Is there anything like an HKS VPC available for the Subaru? I head some talk on another forum that someone was rying to come up with something to convert MAF to speed density as a seperate system (so you could run an EcuTek or Cobb without the MAF).

That would be tough. You'd not only need a look-up table to convert MAP and MAF voltages, you'd also need a VE table (a really good one). The problem with VE is that it changes with your mods, so you'd need several VE tables. You are talking about inserting code into the stock ECU's logic, and adding a number crunching step. Getting the conversion to happen on the fly would not be too hard with a MHz processor, but it will depend on the current bandwidth through the processor(s).

Something like the Hydra's MAP based fuel map could be used to derive VE for several different turbos, headers, exhaust combos. With a list of several VE tables you could probably get close to most peoples set ups, then tune around any variation. VE is why many dropped speed density in the first place ;)

So, my vote is yes it could be done with sufficient processing power and efficient code. You've reached the limits of my knowledge.

But how did it work on the Supra?

and a lot of people use them on DSMs, bump for the question.

search for posts on this board by john banks. he did it using a u-controller and mapping it out himself. if i'm not mistaken he still runs with it.

hth
ken