Honda Insight Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
811 Posts
Discussion Starter #1
Hi, my silver 2000 mt was missing all the under body panels (in the front ) when I bought it 6 months ago. I bought the parts (all ~ 500.00 from majestic) and finally got to fix them couple of weeks ago.

At some point i regretted spending so much money for almost nothing as I knew the mpg impact could not be significant anyway.

So i am driving the car now for 2 weeks as it is closer to original configuration (still missing one of the long panels that has been covering the brake lines initially).

I can definitely attest that I feel more engine power even at low speeds which is curious as the drag increase from the missing panels at 30mph or less should be very minimal if present at all.

However I feel more engine power at all speed , bigger lean burn window, less assist used and overall increased MPG. if i should quantify the mpg effect i would say it is somewhere between 4-8 mpg.

I cannot set a more precise number as now I find my car feels better at higher speeds so where I was driving with 48-50 mph before now I keep 53-55 mph and at the end I still get somewhat more mpg than before (even with the "higher" speeds).

It was a pleasant surprise.
 

·
Registered
Joined
·
728 Posts
I find that aerodynamic attention to detail can have a pretty big impact. When I straightened out my front bulkhead and reduced my gaping panel gaps somewhat, the fuel economy improved noticeably.

By the way, what kind of fuel economy are you getting at 55mph?
 

·
Registered
Joined
·
811 Posts
Discussion Starter #4
I find that aerodynamic attention to detail can have a pretty big impact. When I straightened out my front bulkhead and reduced my gaping panel gaps somewhat, the fuel economy improved noticeably.

By the way, what kind of fuel economy are you getting at 55mph?
Yes I saw your post in another thread couple of days ago and i tried different scenarios to find out , my usual speed now is ~ 52-53 mph so a couple of times I deliberately went to 55 and kept it there but there was no easy answer for me .It is hard to say what I am getting at 55mph on a level road as the roads i drive almost everywhere have some sort of incline or decline . even when there is some so so level part, then the wind plays a big role.

so I would say when there is a very small incline or a little unfavorable wind i am getting ~ 105 at 55mph when there is some decline or tail wind I see ~125 mpg.
 

·
Registered
Joined
·
811 Posts
Discussion Starter #5
anyone have pictures of what the underbody should be? should the bottom be totally covered?
somebody posted their underbody pictures a couple of days ago , it was a blue insight for sale ~ 11000 dollars , 2002 with either 30k or 60k miles

I do not remember the thread name but I cannot create links anyway...
 

·
Registered
Joined
·
51 Posts

·
Registered
Joined
·
804 Posts

·
Registered
Joined
·
13 Posts
I have seen a similar win with mine on and off there are some interesting effects on stability as well, autospeed in oz, "julian edgar" tried to improve the insights aero and failed,

with the aero tweakers there always talking CD but you need to look at CD x Area CDA, this is where the insight wins it has a very small frontal area, even compared to the EG civic shape.

it's quite interesting to look at the the CD of F1 as well .7, 1 with big wings :)

p
 

·
Registered
Joined
·
804 Posts
Speaking of the AeroCivic, I intend to complete a similar tail extension. Concern for aesthetics had stalled the project, but my need for good fuel economy at >70mph has me working on a removable tail extension.
I've been following your thread some. Be interested in the results. Hope law enforcement does not have issues with the boatail, as I'm thinking about it.
 

·
Registered
Joined
·
243 Posts
Hi, my silver 2000 mt was missing all the under body panels (in the front ) when I bought it 6 months ago. I bought the parts (all ~ 500.00 from majestic) and finally got to fix them couple of weeks ago.

At some point i regretted spending so much money for almost nothing as I knew the mpg impact could not be significant anyway.

So i am driving the car now for 2 weeks as it is closer to original configuration (still missing one of the long panels that has been covering the brake lines initially).

I can definitely attest that I feel more engine power even at low speeds which is curious as the drag increase from the missing panels at 30mph or less should be very minimal if present at all.

However I feel more engine power at all speed , bigger lean burn window, less assist used and overall increased MPG. if i should quantify the mpg effect i would say it is somewhere between 4-8 mpg.

I cannot set a more precise number as now I find my car feels better at higher speeds so where I was driving with 48-50 mph before now I keep 53-55 mph and at the end I still get somewhat more mpg than before (even with the "higher" speeds).

It was a pleasant surprise.


After removing my underpanels I didn't see much difference in mpg. Maybe 1-2 mpg at most. I get 50 to 55 mpg driving 60-75 mph. And pass when there's room. Its my CRZ.
 

