lx to hf expectations

[civic lover]

What can I expect to gain for mpg with the hf conversion? I understand epa is 50 plus but you have to remember i am toting around a few hundered pounds more. Is there anyone out there with some good gas logs of the same conversion? Thanks...

[civic lover]

someone has to have a log on here...

[Hateful]

I know nothing about civics being I'm one of the few without one. I do remember the EPA estimate allowing for 300lbs of passenger and cargo. I also have read that every 100lbs of extra weight decreases mileage by 1 mpg.By calculation the weight difference you may be able to come up with an estimate.

[StorminMatt]

There is also aerodynamics to consider here. An LX is not going to slice through the air as easily as a CRX.

[civic lover]

I know that is why I was wondering if there were any logs out there. (I am still new here). It is hard to calculate the weight and aero drag and so on. It is much easier to calculate based on some real numbers from other people.

[FritzR]

I don't think the gas savings would pay for the work unless you do it yourself. Even then I think the savings would be pretty marginal. Sure my HF gets 65 MPG on a flat surface at 65 MPH but only just maintaning speed. I only got 45 today in a 20 MPH headwind on a run that would normally get me 55+. You would not want to use the HF tranny in a 300 lb heavier car. I figure a LX with a HF head would get you maybe 40 on the freeway and around town would drop your average. If you did a bunch of aero mods it would do better but I don't know how much better than leaving the engine alone with those mods

I think some kind of metering for the gas consumption would probably make a bigger difference with some practice. A duty cycle meter on an injector wire, $19.95 at sears, so you could figure out your consumpion per hour would do. You could also try the DIY mileage computer from the how to section or wait for them to figure out the one they are working on at ecomodder.com

For your money doing the federal VX swap would be a better idea since you already would have to modify your wiring for MPFI. You could pick up a complete swap for $400 plus the O2 sensor or so. I think the 62 HP HF motor would end up working too hard and might even cost you extra gas if you do a lot of stop and go driving.

Is the new owner of the Frankencivic on this site to fill us in on how a VX/LX performs?

[civic lover]

I hear you, but if you were to add a passenger to your rex would your mileage significantly drop? If so then this swap would be pointless (because of the 300 lb difference). I did do some weight reduction to narrow the gap. Minnesota also did some wonderful weight reductions too, due to the salty roads in the winter. I have the whole HF swap ready to throw in (from a parts car going to the crusher), but am still contemplating. In other words it wouldn't cost me about 100 bucks said and done. I do feel however by doing the mpfi swap with the hf ecu I would net some mpgs.

[FritzR]

Well if you already have all the parts I say go for it but stick with the original transmission. It's not the weight that will hurt your freeway mpg much it's the wind resistance. The hf motor also runs smooth down to 1000 RPM. From my experiments with the supermid it's best to accelerate pretty hard to get out of the low gears. 20 MPG is the best you can get in 1st so get out of that gear fast. Race it up to cruising speed and skip a gear and cruise seems the best. Take it up to 35 in 2nd and then go straight to 4th and cruise.

[civic lover]

yeah I shouldn't have to worry too much about highway or interstate speeds cause most of my driving is country roads that are flat. I guess someone needs a gas log on here with the swap in a sedan. I guess it will be me. I guess you could look for me starting my log in about June.