I installed my Kenne Bell GT500 Dual fuel pump "Boost-a-pump" today. It was very easy and straight forward.

The Boost A Pump is a great gadget that, when activated via boost pressure switch runs the fuel pumps at 17.5 volts instead of the regular 12-14v. This makes the pumps deliver more fuel, thereby raising the fuel delivery boundary. I installed it because the 4.0 injectors do not flow very much, and I have a goal of adding 80+ hp over stock to this engine to get it to 450 flywheel hp on the motor, then more with a NOS system. I will be adding a +4 lb lower pulley, 92mm MAF, 4" to 3.5" intake tube, water/meth injection, and high flow cats soon and wanted to have this installed before I upped the boost. My goal is 15-16 psi with the water injection running before the ported eaton M112 blower.

Photos of install :

1 exposed wiring, "before" photo

2 found a convenient location to splice into the wires. The power to the pumps wires are brown with green stripe and solid orange. These wires are a bit larger than the rest so they are easy to find.

3,4,5,6 I fished a 20 gauge copper wire between interior parts and pulled it through the trunk area, then taped black wire to the copper wire and pulled it back through. The goal was to get the black wire from the trunk to the cabin, then ultimately to the engine bay. I tucked it away so it can't be seen.

7 Shows boost a pump all wired in, "after" photo

The black line that went into the cabin continues to the engine compartment and hooks up to a pressure switch that is simply teed into the pressure/vacuum tube that comes off the lid of the supercharger (the thing that says V8 on it). I think it is a 6lb switch, meaning it activates the Boost a pump to turn on at 6+ psi.

 

And this was to fix dropping fuel pressure?

 

This was a calculated preemptive strike against going too lean and melting my motor as I will be requiring more fuel than this system was designed for (hint giggle gas, the juice, this baby is going to be bottle fed). Also, I have a few big power drawing items, like the water/meth electric high pressure pump that sucks up a lot of juice, so I though it best to pump up the voltage to the fuel pumps to keep on the safer side.

Here are my actual flow rates from my injectors after being cleaned:

@ 3 Bar 3.5 Bar

1) 356 cc 388 cc
2) 364 396
3) 356 388
4) 361 392
5) 357 388
5) 361 392
6) 361 392
7) 361 392
8) 360 392

Average flow 359.5 cc 391 cc
Low flow 356 388
High flow 364 396
Spread 8 8
Deviation 2.69 % 2.64%

So as you can see, there is not too much "extra" capacity left here.

My mods list is/will be:

92mm MAF
4'-3.5" intake tube
82mm maxbored TB and port matched elbow
Ported 5th gen M112 with special immune to fuel rotor coatings
+4-4.5 lb lower pulley
Water/meth injection injecting before the blower
one step colder denso u-groove plugs, recommended by Kenne Bell
High Flow nameless Cats
ECU Tune: 6500 rev limiter, -4 degrees timing, target 12.5:1 AFR
NOS mooo hooo ahhh hhaaaahhhhh

This should be somewhere in the neighborhood of 360-380 RWHP on a dynojet on the motor alone. If so, the stock injectors would be possibly at or over the limit of what they can deliver. I did this mod to have a little insurance against going too lean, especially when adding lots of extra fuel to match the Nitrous. Maybe I could have survived without it, but I would rather not chance it. This was the easiest mod to upgrade my fuel delivery. The 4.2 injectors would flow something like 10-15% more I think.

for reference, here is the link I had posted a while ago about testing xjr injector flow rates https://www.jaguarforums.com/forum/x...jectors-83425/

 

Mmmh, had 480rwhp with stock injectors whilst still being on the rich side with the a/f measurement, so it could be some overkill to have a BAP with your setup.

Anyway, am just puzzled how you wired the pumps. You know that under 3000 rpm only 1 pump is used? I am getting the impression now that you have cross wired both, so they are both always on, or am I missing something?

 

It could be me who was missing something as I am not understanding why this is a problem since it appears that the "Dual" unit has 2 different independent circuits as it has a fuse for each side (red and blue) which leads me to think that they run independently. I think it just lets the current voltage (or no voltage) through each/both sides until the pressure switch activates the unit and then it gives 17.5 v to both sides. So when there is power to only one pump, I don't think it adds power, or evenly distributes the power from one power in to both power outs, do you? When the activation switch is "On", then it does kick them both up to 17.5, but at that point they both ought to be getting their source power anyways since I shouldn't be hitting the activation threshold of 9 psi until approx 3000 rpm anyway.

