Smogrunner

iTrader: (5)

(AEM and Xede vendors/tuners are invited to share their technical expertise in this thread. But keep on topic. Compare THESE TWO CARS.)

I've been hearing for years that the AEM will immediately make more power than the stock ECU/stock ECU with Piggyback. Usually the argument goes something like this: "Dude, just getting rid of the stock MAF and going with speed density will make you 30hp."

Next, a huge group of people have simply the notion that "If you get a turbo upgrade, you really need to go with a stand-alone," ie AEM.

So, I decided to do a little experiment. Keep my Xede/with Xflash and go whole-hog-wild on an engine/turbo build up and see where the limits are. If I get to the promised land with the Xede, I'll keep it. If I can't, I'll get rid of it.

When I saw that awesome thread about the 2.0 vs 2.3 with identical mods I took a close look at the 2.3 with 35R and AEM. From the description of the mods, it seemed almost identical to my car (except engine management). I'm posting up the two graphs below for comparison purposes. https://www.evolutionm.net/forums/sh...d.php?t=171831

My car was at just a tad over 27psi, maybe 27.3 max. The other car was at 28psi. Given variances in gauges and where the gauge measures pressure, I'd call the boost "comparable" between cars. Both cars used high octane fuel: 93 + methonal vs c16.

Finally, I hope everyone at least recognizes that both systems offer advantages over each other. The logging capabilities of the AEM are fantastic. However, with the AEM one has to tune for things like cold start, an issue the Xede powered car avoids entirely.

I recognize that the example used below is leaving a BUNCH of hp/tq on the table on both setups. Both cars can easily boost another 5 to 7 psi which could yield very different results between the two.

Let's really analyze here please.

Xede powered car:


AEM powered car:

VTECH8TR

iTrader: (70)

Smog,

Good post, but keep in mind that the AEM problems you listed are non existent at the present time. The cold start issues started to come out when the AEM was new and everyone was getting one. The cold start issue i can fix myself in 10 mins. Most of these tuners that tune your AEM don't spend the ample time to tune the car right as they are on a schedule to get you on and on to the next guy. If you have a tuner that will take his time and tune your car correctly, thecar will drive like stock. Buschur has said this many times on here. Also comparing pump gas + methanol to C16 is not a fair comparison.

In the end the AEM has alot to offer, you have to be able to learn it and use its capabilities to your advantage. Most people that complain about the AEM are the types that want to go with an AEM but want it put in and don't want to touch it. The only downfall i see with my AEM is the initial crank start time. It usually takes 2-3 cranks for my car to start.


Awesome power for your car BTW .

x838nwy

I don't really know what you want, but if you compare the Xede against the red AEM plot, the AEM is making quite a bit more power, up to about the 5k rpm point, around +30hp at 4.5k rpm.

The rest of the plots I'd say are pretty much the same. So if you keep both cars at around 5-7.5k then they should be roughly on par with each other.

Now, this might be down to cams cos I think the AEM plot came from a car running 272's. I don't think these are specifically know for their low end but it might have something to do with it.

From just these plots there seems to be very little between them (assuming it's the cams making the difference) in my opinion. Looks like the piggybacs aren't all that bad afterall...

Smogrunner

iTrader: (5)

Thanks for the input, but at 27 to 28 psi, I don't think the different types of fuel are making a big difference. Also, I have seen 93 + Meth make race-fuel-only type power repeatedly. Also, I completely agree with you about top-expert AEM tuners getting AEM cars to run like stock. Unfortunately, drivability issues run rampant despite this with AEM cars.

Also my car made this power on slightly less boost than the comparison car and in near 100 degree temps:

Juiced

it seems that with a little more tunning the AEM would be able to mimic the smoothness od the XEDE system.

In my opinion the best thing about the AEM is the Speed Density tunning. I like not having to deal with a MAF specially one as bad as a votex unit.

blitz118

iTrader: (8)

If your having drivability issues with the AEM then it's the tuners fault and not the AEM. You should contact Sean Ivey he can make a AEM run with no drivability issues.

gofaster87

iTrader: (7)

Smog, I have had my AEM for over a year and a half now and never had a driveability issue. Whomever you are hearing this or seeing this from has some tuning issues. Ill bet you your car drives no differently than mine, for gods sake no one can even tell I have 280 cams, it idles perfect. On another note you will not get the same performance out of c16 and 93+meth, if so, theres tuning issues there as well(depending on how much meth is injected.) This difference alone makes your comparison null along with the difference in boost which you think is comparable and may not be.

