The amount of horsepower lost has next to nothing to do with the fuel mileage you lose. My old car was a 90 horsepower 2.5L, the RA is a 162 horsepower 2.4L. The mileage numbers are somewhat similar (I think the less powerful one actually used MORE fuel though). Yet the RA makes WAY more power, out of a smaller engine, with less fuel. So less fuel, for more power. Doesn't make sense. And losing power for the old engine doesn't mean using more gas (it was a little worse on gas, but still about 25-30MPG).
True, the alternator never uses all that much extra fuel, but it still DOES which is the point we are making, and when it is putting out a lot of current, it is putting quite a load on the engine.

 

Internal combustion engines are horribly inefficient. Something in the range of 5-8% efficient last time I read about it*, meaning 92-95% of the potential energy in the gasoline is wasted. A lot is wasted as heat, some is wasted by incomplete cumbustion, etc.

Your RA is just more efficient than your old car.




*note: the statistic I quoted about engine efficiency is WAY out of date. New gas engines might be in the low teens by now, but that's still pretty bad, when you stop and think about it.

 

I've upgraded my head unit, speakers, and now have 60 watts RMS to each corner. Keeping my radio not only keeps the radio amp off, but my separate amp as well. BTW, synthetic oil and lubrication helps mileage as well.

 

I love this guys , can we all get along .............................
and lets get back to topic , Thank you.

Ralliart86, I had the same result then you in this pass days, I drive 120 round trip at day to go to work and my miles with and wit out MIVEC word the same ........

 

Actually it's more in the 20s now, at least. Still inefficient. But the wasted heat is still a conversion of energy. Chemical to heat, instead of what we want, chemical to motion. Did my old car have more waste heat than the RA? No, the intake, exaust, head design, accessory design, carburetor size/design etc all came together to restrict the amount of fuel and air to get freely into and out of the engine. The inefficiency of internal combustion engines hasn't changed THAT MUCH. It has gotten better, but not by much. Not nearly doubled as we would think to nearly double the horsepower. The reason is today's engines flow air and fuel MUCH better with their 4 valves per cylinder, VVT, better intakes/exaust, fuel injection etc. They pack more fuel and air into a similar sized engine AND get more out of a charge of fuel, which is why fuel mileage doesn't suffer all that much. We are burning the fuel more completely and less horsepower is used by the accessories and engine itself.

 

I'd venture to guess you would see the same fuel savings your seeing in and out of MIVEC at those speeds with any 4 cyl. regardless of MIVEC, VTEC etc. A regular motor will probably use just as much gas if not more over 70 mph. The amount of fuel needed to increase speed at those speeds increases exponentially. I think that having MIVEC is actually helping you to save fuel over 70 mph. A non mivec 2.4 would probably use more fuel at the higher speeds.


**I have no actual test data to back this up - its just my theory.

 

I second that theory. A non mivec engine would have to work harder, therefore, use more fuel.
Having said that, I also understand that keeping it out of mivec territory when just cruising will save you aswell.

 

Those are the results I get also. I've been testing the gas milage with and without MIVEC for the last 3 months or so. The only reason I've paid so much attention is because there are guys on here that are getting 29mpg+ and I've had yet to come close to touching that kinda gas milage. I think these people are cheating. Like driving halfway to work, then turning the car off and pushing it the rest of the way. lol

 

The valve timing of the MIVEC T-Lobe is for wide open throttle. That really isn't set up for partial throttle highway cruising. That's why there is such a big difference.

 

Back in October I reeled off about a 900-mile run in one day along I-70 from St. Louis to Colorado. Averaged about 28 mpg, with speed generally in the 75 - 85 mph range.

I probably could have done 2 or 3 mpg better if I hadn't:

1) Been bucking a little headwind for a few hundred miles.

2) Taken the car off cruise control a number of times to give it "a little stick".

3) Opened the windows occasionally (increasing drag) to let out the cigarette smoke.

4) Driven the car in 4th gear for about 30 or 40 miles due to inattention (damn, that engine is smooth)!

5) Stopped about every 150 miles (wasting all that kinetic energy) for refueling and "dewatering".

6) Driven like Reginald Milktoast at a steady 50 mph (for about 18 hours + stops...sigh)

I also discovered that the RA's fuel range was about twice that of my bladder........tho' younger drivers may be able to reach a 1-to-1 ratio!

 

You smoke in your RA ????



Just bugg'n.

 

Damn, driving 85 mph in 4th gear and you didn't notice?? Poor engine must've been screaming. Get yourself a louder exhaust and that won't happen again.

 

Just like being at idle compared to my Suzuki motorcycle!

 

That SR20 is a bit of a screamer as well. If memory serves me correct, you could wind it out to almost 8k!

 

Yup, my '91 SE-R, with the original version of the SR20DE engine, redlines at 7,500 rpm. The later versions (change from high port to low port?) had the redline at about 7,000 rpm. Despite its high revving nature, the SR20DE engine was quite "torquey" for its day: 132 lb.ft + 140hp in a 2600 lb. SE-R.