Can one EFI box make "more power" than another, all else being equal??

[dieselgeek]

I participated in an interesting "shootout" that a popular race engine builder put together this past weekend.

I always believed that if the tune was correct, that any EFI system would make the same power as any other - all else being equal.

I was wrong!!

This shop builds NHRA superstock engines and they were looking to partner up with a vendor to supply both their systems, and a calibration engineer (fancy word for "tuner") to provide their customers tuning support. Since I had tuned aa few different EFI systems (FAST XFI, Motec M800) for three of their existing customers, I got invited to bring a box of my own choice and see how it compared to the other guys. I've been working on a "plug & play" system based on Megasquirt-3x - same configuration as our Engine Masters Challenge engine - that is designed for the exact same engine used in the shootout. So I brought the MS3x PNP for new Hemi engines and set her up.

I was surprised at the results.

After 22 pulls and about 3 hours of tuning, throwing every single trick I know at this engine - the MS3 bested the other two finalists by 7hp. I arrived at the exact same ignition timing advance and AFRs as the other two tuners (who were there on Tuesday and Thursday - Friday was mine), but the MS3x made more across the board despite showing the same timing and AFRs.

How?

I'm 99% sure this is the result of more accurate ignition event placement at high RPMs. In reality, I can't take credit being a better tuner than the other guys, because we all arrived at the same results. I have to give credit to the Megasquirt designers and coders for simply having a better system (for this particular engine). The MS3X was very consistent and repeatable - always making 7 more hp than the other guys.

This is the first EFI shootout of this kind that I ever attended, now it makes me want to do more. I wonder if we could talk Chad and Brian into sponsoring an EFI shootout with more vendors?

-Scott

[TheSilverBuick]

[dieselgeek]

And, I didn't really mean for this to be a "Megasquirt Trumps All" message. Truth is, who knows if the same results would happen on an LS engine or a Ford modmotor? There is different software for each of these ignition systems.

Honestly, when I found myself 14hp down and no more fuel to take out, I thought we were beaten. It turned out that this particular engine *seriously* wanted proper injection event phasing. Usually, this only helps the lower RPM range and torque (nobody cared about that on this engine), but it actually gained a lot on the top end too. I have ZERO explanation for this as the injector was running at 75% duty cycle, way more than the intake valve is open (about 25% open duty on the intake valve). I cannot explain this at all, it baffled me but I am glad I tried it.

So in the end it took careful individual cylinder tuning (thank you Engine Masters Challenge for giving me practice at this!), careful phasing of the injection event versus intake valve events, timing that was adjusted in one-tenth-of-a-degree increments, to get every last HP out of this engine. Yes, I was actually making 1/10 timing adjustments to get my final number. That's pretty crazy.

I sent a nice email to the Megasquirt coders, Ken Culver and James Murray, thanking them for their efforts and I reported the results. Those guys kick ass.

-Scott

[dieselgeek]

and apologies to Schtauffer as I invited him out to watch, not realizing that this was going to be such a serious event. Tensions were kinda high but hopefully he enjoyed it. He got to see us crest the 2nd place system and put a few extra HP up for good measure. Gene, normally EFI tuning is NOT this tense or crazy. Usually it's a lot more fun. Hopefully we didn't scare you away!

-Scott

[Schtauffer]

What pressure?

Seriously, I didn't really grasp what was happening until one of the much needed smoke breaks- the other guys kind of filled me in a little. For some reason I thought you were tuning a Bonneville motor. I can be a little slow on the uptake.

Once I realized what was happening, it was all the more awesome to watch the tiny little changes and the hp improvements they made.

[CDMBill]

Scott, first of all congratulations! Second, I think you answered your own question regarding the why of it. The ability to repeatably manage fuel and spark at the individual cylinder level across the dyno pull RPM range allowed you to level out those fascinating and sometimes scary variations in net effective AFR's by cylinder we've seen previously. The dynamic nature of each cylinder in a common plenum engine will demand the variations you gave it at a micro level. The native VE of the engine at each hole is similar but not identical and of course changes as the engine gains RPM.

The interesting question is what will happen at the track when the engine see several distinct acceleration rates. I would bet that a truly optimized tune would change gear by gear and realistically within the rpm range of each gear. I suspect the F1 guys have done this for some time and the quality of the MS3X box and software gives us glimpse of that.

