MFI Pump Dyno build- My newest project

[Gary De]

Fantastic job. I may show up at your front door with a couple of pumps and a cold twelve pack. I wonder how the airlines feel about pumps as a carry on item. Have friend that tried a Muncie 4 speed with his luggage. They were not happy about the leaking gear lube. Know one seems to have a sense of humor these days. Keep the pictures coming.

[rswannabe]

Originally Posted by 911st

It would be interesting to develop some type of model or program so custom space cams could be CNC'd to fit a given builder's needs. Would not be complicated for the right person. Basically just a physical map of throttle position by rpm.

Fantastic information here and I love where this is going. Custom Space cams for engine configurations not contemplated by the factory would be too cool!

[356RS]

Finished up the graduated cylinder stand today. Funnels fit great.



Injector mounting plate and graduated cylinders look OK.

[911st]

First, wonderful work.

Originally Posted by rswannabe

Fantastic information here and I love where this is going. Custom Space cams for engine configurations not contemplated by the factory would be too cool!

It should not be that hard for someone that has the skills.

The space cam is just a simle three dimensional map carved out of metal that a stylist rides on to determine fuel quantities.

Along one dimension is throttle angle or load.

Along the other axis is RPM.

A stylist rests on the physical map and the lower it rides, the more fuel delivered per cycle.

The lowest point is likely at WOT and TQ peak.

Then this map is wrapped around a barrel that a stylist ride on. The deeper the indent the more the fuel. The map rotates under the stylist with throttle angle and is pulled from one end of the barrel to the other with changes in rpm by the centrifugal force of the rotating weights.

Measure fuel delivery at various heights of the stylist and you have the fuel delivery part.

Take a TQ curve from a similar cammed motor and your have your delivery curve.

We just need a program where we can enter enter the equivalent of duty cycle numbers into a the cells on a spread sheet and so the program can translate that into what a mill needs to carve it and we are set.

Would be cool.

[356RS]

911st, Thats a great idea, especially because of the cost of a NLA space cam today. $750 for a new RS space cam. fits in the palm of your hand. I have no idea what the tooling would cost to get something like this going. I have a NOS RS space cam that I could let someone MAP out. Great ideas.

[911st]

Copying a cam should be a bit easier.

The kind of person that can make this happen should also be able to set up a tool to scan in the different space cams profiles.

The RS cam I bought about 10 years ago cost me just over $400 through EBS I believe.

I hope one of our more technically gifted will step up so we can see how easy this all could to do.

Instead of burning EFI chips, we would be carving space cams.

[kenikh]

Originally Posted by 911st

Copying a cam should be a bit easier.

The kind of person that can make this happen should also be able to set up a tool to scan in the different space cams profiles.

The RS cam I bought about 10 years ago cost me just over $400 through EBS I believe.

I hope one of our more technically gifted will step up so we can see how easy this all could to do.

Instead of burning EFI chips, we would be carving space cams.

Aerospace machine shops with CNC grinding equipment could do it pretty easily, as long as you can provide them a program. They may even have a scanner that can capture it. Call around - I'd bet there are a few in Seattle since Boeing is here.

[Gary De]

Mark, I have access to Pro E software to create a solid model of the space cam and a CMM to get some measurement to clone some RS space cams. Not sure about the material or surface hardness but you should be able to hard turn without finish grinding.

[356RS]

Gary, I don't know much about the hardness data, but I can tell you the material is HARD.

[911st]

I remember them being hard but I had not problem taking a Dremel grinder to it or using a normal flat file on it. Was only on the 2.4, never did an earlier one.

[YTNUKLR]

I could model it, as well (Pro E or SolidWorks). I have already done so with a 69E cam for the '69-71 pumps. The 2.4/2.7 pumps are a bit different from the '69-71 (roller stylus and the space cam is taller-same dia.); I will do a 72E space cam (which I have ) when I have some spare time (never). Then we could compare the differences of the 2.4E to the 2.7RS and figure out the appropriate amount of grinding to convert an 015 (2.4T) cam to RS or other similar hot rod spec.

I also have a real 2.8RSR Space cam and the lightweight set of flyweights and RSR springs that accompany it I have thought about this project before; very interesting..let me know if you ever want to talk further about it Mark. I also have the fuel distribution graph and soon should have dyno sheets for a ~RSR spec. 2.8 engine I am building.

