Difficulties in Effective A-B-A Testing of Insight 1

[3-Wheeler]

Originally Posted by jamesqf

And those fasteners tend to break on removal after they've been exposed to the elements for a few years, and they are not cheap. Though FYI, you can find them online much cheaper than from the Honda dealer.

Hi James,

I don't have stock under body panels, but I know what you meant.

Mine are mostly held on by 1.5 inch plated plaster board screws.

When things get a little warmer, it will be time to get a look at everything after a long winter's driving with the new panels.

Jim.

[jime57]

Originally Posted by 3-Wheeler

Maybe not as clean and consistent as doing all the changes in one day, but adding under body panels AND the tail extension to the car would take multiple hours to accomplish just one change.

Practicality speaks!!

Jim.

I certainly agree about practicality!!! It is a powerful constraint.

I did some experimental driving today on I64 east to Williamsburg. I was interested in the lean burn performance at speed. This route has long gentle hills, pretty much one after another, for most of the distance. I targeted two cruising speeds, 55mph +/-2, and 60 mph +/-2. I was able to pretty much hold his over the entire distances. I think that level of speed control is adequate, since the errors will cancel. I noted that on my car I was able to stay in lean burn at both speeds, with an occasional downshift to 4th, clicking right back to lean burn. On the boattail testing, I think 60 mph gets the nod because we are trying to improve the high cruise performance - if I'm not mistaken.

I think I am going to search for a good interstate section of about 10 miles one way as a test course. (From memory, I believe that I95 south of Richmond is superior to I64 east, but I have to have a look.) For most areas that I have seen the interstate is near optimum for testing at this speed. The occasional truck that approaches from the rear can be warned with a couple of quick flashes, as can any dense traffic approaching from the rear. There seems to never be any forward obstruction at this speed

It seems to me that on something as complicated as a boattail testing, it almost has to be tested and baselined on different days. As you alluded, that will mean that one must observe temperature and barometric pretty closely and duplicate conditions as closely as possible, or be able to make some adjustments as suggested. Of course, tuft testing can be done on most any day unless it is raining. (Any substantial testing in one day usually involves changes in temp anyway, as you noted.)

[3-Wheeler]

Originally Posted by jimepting

...I think I am going to search for a good interstate section of about 10 miles one way as a test course. (From memory, I believe that I95 south of Richmond is superior to I64 east, but I have to have a look.) For most areas that I have seen the interstate is near optimum for testing at this speed. The occasional truck that approaches from the rear can be warned with a couple of quick flashes, as can any dense traffic approaching from the rear. There seems to never be any forward obstruction at this speed...

jimepting,

The question I have, is on the Interstate, how do you pick a time when others will not try to pass you in the other lane??

In Wisconsin, we have I-94 within about 10 miles of the house, but there is so much traffic there, AND there is always someone who is going 70 or 75 that will cause air turbulence for your aero testing.

I agree that driving faster is better to measure the affect of the aero mod, but can't figure out how to accomplish this without doing it late at night on the Interstate.

Jim.

[jime57]

Originally Posted by 3-Wheeler

jimepting,
In Wisconsin, we have I-94 within about 10 miles of the house, but there is so much traffic there, AND there is always someone who is going 70 or 75 that will cause air turbulence for your aero testing.

I had not thought about that issue. Do you think it is a serious error inducing problem? Hard to account for I suppose. If one baselines about the same time of day on the same road section, then the net impact on the percentage improvement, if any, would probably be small - maybe

If not an interstate, then we have to look for a 4 lane section of a blue highway I guess, but the problem doesn't necessarily go away. There is no way to maintain any stable test speed on a two lane.

The only infallible way is a wind tunnel. Maybe someone can find an aeronautical engineering grad student, with wind tunnel access, who needs a thesis subject Maybe we can copy the Wright Bros. low speed tunnel where the reynolds number isn't much different.

[user removed]

Try route 58 from Emporia to Suffolk. A few miles east of Emporia it's very flat for something like 40 miles. I once drove 40 miles west on 58 and never got close to more than 15 cars going in the same direction. 55 MPH divided highway.

The week Princess Diana died.

regards
Mech

[jime57]

Originally Posted by Old Mechanic

Try route 58 from Emporia to Suffolk. A few miles east of Emporia it's very flat for something like 40 miles. I once drove 40 miles west on 58 and never got close to more than 15 cars going in the same direction. 55 MPH divided highway.

Hi Mech,

I'll take a look at that. Drove over your way yesterday while doing some experiments with lean burn. Looked at VA 241 as your suggested. It is a nice section of road, but the level uncongested part isn't long enough to be practical for testing. In my case there is an additional problem. That section is so far away from my garage that the "commiting" distance to any tests would be too great. But I fear I'm going to have that problem with anything I use. I want to check out the section of I95 between Richmond and Petersburg, but of course that is truck "alley." At least it is close.

[3-Wheeler]

Originally Posted by jimepting

...If not an interstate, then we have to look for a 4 lane section of a blue highway I guess, but the problem doesn't necessarily go away. There is no way to maintain any stable test speed on a two lane...

And that's the reason I like this old country road about 15 miles from the house.

It's on the way to work, rarely traveled, but quite bumpy right now, due to the cold weather.

Once I get ready to try some changes to the car, I could drive over there on a Saturday morning, and run laps back and forth. It would be at 60 mph, and maybe not a nice as traveling on the Interstate but certainly less crowded.

Jim.

[jime57]

Sounds like you may have the perfect road. Unfortunately, it's going to be a bit of a trip for me to use that road The problem we have around Richmond is a high level of congestion generally. We are on the main north/south coastal route and certainly a part of the east coast megopolis. I don't expect to find a testable 4 lane that doesn't have some truck traffic. I'll need to study the traffic patterns to see when it is at a minimum.

Question: I did some experimental sanding today on a piece of packing type styrofoam. I used 80 grit and I noticed that I had to get the pressure just right to avoid ripping the little balls away whole. Of course that made the surface very rough. Does the construction grade white and pink sand better?

Got under the car this morning and did a bit of looking at the stock Honda bellypan work. It would appear that there is a little additional work that can be done at the rear, in the area of the axel, that would make the boattail perform better, but Honda did a pretty good job otherwise. I think I'm willing to do the slight bellypan work and any boattail I can work out as a single step in the testing and chalk it all to the bellypan.

[RobertSmalls]

You don't need to have the road to yourself to do high-speed coastdown testing. In a 65mph zone, you can coast down from 74mph to 60mph with a small break in traffic. In Buffalo, there are expressways where you could do that 20 hours a day.

You'll want to do runs in both directions, to account for gravity. As for Crr, ideally you'd do low-speed testing on the same pavement, so you may have to test for Crr on side roads and just hope the numbers are similar.

Sure, passing cars, gravity, etc will interfere. But you can deal with noisy data by having a very large number of samples.

[3-Wheeler]

Originally Posted by jimepting

...Question: I did some experimental sanding today on a piece of packing type styrofoam. I used 80 grit and I noticed that I had to get the pressure just right to avoid ripping the little balls away whole. Of course that made the surface very rough. Does the construction grade white and pink sand better?...

I answered over here to keep the question with the tail extension discussion... Hope this is OK.

http://ecomodder.com/forum/showthrea...tml#post164865


Jim.