WOW losing lots of mpg from poor aero.

[WD40]

With the $ saved on gas, you can laugh all the way to the bank.

[steffen707]

Well i just put on my new muffler, first impressions are that its quiet, might get better mpg in town, but lost power on the highway.

I've noticed I can press the gas pedal down a lot farther now, but on first impression it seems to lose speed faster I gotta drive 40 miles on wednesday, i'll try to compare previous trips to this new one.

[California98Civic]

Originally Posted by aerohead

I believe that at the time the VX came to market,that the National 55 MPH speed limit was still in force.The VX would have been calibrated for this speed for the Federal Test Procedures at EPA Mobile Sources in order to optimize the EPA HWY rating.
By operating the car at 65 mph,your asking it to perform in an environment that it was not optimized for.

Speed limits began to go up from 55 in 1987 or 1986, five or six years before the VX engine.

Originally Posted by aerohead

You may want to follow basjoo's lead with the aero.You'll get your lean-burn for sure!

Maybe the lean burn engine was designed with the better aero and taller gearing of the HF in mind?

[steffen707]

Originally Posted by California98Civic

Speed limits began to go up from 55 in 1987 or 1986, five or six years before the VX engine.



Maybe the lean burn engine was designed with the better aero and taller gearing of the HF in mind?

Didn't the crxmpg.com guy (forgot his name on here) get really good gas mileage with his HF gearing in his CRX? If I recall he had dx gearing to begin with and then swapped in the HF final drive and said it was awesome.

[basjoos]

Originally Posted by steffen707

Of course aerocivic mods would help a ton, but I'm not sure i'm ready for all the laughs.

I've had people ask if my car was a hybrid, an EV, and an amphibious car, but I haven't heard any laughs so far.

The aero mods have produced well over $5 grand in fuel savings so far over in close to 190,000 miles of driving, saved my car from being totalled and me from injury when I was rear ended by a speeder and prevented major front end damage in two deer collisions. Plus no dead bugs to clean off the front of the car and the car's body remains mostly clean of dirt and salt spray.

[steffen707]

Originally Posted by basjoos

I've had people ask if my car was a hybrid, an EV, and an amphibious car, but I haven't heard any laughs so far.

The aero mods have produced well over $5 grand in fuel savings so far over in close to 190,000 miles of driving, saved my car from being totalled and me from injury when I was rear ended by a speeder and prevented major front end damage in two deer collisions. Plus no dead bugs to clean off the front of the car and the car's body remains mostly clean of dirt and salt spray.

That's quite a bit of savings. I don't drive a ton though. Maybe 7,000 miles a year, so i'm just trying to figure out my best course.

Thanks for chiming in though, I loved that deer getting hit by the race car video you posted. Pretty amazing.

[aerohead]

Originally Posted by California98Civic

Speed limits began to go up from 55 in 1987 or 1986, five or six years before the VX engine.



Maybe the lean burn engine was designed with the better aero and taller gearing of the HF in mind?

Thanks California for the chronology!
I guess my second thought is that the FTP for EPA HWY cycle would still have been run with the max. 60 mph velocity,and average 48.6 mph on the dyno,so regardless of posted speed limits,the EPA HWY MPG would still reflect the lower speed testing.
My friends the Gilkisons had a VX which we tested at 55 mph on a camping trip beyond the Very Large Array,on to Datil Wells State Park,New Mexico and around Silver City,back into the Las Cruces area.I think we broke 60 mpg.
Nowadays,they have dynos which can withstand 0-60 in 7-seconds without slippage and speeds to 80 mph.

[steffen707]

I've been playing with that aerodynamic calculator and comparing my cars CDA of 7.62 to the vx CDA of 6.16. It shows 14.83hp needed to keep the car at 65mph in a VX and 17.96hp needed in my car.

Do you guys think I will see a large improvement switching chassis to a 92-95cx/vx hatch?

I know guys are talking about putting electric motors on their engines to give a few HP boost, and if this calculator is close to accurate, I have to think I should see a huge improvement in my car wanting to stay in lean burn(making enough power to overcome the drag). I think i calculated that yesterday and it was a 20% reduction in power needed.

I know people have said just aero mod your car to achieve the same results, but it would be easier for me to swap I think.

[aerohead]

Originally Posted by steffen707

I've been playing with that aerodynamic calculator and comparing my cars CDA of 7.62 to the vx CDA of 6.16. It shows 14.83hp needed to keep the car at 65mph in a VX and 17.96hp needed in my car.

Do you guys think I will see a large improvement switching chassis to a 92-95cx/vx hatch?

I know guys are talking about putting electric motors on their engines to give a few HP boost, and if this calculator is close to accurate, I have to think I should see a huge improvement in my car wanting to stay in lean burn(making enough power to overcome the drag). I think i calculated that yesterday and it was a 20% reduction in power needed.

I know people have said just aero mod your car to achieve the same results, but it would be easier for me to swap I think.

If you do the aero mods you'll be practicing load avoidance which is the most elegant form of engineering.
It would be like adding insulation R-Factor to your home.You're reducing its inverse,the heat transfer 'coefficient,' and with the same indoor/outdoor temps,you can be just as comfortable with less heating or cooling.
If you consider adding S-Factor to the car,then its inverse,the drag 'coefficient' is reduced,and you can operate at the same speed on less.
This efficiency will be built in to the car and it can't ever go out of tune,nor ever require replacement parts.
My CRX is at CdA 0.404 sq meters with the kit.You could easily match it with what you have.

[basjoos]

Any aero mod that allows you to go faster on the same horsepower will give you better fuel efficiency at normal speeds.