Gave up on heating fuel, will live with 49.9 mpg at 65 mph

[cheapybob]

I hate messing with fuel systems. Came up with the idea of heating the fuel using a heat exchanger made out of a gas filter wrapped in copper tubing hooked into the heater hoses, but it was a nightmare changing the filter, and the it leaked terribly, spraying gas. There was a slow drip where I spliced in my heat exchanger modified filter, and the stupid Fram filter had a bad connection on it (crimped, no clamp) that was literally spraying fuel.

Anyway, after I got that mess fixed i went to plumb it into the cooling system, but since I have a piece of crap car and am incompetent at mechanical work, I found that I can't disconnect the line I wanted to hook into without breaking the line or ruining the ferrule.

I did wrap the tubing from the airbox up to the throttle body with insulation. I found that its not just a tube like I thought, and its actually double or triple the tube size up near the throttle body, essentially providing storage of already filtered air, I guess. I suspect that without this tube being insulated, it allowed the air to cool a bit, especially if I shut off the car and came back 10 min later and tried to restart. so I'll see if I can now get it to restart when warm without having to trick the IAT into thinking the air is colder.

I also completely sealed off the front end and removed the license plate bracket, so its as clean up there as it can get, now, without resorting to a belly pan or something. The radiator can still get air from underneath.

I did another test run just to make sure I had no more leaks. Outside temp was about 70f. Same tank of gas as my 53 mpg run at 60 mph the other day. My IAT was at 185 and ECST at 195 at the start. I made the entire run at 65, with max TPS of 17 except during the turnaround at which point I was forced to downshift and go TPS 70 to get back onto the expressway because there was traffic bearing down on me. Usually I don't have to do that. My speeds varied a bit on the highway from as low as 63 to as high as 67. I didn't use cruise control. When I completed the run, my IAT was up to 232 and ECST up to 211, which is very good. MPG at the end of the run was 49.9. Not bad for a 65 mph run with a gas hogging turnaround.

[Matt Timion]

49.9mpg is pretty good, but you already know that :P

I agree with staying away from the fuel stuff. I just recently had to drop the tank on my honda n600 and I'm still paranoid that I did something wrong. There is a certain fear that only combustible gas can give you.

*shudder*

Anyway, I'd focus more on aerodynamic modifications now if I were you. There is to be a few MPG you can squeeze out of that bad boy.

[The Toecutter]

Only a few? Talk about an understatement!

With rear wheel skirts, removed passenger mirror, underbelly, he could probably get highway mileage at 60 mph to around 60-65 mpg.

[cheapybob]

Originally Posted by The Toecutter

Only a few? Talk about an understatement!

With rear wheel skirts, removed passenger mirror, underbelly, he could probably get highway mileage at 60 mph to around 60-65 mpg.

I'm not going to take off the mirror. I LIKE the mirror.

I'll take off the wipers and use rainx like I do on the race track. It works well.

I'd agree that a belly pan SHOULD help, but I bet it wouldn't be by much. I'll see if I can get some thin scrap aluminum sheet from a place a friend works.

I doubt fender skirts would give much MPG. I'll have to look and see if someone has done a heads up test, here.

I wasn't able to document any gains from my aero mods thus far, and I'm absolutely sure I improved it significantly. I used to build model airplanes and rocket cars for fun, so I'm familiar with what will cause drag.

I think the next thing I should try would be to switch to lighter wheels/tires with fewer RPM's per mile and low rolling resitance. My tires look like they have 50k left in them, so its going to be a while unless I find a real bargain.

[Matt Timion]

Originally Posted by cheapybob

I think the next thing I should try would be to switch to lighter wheels/tires with fewer RPM's per mile and low rolling resitance. My tires look like they have 50k left in them, so its going to be a while unless I find a real bargain.

If you're doing mainly city driving, rolling resistance is where you will get the most gains. Aerodynamics really don't have an impact on fuel economy until around 50-60mph.

[MetroMPG]

Originally Posted by cheapybob

I doubt fender skirts would give much MPG. I'll have to look and see if someone has done a heads up test, here.

wheel skirts plus grille block = +5.7% mpg improvement on my car

http://www.metrompg.com/posts/grille-blocking-part-2.htm

[cheapybob]

Originally Posted by MetroMPG

wheel skirts plus grille block = +5.7% mpg improvement on my car

http://www.metrompg.com/posts/grille-blocking-part-2.htm

Yes, I'd seen that, and that's why I put the effort into streamlining the front end of mine. Unfotunately I got no gain from it, or lost that gain due to the different tank of fuel. I even tried my test at 5 mph higher this last time to see if there would be a difference, and there was none over my last 65 mph run. Again, its a different tank of fuel, too.

Maybe your car has a higher percentage of its drag as aero than mine, so you are seeing bigger gains because your overall friction is being reduced by a higher percentage. You have a very small, light car and an engine about 1/2 the size of mine. It stands to reason that areo is going to have a more pronouced effect on it.

[cheapybob]

I found out that the problem with leaks is because I need to use a flaring tool on the lines. As I've said, I'm no mechanic, so even minor things like that become obstacles becuse there are so many things I don't know.

[SVOboy]

Hell, I dunno what it is either,

When I test this I'm just going to T off a line with a spare molded 180 bend I have. I wonder if I'll see anything.