How to Megasquirt your 3G Hemi

lxmodguy said
I don't spend a lot of time over here. I hand some time to read through this tonight. It is a very interesting build. Have you had it on the dyno yet? If so what did it make at the wheels? I have tuned several individual throttle body setups. They have all kinds of issues fueling and metering air evenly on a per cylinder basis. It can really give you fits trying to make it balance from side to side. I don't know that I agree with your fuel and horsepower assumptions. I will just leave it at that. I would love to see some dyno runs. I dig the MS3 setup.

Dyno runs were posted in another thread.

The math I posted for VE should've been close, but I don't think these 6.4 injectors flow what I assumed they did, skewing the numbers.

I have not had much issues with the ITB's. The linkage has adjusted itself more than once, and the airflow could use more balancing at idle, but it's plenty fine for everything I'm doing.

I have since killed this motor at the Texas mile. Ran it lean at 7200 rpm. Battery cable ground itself to chassis. 4 melted pistons. I put a bone stock 6.1 in for now, and will build a stroker to replace it.

Here's the dyno numbers from the 5.7. Peppy little motor. RIP

Uhcoog1 said
Finally dyno tuned my motor today. I'm very pleased. Picked the car up A LOT driving it home.

Quick breakdown:
1973 plymouth duster
forged 5.7, 11.6:1 compression, 03-08 GTP Extreme heads, Hilborn intake, custom shorty headers welded by me (around P/S box), 218/224 on 113.5+2 (xfi exhaust lobes- very mild)
TKO600 standard tranny, ford 9" floater rear, 3.60:1 gear with locker, heavy wheels all around.
Megasquirt 3x engine management tuned by me.
straight 30 weight conventional oil for all pulls.

We started the day in the 370's (rwhp) using a modified stock 5.7 timing curve. We kept adding timing until it dropped power, and backed it down 2* to the previous higher point. Ended up with more timing in the higher rpm range than most. I wanted more peak torque, but I am very pleased with where we ended up. ~300 rwtq from 3,000-7,000 will do just perfect for road racing.

All on 93 octane unleaded. No knock sensors. Craig at Bumbera's was listening, and I was doing the same through a microphone clipped to the knock sensor point on the block. Neither of us heard any knock the entire day, including when we tried 2* on top of our final curve just because (dropped power across the board, did not knock though).

Honestly, I did not expect the motor to pull this high with this little cam. I expected the hp peak to be below 6000 rpm, as that's where this cam peaked on 5.7's & 6.1's with a normal intake. Guess not with my build.

A couple back to back runs at the end:

And my timing curve. DON'T YOU DARE use this curve and expect it to work - way too much timing for most - you'll blow your motor ;)

Point worth noting: I marked TDC on my balancer and put my timing light on the motor to verify what the MS3x is commanding is what the motor is seeing. I found 1-2* of retard (light vs commanded) at 15-18*. That is within the range of measurement error, though it's very possible that the engine sees timing at 10% less than commanded. All I want you to take away from this curve is adding timing after peak torque was VERY beneficial for my motor. Further, this is the actual MBT for my motor on 93 octane, and MBT was reached before knock. Every motor is different so what worked on mine may not work on yours. Disclaimer: I'm not liable if you blow your motor trying to run 30*+.