94 Volvo 940, trying to break the 27 mpg barrier

[RobbMeeX]

Aww... I wanted to play redblock ecotuning, but the best tricks are already out. I gained... maybe 3-4 mpg replacing (well it wasn't there originally) the airdam with a curve sheet of aluminum that used to be a sign. Electric fan... is that on a 94?

[SmellyCat]

I guess the red block is the Volvo engine. it is a great big station wagon with a little bity red engine. It has an electric radiator fan. . I like the idea of the Alt switch. I have ran the battery down to critical 3 times that the tach and speedo start getting wiggy and I die at the roadside. I have maybe a minute to hook the jumper cables under the hood and connect to the 2nd battery on passenger floor board, The Summer sun takes the fun out of conking out on the side of the road.

Will it hurt anything it I hook the marine battery and the start battery in parallel and charge them together. pResently the Marine battery is on the 10 amp charger and and the starter battery is on the 2 amp trickle ... SC

[Tonys9]

First time I've seen this thread. I have been running an mpguino in a 940 for a few years now. ( figure in imperial gallons)

Car: 1995 B230FT estate
Modifications: Mainly none, lowered to sport levels, Bosch super 4 plugs, stainless exhaust.
Max average: 40mpg using pulse and glide, 60-80mph
Max flat: 46mpg at 30mph

No alternator - the lower/dropping voltage will screw up the mpg readings, as well as reduce the efficiency and calibration of everything in the fuel and ignition. You need to use additional batteries and/or solar cells to keep the voltage stable at 14V.
It should be worth something, typical min load is 300W. Hightbeams add about 0.03 gal/hr to the fuel flow at tickover. so that is about 0.03 gal/hr per 100W, which means fuel flow should drop by 0.09, which is about a 30% drop at tickover. The benefit is less the faster you go, say 15% reduction at 30mph, but would be a 4-5mpg improvement.

I must try that, need a good 2V battery.

I think you could fit 600W of solar, but you don't need that amount. 100W would be plenty with suitable batteries depending on your daily milage.
It might be worth increasing the amount of electricity used say with a electric water pump, steering, turbo etc to make use of solar.

Another thing I've notice is gearbox, engine and diff oil. MPG takes a while to get up there in cold mornings even after engine has warmed up. Maybe benefits with thinner oil or heater pads.