MPG question

[Mieran]

If a Cavalier and a Nova had the same engine, gearbox and wheels/tyres over a distance of 100 miles and both doing 70mph steady will the mpg on both cars be the same or does car weight have a factor here?

[Spudly]

In theory the nova should do better mpg, but if both cars were side by side and driven at the same time, same road and exactly the same way (im guessing gently) then they should, in theory be identical!

[Nova_Sean]

It would only matter getting it up 70mph i would imagine, due to the greater mass of the cav...

Once its rolling i'd imagine it wouldnt have much init. Appart from aerodynamics if you was being incredibly anal about it

[Nova_Tek]

Getting to that speed the Nova would probably use less fuel as it's lighter. At higher speeds the Cav would claw a bit back due to the 0.29 drag co-efficient against the Nova's 0.36 (hatch).

Would be very similar and very little between them I'd guess.

[Novasport]

Roads do have inclines too so the Cav will use more fuel to pull the extra weight up the hill.

[mowgli]

the cav td does better mpg than the astra mk3 td with the same running gear

go figure..

[Southie]

All depends on your right foot.

[windfreek]

Roads do have inclines too so the Cav will use more fuel to pull the extra weight up the hill.
but the cav would use less down roll as the weight will help overcome drag

however due to the (D^2) 0.29 drag co-efficient of the cav against the Nova's (D^3) 0.36 (hatch) ((calcs - are these accurate?)) if so then the cav could climb up the gradient, for example, of 12', at a speed of 55.92mph based on its curb weight of 1,199kg against the nova of 897kg we can calculate that:

(CAV)

D^1 = D^2 X (1,199/897 = 1.336)

D^1 = 0.29 x 1.1336

D^1 = 0.387

(Nova)

D^1 = D^3 X (1,199/897 = 1.336)

D^1 = 0.36 x 1.1336

D^1 = 0.4048



P^1 = D^1 V^1 = 0.387 x 0.4048 DV = 15.665%


ergo - for example if the nova ran at 40mpg then the cav on a 12' incline would do 33.73mpg AVG

and for the gradient of the same angle on a downhill and without listing all the math again, and yet again based on the nova achieving 40mpg, the cav would be doing 56.431mpg

therefore the incline is of no effect to the cav due to its drag co-efficient and overall on the gradients and flat, be more efficent if that is the answer you were looking for? lol

[ryansnova]

the cav is more hevyer so there is constently more weight on the tyers pushing down on the road so it would take more power to push the car along the road so i would think that the cav will have less mpg......

but i dont think it would be that much of a diferance lol

Cavaliers are sh*t enyway lol

[Novasport]

Modern cars have fuel cut off on over-run so neither will use any fuel on descent if driven economically ;)

[windfreek]

the cav is more hevyer so there is constently more weight on the tyers pushing down on the road so it would take more power to push the car along the road
but due to the brick-like aerodynamic properties of a Nova, the Cav outweighs the equation regardless of mass, but it is true that the cav would need more force to attain the 55.9mph due to its mass, however due to when the cars reach their maximum potential kinetic energy, then the kinetic energy begins to be converted to gravitational potential energy and also wasted via drag The sum of kinetic and potential energy in the system remains constant, and the gravataional forces are minimal to that of overall drag that acts upon the cars.

[windfreek]

Modern cars ....

lol

Modern... Nova = Nope

Modern... Cav = Nope

[Novasport]

OK, fuel injected cars from mid 80's onwards.

[Novasport]

but due to the brick-like aerodynamic properties of a Nova, the Cav outweighs the equation regardless of mass, but it is true that the cav would need more force to attain the 55.9mph due to its mass, however due to when the cars reach their maximum potential kinetic energy, then the kinetic energy begins to be converted to gravitational potential energy and also wasted via drag The sum of kinetic and potential energy in the system remains constant, and the gravataional forces are minimal to that of overall drag that acts upon the cars.

Oh btw, please prove your theory:thumb:

[windfreek]

lmao its not my theory, try arguing with Isaac Newton and Einstein!

[Novasport]

Oh, and there is a wind speed of 13mph in a North Westerly direction, it is 11 degrees celcius and it looks like rain lol

[ryansnova]

but due to the brick-like aerodynamic properties of a Nova, the Cav outweighs the equation regardless of mass, but it is true that the cav would need more force to attain the 55.9mph due to its mass, however due to when the cars reach their maximum potential kinetic energy, then the kinetic energy begins to be converted to gravitational potential energy and also wasted via drag The sum of kinetic and potential energy in the system remains constant, and the gravataional forces are minimal to that of overall drag that acts upon the cars.

^^^our work here is done^^^

:thumb: lol

[windfreek]

Oh, and there is a wind speed of 13mph in a North Westerly direction, it is 11 degrees celcius and it looks like rain lol

...and in what direction are the cars travelling?

lol :d

[bmw156]

but the cav would use less down roll as the weight will help overcome drag

however due to the (D^2) 0.29 drag co-efficient of the cav against the Nova's (D^3) 0.36 (hatch) ((calcs - are these accurate?)) if so then the cav could climb up the gradient, for example, of 12', at a speed of 55.92mph based on its curb weight of 1,199kg against the nova of 897kg we can calculate that:

(CAV)

D^1 = D^2 X (1,199/897 = 1.336)

D^1 = 0.29 x 1.1336

D^1 = 0.387

(Nova)

D^1 = D^3 X (1,199/897 = 1.336)

D^1 = 0.36 x 1.1336

D^1 = 0.4048



P^1 = D^1 V^1 = 0.387 x 0.4048 DV = 15.665%


ergo - for example if the nova ran at 40mpg then the cav on a 12' incline would do 33.73mpg AVG

and for the gradient of the same angle on a downhill and without listing all the math again, and yet again based on the nova achieving 40mpg, the cav would be doing 56.431mpg

therefore the incline is of no effect to the cav due to its drag co-efficient and overall on the gradients and flat, be more efficent if that is the answer you were looking for? lol

Never have i found someone with a more appropriate user name
good work.

[Spudly]

Cavaliers are sh*t enyway lol



You seem to have found yourself tickled with my neg rep for that comment:p

[Nova_Sean]

Cavaliers are a true gods transportation :d

[Stuart]

for constant speed on a flat plane with no wind, simply use my power in gear calculator to see which needs more power for the same speed... more power = more fuel used.

DONE.
In terms of accel/decel then the cav will use more fuel if you did exactly the same drive cycle as the nova. Decel would be a grey area due to the weights and possible lack of fuel cut off on the rotary pumped dervs.

[windfreek]

for constant speed on a flat plane..

Praise be to the lord,
we dont wear clogs for our flat pastures
we dont grow tulips amongst the windmills
and that our roads will forever be twisty and full of ups and downs
Praise to the lord....

also if there was no drag effect on a car, we would never need anymore than 180bhp to attain 200+mph

[Stuart]

lol
for use as a 'rough' guide since engine condition, tyre type, tyre pressure, wheel width, gearbox condition/fluid type will ruin the 'fair' comparison too

[jaygsi]

The Nova would be better as light weight, but if going down hill the caviler would win easy, as i once drove 5 miles out of gear in my old cavalier, best free rolling car i've ever had

[mowgli]

Cavaliers are a true gods transportation :d

as in people always bang on about them being great, but can never actually prove it?

[jaygsi]

My dad owned 2 cavalier 2.0 8v both did 200.000 miles untill the body work rotted away