Not too long ago I was posting on here about how wonderful my gas milage was, usually 20 - 22 mpg.
A couple of months ago, I changed tires and went 6% or 7% shorter than stock. The performance is great, but my wonderful milage is now 16 - 17 mpg.
I am amazed at the difference this has made. I assume that I am now "cruising" outside of the injections expected "cruising range".
Thats OK. Keep the gas milage, I'll take the performance!
Fuel Milage
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Mayhem_J30
- Posts: 2643
- Joined: Tue Apr 30, 2002 2:00 am
- Car: Ummm...My Car
- Location: Louisville, KY
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Since the idle speed is a direct function of coolant temperature until it reaches 176F, it is important to make sure your thermostat is in new condition [about every 3 years].Every extra unneeded rpm uses EXTRA gasoline.
But even 10 minutes of cold start idling [1300 rpm>750rpm] doesn't use 1/4th of a gallon vs a single 15 second quarter mile run which uses a similiar amount.
If a car uses x at idle multiply by 5 then multiply again by the rpm increase 6000/750=8......times 5= 40 times more per minute.
Obviously you would have to average the rpm vs time to zero in on an exact figure for an acceleration...............but a 300HP engine making 300HP requires 25 gallons of fuel per hour....0.4 gallons per minute and all engines pour in extra fuel to cool so a more realistic figure is at least 0.5 gallons per minute.
Above 55 mph you consumption increases roughly at 2/3 the ratio of the rpm 80v s 55 uses at least 25% [probably more like 33%]more fuel per hour. On the highway you can have either 25 mpg or 18 ............or 7-9 on the Autobahn.
But even 10 minutes of cold start idling [1300 rpm>750rpm] doesn't use 1/4th of a gallon vs a single 15 second quarter mile run which uses a similiar amount.
If a car uses x at idle multiply by 5 then multiply again by the rpm increase 6000/750=8......times 5= 40 times more per minute.
Obviously you would have to average the rpm vs time to zero in on an exact figure for an acceleration...............but a 300HP engine making 300HP requires 25 gallons of fuel per hour....0.4 gallons per minute and all engines pour in extra fuel to cool so a more realistic figure is at least 0.5 gallons per minute.
Above 55 mph you consumption increases roughly at 2/3 the ratio of the rpm 80v s 55 uses at least 25% [probably more like 33%]more fuel per hour. On the highway you can have either 25 mpg or 18 ............or 7-9 on the Autobahn.