FAST or AEM for the 6.1 HEMI??

[challenger73]

I am in the process of installing a 6.1 Hemi into my Challenger. Trying to decide between the FAST XFI/XIM system or AEM to control it. Has anyone out there had experience with either of these systems for this motor or at least with a coil-on-plug set up?

[vipercuda]

We have a FAST system on a 5.7 Hemi-works great. We did a cam change and some slight head work with a stacked style injection system. It works incredibly well.. I would highly recommend one....

Mike
owner of Time Machines Inc.

[Blown353]

My vote is for AEM-- if you don't mind the slightly more complex setup & learning curve. It's just a more capable system in the end especially because it has some nice features for boosted engines that the FAST lacks (timing retard vs. IAT and some other nice little features.)

However, the FAST will likely serve you just fine and do everything you want it to. I run an older FAST on my car and I've put a couple XFI's in now and been happy with them... but if it were my car all over again I would be using an AEM or Autronic.

[challenger73]

When you say AEM is a more capable system do you mean it's tunability for everyday driving or it's additional features(ie booster input)?

[Blown353]

More capable in just about everything and can have better driveability. There is more resolution in the VE & timing tables, there are more options for IAC & AC control (i.e. it can delay the kick in of the AC clutch until the IAC bumps the idle), more AE fuel & decel fuel cut options/parameters, etc. It also has traction control built in, more switchable inputs/outputs, and lots of nice boost related features-- With a FAST when intake temps heat up you can only add fuel, but with the AEM you can add fuel, subtract timing, and if turbo'd and controlling the bleed solenoid with the AEM you can have the ECU pull boost out too in whatever combination you want.

It is far more involved & intensive to tune the AEM compared to a FAST but there are a TON of nice features. Unfortunately if you don't know what you are doing you can get in over your head in a big hurry! Their tuning software has a lot of things shown that the FAST software hides in order to be less confusing and more user friendly.

What it boils down to in the end is that it's always best to buy a system either you feel comfortable tuning yourself or has local tuning support. The best and most capable ECU out there won't do you any good if you can't tune it yourself or nobody locally can help you tune it.

[challenger73]

Is this true of the new XFI/XIM FAST system or only the old system you originally used?

[Blown353]

I've used both the original FAST and a couple XFI's now and the AEM is still ahead of the XFI when it comes to features and capability. I'm in the middle of an XFI setup right now on an all aluminum 427 ford with an F1R Procharger, I went with the XFI because that is what the car owner wanted. Will it do everything I want it to do and be very tame and driveable? You bet, but I wish I had some of the other features of the AEM, especially the timing retard vs. IAT-- especially out here where it can get to 110F in the summer.

Don't get me wrong, the XFI is a very good box but it's a bit on the "simpler" side compared to some of the other offerings out there. At the same price point of the XFI there is also AEM & Autronic, both of which are great boxes with more features, however neither are as "newbie friendly" as the FAST. I have not messed with a MOTEC yet but I really want to, same goes for a Delphi UH4.

If you want, you can download the AEM ProTuner software and install it for free and look through all the tuning options-- it's way more "in depth" and setup much more for guys with EFI experience when compared to FAST's C-Com WP, the Accell Gen VII, or the Big Stuff 3, all of which have very well polished and very "beginner friendly" interfaces.