Are you suggesting I only need/should install a BAP on one of the pumps or is there some other option of how to wire this?

Could it cause any problems if it comes on at 6 or 9 psi? (I am going to switch it to activate at 9 psi instead of the current 6)

I installed it as the directions show, which is to simply splice into the existing lines.

As the instructions showed, I cut the orange fuel pump power feed wire as it goes to the pump, then spliced into the red input on the BAP, then wired the red output to the same orange wire feeding the pump, and did the same with the brown with green stripe wire so to me, the wires do not appear to be "crossed" but both pumps will kick up to 17.5v when the pressure switch tells them to.

Any potential problems I should look out for?? I still have the stock pressure regulator so the car can pass visual smog inspection here.

small clarification: My goal is 450+ Flywheel HP or approx 370+ Rwhp on the motor, and "a wee bit more" with the NOS. (Evil Grin) Any idea/guess at what point the stock rear end breaks?

 

Ok,

So to be sure of how the boost a pump operated, I called Kenne Bell and talked to Mike.

It was as I suspected, if the pressure switch is not yet activated below 3000 rpm, and there is no voltage feeding into pump #2, then it stays as it was stock, as in #1 pump runs, but #2 pump does not.

It is only when the pressure switch is activated that both would run 17.5 v, regardless of the rpm.

So what I am going to do is to set my pressure switch to approx 9 psi which is about 3000 rpm anyway.

So, all is now happily clarified

 

Interesting device, but I have to disagree with one of your statements (the part in red)- "this device feeds the fuel pumps 17.5 volts instead of the regular 12-14v. This is easier on the pumps" - where did you get this idea?

Power dissipated in the motor is a function of voltage squared - so going from 14V to 17.5V increases the power dissipation (HEAT) generated in the motor's windings and brushes by 56% (17.5^2 / 14^2 = 1.56)...

The fuel pump motors were not designed for this increase in power dissipation so one thing is certain - it is NOT better for them - and since fuel pumps are already one of the common failure points in our XJs, I suspect it most likely will lead to a shorter operating life.

 

This is way out of my area of expertise, but if you read about it here: Boost-A-Pump they disagree.

Kenne Bell has a pretty good reputation for only putting out good products that work.

 

Um.. would you expect them to tell you their product might reduce the life of the fuel pumps?

Only related statement I see with a quick scan of their site is:

"Does not affect pump life. Actually increases life of returnless pumps."

First part of this statement is what I argue as wrong. The latter part of this statement could possibly be true, as they also can reduce voltage to the pump to regulate pressure - but it is not applicable to Jags - we have a full return fuel system.

 

No, of course not, your point is a reasonable one, going faster ought to shorten the life of the pumps...I can't logically argue against that....at all.

 

Yeah, and I didn't even consider the fact that the bearings are being run at higher than design speeds...

I added some text to my previous post, if you're interested. AND, I'm just speculating here... I have no evidence one way or the other - just being devil's advocate.

 

No evidence needed, it is completely logical and rational that running the pumps outside of their design parameters could/would shorten their life. In reading your post, it became immediately obvious to me that I had not thought about shortening the life at all, I was just accepting what was written by Kenne Bell.

Devil's advocate can be a very useful position in these situations, especially when I was blindly accepting what was being written.

I'll just expect that at some point, the pumps will fail, maybe sooner with the boost a pump than without it, and I will have to replace them when that happens.

I still think it is useful to have the extra fuel delivery when I am at 15-16 psi of boost and spraying

 

I think you have reached a new record of editing your posts ;-)

I didn't know this BAP had 2 independent circuits, that is why I was puzzled with your setup.

 

$0.02 worth:

A BAP might not be required if voltage drop in the feed and ground circuits are addressed first. The wiring on the X308 is woefully inadequate when compared to the usual sizes run by fuel hungry JDM turbo cars.

If the wiring is not adequate, all the BAP is accomplishing is to overcome the voltage drop that could have been addressed by adequate wiring.

The usual size is 12-14 AWG.

Finally, a pair of bigger pumps with adequate wiring seems like a better solution than winding out stock pumps on inadequate wiring at higher voltage.

