Carburetor efficiency question.. - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

luvit · 02-28-2010, 11:28 PM

daverbmxer,
i opened a thread with the same question. -- i already had my VAC gauge installed.
i did find conditions, like a highway on-ramp, where the lower gear yielded better vacuum.
i have an automatic transmission, so lugging is pretty unlikely to happen, but i come close.

the only reasonable response i received was old tele man's response.

my vehicle is too old for a scanguage to compare these gears, but i think he made great sense.

comptiger5000 · 03-01-2010, 07:40 AM

Luvit - You could install a marine fuel meter, such as a flowscan, to determine GPH usage of the engine.

luvit · 03-01-2010, 08:19 PM

what do i do with that GPH figure? ..kinda see GPH in either gear?

daverbmxer · 03-01-2010, 08:35 PM

Those can't be cheap..

comptiger5000 · 03-01-2010, 09:26 PM

If you know GPH and MPH, you can compute MPG. They aren't overly cheap, about $150 for an analog gauge type, more for digital display. For a carb, however ,there isn't much other choice.

121madness · 03-01-2010, 09:52 PM

Quote:

Originally Posted by bestclimb

When cruising in 4th or 5th gear even with identical throttle positions you are sucking more air through at higher rpm which mean more fuel as well.

Here is the answer

sc2dave · 03-03-2010, 01:34 AM

A tall velocity stack on the carb perhaps?

SentraSE-R · 03-03-2010, 02:01 AM

When I first got my Scangauge, that was the first test I did - a 4th, 5th, and 6th gear mpg comparison drive at the same 35 mph speed on a slight uphill climb about a mile long. The mpg results showed 5th gear beat 4th, and 6th gear beat 5th. This was in my SE-R.

Here's another. I've run the same 10 mile loop in all three of my family's cars in top gear and the next gear down. That's 35 mph in top gear v. 30 mph in the next lower gear. The route is essentially level, driving at sea level with at most about a 50' elevation gain in a couple of places. Each car showed better mpg in top gear.

gone-ot · 03-03-2010, 09:35 AM

...the ecomodder jingle, repeat after me:

"the slowest RPM in the highest GEAR that doesn't 'lug' the engine."

"the slowest RPM in the highest GEAR that doesn't 'lug' the engine."

"the slowest RPM in the highest GEAR that doesn't 'lug' the engine."

comptiger5000 · 03-03-2010, 04:07 PM

Old Tele man is right. That's why low end torque is good. It allows you to run in a higher gear in a lot of situations.