2011 Ford Mustang V6 rated 31 mpg highway

[Tmall]

Originally Posted by Homeslice

Well I'm not a physics major, but if you take 2 engines with the same displacement but different HP, I don't see how more horsepower ALWAYS means less fuel economy UNLESS someone is actually taking advantage of it by accelerating harder. And I doubt the EPA test is doing that, does it?

Personally I think the increased weight of today's vehicles is more to blame.

Because you have to rev it higher to get more power from the same displacement, and then they likely gear it lower so you're riding at a higher rpm for a given speed.

Just an example, car a is a 3.5 litre, car b is a 3.5 litre. One makes 200hp, the other 250. The higher hp one likely makes more power by spinning faster. It'll also likely have a shorter stroke and wider bore due to it's higher redline, to keep piston speed down. This will usually mean less low end tq, so they gear it so you're at 3500rpm at 60mph as opposed to 2500rpm for the lower powered car.

3500rpm time 3.5 litres gives you 12,250 litres of air/fuel being pumped through that engine. 2500 times 3.5 litres gives you 8750 litres of a/f mixture.

I hope that's what you were getting at slice, because that was a lot of typing that made my head hurt if not..

[Rider]

Originally Posted by Tmall

Because you have to rev it higher to get more power from the same displacement, and then they likely gear it lower so you're riding at a higher rpm for a given speed.

Just an example, car a is a 3.5 litre, car b is a 3.5 litre. One makes 200hp, the other 250. The higher hp one likely makes more power by spinning faster. It'll also likely have a shorter stroke and wider bore due to it's higher redline, to keep piston speed down. This will usually mean less low end tq, so they gear it so you're at 3500rpm at 60mph as opposed to 2500rpm for the lower powered car.

3500rpm time 3.5 litres gives you 12,250 litres of air/fuel being pumped through that engine. 2500 times 3.5 litres gives you 8750 litres of a/f mixture.

I hope that's what you were getting at slice, because that was a lot of typing that made my head hurt if not..

HP is a function of Torque. Torque is measured and HP is calculated. If you build an engine that is capable of higher RPM of course it will make more HP but not necessarily more torque.

[Tmall]

Originally Posted by Rider

HP is a function of Torque. Torque is measured and HP is calculated. If you build an engine that is capable of higher RPM of course it will make more HP but not necessarily more torque.

Agreed 100%. You can also change the tq curve by descreasing stroke and increasing bore and vice versa.

[Apoc]

Originally Posted by MILK

2010 Camaro 29 mpg

thats all fine and good, but whats it gonna get when someone actually drives it.

[Amber Lamps]

Originally Posted by Rider

Damn good mileage. I'm partial to GM but with numbers like that...... I could be lured into buying one.

I'm a GM guy myself but the Camaro is high dollar and a clean Mustang V6 can be had for under $10,000... I missed my chance to look at it today, worked late but I'll try and check mit out before I leave for Daytona.

[derf]

Originally Posted by Homeslice

What happened to 20 years ago, when fuel economy wasn't considered impressive unless it was 30 city?

The environment

[101lifts2]

Originally Posted by Homeslice

Well I'm not a physics major, but if you take 2 engines with the same displacement but different HP, I don't see how more horsepower ALWAYS means less fuel economy UNLESS someone is actually taking advantage of it by accelerating harder. And I doubt the EPA test is doing that, does it?

Personally I think the increased weight of today's vehicles is more to blame.

You are forgetting about emission output. The lower the NOx requirement, the more EGR dillution and less power. Also, if you have to heat the cat up faster, more fuel. Plus cars are heavier today then in 1980s.

[Krabill]

Originally Posted by z06boy

That is impressive.

Yeah gearing probably is the difference...or most of it.

I know with my Vette when it was stock...it would get 28 mpg on the highway but 6th gear had no umph...and the car would lull down the road at around 1500 rpm.

I changed the gearing from stock 3:42's to 3:90's.

Just out of curiosity, what kind of mpg are you getting out of it now?

[z06boy]

Originally Posted by Krabill

Just out of curiosity, what kind of mpg are you getting out of it now?

I'd have to check...not sure to be honest but it's not too far off from where it was if I drive it normal. It's probably 2 or so mpg down but keep in mind it now has a blower...a different cam...and the 3:90's.

I'm sure there is a bigger drop during "spirited" driving.

My shift points are different since the change.

If I had it to do over again...with the blower...I may have gone with 3:73's if I was going to change from the stock 3:42's. Hard to hook on street tires but not that big of a deal since I rarely dump the clutch from a dead stop.

The reason I changed in the first place is due to my rear gear beginning to whine and since I needed to do something and was having to pay the $$ I went for more performance. I also had a hardened output shaft installed.

That's been the only mechanical issue with this car since I bought it in 02 so I feel pretty good about that.

[Krabill]

A Z06 with a blower. I'm sure you've heard it before, but that's just fucking awesome