if you change the pulleys, it will make the pump "act" like a 4.69 GPM pump. I would use my 1st numbers as a guide.


Joe

I’ll try those before the pump then.

If the 36/54 doesn’t work then I’ll 1 to 1 the pump and if that fixes it I’ll order a new pump. I wanted to flow the system to avoid all this and told him if I needed a pump then needed to add a high speed for a bigger pump it wasnt a problem. Instead I spent the money to flow it and ended up just as much in the dark as I’d been if I didn’t flow it

I have not Flowed any of my stuff and doubt I ever will. In my opinion it is really a waste of time and money as your motor, cam, heads, RPM etc will determine how much fuel each cylinder needs.

I am a firm believer in good data. I now run 8- O2 sensors and am able to get each cylinder operating right. Flowing one would never do that.

Also a good dyno operator will know exactly what the motor needs. For a carbed application it is not as important but for MFI dyno time is a huge benefit.

I’ve added 4 racepak 02s and plan on adding the other 4 later.

joe shouldnt rhe gpm need to be closer to 6

I think the whole problem is the old dyno not having the proper data logging capabilities, if it did you wouldn’t be guessing what the motor needs. Can’t you pull your logger from car and use it in the dyno room, might save you headache and possibly a motor.

Yes I could pull the logger from the car but we’ve never had issues like this on the dyno. They don’t do many injection motors but I’ve been there the last few fridays and he’s pulled 2 MFI motors that were easy to tune and now mine. Usually they can get close with the 8 egts but they have only moved 1050 to 1075 and the changes we’ve made should have been an easy 150 temp swing. I think the pump ias to small running the 2 1475 Terminator’s and it Just can’t keep up with all the air. I was having a conversation with the guy that flowed the injection while he still had it and he told me with MFI you could be so lean the motor wouldn’t make any power, wouldn’t melt anything or build heat and the plugs would look fine. I think that’s were we are with it and if fuel PSI had been hooked up we’d know if the pump is it. He’d said if needed I could run the pump 1 to 1 and be fine but I also have an APD pump that is bigger so if the things joe has said doesn’t work I’ll put it on and try it to see if it responds.

egt's are a lousy way to tune a engine, great for checking fuel distribution. I got on my soap box a while ago.
https://drr.infopop.cc/eve/foru...187002186#1187002186

One more thing, if you are running NGK plugs, put another set in, they don't seem to like being run lean.


Joe

I think you need a bigger pump. If you look at James Monroe's web site 0 gear pump is only rated to 650hp.
Is it a gear pump or gold vane pump?

Started out with 0 1/2 pump when I bout the system last year and could not get a tuneup to run consistent. Went to the 0 and the car was much better. Not saying it doesn’t need it now but we have made some headway today on the dyno

^^^^^ Do you think a single 1475 terminator could possibly be a better choice instead of the dual terminators??

quote:

Originally posted by C Hodge:
I’ve added 4 racepak 02s and plan on adding the other 4 later.

That will work just fine. Put bungs in all 8 header tubes and you can change them out occasionally to check each cylinder. One weekend check even cylinders next weekend check the odd cylinders.

I completely agree with Joe on the EGT's from my experience they are totally useless and tend to send you on wild goose chase trying to get that magic number. Only magic number I care about is ET slip and I use my O2's to once I get best ET to keep it there. EGT's= useless in my opinion.

O2's mine works best at 12.9 to 13.1 on the gas scale I run alcohol but prefer to use the gas scale for recording. That is where my motor ran best at the track and on the dyno. Your "Magic Number" may be quite different.

Several people have said your pump may be too small and that may be true. You may be able to speed it up some to pick up GPM but if it is too small best thing it to get proper sized pump.
On my junk I have a way too big pump and send a lot back to tank. I am able to control my fuel where ever I want but it does take several bypasses. Which complicates it and is things to fail.

A pump that flows 3.55gpm is no doubt borderline small for a 421 capable of 700+. That said though it is the main reason why it would want a 50 something pill. Bigger nozzle jets may help some as you will be able to get the flow into the engine easier. Even with it being borderline you should be able to get there.

BUT, you are down power after the engine changes. To me it appears something went wrong with the changes or re-assembly of the engine. Or maybe you got bad plugs or wires etc.

Scott

We pulled it off the dyno and started pulling it apart today. The only internal part changed other than the normal freashen was pistons. Lean it out and it’s smooth and crisp put hits a wall at 6200. The piston dome takes up 3/4 of the spark plug hole looking in with a light and doesn’t have a notch for the plug. As we add fuel it starts missing and we think it is puddling fuel around the plug and not burning like it should. Cutting a notch in the piston and doing a little chamber work so hoping that will fix the issue and it will take the fuel. Plugs show lean with last years tune of 32/84 but it won’t burn it if we add fuel.

A sheet metal manifold doesn't guarnetee better power over a good single plane either. The sheet metal must be built to match the engine. If build for a different cubic inch engine with a vastly different rpm band it could actually make less power.

Scott

It’s built for this engine so should make more power but may not. I think if we can get it to burn the fuel it will make power.

what rpm does peak torque occur at?



Joe

That I’m not sure of. When it wouldn’t make any power we’d go to talking about what to do next and I never looked at what the torque was.

I am no expert or even have any experience with injection but dual 1475 terminators sounds a bit much for a 421 ci motor if you ask me. That’s more cfm than I have on my 548.