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Twin Walbro's :)

If only running one at a time I would just use a 1/4" ball valve at each LP. Just open it when that LP is powered.
 
HIgh flow check valves are crazy cost. Ridiculous, like $75 for one with compression fittings. I bought one and it leaked, so I returned it to Summit.
 
As kinda sorta similar I have noticed my lowest fuel pressure at IP inlet is when I roll into throttle and let RPM's and throttle rise slower than just mashing the pedal to the floor. The truck seems a little stronger that way too. Probably my IP is old and tired but something about the way boost builds and maybe just maybe how the IP can maintain better optimized timing and complete burn better. It still takes a little more go pedal and upwards of 2600 rpm to to drop to zero fuel pressure. But between 1700 and 2200 it seems to want more too it will drop to 1-2 psi. Which I think is too low for good performance.

I am stock program & factory fuel system (just added guage & and have replaced LP with OE equivalent) and my filter is due for change. As a side note most of the times the flow rating of a filter is when new (and for a certain viscosity -temp and pressure differential) once used and getting plugged its an unknown (I guess it is variable depending on micron sizes and contamination somewhat). A differential guage is probably the easiest way to tell semi accurate cleanliness of filter element (like Kennedy's site).
 
schiker said:
As kinda sorta similar I have noticed my lowest fuel pressure at IP inlet is when I roll into throttle and let RPM's and throttle rise slower than just mashing the pedal to the floor. The truck seems a little stronger that way too. Probably my IP is old and tired but something about the way boost builds and maybe just maybe how the IP can maintain better optimized timing and complete burn better. It still takes a little more go pedal and upwards of 2600 rpm to to drop to zero fuel pressure. But between 1700 and 2200 it seems to want more too it will drop to 1-2 psi. Which I think is too low for good performance.

I am stock program & factory fuel system (just added guage & and have replaced LP with OE equivalent) and my filter is due for change. As a side note most of the times the flow rating of a filter is when new (and for a certain viscosity -temp and pressure differential) once used and getting plugged its an unknown (I guess it is variable depending on micron sizes and contamination somewhat). A differential guage is probably the easiest way to tell semi accurate cleanliness of filter element (like Kennedy's site).
Click to expand...

That is how I always drive, and since doing FTB it hangs around at 5psi alot longer, and it pulls VERY VERY strong.

I've never 'floored it'. I think there is slight benefit to maintaining 5+ psi.

FRB 28 coming out is supposedly rated to 15psi, which after the filter loss's should be right around 10 or so I'm going to guess, which is perfect IMO, based on nothing.
 
NVW said:
If only running one at a time I would just use a 1/4" ball valve at each LP. Just open it when that LP is powered.
Click to expand...

So far I've not found the need plus since I'm capable of switching on or off from the cab, I don't feel like crawling under cab to open/close the vale, it would work but not necessary since the "guts" of both pumps are in the same operating pressure envelopes of each other, IMO minimal to no risk of one pump damaging the other from system pressure.
 
I did it.

Both pumps benched over 10psi.

Lesser pump idled at 2psi and fluctuated from 0-2 on heavy highway use.

Better pump (constant velocity) Idles at 5psi, and 3psi heavy highway use. (This is pulling through fresh 10 micron Racor, AND Inactive 2ndary Walbro.

I put the walbro screen in the lesser pump, the one before my racor. REmoved screen from 2nd walbro.

With only the one pump running gets 5-6idle, 5 average driving around, and 3 on heavy demand.

Flip the switch, takes about 10 seconds or so, but wham the psi comes right up to 9-10 at idle AT THE IP. On heavy highway use its around 7-8, and driving around sits hard at 9. Never seen it break 10 or 7 for that matter. It holds pressure a lot longer too before dropping. The racor must act as a large expansion chamber, now being pressurized.

It is without a doubt smoother at idle, and it feels 'tighter' and a fair amount quieter with both pumps going.

I have it on a toggle switch (rocked arming style :)) and got a toggle plate from Jegs a while back, so already had that in the truck just waiting for something to do! (Need to wire up another for the xfer lift pump)

I'm very happy with my fuel pressure now. I without a doubt will get more use out of my Racor filters now, as when pressure drops It still has a pusher. And the easy to change walbro's screen is in a good spot, and will stop any large rust or who knows what even before the racor.

:thumbsup::thumbsup:
 

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Nice work, might justify people purchasing a more expensive higher pressure single pump. or leaving stock on one with a Walbro, or these twin walbros. Having the one prefilter and post filter is probably your big gainer. You could test them right in line instead of separated by a filter.
 
