Edit:
Answers to some of the questions here:
https://www.ford-trucks.com/forums/1...l#post15952431

In this truck, I have a rebuilt 7.3 IDI motor with a Banks Sidewinder(wastegated) turbo. R&D IDI Performance DB2-110 pump and Stage-1 injectors.

In September, this truck made 250RWHP in an earlier video. It was making 15 PSI boost absolute maximum, and usually a bit less than that.

Late September, I replaced the crossover pipe with one from R&D due to a big crack; I think I cracked it /after/ that run.

Over the last couple of months, I've revved the engine a bit higher than I should have, leading me to decide that I really want a governor on the engine -- it would rev over 4500 RPM.

This morning, before I fired up the truck, I decided to swap out the stock light-load advance cam for one I made earlier; I've always had a problem with this RD2 pump getting it advanced enough to start cleanly while retarded enough to give me the most power higher up. This advance cam I have is stock except that I machined the idle flat on it down .020, and blended that into the stock ramp.
Drop it on, adjust it by eye, and the truck fires right off first try with very little smoke. So that little bit of advance worked wonders.

After that, I had some time, so I decided to put a stock governor spring in it.

One thing I noticed -- On my R&D pump, the guide stud was in /all the way/. On the stock pumps, it's usually out about 1/4" or so.


Here's the two governor assemblies, left is the R&D assembly, right is stock:


Taken apart; left is stock, right is aftermarket:


New assembly:



I put the pump back together, and installed the guide stud with 1/8" between the top of the nut and the end of the bolt threads(halfway between what I figured is 'stock' and the RD2 pump).
It fired right off, and I found that it was idling at 1400RPM.
Adjusted the idle down to 800 using the idle screw; I moved it a good 1/4 inch(Adjusted the high idle solenoid back as far as I could as well). I'm literally at the end of the throttle cable; no play /at all/ at idle. I will probably have to space the bracket out some to make it idle down to 750.

Ended up playing with the timing just slightly too; due to it not feeling slightly advanced when I took it out for a test run. I had to adjust the light load cam as well, because I had adjusted the idle position.

I found out that this combination gave me a no-load governed speed of 35-3600 RPM; right in the stock range(so much for the spacer).

I then went for a full-speed highway run, and found this out:
I'm getting 20+ PSI out of the pump, pegging my boost gauge(and if I can do this with no load, it'll be a bit higher on the dyno or with a trailer).

It /feels/ a bit more powerful, more responsive and overall /better/. And I don't understand why the governor spring(which should only affect max RPM) is doing this.

I'd say it had something to do with the timing, but the clack is at the same level as I try to keep it; any more retarded and I get a mushy pedal; any more advanced and it makes a top end clack under acceleration and feels less powerful.
The modified cam only affects idle; anything above it is stock. It just makes it clatter a bit more at idle, so it starts up cleaner.


I'm really curious about your thoughts on this. Because this is totally unexpected.

 

Well, it is interesting.?

 

I assume the only people who might have a clue about this are Justin(R&D), Typ4 and perhaps a couple of others... Most people don't try messing with the internals of their pumps, for some reason.

I still don't get /why/ it works better... but it's still working a /lot/ better than before I changed the governor. And I can't figure out why.

 

Well at the risk of sounding like a goon, is this purely a rpm governor, or does it also control full fueling?

 

This may help a bit:
There are three springs in the governor assembly(the two visible ones, and one at the end of the rod that the whole assembly rides on).
The "open" end of the assembly(where there is that short spring) pushes against a lever which is pushed against on the other side by the governor flyweights; the top of this lever then controls the metering valve(which controls injected fuel) via another spring(black assembly visible in the video).

Beyond that... I don't know /how/ the governor works in operation. The /principles/ of it are simple -- more throttle lever input pushes the entire assembly towards the rear of the pump, which pushes on the lever counteracting the flyweights, this pulls on the black linkage adding more fuel -- but in practice I think it's a bit more complicated.

I haven't found a good explanation of how each spring affects overall pump operation, or what shorter/longer springs would do in each. Same with the overall length of the governor assembly. I'm sure it would have a major affect, but I've not seen any information on it. Even the rebuilder manual just expects you to use stock parts and replace if broken; to my knowledge there isn't a whole lot of information out there on how to modify a pump to do different things.

 

It would be interesting to hear what the builder has to say about the governor mod decreasing performance. As well as his reasoning for modifying it in the first place.

 

Please delete

 

The affect that changing the governor spring had is quite interesting. It would be crazy if it increased fueling somehow.

Btw, is that a monitor on your dash? If so, did you make it and what all does it monitor?

 

Well, one of the selling points is the 4K+ RPM governor.
When looking at the internals of one of these pumps, it's /obvious/ that a stronger spring should prevent defueling at higher RPMs. And it does....
But it may affect mid-range fueling in some odd way.

Yeah. And to be fair, it did rev really high and have fuel while doing so. I had a pump sheet showing 94CC at 4K RPM, which isn't bad.

