I hope I'm posting this in the correct forum. I'm just getting into burning my own chips, studying and doing research before I even buy the equipment I'll need. I read Traxions page and it's an excellant place to start. But....I have a question.

Will the stock ecm of any year (86-92) be able to control the fuel and spark requirments of say, a 468 big block? I've been thinking of building one (fairly mild for street use) and I'd like to run a stock type ecm and GM sensors if possible. I doubt a MAF system would flow enough air, maybe with the Well's MAF but I don't know.

My thinking is like this. Run about a 230* - 240* @ .050 duration hyd roller cam, about 10.5 compression, no more than 6000 rpm, and some type of decent flowing heads (probably alum). I was going to run a tunnel ram type intake with probably a TPI type plenum and run a stock style (1000 cfm) throttle body.

Is this possible with a stocktype ecm if I burn my own chips? Any ideas anybody can come up with is welcomed. I don't have to worry about emissions but I need to keep this as budget based as possible too. Thats why I'm not looking at the hi $$$ Accell type controllers and I'd like to keep it as stock as possible for replacment reasons when on road trips. Thanks for any help!

 

The SD ECM can support an engine displacement of 8 Litres (1000 cc per cylinder). The difficulty will have more to do with how much HP you intend to produce.

The problem is the high-impedence injectors used by the stock ECMs. The size of injectors needed to support big HP engines generally cannot produce pulse widths short enough to maintain a good idle.

Bruce can probably explain more about the difficulties, but around 500 HP starts to become the "cut-off" point where you need to look at other alternatives.

If you don't plan on making more than 500 HP, then give the SD 7730 a try. You can always look at other alternatives later.

 

I'd even drop it down a little from there, if your looking for a nice street driven engine.
If you like hassle free driving with big HP it's going to take time effort and money anyway, might as well figure getting one of the newer aftermarket ecms, and ignition systems (eDIST).

 

Bruce, if it was a 383/400 SBC I would definitely think lower HP limit. The only reason I was being a little "generous" for a BBC was the larger displacement would require more fuel at idle and hence the "too short of pulse width" issue being a little less of a problem.

I'm going by the "what's wild on a small motor is often mild on a big motor" adage. But, if the "poster" is planning on more HP on the future, he should consider biting the bullet and going DFI from the start as you suggest.

Who says that you don't like/recommend DFI systems? I should keep this post to show that you DO recommend DFI (when it's the right thing to do).