When I decided to go with duals I talked to James and ask if I needed to drop back to dual 1000 and he said no it will only pull what air it needs. I’m far from an expert on injection but trying to learn. I do agree the motor needs the 0 1/2 pump now. The pump has a 36 tooth pulley and I have a 28 so I can speed it up some. I’ve got an idea of what it needs fuel wise with the 0 pump as is even if it’s small bypass pills. I’ll change pumps after I figure out why it won’t burn the fuel

What cylinder head is on this 421 ?

Pro topline 23 degree 242 with some port work

Them should be enough to do the job !

What the ignition timing set at?

his timing is set at 36. I don't know if he tried pulling timing out.

about air flow, i run a bird catcher on a 512, it flows 4500 CFM, runs fine.


Joe

36, 40, 32 and back to 36 on the timing. Made the most power at 36

Didn’t try less?

We didn’t see any need when it fell off at 32. When we get it to burn the fuel it may want less timing

Got the engine back on the Dyno yesterday and the camber worked did fix the miss. Still not where it should be rpm wise as it’s peaking at 6500. Last time on the dyno it peaked at 670@6700. I was looking for that to move up with the tunnel ram but didn’t. We’ll see how it does if we get to race this year

I've spent my time on the dyno with MFI big block chevy's in the 850 HP to 1100 HP range. If you are moving fuel around and it's not impacting the torque and hp numbers, you may need a larger pump. My systems are enderle, but in general all the systems operate on the same premise.

My take here:
Having too much Air flow capacity in the "air valve" doesn't matter at all. Similar to one of the others commenting here and James M's comments, the motor only takes what it needs. Air valve sizing only becomes a problem when you don't have enough air flow capacity and start to limit the amount of air the motor can pull through the air valve. Your twin terminators are fine.
The tunnel ram vs. standard intake conversation is an interesting one. I'm currently working on putting a single 5" enderle system together on top of an Edelbrock SV632 and intend to conduct some testing to compare the two on a 598, Dart Pro2 cnc headed motor. The motor currently runs on a 20+ year old Edelbrock victor 2R tunnel ram and Enderle Bird Catcher. I'll share results hopefully in the next few weeks.
Lacking data on the dyno isn't the biggest issue. Tune the motor to make power, the data you get is just a benefit. Read plugs, tune to make max torque first, then add in a high speed lean out if the motor will take it. If it has O2's look at those too, but tune to make max power and torque. Fuel pressure at the distribution block is great to have just so you can reference later on and helps to verify everything is still functioning as designed.
I would have guessed the recommended fuel flow on a pump for 700 hp would be somewhere around 6-7 gpm and just return whatever the motor doesn't need. I guess if you get one that flows too much you'd end up needing to have a bypass loop on it. In your case i think you need more fuel pump, but James would be my go to person if i were you.
Not all motors seem to like a high speed lean out. My previous 565 loved it, saw that motor pick up roughly 40 hp on the high speed, the 598, 615, and a friends 522 seems to just not like the high speed at all. No difference and or lost power. I'm guessing this is all a function of air flow, efficiency, and camshaft selection. There are tons of other things that play here but i'm thinking those are most impactful.
My 565 with 15:1, dart 355's, seemed to like lower timing (best was 32) and the high speed was the key to really optimizing the motor on the dyno. This was also a crisp day where the corrected numbers were actually very close to the actual data. I have not had a similar experience on the dyno with any other combination i've been there with since. The 565 worked like a champ and responded to every change i made very predictably and worked flawlessly. The other motors i mention were different stories, none seemed to respond well to the high speed lean out. One interesting note, all of the other dyno days have been in either Hot Sweaty Clear days, or overcast nasty humid days. I intend to look for good weather window for my next outing and test session.
I think the RPM where it runs out of steam is a function of the camshaft and timing. I saw higher peak numbers with lower timing on my 565. MY 598 and 615 are just pigs on the dyno up high so i'm working on cam swaps for both of these motors right now. Your situation is similar to mine, testing with a standard intake will prove one way or another i hope.

My theory is the tunnel ram vs. standard intake will result in little to no difference. I'm sure kinsler would have a different opinion as they are champions of the stack injectors and only real difference there is the intake configuration. There's something there i hope to find more info out in my next trip to the dyno.

There's another gentleman here who's got a dyno over in Texas (austin area i think) and he does a SIGNIFICANT amount of work with MFI engines. He's got some really good info and trick fuel measurement systems on his dyno that could help you. If you interested PM me and i'll put you in touch.

I hope you get it figured out. Please post what you find.

Kris

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