Is DE deceleration enleanment or enrichment? When I take my foot off the gas the W.B. goes to low 12's for a few seconds before returning to normal. A datalog shows the commanded AFR stays at 14.7. I'm using SAUP v5 with a 383, 225/231 cam, and a Super Ram. I'm trying to understand why with VE's of 128-132 I can't get better than 13 mpg driving conservatively.

 

DE is decel enlean IIRC...

Is that average 13 mpg? City only? Highway only?

At low rpms, that cam is probably throwing away quite a bit of fuel air charge out the exhaust (before the exhaust valve closes) due to the overlap...

 

Thanks Mike. It's a combination, leaning more towards highway. Low rpm VE's are good, although WB at Idle is 13.8, - 14.8 I saw in a previous post of yours that you get 20+. I'm jealous.

 

well, if I averaged my mpg, its probably not much higher than yours. my average would probably be around 16-17. I haven't measured my street fuel economy but I'd bet it's around 13 if I drive normally.

I think what gets me in the high 20s on highway is the highway mode fueling plus the cam is probably just right for cruising at around 2000-2300 rpm.

 

What are your AFRs and RPM at highway cruising speeds?

 

I'm running about 16:1 at light throttle cruise on the highway.

 

Much the same here although I'm carbed. 16:1 cruise, 2300 RPM, 45-50 degrees of timing. That's with a 236@.050" cam on a 110 LSA.
Slightly better than 20 miles / U.S. gallon. All highway. 400 mile round trip.