Hah, the way I have the turbovan setup, I can convert it from 15mpg premium to 40mpg regular in about an hour 
I generally run it 30-ish regular, which is, boringly, very near stock. Any better than that and it involves sticking the wastegate open, and no boost on a 4cyl is SUCK when you're driving a brick. I'm sure the Scion xB crew can attest to that
I generally run it 30-ish regular, which is, boringly, very near stock. Any better than that and it involves sticking the wastegate open, and no boost on a 4cyl is SUCK when you're driving a brick. I'm sure the Scion xB crew can attest to that
This is the reason why I'm driving my Sentra instead of a TSX right now (which I had a chance to purchase at a fair price).
I probably drive 35,000 miles a year
Sentra gets me 45 MPG = 780 gallons
Regular @ $2.00 = $1500 a year
TSX gets me 30 MPG = 1166 gallons
Premium @ $2.25 = $2500 a year
The Sentra is saving me ~$1000 a year
And that's not including the difference in insurance I'll be paying.
I probably drive 35,000 miles a year
Sentra gets me 45 MPG = 780 gallons
Regular @ $2.00 = $1500 a year
TSX gets me 30 MPG = 1166 gallons
Premium @ $2.25 = $2500 a year
The Sentra is saving me ~$1000 a year
And that's not including the difference in insurance I'll be paying.
If they can make these huge v8 sedans that get 30ish MPG but 400hp, why not use that same technology and make a 100mpg+ 80hp car? I'm still not quite sure why no one has done this.
It doesn't work that way. Fuel consumption is proportionate to the HP that the engine is currently putting out, not what it's capable of. When you're cruising on the highway you're only using about 40 hp.
If both engines were at wide open throttle, expect the 400HP engine to get gas mileage that's proportional to 400HP, the 80HP engine to get gas mileage proportional to 80HP.
StageLeft
No Lifer
- Sep 29, 2000
- 70,150
- 5
- 0
Yeah it's great when people buy a new hybrid to "save money on gas", even though now they're paying out tons of money on car payments. If they'd buy something for half the price they could get a used car that trumps the hybrid in every area, except for gas, and use the cost savings to easily pay gas over the life of their ownership.Originally posted by: 91TTZ
Originally posted by: fs5
city low mid-30's?
I've got a better idea- don't buy a new car and use the money for gas instead.
If your car currently gets 30 mpg,and you spend $2000 on a car that gets 40 mpg, that's only a 10 mpg difference.
$2000 will buy you 667 gallons of gas at $3 a gallon. You could drive over 20,000 miles on that gas.
If you already drive 20,000 miles a year, you currently spend $2000 on gas a year. If you buy a new car that gets 40 mpg for $2000, that will cost you $1500 a year for gas plus the $2000 for the car.
Buy shorter spark plugs. Shorter plugs waste less coil electricity since the electrons have to travel less distance before firing. Shaving your plug length by half is good for 5-6% better gas mileage.
Originally posted by: arcas
Buy shorter spark plugs. Shorter plugs waste less coil electricity since the electrons have to travel less distance before firing. Shaving your plug length by half is good for 5-6% better gas mileage.
Or you could go with the longer spark plugs to get it closer to the top of the piston so the spark doesn't have to work so hard to light the gas.....
It's usually because presently you can only optimize for one thing due to cam technology. An engine's peak efficiency usually occurs around its peak torque output. You can either make your torque peak down low, midrange, or up high. Making peak torque down low is more efficient, but produces less HP.
With variable cam timing like VTEC you can help this a bit by changing the cam profile in mid-operation. You can have the engine cammed to be efficient, and then when you rev it higher it will switch to a different lobe that makes peak torque up higher, delivering more peak HP.
Another thing is that for normal cruising, you only need around 40 hp. An engine that more efficiently can produce 40 hp will probably be a smaller engine, but it'll never make a lot of peak power. A larger engine will be capable of making big power, but at the 40hp point it's overkill.
OS
Lifer
- Oct 11, 1999
- 15,581
- 1
- 76
I think the number is less than 30 HP for cruise at 65 mph, but whatever. Even though it does take only a small, fixed amount of power to maintain speed, big V8s with RWD will always get worse mileage than a FWD I4 even if you keep the chassis size the same.
RWD has more rotating mass and inertia; long driveshafts, directional change in the differential. This works against you TWICE because the same drivetrain, big ass engine+tranny is also static mass/weight. To maintain cruising speed, using NET power at the wheels ignores the greater parasitic losses associated with RWD.
Also, V8 simply takes more fuel to run at equivalent RPMs. You can't just lean out the A/F ratio to save gas unless you like burning holes in your pistons. Big cylinders means more air which means more fuel pumped in to keep the ratio correct.
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