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SignUp Now!KLHAMMETT said:Youve got mail,This is a 75# program that was turn key purfect on pump fuel
RonRed89 said:Any chance to take a look at this. Having the same problem on my NA SBC 396. Otherwise my program is very good, but the cold starts are an issue.
redcorvette@brightdsl.net
Thanks,
Ron
JDEstill said:I spent a little time pondering the cranking fuel issue earlier this year, trying to help out a guy who was having cold start problems (among other things). I was thinking that if we started with a car that has a known good cranking fuel table, then we could use that on any car with the following relation:
new cranking pw = old cranking pw x (old inj size/new inj size) x (new cyl size/old cyl size)
For example, the demo program I seem to remember coming with the FAST box was for a 265 cid V-6 with 83# injectors. At the coldest temperature the commanded cranking fuel was 11.5 ms.
Now, big assumption, lets assume that is a good, well tuned value. We now want to figure up the value for a 396 cid SBC with 55# injectors. The V-6 has 265/6= 44.16 cid per cylinder (or per injector if you want to think about it that way). The V-8 has 396/8=49.5 cid per cylinder. So that first cranking pw point would be = 11.5 x (83/55) x (49.5/44.16) = 19.45 ms.
So we'd put 19.5ms into the first point on the cranking fuel table, and then go to point #2 and do the same thing. To my way of thinking this should give about the same volume of fuel per cubic inch of displacement during cranking for both engines. And so if the base engine was tuned well, then the new engine ought to be dang close.
I don't think the guy I was helping ever tried this out though, so don't know how well it worked. I'd like to take the cranking pws from a stock GN and do this exercise, see how that compares to the values people end up with that work well, but I never got around to it. Be interesting to see though.
Maybe if this works, someone could post a table of their (cranking pw x inj size / cyl volume), and then anyone could take that table and use their own cyl vol and inj size and create their own cranking table easily.
If anyone gives this shot, let us know how it works.
John