Sooo, . . . . . Has anybody tried replacing the . . .

[cubedeficient64]

Is there a pilot port from the case to the inlet off the ksb or is that pressure just what makes its way past the piston? If there is a port do you know roughly how big it is?

[RCCUMMINS89]

Back on page 2-5.............there is a few pictures of it.

[cubedeficient64]

Yeah I have looked at those but they dont show where the ksb gets its case feed from. Im trying to get a rough base line on the size of return hole restrictions, I originally was thinking the ksb return plus the reg holes would add up to roughly the same surface area restriction holes in a non ksb reg.
Going by what has been said a post or two ago by blocking the ksb return or turnjng the ksb on pushes case pressure up bit it must also still be a safe value of restriction that with the ksb on at high idle there is still enough of a relief not to damage the pump.

I have a relief that could run some sort of boost compensation and then you can use a smaller orifice to set overall base line high pressure and have the relief raise pressure under revs and increased boost signal.

lower rpm low boost conditions would then still have the lower case pressure and not effect dynamic timing.

Measuring various timing springs shows that they vary the pound pressure anywhere from 88 to 118 pounds on the ones I've got and their compression lengths vary greatly too. Same again with timing piston travel as bc mentioned early on.

[BC847]

Over the last couple or three weekends driving to the coast and back, I've been toying with the static timing combined with the spacer gizmo.

After the remnants of a tropical storm, another weekend at the beach, and a couple of evenings of violent storms, I finally had an evening available while I still had some steam in me.

I've actually tried messing with the truck a couple of times this week but with the warmer outdoor temps combined with apparently well advanced timing, my daggum engine cooling fan has been kicking in and running constant. I tried running it up one time while the fan clutch was engaged. Literally smoked the serpentine belt.

Anyhoot, It was a little cooler this evening.

- With 12psig input fuel pressure, the case pressure regulator set to 75psig @ 800engine rpm, has the case pressure level off to about 130 ~ 135psig @ 3200 engine rpm (no load / free-rev).
- Raising the input fuel pressure to 16psig has the 800rpm case pressure rise to 76psig, and rise to 140psig @ 3200 rpm (no load / free-rev).
- Adding to the above, clamping-off the IP's overflow restriction line presents with no difference at 800 rpm, but the case pressure rises to about 145psig @ 3200 rpm (no load / free-rev).

- I noticed that the case pressure went from 75psig @ 800 rpm, to about 120psig by 2200 ~ 2400 rpm. The increase in case pressure from that point on up to 3200 rpm was much slower.

- Doing a couple of 15 psig or so boosted launches and running it on up to 60mph or so saw the case pressure at about 110 when I hit it, and then rise to about 130psig by 3400 or so rpm. With it wound up and letting off the throttle, one saw the case pressure jump on up to 130 ~ 140 before the engine unwound. These injectors clearly tax the thing.

- Baking off the static timing as I have, in an effort to dial in things including the spacer gizmo, has the heap smoke pretty heavy with leaning into the throttle with no to low boost.


I'm wondering if my cooling fan's thermostatic-clutch has gone bonkers and is now a little too tight, meaning it engages a little too early. With the static timing up toward that which the heap historically runs good at, the daggum fan is fully engaged with regular no load highway driving with outdoor air temps as low as 60ish *F. All the while the engine temperature gauge never budges from the typical half-way of the gauge.

[RCCUMMINS89]

So you are maintaining case pressure with the overflow clamped off?

Did I read that correct?

[BC847]

So you are maintaining case pressure with the overflow clamped off?

Did I read that correct?

In a no load / free-rev setting , . . . I saw a general increase in case pressure of around 5 psig @ 3400 rpm.

I've not tried it during a hard run. It was getting dark and I was chicken. I don't want to hurt the IP by overheating it. Frankly, I don't know if it would right away. I don't know how hot things would get nor how quick. Those who've made comments to the effect that clamping off that line made a big difference didn't include comments about the heat impact.

I'll try it soon though I have no means of noting any performance improvements other than the seat of my pants. I'm not gonna mess with the track till I get a light on it and dialed-in. I'm gonna try to do the timing light thing this weekend . .. again.

[93flatbed]

Many years ago there was a dude out of Canada with the screen name of Cummins king. He tried messing with stopping the flow of the return side of the pump by installing a 1/2 turn ball valve of some sort. The pump died in short order, possibly it was on its last leg but fuel cools the pump so.... I wouldn't be messing around with stopping flow on return myself. Only thing I can think of installing would be a gizzmo to stop return at full tilt boogie. You have a much more brilliant mind than I and your background in house HVAC probably would give you a great plan on how to do that. That is if there is any return at high demands of the pump.

Next thing I have tried to bring up on other sites is feeding very high pressure into the H&R once the case pressure drops bellow "x" amount. David you were in on that thread but it went a little sideways and some off the wall questions put the topic off kilter.

So I will pose the question on here since this is more of a "performance" oriented group of guys. Whatcha think of shoving high pressure into FSS once the case pressure drops out?

If this is too off topic feel free to kill my post.

[RCCUMMINS89]

Well.........essentially that's what KTA did.

It works..............but I'M looking into changing the curve as well.

I am alone on this, but it is EXTREMELY plain to me that our timing needs to run off both boost and rpms for the best driving characteristics.

For example............David needs a certain idle timing to clean up the smoke, which results in over advanced daily driving in the mid rpm range. Then it is perfect (possibly under?) timed at WOT.

So we need our case pressure to maintain closer to a constant under normal driving conditions. Then increase when we get on it.


When timing (pun intended) is right for me I'll have a case pressure gauge and persue the boost controlled stuff via controlling the ksb tube flow of fuel.

I'm HOPING to have it all done by August, so that I can hit the dyno in Sept.

[93flatbed]

Maybe think of this all wrong but, wouldn't using a boost/rpm referanced fuel inlet pressure gizzmo do that if you block off the passages going to the H&R? Then just have a belt pump keep the H&R feed all the time at? That would give you rpm referanced fuel to the H&R and how ever you decide to feed the inlet of the VE could be either boost or RPM or both so you could do Whatcha want for timing advance.

[RCCUMMINS89]

Your vane pump and regulator still would control case pressure as they would stock.

[BC847]

So I ended up going to the track tonight anyway.

I'm missing fuel I think. A lot of it. All the heap could muster got 8.7 in the 8th.

Phht! I'll mess with it this weekend.

[cubedeficient64]

In regards to boost reference do you think it should retard the timing with more boost like petrol engines or advance still?

[AHineman]

Advance.

[RCCUMMINS89]

Oddly enough.,................it makes sense that you would retard the timing............as more air requires less timing, as it would burn/ignite quicker.

However, it needs more timng..............because the more fuel one dumps in, the higher the boost. It is just a way to monitor it.


BC....................WTH? LOL. Wonder if your h/r isn't doing as well as the ol' one did

[oldestof11]

Timing should be related to fuel burn time over RPM.

Air is the limit for the amount of fuel.