Engine/Transmission (1998.5 - 2002) Swapping cams for lift 12V lift pump

[Fishin Guide]

Swapping cams for 12V lift pump

Curious if anyone has swapped out the cam on thier 2nd gen truck. I am considering doing this mod to help spool the turbo a little sooner and the real reason, 12V lift pump.



Just looking for feedback, suggestions and comments. I would appreciate hearing from anyone, but specifically those that have tried various cams and what the honest benefits were. Many I have talked to have said they noticed no change on any of the manufacturers claim except for milage. That seems to be the one thing most have told me. And cruise temps are a few degrees lower.



I am not interested in any electric pump. Sorry. Looking for a more reliable fix. Also, the ability to pull stock parts off the shelf in the event of a major issue is nice.



Dave

 

[I-6DZL]

If i may... ... What about a RASP? All mechanical, but as far as i know you can't just pull parts off the shelf. But look on the other hand, you shouldn't have to either!



Wish i could help about the cam swap.



Good Luck

Curtis

 

[Fishin Guide]

Curtis,



that's my other option. I feel like I am pretty informed on the RASP. It looks like a great system that will work for years to come. I do not have a reservation with it other than the plumbing, location of pump, ect.



That may be the way I go. I just want to be fully informed about the 12V pump on the VP equipped trucks.



I have heard good things in the past and I continue to hear the same things. Just curious how others results compare.



Dave

 

[Fishin Guide]

to the top... .

 

[Lsfarm]

Enough Volume??

I'm not sure that the mechanical fuel pump from the 12's pumps enough volume to keep a VP pump cooled and lubricated properly.



The electric lift pump provides a lot of volume to the VP44, only about 10-20% maximum is used to run the engine, the rest goes through the VP and back to the fuel tank, taking heat from the VP with it. The extra fuel also provides the only lubrication to the VP44.



I have run a VP truck with a five gallon fuel tank, and in 50* weather the fuel in the tank went from 55* to over 110* in ten miles of driving. Put your hand on your fuel tank after a freeway run and see what you have.



The 12v mechanical pump provides plenty of pressure, over 20 psi to the P7100 injection pump, but the return to the fuel tank is just excess pressure, not excess volume used for cooling and lubrication. The P7100 pump is lubricated by engine oil.



I'd ask Piers if he thinks a 12v lift pump provides enough volume to keep a VP44 alive. I'm sure he has the answer.



My experience: three factory warantee'd lift pumps in less than 20K miles, then I added a 7psi pusher pump. Now 35K miles later, the same two pumps are still doing their job. I don't run the fuel tank below 1/4.



Simple and easy fix: add a pusher pump, or move the factory pump to the frame rail in front of the fuel tank.



In my opinion, the factory lift pump is like brake pads on our trucks. A maintenance item that if ignored results in a disaster: bad brakes= bent up truck, bad lift pump= dead VP44.



Hope this helps, Greg L

 

[Fishin Guide]

Thank you for the response.



That is a great idea about calling Piers. I will do that.



As far as flow goes, I have no idea. My fuzzy logic would tell me that a pump that produced twice the pressure in the same system would have to deliver more flow. However, I think the size and volume of the VP bypass may have more to do with that than anything. Obviously, none of the lines to the pump or VP would have changed in a swap like this.



Gives me some to think about!!



Dave

 

[KLockliear]

The 12v lift pump works great on the VP44's. Our cams have the lobe, and we've done it. 50 psi inlet pressures! No problems in 50k on our test truck.



For an honest opinion, call Lenny at Dyno-mite Diesel in WA. 866-774-3966... they have installed our cams as well as other makes and tested/driven them. See what they can tell you.

 

[Fishin Guide]

Thanks Keith.



I talked with the folks at Dyno-mite. I am just getting as much info as I can together. While I need to fins a permanant solution to this lift pump issue, as I spend 3-4 days a week on the road all over the NW.



I also hope that the side benefit would be faster spoolup, to support a slightly larger charger, and increased fuel ecomony. EGTs are not an issue as I not pierced the wire, yet. But, hopefully it'll give me a few degrees of relief there as well.



Dave

 

[RustyJC]

The 12v lift pump works great on the VP44's. Our cams have the lobe, and we've done it. 50 psi inlet pressures! No problems in 50k on our test truck.

Keith,



I thought 50 PSIG was well above (like 2. 5 times) what Bosch advises the VP44 wants to see as a fuel supply pressure. Am I missing something here?



Rusty

 

[Fishin Guide]

Rusty,



I thought I had heard the same thing, But I cannot find anyone that has had a VP failure with the 12V cam and pump. Maybe there's just not enough miles on those rigs, but it seems to be ok.



I think I am going to try the cam. Questions is, which one? Since none of the vendors will publish thier specs, I guess I am going to have to test all of thier return policies. I need to place a cam in the engine and get all the specs at the rocker.



Too bad someone has not done this with all the cam distributors. It would be nice to know the basic info of the cam versus what it is "supposed" to be.