It sure feels like it did. I'd /love/ to get this thing on the dyno, or put the pump on a test stand right now.
I keep thinking that the fact that the same idle RPM is at a lower throttle position means that there is more usable travel, which /should/ increase maximum metering valve position...
But I still don't know how in the world the idle RPM changed!

It's a 20x4 LCD display driven by an Arduino. It measures RPM accurately and translates that into MPH in 4th, 5th and 6th(5th + GVOD) gears.

 

I have absolutely no clue what is going on here, but this is the most interesting post I have seen in a long time. It has to be fueling harder at lower rpm's, so was this a sacrifice when calibrating it for a flat-ish fuel curve at high rpm? I would really like to know what the bench numbers looked like before and after.

 

Cool. Yeah, it sure doesn't look like anyone modifies pump guts around here, sadly.
Could be... But if it really is putting out what it feels like, that's a sacrifice that isn't worth it -- it sure feels like it's putting out more power at 2800RPM, which is peak power anyway.
Once you're up beyond 3K, you are past the peak, even with this pump /before/ I modified it(see my dyno charts for more info).

So would I.
I don't know how to make that happen, though.

I /will/ be looking into a local speed shop that just opened up and seems to have a dyno in a couple of weeks; if they don't charge too much, it would be a great resource to have.

 

So the 110 and bigger pumps dont have a governor basically? I knew they used a heavier spring, but that thing looks like it wouldnt ever back off. Im all for a 4k governor, real handy when towing stuff WAY heavier than you should and you need to go from 1-2 without dropping down to 1300rpm

As i recall it, the heavier spring was to keep them from de-fueling at the top, because even the 6.2 spring would start pulling some fuel as low as say 3200 rpm, but wouldnt "govern" until 4400ish. The big heavy spring was an early mod to increase top end fuel, but i wonder if after the pumps got the extra machine work, the heavy spring isnt necessarily needed anymore, as indicated by your experiment. My throttle cable has stuck more than once from binds, floor mat, sticks... im sure it will happen again too.

When you put the "assembly" back together, did you mic the length before / after and assure they are the same? The slightest difference will affect low / high idle. Im talking in thousandths of an inch, and not very many of em. I used dial calipers when i shimmed mine, so could be off a couple thou. and raised my idle to 950. I stuck a 5/16 nut in there that i drilled out. Pretty much stops at 4k-4100, but will climb a little if you keep your foot in it, going into the red is one thing, going past it is another lol

Im curious about your timing mods too, im wonder if justin ever got around to playing with the timing on em, that was a long time ago conversation. My 79 started harder the more advanced i went, which seemed odd, as it seemed to turn over easier.

 

That could very easily be an effect caused by your little turbo running out of air / efficiency. As i recall its still set to 15psi?

 

Nope, no (realistic) governor at all.
I'd actually like to get that figured out -- something almost /exactly/ 4K, give or take 100 RPM.

Interesting.

No, I didn't. I just looked at the threads sticking out.
If it's that sensitive, it explains a /lot/. If you look at the pictures, I used the 'stock' governor as my template for length -- it had just the faintest bit of a thread sticking out the end. The 'RD2' governor had a whole thread sticking out.
That would explain the extra power -- the entire assembly is probably .020-.030 longer than it was, resulting in more push against the governor, more power.

When I talked with him in September, I got the impression that he really hadn't done anything and didn't think it important -- He seemed to care more about peak HP than 'area under the curve' or driveability.
I understand it -- HP numbers sells pumps -- but in my case, I'm willing to 'sacrifice' a few top-end HP numbers for a better low-end curve(where I do most of my driving).


Could be, but I also got that number out of Justin when I asked him about what it was going to take to get useful HP in the 4K range. He told me that the 2800 range is the 'crossover' point between increasing boost and decreasing fueling due to the physical limitations of the pump. Until he builds a V-style P-pump for an IDI, we probably won't see peak HP numbers up beyond the 3K range.

As far as 15 PSI goes, nah, it's not set to anything. I unplugged the wastegate long ago(with it connected, I'd get about 10). I tried wiring it shut, just in case... but it didn't affect anything. The spring holding it closed is pretty strong.
It's just that, it seems, I wasn't getting enough fuel to spool it beyond that.

And it 'feels' different, too... More 'positive' feeling, less 'leaned out', and surprisingly, less smoke.

I'm thinking that, with the metering valve not fully open, the fuel going through that would be the limiting factor more than the roller-to-roller motion. This would mean that as RPM increases, it would tend to 'lean out', resulting in more retarded timing(as it would take longer to squish together to the injection pressure). More fuel through the metering valve = more plunger opening = injection pressure reached sooner = more advanced timing high in the rev range.

I'm going to have to do some more experimenting at this point; probably get some longer bolts and shift my throttle bracket forward a good 3/4 inch, pull the idle screw back as far as I can, and lengthen the governor assembly to get my idle back. This should give me as much travel as possible, and hold the metering valve open further(if it's not already maxed out).

 

Very cool macrobb, I haven't dug into any of my pumps, I might take on of the free ones I got and play around with so at least if I fudge it up I don't loose any money, I would love to get a 4k governor. I curious of how much you can do on a stock pump, it would would be interesting to see, nice time take some measurements and post it.