Also I know a guy that has a scanner (as opposed to modeling it). I don't have much experience in that area yet.

[356RS]

Gary; 911st; and Scott. All great ideas. I know nothing about the Cad or Software end of this. What I really need to know next is the step by step procedure for getting a pump ready before it goes on the test dyno. Then the adjustments and readings needed to do the job right. To be honest with you, I got the test stand ready, but really have no idea how to test it correctly. Just for fun today I put on a 72 T pump and run a series of tests at different throttle angles and RPM's. As per the factory spec sheet the pump was + - 2ml on all tests. Pictures below of the test tube stand.

[911st]

I am extremely impressed!

Are you saying you are getting the same fuel delivery as different rpm's? If so you rack may be stuck.

What is your goal for doing this. Is it to calibrate a pump back to stock settings?

[356RS]

No, I'm getting pretty close to the factory specs. at each of the set throttle & RPM settings. There's about 18+ different throttle & RPM setting for the complete test. I'm at home now and do not have the specs I wrote down during the tests. All I can say is it's very easy to read the ml's after each test, and then I can lift off the test tube panel and dump all the Stoddard Solvent back into the drain and then run another test. The space cam ideas from everybody are exciting and I can't wait to get into that. I'm packing up tonight and going to catch a plane to LA for this weekend's Porsche festivities.
PS: 911st My goal is to be able to test and recalibrate customers MFI pumps. Also be able to modify the pump for larger engines and, or, replace there stock 72-73 T space cam with an RS space cam.

[YTNUKLR]

You need a few things:

These are the inputs to the pump. Know these inputs and what type of pump space cam you have, and you can determine its output.

1) Altitude calibration. The gold-plated barometer canister can on the top of the pump controls the little barometer adjustment rod inside the pump. The range of motion is not much; you could also substitute a bolt and then have an external barometer (like how they do it for the weather) to dial the pump in for that barometric pressure.

2) The warm-up thermostat (stack of disks) that is on the front of the pump. Sometimes, this thermostat is removed.

3) Throttle Position Protractor. There is a protractor that goes on the throttle rotation lever and controls the degree of rotation of the space cam inside the pump. The lever has a range of motion {0°<θ<90°}. Similarly the space cam as you've seen does not revolve, it simply rotates within a range of 0-90°.

4) RPM. Self-explanatory.

Once you know these things, you are totally in business. This is an awesome project, Mark.

[kenikh]

Now to set up a digital flow meter, so everyting can be graphed!

[356RS]

Scott, thank you very much. I'll be getting back to you in a PM today.
Kenikh, I have already looked into this idea. I found some very low flow, and high pressure digital flow meters, but out of my budget right now.

[jcge]

You need a few transfer functions to achieve this...Ultimately you need to get to Throttle butterfly (or slide) position vs RPM vs cc fuel per stroke

so the base transfer functions could be.....

1 Throttle butterfly (or slide) position vs Pump lever angle (Correlation)
2 Pump lever angle vs Space cam rotation
3 RPM vs Space cam displacement (fore/aft)
4 Space cam "lift" vs Rack displacement (Translation mm vs mm)
5 Rack displacement vs Delivery volume (speed & viscosity effects)

and for compensation

6 Temperature vs Thermostat displacement (linear 18.25mm+0.091mm*T°C)
7 Thermostat displacement vs Rack movement
8 Barometric pressure vs Baro cell displacement (linear 0.58mm/100mmHg)
9 Baro cell displacement vs Rack movement

I wouldn't assume they are necessarily linear, or independent....

[356RS]

John,
Your so right. The space cam has many important map area's that have to be contoured into the design for each type of engine. Not easy for the custom ones, but maybe a little easier for stock reproduction ones.
Right now I'm working on the tools to get the pump dialed and set to factory spec before the flow tests begin.

[kenikh]

I think the bottom line is that the stock ones give enough flexibility that any configuration can be supported if you can create the factory spec ones. Evidenced by Jeff Higgins being able to (just barely) get a stock 2.4T pump to work flawlessly with a "hotter than S" 3 liter, If you can get T, E, S and RSR space cams, you should be able to cover any config at any displacement.