Oem vs. Aftermarket
 

Can anyone tell me the advantages/disadvatages of running an OEM ECU as opposed to F.A.S.T., Big Stuff 3, etc? I know the aftermarket stuff is more pricey but that isn't my concern. I'm more concerned about tunability with custom and future mods, etc.

the aftermarket stuff usually has more features, bells and whistles, etc. On a super/turbocharged engine many of the aftermarket systems come with a wideband O2 and the ability to stay closed loop even under boost. Kind of nice that the ecu can add fuel if needed under boost, the oem stuff can't do that. Many have boost controllers, trans controllers, nitrous controllers, etc. built in.

Both can work very well, with the correct tune being the key. I think the aftermarket stuff is easier to tune, mostly because there are fewer parameters you can get into when tuning. But the factory computers are very capable for nearly any combo you'd run.

Jody

I just went throught this with our Bull Run Racer which runs a LS3 with a 4 barrel TB. While it has to be tuned in Speed Density, it still seems to be the best choice.

Based on your sig your engine is a factory LS engine, use a factory ecm. The factory ECM is faster, smarter and les money then aftermarket. The aftermarket systems will require a additional ingnition box for the multi coils on the LS engine, the factory ECM handles it all inclusive. And if your running a automatic, you can use a factory trans controller also. Mucho less dollars.

But if you decide on a FAST or Accel, we are delaers. Guess I kinda shot my foot off on this one!

some of the aftermarkets units run the factory coils without additional boxes, and have trans controllers built in. If you go aftermarket, call Frank, he'll set you up at a great price. The oem computer would also work well in your case.

Jody

I guess I should have stated this before. With my Chevelle, the 6.0 has SLP Performance's L92 heads with 64cc comb. chambers and cam & rocker arm upgrade. Cam specs are .561 & .562, 113 lobe sep. So it isn't stock, but not too radical. The reason I asked this question is I already have all my F.A.S.T. wiring & XIM Ignition controller. I only lack the XFI ECU but was told to send all that back and use OEM ECU and wiring harness by the guy who was going to do my install. I didn't know if he was trying to sell me his stuff or what or was he making any sense. He is also a F.A.S.T. dealer and installs and tunes F.A.S.T. too. I admit the OEM stuff is cheaper, but since I already have the F.A.S.T. stuff minus the XFI that's why I wasn't worried about the price because money was spent. But don't mind sending it back and saving money if OEM is the better way to go. My car is strictly a street car, no racing and will be matted to my brand new T56 Magnum. But want to keep my options open in the future if I choose to stroke it or change to a bigger cam as far as the better ECU tunability. Frank....how much for the F.A.S.T. XFI? Thanks guys for all the replies and help!!!

Frank, you are correct for that application. The aftermarket ECU's are extremely expensive, if you want one that is capable of lots of features. The ECU's such as Motec's 800 series or such can run as much as 8k. The after market ECU's are made to be tune real time though, the GM ECU's are not that forgiving unless the ECU its self has enough physical ram to do real time tuning. I will say though for the money you cant beat a Factory ECU, thats unless you have a twin turbo 2000 hp setup from TOM Neslon.