I know they want people to not take the specs and run down to the local cam grinder and crank it out, but come on already. All I have found is, "great for towing", "high horsepower only", ect. No mention of Trans setup, auto or manual, horsepower, intended use, ect.



Art least the distrubitors could give us more to go on than here it is, check or charge?



Sorry for the rant, just makes it impossible to make an informed decision on anything.



On edit, I guess I can get a 24V cam copied with the 12V lobe. Would be WAY cheaper than the current offerings and I know exactly how that cam works...



Dave

 

[KLockliear]

I thought 50 PSIG was well above (like 2. 5 times) what Bosch advises the VP44 wants to see as a fuel supply pressure. Am I missing something here?

Rusty

Just goes to prove again that what is supposed to be the limit or not work in theory, is totally different in practice. Takes the time and testing to find out.

 

[Fishin Guide]

So Keith,





Does that mean that testing has been done and completed? I haven't heard of any failures with this setup and that's what I am after. I admit, the high inlet pressures concern me, but I am more concerned about blowing the plastic cover on my fuel canister apart.



Dave

 

[KLockliear]

There are a few trucks running it. Certainly a $1500 cam isn't really all that cost effective for just a lift pump fix. That same $1500 buys our big line kit, pusher pump and 4 SETS of a replacement stock lift pump and pusher pump before it breaks even. I have not seen or heard any of those guys having problems.



Now, the cam does have it's own benefits, which is why they are there in the first place. Specs on the cam are kinda like specs on some of the turbos for these diesels. Gasser thinking would say it shouldn't work, but it does, and works well.



Oh, and there isn't a return policy on the cam, sorry. If it gets installed, it's yours.

 

[Fishin Guide]

I understand Keith,



I am not trying to say that the cam does not has it's own benefits. And I am prepared to pay for those. All I am saying is, what measurable differences are there between my current setup and then swapping in your cam? I think with this much money on the line, I should get more than it spools a tubo quicker. I know it should, but how do I measure that? And you have always stood behind your products, but how do I dispute something that is subjective?



I don't want to come off like this is an attack on you or any other vendor. I am just trying to see what I am getting for my money. That's all. There will always be trade secrets, but it does not help a guy like me. For instance, why DD and not Piers? How do I compare the two products and know that I have made the best choice for my application? Are you going to tell me I should buy a competeors product because it will work better in my application?



Again, sorry for going off on you. I have been happy with your products in the past. I guess the argument can be used on fueling boxes, turbos and the like. But a more informed customer is the driving force in sales. I give away market info every day in what I do, knowing full well that I just made it easier for the customer to shop me. But, I am the "go to" guy in my market. I choose to lead the market. I don't get everything, but I usually get the first and last call.



Can you tell me why exactly your cam is better than the other guys? I want one, but I don't know which. The biggest benefit based on everything I have heard to date is that they all have the 12V pump cam lobe. I know your cam flows more air than the stocker. I think you probably change a little in lift, some in duration and some in lobe seperation. You play with overlap a little and basically allow the engine to take a bigger gulp of air and keep an eye on chamber pressures. That's all fine and good, but how is your product the right one for me?



Please, don't take this personally. I value the information you choose to share on these boards. And taking hits like this one in stride. I am just dying for info. We'll start a thread about turbos soon, I promise. . :-laf



Thanks,

Dave

 

[KLockliear]

Well, there's the rub. I don't have a data acquisition system on our R&D trucks, so I can't show you actual data, other than a dyno run. HP is not really the goal, but you can see on the graph that the power comes in sooner - which is because the turbo was up on boost quicker.



#ad




Since you're in WA, go to Dyno-mite diesel. They have a cam in at least one truck up there. I know they have customers that have ours and other cams in their trucks. Go drive them. I realize it might be harder to compare since it's on different trucks with different mods/trannys, etc, but it's what you have available to you.



As far as Piers vs. us, I won't go down that road. I'm not on this board to "compete" so to speak - more to inform. Make a phone call though if you're really interested. We have our own thoughts about our cam, and why we do what we do. I can give you those facts, then you can call them and get their facts and make up your own mind.

 

[Fishin Guide]

Thanks for the reply Keith. I don't want you to make any direct comparisons, I'm just looking for comparable info.



The graph speaks volumes! That is very helpful. That helps me see how that cam could spool a slightly larger charger. Even though there is a slight dip in max HP I think that could be overcome with some more air on top.



And I will try to make it up to DDP and see about a test ride.



Thanks again Keith!



Dave

 

[KLockliear]

Actually, the truck cleaned up on top very well, and probably could have used more fuel.



If you want more specific info, call me. It's quicker.

 

[PC12Driver]

Not everyone keeps the specs a secret. Van Haisley showed me the specs on his cam vs. stock vs. others. Definitely a visible difference between his street grind and the stock cam, too (mostly on the exhaust side).

 

[Fishin Guide]

Thanks Keith, I'll call you next week.



Dave