v8440

Hi all,

Some of you have been bearing with me through all my questions about which fuel injectors to buy, and how to adjust the governer lever in the pump. I mistakenly thought our local chassis dyno had a room too short to test my truck in. We were thinking that the front of the truck would hit the back wall of the dyno cell before the rear wheels were on the rollers. This was not the case, so I dynoed it today. Here's what we got:

Max hp-325
Max tq-572

According to what I've read, these figures are low for the modifications my truck has. There's one thing I have a question about that may have something to do with this. Yesterday afternoon, I went and checked the position of the governor lever. Following the instructions on pier's website, I removed the afc housing, and turned the key on to actuate the shutoff solenoid. I moved the throttle linkage manually while watching the lever. At no point did it come within 1/4" of the fuel plate, which is a tst #8 pushed all the way forward. The problem wasn't the height the lever was set for, but rather that it was not coming FORWARD enough to contact the plate. I was under the impression that the governor lever adjustment set how high the lever started its travel in, not how far forward it was. I eyeballed it and saw that it was sitting right about level with the "tip" of the fuel plate, just not far enough forward to touch it. Satisfied that the height was correct, I put everything back together. Today's dyno results make me think that perhaps I have a problem that needs to be fixed, and the fact that the lever did not even come close to touching the plate kinda jumps out at me. Any thoughts?

JD730

I'm far from an expert on a chassis dyno, but what kind was it? Dynojet, mustang, etc...

I dynoed on a Mustang dyno and I had on the dyno sheet 252 hp and 733 tq at 1750rpm. That was with my 93.

I unfortunatly don't know much about p-pumps yet, so I can't comment on that.

v8440

It was a dynojet.

TRCM

I think this is correct.....or at least the way I understand it from some testing I did with shop air.

The lever shouldn't hit the fuel plate until boost is above 6 psi. The boost acts on the diaphragm in the afc housing to literally push/move the whole governor arm assembly forward in the housing, bringing it in contact with the fuel plate. it also moves the star wheel 'plate' out of the way, which is what controls fuel below 6 psi boost.

v8440

Ok, that makes it seem like maybe my pump is set up correctly. How about this-I have a boost elbow that I think the previous owner got from tst with the #8 plate. This elbow has two hose barbs, an allen screw, and a small hole to atmosphere. I thought that I understood the way it worked. I backed out the allen screw a few turns, and observed maximum boost increasing. BUT, today on the dyno, I tried screwing the allen screw in, and power/torque jumped noticeably. I ended up screwing it all the way in, and this produced max power and torque. The funny thing was, it also produced the LEAST smoke. I thought that loosening the allen screw bled some of the boost signal off to atmosphere, thus causing the wastegate to remain open until a higher boost level was reached. This seemed to agree with what I saw when loosening the screw a couple of days ago. So, why would the hp and torque go way UP when TIGHTENING the screw?

A possible clue: The elbow is in the line between the afc housing and the wastegate. Perhaps by locating it there, it's also bleeding off boost signal to the afc housing, which in turn might be limiting fueling? Should I try locating the elbow elsewhere?

I just went outside and looked at the truck. The boost reference is taken from a SMALL plastic line that's hooked to the intake manifold. The other end of that line goes to the afc housing. From another port on the afc housing is a bigger line that goes to the wastegate. It is this line that has the elbow. Perhaps I ought to give the afc housing it's own boost supply, and use another port in the manifold for the wastegate/boost elbow line so that air can be bled from the wastegate line without affecting the boost that the afc sees?

govspringbounce

Screwing it in blocks the boost signal & keeps the wastegate closed. You'll see max boost & power @ that setting. You can adjust the screw so as to keep the boost # within the best zone for your turbo. i.e. too much boost is only generating hot air, lowers hp/torque.

The reason you're seeing less smoke & more power is because you've got more boost/air, which is burning all that fuel better.

v8440

I misunderstood the operation of the elbow at first. I thought the allen screw was bleeding some boost out of the little hole in the side of the elbow, and curbing the signal to the wastegate that way.

Lil Dog

The hole does bleed to atmosphere.. It just bleeds the line down between the pinch or the allen screw and the wastegate actuator. The more you pinch down the screw, the less air is available to fill the wastegate actuator to overcome the "leak" of the hole in the elbow. You are controling the flow of air to the wastegate line over the leak to atmosphere.

The AFC only controls the governor arm assembly when put all back together. Without the AFC in place and the engine not running, the lever can't over travel its set position for idle. If you wanted the lever to contact the plate, you would need the pump to be turning to let the governor travel up to the plate. There is a "droop" spring setting in the pump that will only allow the lever to travel a certain distance past the governed speed. Shut down the lever can't travel far enough to contact the plate at full foward, it wants to spring back.