·
Registered
Joined
·
32 Posts
The Guys at Oaktec extended the underpans on their rally car back to the rear fender which hangs down below most everything else at the back. I don't know if they ever calculated/measured any improvement in m.p.g. Might be worth contacting them for info.

XXhttp://www.oaktechybrid.co.uk/site/content_home.phpXX

I have toyed with the idea of closing in the exhaust system, hardly the most streamlined structure, with sheet alloy to have a comletely flat underbelly and trying to arrange "dragless cooling" by having an intake scoop and exhaust expansion cone. This would work on the ram jet principle as used by some piston engined aircraft in the past. This also has the benefit of being a relatively cheap mod but the consequences of an overheated exhaust system in an aluminium car do not bear thinking about. Even if it didn't ignite the alloy could get hot enough to lose it's strength :-(
 

·
Registered
Joined
·
728 Posts
...or to increase the A/C load in the cabin. What if you have loose fiberglass batting above, and air space below, the exhaust?

But I'm just going to leave my exhaust unpaneled for now, especially forward of the gas tank.
 

·
Premium Member
Joined
·
1,067 Posts
The Guys at Oaktec extended the underpans on their rally car back to the rear fender which hangs down below most everything else at the back. I don't know if they ever calculated/measured any improvement in m.p.g. Might be worth contacting them for info.

XXhttp://www.oaktechybrid.co.uk/site/content_home.phpXX

I have toyed with the idea of closing in the exhaust system, hardly the most streamlined structure, with sheet alloy to have a comletely flat underbelly and trying to arrange "dragless cooling" by having an intake scoop and exhaust expansion cone. This would work on the ram jet principle as used by some piston engined aircraft in the past. This also has the benefit of being a relatively cheap mod but the consequences of an overheated exhaust system in an aluminium car do not bear thinking about. Even if it didn't ignite the alloy could get hot enough to lose it's strength :-(
Go ahead and insulate the muffler with fiberglass batting.

I have it on my first cat con next to the engine, and it works fine. I have under-body smoothing panels that keep water from splashing on the fiberglass, so that it stays dry.

Not only does the cat con heat up more quickly, but keeps heat losses in the engine compartment down as well.

Jim
 

·
Registered
Joined
·
642 Posts
The Guys at Oaktec extended the underpans on their rally car back to the rear fender which hangs down below most everything else at the back. I don't know if they ever calculated/measured any improvement in m.p.g. Might be worth contacting them for info.

XXhttp://www.oaktechybrid.co.uk/site/content_home.phpXX

I have toyed with the idea of closing in the exhaust system, hardly the most streamlined structure, with sheet alloy to have a comletely flat underbelly and trying to arrange "dragless cooling" by having an intake scoop and exhaust expansion cone. This would work on the ram jet principle as used by some piston engined aircraft in the past. This also has the benefit of being a relatively cheap mod but the consequences of an overheated exhaust system in an aluminium car do not bear thinking about. Even if it didn't ignite the alloy could get hot enough to lose it's strength :-(
Audi have a panel you can buy for the A2 to close off the exhaust, it was a standard item on their 1.2 TDi Eco model (3L/100km & 0.25Cd) but people are getting some of the items from dealers for their 1.4 versions (0.28Cd)
 

·
Registered
Joined
·
243 Posts
Hi, my silver 2000 mt was missing all the under body panels (in the front ) when I bought it 6 months ago. I bought the parts (all ~ 500.00 from majestic) and finally got to fix them couple of weeks ago.

At some point i regretted spending so much money for almost nothing as I knew the mpg impact could not be significant anyway.

So i am driving the car now for 2 weeks as it is closer to original configuration (still missing one of the long panels that has been covering the brake lines initially).

I can definitely attest that I feel more engine power even at low speeds which is curious as the drag increase from the missing panels at 30mph or less should be very minimal if present at all.

However I feel more engine power at all speed , bigger lean burn window, less assist used and overall increased MPG. if i should quantify the mpg effect i would say it is somewhere between 4-8 mpg.

I cannot set a more precise number as now I find my car feels better at higher speeds so where I was driving with 48-50 mph before now I keep 53-55 mph and at the end I still get somewhat more mpg than before (even with the "higher" speeds).

It was a pleasant surprise.
Just out of curiosity has anyone used skirts to improve aero? As far back as the mid seventies we used molded floor panels from Lowes toencircle the lower body 'edges' to create a restriction to air flowing under the car. The portion under the front bumper was also a spoiler much like today's NASCAR and IMSA racers.
The move always yielded more top speed which should be due to aero improvements but then hp/lb was much higher than our gen 1's. Lot easier to do than underbody panels and permits easy access to oil changes.
Still, with low hp the increase in body frontal area may cost mpg.
 
1 - 19 of 19 Posts
Top