Thanks for the info Jeepers.
Hopefully I have not derailed FastPlastics thread too far...
Glad we can help out a fellow Jeeper. It's Nice to see I'm not the only one with a Jeep on these forums. Sadly I've been busy the past couple of days so haven't had time to do any work on the Jeep. Plus haven't been driving enough for mileage readings. Man I wish I had a scan gauge . So it's nice to see the thread still moving.
To me the Jeep is like a sledge hammer.
Crude but effective and pretty unbreakable.
The aero sucks but it's not heavy for its size (1000 lbs less than a TrailBlazer). I really think with the right tuning it could do a lot better on mileage.
Ok for those of you following this thread. Recently I did some highway driving to my buddies wedding about 60miles away. Sadly I didn't have time to fill up right away after getting back in to town. So all I have is estimates on what I got for highway mileage.
I traveled 190.1miles on 9.496Gallons. 120 of those were highway. If you use my previous high of 16.44MPG in town you will get the following numbers.
70miles in town / 16.44 MPG = 4.258 gallons for highway
9.496gallons - 4.258 in town gallons = 5.238 gallons
120 highway miles / 5.238 gallons = 22.91MPG highway
If you use the last tank which for what ever reason was quite a bit lower 15.25MPG in town.
70miles in town / 15.25 = 4.590 gallons
9.496 gallons - 4.590 in town gallons = 4.906 gallons for highway
120 highway miles / 4.906 gallons = 24.46MPG highway
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
Ok so I had some time today to work on the Jeep. I decided to start working on the under body, hopefully to smooth the ruff under belly of the Jeeps. I'm following the input of many of you and starting at the front and working my way back. So far all I got done today was make the brackets to hold the panel on. But It's progress anyway. The panel is going to be about 12X38in and should push most of the air down under the front axle.
Any suggestions on what to make it out of? I have a good size sheet of steel but its hard to cut and weighs a lot. I was thinking about using a sheet of galvanized steel used for air ducts in houses. I know it's a little light weight but it's easy to work with and I think if I would roll the edges it would probably hold up pretty well.
Another question is should I wrap the sheet around the sides of the brackets? Or just the under side? Or should the panel angle as much as possible towards the wheel wells?
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
Boy Blue - '93 Cherokee Country 90 day: 18.55 mpg (US)
Glad to see this after our own exchange. This'll be inspiration for sure
I was wondering about your airdam, if you plan to only have it within the bounds of the front wheels, or will it wrap to shield the front wheels at all?
The brackets look good. I'm interested to see what your results are; you're starting with a pretty rough underbody!
I like your idea of the ductwork - metal (24 gauge I think). Would be pretty durable for your jeep stuff, but light and easy enough to work with. I quoted it out at local heating and air conditioning shops at ~1/square foot. Depending on how my coroplast holds up, it may get replaced with that stuff. As for right now, and during testing, I'm glad to be using free material with $10 in duct tape, $10 in screws/washers, and $10 in spray paint.
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"You laugh now at my recycled materials-ecomodded car. I laugh later when I see you at the fuel pump!"
The day will come (soon) when a Geo is worth more than a Hummer, except for scrap metal. http://www.scientificmethodfueleconomy.blogspot.com/
Glad to see this after our own exchange. This'll be inspiration for sure
I was wondering about your airdam, if you plan to only have it within the bounds of the front wheels, or will it wrap to shield the front wheels at all?
I think I'm going to keep it within the bounds of the front wheels. Making it kind of a light weight skid plate.
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
Thanks to thirdman for finding the Flow Illustrator. I decided to give it a whirl using the under body of my Jeep and the new skid plate I'm working on. It's a very basic flow pattern (2D for starters) and not perfectly to scale or anything. But I think it gives the general idea anyway.
Let me know what you think and if I need to adjust anything.
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
Cool, I'd say see if you could extend it a bit more towards the bottom of the axle tube since it seems like you are still getting some flow over and above the axle
Cool, I'd say see if you could extend it a bit more towards the bottom of the axle tube since it seems like you are still getting some flow over and above the axle
Ok so I ran a few more tests and found that making it longer did help a little getting it under the axle. But I found adding a lip at the end seems to make the biggest difference. Plus I think adding the lip would help strengthen the trailing edge of my panel as well.
Thanks for the help.