Noize

iTrader: (24)

Smoggy,

The only way to make real headway in your theory is with the same car, same dyno, same tuner. That way, car to car variances, weather and altitude differences, dyno differences, and tuning style are ruled out.

Often I'll see someone who claims a reflash, piggyback, or stand alone is superior to another form of tuning, only to find out that the owner of the other system's problem is that his actual car has a higher tendency to detonate.

I'd really like to see this test done on a Dyno Dynamics, as you get to see the actual power and not so much wavy gravy from the Dynojet rollers themselves. In contrast, I don't like the lines from a Mustang dyno, as they are ultra smoothed.

If I were conducting the test, I'd see if you could get a volunteer to loan you an EMS so you can conduct the test in the correct environments.

My theory is that it would be close enough in output that I wouldn't be convinced to do the swap to lose a bit of drivability.

Any ECU solution is only as good as the tune, so using an intelligent and competent tuner to conduct this test is a must.

Mr. Stock

iTrader: (3)

The only variables I see between the stock ECU, piggyback and stand-alone would be processing speed and resolution. The greater the processing speed and resolution, the closer a tuner can bring the tune to optimal with a smaller safety margin, ie. more hp without inducing unwanted knock and blowing things up. Modified stock ECU's with faster processors are quite popular in Japan on cars such as RX7's which are typically offered in 8, 16, and 32 bit. With each bump in processing power comes a bump in wheel hp due to the factors mentioned above. For me, it'd come down to the system architecture, features and resolution. Everything else is just the tuner and which way the wind is blowing that day

Smogrunner

iTrader: (5)

I said in my original post that AEMs can have drivability as good as stock. I know for a fact this to be true in a couple of AEM cars I have been around. I also know that Xede or other piggyback powered cars can have all kinds of problems as well.

I also know that this is not a perfect apples to apples comparison. With that said, the Topspeed car does have a nicer powerband than mine. That could be due to a couple things: A little more boost, cooler weather, a better tune, cam gear settings.

But what is not really up for dispute as far as I can see is that the curves and power production are very very similar and impressive on both.

I would really like Doug (BadazzCr) to post up a graph of the atmospheric conditions during the TopSpeed Car's run.

If anyone want to know any specific details of my cars mods, please ask.

Ted B

iTrader: (6)

The single most important thing that can be derived from the graphs is the fact that one can attain the power levels typical of cars equipped with a GT35R and standalone, while keeping an extra $1000+ in his pocket and the car completely OBDII compliant.

Smogrunner

iTrader: (5)

I would be more than willing to do this. I'm pretty sure I could get the dyno time affordably. We could do it under fairly controlled conditions: 27 psi, same tank of race fuel, same dyno, same AFR's, etc. If someone I trusted on the AEM platform was at the controls, I wouldn't mind at all. Problem is the amount of labor involved in swapping the AEM in with associated sensors and speed density, plus tuning, might end up being more trouble than it is worth.

So, if Martin M, Sean I, Scott G, Tym S, Jason S, etc. want to take a crack at it, I'm ready to go. ( That is me waiting for one of these guys to actually offer to do it.) Alfred at TT will touch up my Xede map to match the AEM. There has gotta be somebody on these boards that will loan out their AEM and stuff for the test.

VTECH8TR

iTrader: (70)

Ted,

How did i know you where going to say this .

Ted B

iTrader: (6)

Because you're even smarter than you think.

madpacket

iTrader: (3)

Here is my extremely lame attempt to put both cars' curves onto the same chart. As best I could using Excel I plotted at each 500 rpm tq & hp curves between 3500 and 7000 rpms (smoggy's chart doesn't hit 7500 and czr's doesn't start till 3500).

It's not terribly accurate nor insightful perhaps except for to confirm that smoggy's car lags a bit till 5250 when czr's has a dip until 6000.

Anyway if you were frustrated like me trying to mentally compensate/reconcile the two charts this may help a tiny bit. It certainly lacks the resolution of the dyno charts but gives the basic trend.

Finally- does anyone know how to calculate the area under the curve? Isn't that just a simple calculus function? Do any of the dynos do such a thing? If they did, what result would you get? hp/cm^2 or something?