 

I am thinking to change smaller pumps. Pair of Walbro 255s pushed pressure too high and even good FPR can not ajust pressure down to the right level. It's common problem with high pressure pumps. Maybe 2x190l/h would be better choice with
stock 3/8" fuel lines and -6AN FPR connectors.

 

What I am trying to do with raising the voltage is to increase the flow so as to be able to run 16 psi and a 100 shot of NOS if I ever decide to go that high and still not run the injector cycle over the recommended 80%. The BAP was my first choice because the installation is so easy and completely reversible.

For now I am not going to have it activate until I've installed the lower pulley and my larger MAF/intake, etc. I'll then try to get a dyno with datalog so I can see my injector duty cycle and then I will know at what point is optimal to activate it with the NOS.

Basically I am, as cheaply and safely as possible bringing the car up to approx 360-380 RWHP on the motor, then the NOS can take me to whatever level I choose. The total investment is not terribly much this way, and NOS is really fun!

A bonus is that nothing cools IATs better than injecting a gas at -126 f into the intake, so cooling the intake air while using a hopped up Heaton is no longer an issue when spraying. I may only run a 30 or 50 shot of NOS for this reason, and save the larger 75, 100, 125+ NOS jet sizes to see what it takes to get my car into the 11's in the 1/4 mile.

If I had to do it over again, I would probably use 2 of the adjustable voltage with dial BAP units, so I could fine tune the voltage as needed.

 

Yes I edited this post many times as my understanding of the situation and when I would set the BAP to activate evolved. This is to the end that the next person who reads this thread from the beginning can more easily understand the scenario so they can decide if a BAP would or would not be useful for their situation.

As should be apparent by now, my style is to try stuff, see if it works for me or not, and then post my experience on this board, even if I completely screwed up, so other forum members can get an actual account of results from someone other than biased manufacturers advertising claims who are just trying to make a buck.

The benefit of my editing to other board members who read the thread after I've edited is that they may have the benefit of my experience, good or bad, so that they do not have to duplicate my R&D efforts and expense. This is especially helpful when I try things that do not work, or through trying something, I come to learn what is a better way, such as in this example, I would do 2 single adjustable voltage units instead of the one dual non adjustable. I would still use 2 units to have more control and margin of safety, Your choices may be different as you see fit.

When I first came to this board, there were fewer end users sharing their actual experiences, so it was difficult to get accurate honest information about the true results of various mods.

 

Personally I prefer not to edit unless its used for technical reference or for a correction with the text marked so people know what you changed, but each to their own. Not sure why you bring up the rest, can't see the relevance of it here.

Anyway, imo It would be better and $200 cheaper to install the standard 40 amp bap before the relays. This way you still have an individual control and individual (stock) fuse setup.

 

There are only 2 models of the BAP:

The standard adjustable voltage 40A BAP only runs one pump.

The GT500 runs 2

If I were to do it over again I would run 2 individual adjustable voltage units. These could even be staggered as to when they activate.

You can customize when you want the BAPs to activate by adjusting the pressure on/off switch from 3-12+ lbs of boost. This may be best set by data logging injector duty cycles, and then deciding how much safety margin is desirable. I do not think it is a good idea to wait until the injectors are running 100%, or a little beyond that where they start to lean out. That is a very bad way to measure when it is time to upgrade fuel delivery. It is my opinion that the standard, not beyond 80% duty cycle is a good place to be.

Remember, since I will be running extra fuel and NOS via a wet system, I can up the NOS and fuel to whatever HP gain I wish at the drop of a hat, so my system is now fully capable of 600 or even 650+ HP if I have a whim to make it the most powerful XJR in history to date. At these HP levels, the BAP makes sense, does it not?

Say 370 rwhp on the motor with my mods, then:
+100 Nos jetting = 470 RWHP / .83= 566
+150 Nos jetting = 520 RWHP /.83 = 626 Flywheel HP
+200 Nos jetting = 570 RWHP /.83 = 686 Flywheel HP

Under these conditions with running approx 15 psi of boost, the NOS actually gives a little more HP than rated, but these conservative figures are close enough to prove my point that I now have on tap any HP figure I desire as long as my drive line does not blow up.

Pretty fun, yes

 

1 40 Amp Single circuit BAP CAN feed the 2 pumps as i have explained, give it soms thought and you will see.