Phil
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
Ok, this is a little off topic. But I was wonder if anyone knew if a 1998 Jeep Cherokee has what I've heard of "Fuel Cut Off"? When your coasting down a hill it shuts off the fuel flow. I don't have a scan gauge so I don't know if it does or not. The reason I'm asking is the last tank of gas I tried just driving with out shifting to neutral. Turns out I got better gas mileage then I've gotten using the N shifting.
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
Boy Blue - '93 Cherokee Country 90 day: 18.55 mpg (US)
Quote:
Originally Posted by FastPlastic
Ok, this is a little off topic. But I was wonder if anyone knew if a 1998 Jeep Cherokee has what I've heard of "Fuel Cut Off"? When your coasting down a hill it shuts off the fuel flow. I don't have a scan gauge so I don't know if it does or not. The reason I'm asking is the last tank of gas I tried just driving with out shifting to neutral. Turns out I got better gas mileage then I've gotten using the N shifting.
If someone figures this out, I'd like to know the source so I could investigate on my '93 Cherokee as well.
FP - where do you find this Flow Illustrator? Looks useful, and I'd love to put it to work for me. Also, the skid guard looks good, is this going to be with the air dam as well?
FP - where do you find this Flow Illustrator? Looks useful, and I'd love to put it to work for me. Also, the skid guard looks good, is this going to be with the air dam as well?
The flow illustrator is thanks to thirdman who posted the link to the app here. It's nothing special but it gives you an idea of what's happening.
As for the air dam. For now I'm going to forgo building it. I do mostly in town driving and the design idea I had to keep ground clearance would require dropping it down for highway driving. So I decided to work on the skid plate instead. Smoothing the airflow under the vehicle without dropping my clearance.
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
i'm hearing more and more about rock-crawlers using "cutting board" material for their skidplates. light, strong, and slick. apparently you can get the stuff in bigger sheets in various thickness. i think the offroad guys use 1/4" or 1/2", but i bet it comes in thinner pieces.
for the "lip" at the end, cut a strip about an inch wide, the length of the skidplate, with a saw set at 45 degrees. glue/screw it on, and theres your deflector/brace. (you could add more than 1 layer if you wanted to go farther down)
Picked up a sheet of Galvanized steel today (well yesterday now). Only cost $7 for a 24x36in sheet. Sadly they didn't have any long enough so I'm going to have to put a seam down the middle. Not that big a deal seeing as I was going to reinforce it in places anyway. I'll see about posting pics when I get it started.
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
Last edited by FastPlastic; 07-18-2008 at 04:54 AM.
i'm hearing more and more about rock-crawlers using "cutting board" material for their skidplates. light, strong, and slick. apparently you can get the stuff in bigger sheets in various thickness. i think the offroad guys use 1/4" or 1/2", but i bet it comes in thinner pieces.
for the "lip" at the end, cut a strip about an inch wide, the length of the skidplate, with a saw set at 45 degrees. glue/screw it on, and theres your deflector/brace. (you could add more than 1 layer if you wanted to go farther down)
Ultra High Molecular Weight Polyethylene (UHMW-PE) is what you're thinking of. Used all over the place where strength and slippery go together. Awesome stuff, but expensive. You can get 1/8" 4'x8' sheets. I place to do that someday and just cut to fit the underside.
Ordered my ScanGaugeII today!!! I'm excited if you can't tell. Ebay is running a special that you can get 10% off any purchase if you use Paypal. Which tipped the scales for me on weather or not I should get one. Saved me $16 bringing the total cost to $143.95. If anyones interested the code is CJULYFUN0810P. It's good till the 29th of July, so if your interested you might want to pick one up soon.
Can't wait to really do some testing to see what improvements work the best!
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
Last edited by FastPlastic; 07-23-2008 at 03:49 PM.
Ok had some more time to work on the skid plate. Turns out my 2000 pound epoxy doesn't want to stick to the galvanized steel. So I switched to using pop rivets instead. Got the two peices connected together (needed 37" the sheet was only 36". Grr) and all of the cutting and bending done. I plan on putting in a few more pop rivets along the bottom edge to strengthen the panel up a little bit more (plus I like the looks of them). Then about all thats left is the final mounting.
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Adjusted for my driving habits. 80%city/20%Highway.
20mpg city/30mpg highway or bust! Check out my mods so far
. So it's nice to see the thread still moving.