Must be fun to be on frontiers of this stuff. You know what they say about pioneers.

[FoundSoul]

+1

[FoundSoul]

Excellent work Scott!

So in the end do you still think it due to the accuracy in the ignition timing? Or the ability to properly trim each cylinder out? Or the injector phasing, which maybe the other calibrators didn't fine tune?

22pulls, not bad at all. Alot of people might not realize that that's a pretty good accomplishment in that number of pulls-- 8 cylinders, trimming fuel and spark individually on each, can be a time consuming process....

[BKBridges]

Scott,
7hp? Very cool. I got a chance to play with injector phasing at the Good Guys show. I was trying to get the idle smoothed out on a FAST FXI/Hilborn stack EFI system and found that the injector phasing was key. Im hoping it didnt have any effects at the top end that were not good, as I did the cardinal sin of tuning and then running away...Cant imagine a real "problem" at 120 deg off "nominal". Gotta try the MS3 out soon...Definitely time for an EFI shootout!
BKB

[dieselgeek]

Scott,
7hp? Very cool. I got a chance to play with injector phasing at the Good Guys show. I was trying to get the idle smoothed out on a FAST FXI/Hilborn stack EFI system and found that the injector phasing was key. Im hoping it didnt have any effects at the top end that were not good, as I did the cardinal sin of tuning and then running away...Cant imagine a real "problem" at 120 deg off "nominal". Gotta try the MS3 out soon...Definitely time for an EFI shootout!
BKB

One thing I've learned this year - the engine never wants "what you'd expect" for injector phasing. A bone stock 6.1 Hemi wanted a pull to start with 270* BTDC injection event end, passing through 180* TDC finally ending up at 90* BTDC at the end of the pull 6200rpm. This makes no sense on paper whatsoever, but with that mapping the engine picked up power from bottom to top. That was mapping a stocker straight out of the junkyard, for a crate engine company we're working with.

Meanwhile, on this past weekend's test, one of the things that really hurt "the other guys" was an inability to map the phasing through the RPM band, and an inability to map Cylinder Trims through the RPM band. That system only allowed a fixed "trim per cylinder" (example: cylinder #7 always 5% leaner than the rest) and that's just not what an engine wants. The AFR changes per cylinder are dynamic through the pull at WOT - and get even more dynamic with varying loads. You need a VE table per cylinder to make it work properly.

[Barry Donovan]

that is awesome stuff.
a real use to be in pulse width.

the very thing you are doing dynamically has been on a shelf in my own thoughts..

I even gave up an injection setup and reeled in a 34 yr old carb..just for an idle screw and jets.

Still can't do anything about one bank or the other.
glad to see that it can be done.

[dieselgeek]

Excellent work Scott!

So in the end do you still think it due to the accuracy in the ignition timing? Or the ability to properly trim each cylinder out? Or the injector phasing, which maybe the other calibrators didn't fine tune?

Jerry, I was told the 2nd place guys "probably" tuned the phasing, but it's possible they did not. It's either that or the ignition event accuracy, or a combination of both.

The action starts soon, they're talking about a May 4th test session at Maple Grove. I've never been there, so I am stoked to go. Plus, I get to do waaay too little track tuning - I enjoy doing it - so I am looking forward to this.

[Deaf Bob]

Great scott!

Wonderful!
Trying to educate myself....
I admit at times I feel overwhelmed...
For the motor involved, 7 hp is alot! ... That much I know
While on a street motor, it really isn't that much...

When time comes, I know who to bore stiff with questions...
I know the other thread will be followed by me for sure.. (one that asks what is involved)

[CDMBill]

Jerry, I was told the 2nd place guys "probably" tuned the phasing, but it's possible they did not. It's either that or the ignition event accuracy, or a combination of both.

The action starts soon, they're talking about a May 4th test session at Maple Grove. I've never been there, so I am stoked to go. Plus, I get to do waaay too little track tuning - I enjoy doing it - so I am looking forward to this.

I'm hopeful, that you get a decent number of runs.

[JeffMcKC]

Let me know if you need some one to come hold your Shade umbrella Scott ,,,,, LOL