it goes. But, I'd like to think about the upgrade path so that I don't make changes that I'll regret in the future.

 

[UrbanCummin]

i run a stock vp44, with raptor 150 lift pump and edge juice with attitude monitor, my egts dont go above 1365 as i have it set, but on setting 3 out of 5 they never get above 1250~ stock turbo, stock exhaust. i am happy with the setup.

pre or post turbo pyro?