Nobody else has anything to say?? :)

I have to do drill that IP fitting out ASAP. This thing runs so tight with nice pressure. This is the 2nd time I've claimed this now, once after FTB, then I had filter issues, and now its restored. There is an advantage to having the psi up around 7+ at the IP.

Now its not an advancement issue, as it gets quieter, and smoother.

My initial thought the first time I drove it was it smoothed out the pop spray of the injectors by having strong PSI into it. I think by it fighting to fill the chambers its losing the push on the other end, resulting in a non perfect spray. Sure it will still pop at 2000, but it may not push through the entire injection phase at full pressure, causing the inital spray to be perfect, but then lose the psi?

Thats my theory. Someone else has to try this out like this to see what they think. Its really neat to be able to switch one on and off at will. Its not like a turbo boost button, But I can feel the difference in the IP when its working at 3psi and working at 5-7.

I saw 6 on the highway today, but I was climbing hard at 68mph. Hot as hell out today too. All these little mods are adding up, I'm having trouble keeping it at or under 65.

Two years ago I was hating 55. Now I can't keep my damn foot outta it.
 
A raptor set at 12psi would probably be perfect after going through the FFM. Perhaps 13. Should be close to 10 at the IP. Diesel Pro who use to rebuild these claimed 14 is Safe at the IP I'm not sure what the FFM can handle. Raptor is a far better solution than twin Walbro's. However I think the one that is preset to 8psi is too low for the money, only going to be 5-6 max after FFM if its fresh. That PSI doesn't even budge, as its constantly pumping it anyhow, just diverts the rest back into the tank unless demanded for I believe.
 
Airdog is the one set to 8 psi and you have to install straw in fuel tank (would be darn near impossible for you I would think with 2 tanks). AirdogII is adjustable and hooks into factory lines with compression fittings. If a person were going to spend that kind of money, I think the II would be worth for the extra 100.00.
 
I think it is just charge pressure increase and just a tad more initial pressure in the plungers before cam compression. Not that a few psi would make any appreciable change in ~ 2000 - 10000 injector line pressure but.....

I posted this in another thread.... The transfer pump is a rotary vane pump such that I think this is what happens. As the chamber tries to compress the fluid it being a liquid can't compress bleeds back excess volume to the chamber before it which pushes diesel to the previous chamber repeating to the IP inlet. Well with higher IP inlet pressure there is more pressure in each chamber repeating forward til the exit. OK so .... but it doesn't really take any real volume change in a liquid to increase pressure so I guess it just helps in any leakage rate of the plungers while they are at the low cam clock (biggest dia). Or it just helps the plungers push outward a bit more and takes up the max available "backlash or give" in the pumping action. Then the result is just a bit more continuously optimized balanced injector spurt output because it is working the best it can. Judging if 63 mmm/1000 fuel rate makes 190 hp then just 0.1-3 mmm/1000 ???? difference in injector balance over a couple of minutes might feel like an appreciable HP difference.
 
Its no turbo boost button thats for sure. Just running really good, probably the way it should.

My IP also has 100k miles on it now, replaced dealer at 40k or so. So maybe it helps correct a little slop there.

Hot as a MOFO out lately, but the best way I can describe the differences is it seems to eliminate alot of that "Engine making more noise than go" feeling. It just seems tighter, and smoother, and less overall engine "noise", and nothing but good old "GO" going on.

I think Tom has 2 Walbro's, maybe this thread has him itching all over to try it out. I'd like someone else's opinion.
 
Since charge pressure is directly related to fuel rate if you can increase the charge pressure more fuel or the actual correct amount of fuel is getting metered in the pulse width. Pressure and time is how it meters the fuel.
 
I've notice it locks up TCC alot easier now, as if I have less throttle percent. I think thats just it, its getting the correct amount. Running tit. But smoother too... Tighter... quieter. Everytime I flip that switch it just has that feel good feeling like a fresh fuel filter gives you.
 
Holy smoke, Batman!

I finally got around to checking my LP.
I'd never had any fuel supply problems.
After replacing the filter, and all the rubber fuel lines with silicone, I took my old vac/press guage off the turbo boost monitor job and put it to work reading
LP press;
T'd at IP input,
10psi at cold idle, 8psi@ hot idle, 4psi @WOT.

I'll keep my new Walbo in the box until I install the oil cooler kit and motor mounts! 2 new gauges on order...;)
I'll set the LPs up in parralel.

Thanx, Matt, for the encouraging thread!:grouphug:

.
 
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