Miller MAF, Dyno Testing report


Two big take-aways…

  1. Rigorous testing is really hard.

  2. The MAF can make uncompetitive engines, competitive. Surprisingly.

We had problems testing. Mostly what we learned is that cars are not that healthy. A car that is really squared away has a newish (therefore pliable) hose to the idle air control valve (IACV) and the pipes going into the throttle body are epoxied in. But what we found is that most cars (4 of 5) had none of that. So every time we touched the intake tract, there was risk that we were either introducing or fixing a vac leak. Controlling for that variable is hard with intake tracts that are not in good shape.

Of those 5 cars, we got 3 on the dyno. These #'s are coming from recall. I’ll check the data tomorrow.
My car went from 154hp/149ftlbs to 160/155. But I’ve got some other issue going on that is making my dyno curves jagged. It’s impossible to accurately compare 2x jagged curves. The peak of the jagged was 154hp and 160hp but if one ignores the jags, it’s prob 2 less. I note that my 6hp is in line with what the Aussies told us to expect.

Fred Switzer’s car went from 145hp to 155hp. Then we took the MAF off to confirm his AFM #'s and instead of getting 145 again we got 135. We decided that messing with his intake had caused a vac leak.

Philip Springer’s car was being driven by Scott McKay. It got 150hp with the MAF. Scott said that the engine was “completely not competitive” w/o the MAF. We were just too damned busy to get Philip’s car on the dyno again with his AFM. Scott loved the MAF so much he was raving and gesticulating wildly.

So what does this mean? Well, other than my points above, I don’t know. But it’s pretty damned interesting that the MAF turned both Fred and Philip’s cars from “uncompetitive” to “competitive”. It’s easy to imagine the guy that perceives that his engine sucks so he’s contemplating dropping $6k or more on an engine rebuild and then all the sudden that MAF makes his engine competitive. That’s a dimension of this that had not been considered.

Scenario 1. The engines got went from uncompetitive to good hp because the AFM was the problem? That’s cool.

Scenario 2. The engines got good but it’s actually old and worn out. So if everyone had a MAF the engine would just be uncompetitive again? That’s not useful.

Charlie Diradour is taking the MAF to Mid Atl now.

The only way we’re going to get good #'s with this thing is for it to get some dyno time on some healthy engines with nice smooth dyno curves. In order to seriously consider whether the obvious disadvantage of “change” is far outweighed by the charms of no more AFM problems and chipping DMEs going away, we need dyno #'s in order to have an idea as to what this will do to the dyno rule. And SE did not supply that. Sorry.
Hopefully MidAtl can do better dyno testing than we did.

Thanks to Dave Walsh’s Group3 Dyno for all their work.


Trying to evaluate something on the dyno testing by testing a bunch of cars during an event doesn’t work well. The problem is that 1) you can’t really concentrate on it because everyone’s just too busy, and 2) in order to really understand how the dyno standard might need to be adjusted, one has to test cars that both have strong engines but also have engine management in good shape so you get nice smooth dyno curves. One can’t rigorously test cars that are so vulnerable to vac leaks that every time you R/R the rubber intake elbow, you can see hoses that might not be sealing well.

So the way to do this right, as opposed to how I tried to do it, is to first spend some time finding the strong cars with smooth dyno curves, Then find a way to dyno a bunch of them…awful hard to do during a race weekend.

The “MAF fixed weak engines” was a surprise. It’s good news, I suppose, but I’m not sure how it helps us. There was never discussion of a scenario where the MAF became acceptable, but our 160.9 dyno standard remained. That idea would redefine the MAF from “Make AFMs and chipping go away” to “Help the people with serious engine/engine management problems”. It would also put heavy reliance on having a dyno available at the track, which would be a problem.

I’m kinda leery of the “MAF is ok but keep the same dyno standard” idea. Sounds difficult to enforce. Folks with healthy engines/engine management would just say “fix your shit”. Folks with sick engines would say “Give me a break. Fixing my shit could mean a $6k engine rebuild or $1000 of AFMs and dyno time.” Personally, with reasonable arguments on both sides, as a tie-breaker I would fall back to the idea that “change is bad”, but what does the community think?


So the way to do this right, as opposed to how I tried to do it, is to first spend some time finding the strong cars with smooth dyno curves, Then find a way to dyno a bunch of them…awful hard to do during a race weekend

Scott, it sounds like you’re on the right track now. And since I’m still early into a three car build for my wife and kids, I’ll tell you what I’ll do to help the cause. I’d be willing to provide/loan you three cars to test that aren’t on a tight time schedule, you can rebuild all three engines so that they’ll have like machine work and componentry, do all of the JB Weld upgrades and replace all of the hoses to eliminate vac leaks, match good electronics, dyno them to insure strong smooth dyno curves and then you can test them with AFMs and MAF.
For your trouble I’ll even kick in a case or two of your favorite beverage and may even kick in some bucks for dyno time.
Since I’m still an outsider I just figured I’d try to help any way possible :wink: . Look forward to seeing you guys in Savannah after the summer break.