Pressure / flow /RPM

Scratching my head here. New 990 pump, some run time but doesnt actually have a full pass on it.

Didn’t have any data on the first few attempts. Since I started measuring pressure, it won’t open the port check.

system pressure at 8k should now be 230 but can’t get there to find out.

goes 5400 in the brake. Making about 30 psi fuel pressure and 32 psi boost. So no port flow. Put a wideband on and it goes 5.7 on alky scale. Super lean.

anybody can convert expected flow and pressure at 8000 rpm vs 5400? I’ll scout my old textbooks tonight but hoping somebody has it handy. Worst case I’ll take the pump off and get it closed again but still ave the 15.8 flow tag and maybe an hour or two or run time since.

 

Signs of a bad pump- they fail at any time

 

Make sure you don't have something dumb like the cover was removed and not clocked properly during install. I've seen it...it will run but not very well.

 

make sure shut off valve is shutting off return, it will run with the return open just no pressure

 

Thanks for the feedback. I checked the shutoff with shop air. Air goes where it’s supposed to. The notch on the pump is on the right if the pump was vertical and you’re looking at it from the front. It’s belt driven but flipped around like a cam drive. I had it backwards when I first put it on and it did nothing.

I was going to put my old 990 on but I’m not sure I can clock it right (old style housing vs new billet rotateable one that’s on the car).

I might try to run the pump up to alky digger on Friday.

 

Mike, I set it up around 140 at first. Fought ignition issues. Got them fixed and put a pressure transducer in the port distro block. Knocked the blower off at 200’ and only ever read boost pressure in the port distro.
So I moved nozzles around to get a calculated 175, added a temporary mech gauge at the pump outlet and put a wideband on. 6.45 afr and still just boost in the port distro. Mech gauge showed about 40 or 50 on the pump outlet (really bouncy, almost like pump is cavitating).

Moved nozzles again to get calculated 215. Stall check, 5.7 afr and it cracked the port check right as I let off the throttle. Port pressure rose to 49 psi momentarily. Didn’t get a good reading off the mechanical gauge.

Was going to reduce nozzles again to get a calculated 235 max pressure but I’m leaning toward the pump is broke so will take it apart and inspect and then probably run to Nashville.

 

Mike, I’ve set up multiple systems. Never had a problem. This one threw me for a loop.

Afr was dead steady on the converter.

At this point I’m pretty sure it knocked the blower off because something happened to the pump. Just trying to make sure it’s not the tuneup but don’t see how it could be at this point.

It will make 37 psi of boost at 8000 and if I put 12 gpm through it would not only shut off, it would probably hydraulic and kick the rods. Careful with those rules of thumb.

 

Teeny tiny

 

12 GMP is safe at 32PSI , this is a number I have used from data also ....going down to 9.30 would be really on it. again , this is from my own experience but I do agree with Mike in getting the whole thing flowed first.

 

Doesn’t work that way. You don’t even know the motor size, you can’t possibly guess at gpms.

When somebody flows a complete system, how do they account for boost and its effect on total area. The main thing I’m interested in is what rpm do the ports start flowing and I don’t see how somebody can tell me that with certainty on a flow bench.

 

I don’t know if this thing is weird because it’s so small or what. I’d never paid much attention to port opening point before I realized that’s why I knocked the blower off. Pump pressure has to exceed boost + port check before ports will flow. I wouldn’t think it would be exact due to a slight area difference on opposite sides of the port check poppet, but it looks pretty close. Port check cracks at 15 psi when I test it and about 45 psi on the car with ~31 psi of boost.

Originally I had about 30 psi fuel pressure on the converter with 30 psi boost. So nowhere close to opening the port check at launch.

I put my old spare pump on last night and just did one quick throttle whack. Looked about the same on the mechanical gauge. The car shuts off the damn laptop when I wack the throttle and I didn’t hit the button to record onboard.

I’m going to reduce the port crack slightly (although I don’t have much room before they’re open at idle) and take just a little more blower nozzle away and then I think the ports will be solidly open on the converter.


I also though about raising the pump sizer check to about 50 psi but then the ports will be flowing on the 2 step so will probably have to add a converter helper. At least That’s easier to deal with than another boomer

 

FIE

326 Chevy

 

Interesting that you say that about the pump. What is the benefit of a smaller or slower pump vs using a pump sizer loop? Too much turbulence in the tank? I’ve had combos with as much as .250 in a pump sizer and never noticed any problem. This one currently has a .135 and that will get smaller. This is all just a shake down tuneup; boost will go up (and nozzles changed, port activation rechecked, etc) as soon as I can satisfy myself I’m not going to bang the blower again.