Assuming equal states of tune, same gas, same driving style, what gas mileage differences could I reasonably expect to find between an 87 powered by the 305 TPI with an auto tranny, and a 91 with the 350? Or better yet if you have any experience with the stock 350 TPI what kind of gas mileage did you see? Thanks.

 

I get around 24-25 mpg on the highway. City traffic varies depending how much I get stopped. I've seen in as low as 15 when I was just crawling (in nothing but city driving) but generally around 18.

This is all before I got into eprom buring and discovered a hidden GM table called Highway mode. I have already noticed an increase in my city driving gas mileage, but haven't yet had a chance to check it on the highway.

 

Glenn91L98GTA, you get 25 mpg highway with your 350?
I get that with my 305 TBI; being equal to 11L/100km I get this driving highway at an average of 80 km/h refusing to accelerate quickly or drive about 100km/h

I know this will improve once I replace my fuel filter (which I hadn't done this year since taking it out of 8 month storage, dumb), but what else can I check to make sure I am getting optimal fuel effeciency?
I just passed AirCare with no modifications needed and the ca sounds great.
Thanks.
It's been awhile since I've been on the board. Good to see your still here.

------------------
West Coast Performance
1989 Formula 305 TBI

 

when i first got my car i got like 12 with some highway driving, i think its up to about 15 or maybe even 16 if i'm lucky after tune up and whatnot

------------------
90 IROC 5.7l (L98)
ram air, K&N's, air foil,Flows

LIKE A ROC

 

I've got a 91 z-28 L98 and i get 17mpg city if i'm easy on it. Like 24 on the expressway.

 

Adam, yes I get that with a 350 and 3.23 gears. Last summer, driving from Kamloops to just south of Penticton (and back) using the Coquihalla both ways, I got 11.5 km/l or 8.7K/100Km. That is driving between 100-105 Km/h or 60-65 mph.