More VX Info, Factory Dyno Plot, and calculation request
I was correcting some miss-information in a different Forum on the internet and thought I'd throw it out here as well for the furtherance of human knowledgement.
The dyno graph from Honda on the VX:
PS = Metric Horseower (very close to international HP) = 92 HP (international)
Green shading = kgm = Torque (kilogram meters); 13.9 (kg m) = 100.538893 ft. pounds
Blue shading = g/PS-h = Fuel Consumption = grams of fuel consumed per hour per horsepower at a given engine speed. Weight of one US gallon of fuel ~6.5Lbs. = 2,948 grams.
Anyone care to make a little conversion to Gallons per hour from the information provided as a reference to future information seekers? I don't have the time to put into that right now and though it would be good to share.
Wow, I was going about 93mph at 3000RPM --which is only about 50hp out of a possible 92--makes me wonder what the top speed on the VX is. (was trying to get home in time for Xmas). Car passes high speed test with flying colors (no signs of instability or funny noises or anything out of the ordinary, just a bit loud.
Averaging between 75 and 90mph (most of the time I was doing about 80mph) I burned through about 4 gallons of gas over 150 miles (that's a guestimate)--only about 100 of those were interstate (and thus 80mph+). Which equates to a little less than 40mpg. Lot of hard acceleration tho to keep up with the WRX and some other fast cars that I was driving with.
The conversion then is about 4.375 gallons of gas consumed at 3500rpm in one hour which equates to about 24mpg assuming the speed at that RPM is 105mph.
At a little under 2000rpm 2.576 gallons is consumed over 60 miles. 23.29mpg. hmm.. not doing this conversion right. Oh nevermind, I understand. This is max output at the given RPM. So if I was full out going up a slight hill maintaining 105mph at 3500rpm I'd still be getting 24mpg!? That seems pretty damn good. So I'd be getting better fuel economy full out at 105mph then I would be on a grade that would force me to be at full output (up a hill) at 60mph. Interesting. I always wondered if that would be the case because there is more power at the higher RPMs.
If 208 grams of fuel is used per horsepower per hour then you multiply that by the number of horsepower produced at that given RPM right? which would be about 62hp. Then you divide that by 2948 to convert it into the amount of gallons. Or correct me if that isn't the right method. I think I understand correctly what the fuel consumed per hour per horsepower is actually measuring.
EDIT: Seems that the ultimate RPM for power is about 4600rpm. The rag tag mechanic I haven't needed to go to in a long time test drove my car once and said the power drops off at about 4500rpm. He said the car's power band is between 1700 and 4500rpm. He said anything outside that range and the car isn't making power. He was giving me a hard time for running my car at low rpms--that the car wants to be revved to normal engine speeds but he didn't seem at all familiar with the idea of a car being designed to run at a lower RPM to save fuel because he drives an American muscle car. Anyway, I digress.
So I'd be getting better fuel economy full out at 105mph then I would be on a grade that would force me to be at full output (up a hill) at 60mph. Interesting. I always wondered if that would be the case because there is more power at the higher RPMs.
without looking at the #'s and assumptions, I'd think it doesn't take into consideration aerodynamics and the large increase in drag force from 60 to 105 MPH. So while the engine may be slightly more efficient, there's a lot more work the engine is having to do to overcome the aero-drag forces.
right, that's why I said up a hill at 60mph--because you'd have to be at a greater incline at 60mph to be at full output and not accelerate beyond 60mph. At 105mph, you'd have to be at a very small incline to maintain 105mph at full output without accelerating. So, yeah, kind of a dumb point I am making.