Rep Power: 174

would there be any real mpg benefits to switching out my ex transmission for an LX longer geared version?

 
Rep Power: 352

for the cost it takes to swap an EX to LX........the answer is NO.

you are going to be spending a LOTTTTT of money in the process....just use the "money" that you would have spent on the swap (we're talking about thousands) and use it to pour gas.

it'll be more efficient and cost effective as far as how many mpg you get per dollar

 
Rep Power: 174

In the thousands??? Where did u get that number from? I'm seeing lx transmissions going for $400 all day long and I could sell my mint ex trans to recoupe some or all of the money. Unless u need a different pcm or need a tune for the gear ratio change I don't see where the cost is coming from.

What kind of mpg does an lx do at over 75 mph if an ex just squeezes out a tad over 30mpg? The difference is what will or will not make it worth it to me

 
Rep Power: 812

aerodynamics are everything, not rpms. these civics have terrible cd from the factory, but so does every other car (except the ev1). at speeds above 55mph, your mileage will go down quick. most of the energy is spent overcoming wind resistance. this guy got 50mpg at 90mph with his older civic. you dont have to go that extreme, but take a few hints from the guys that race on the salt flats. block the upper grill to provide smoother flow, delete the side mirrors or replace with folding version, get mostly closed rims, fender flares, under car body pan, lip kit, lowering springs, etc.

http://aerocivic.com/

 
Rep Power: 352

there are a lot more than jsut swapping out the transmission, i hope you know that... if u want to get a fully functional LX

 
Rep Power: 174

hi, can you explain more? not going to do this but for future reference what else needs to be swapped? i see a LX transmission with 100k miles on craiglist for $300 right now.

how bad can a civic be aerodynamically? my 2000 regal which is way bigger and does not look as aerodynamic gets 30 mpg at speeds in excess of 80 mph all day long. but around town that number drops to 18 where my civic gets about 28. seemed rpm related when i compare the two but my regals about 2300 rpm at 85 mph where the civic is somewhere above 4k lol seems crazy high for a OD gear

 
Rep Power: 812

this is a good place to start. shows how they were able to increase fuel efficiency in the hybrid civic and insight.

http://www.honda.com/newsandviews/ar...=2003112038102

http://www.honda.com/newsandviews/ar...=2003112040635

and explains how a k20 swapped insight still gets over 50mpg

http://www.tamparacing.com/forums/lh...sight-lht.html

oh yeah the best list here

http://ecomodder.com/forum/fuel-econ...ifications.php

 
Rep Power: 0

Also colder air is harder to drive through, so you will get better mileage if it is warmer outside.

 
Rep Power: 0

I've done 3 trips from Canada to the U.S recently about 1500km/1000 miles each way every trip in my 04 lx. If u want to be doin 75mph+ your gas mileage will be less than doing just 5 miles under. I learnt to drive according to rpm's rather than speed. Keeping ur civic at 3000rpm on cruise still keeps you going at 70mph and gives you optimal feul efficiency imo while still moving at a steady pace. If time and passing people is a big factor for you then u'll pay for it in fuel, I'll personally save money on fuel... but thats me, i dont mind layin back, pumpn some music and enjoying the ride. I dont know about the comments from other maybe more experienced posters but Im speaking from my personal experience.

 
Rep Power: 313

My civic goes 60mph at 3200 rpms.

 
Rep Power: 174

yes exactly, so 70 mph is 3k rpm in an lx and 60 mph is 3200 rpm in an ex. thats a big difference. you could to 80 in an lx and pull less revs than 70 in an ex

 
Rep Power: 812

on my auto ex, i can go 68mph around 2800rpms (before vtec crossover for better mileage). its right at 3k rpms going 70 but gas mileage takes a big hit for hardly any speed increase.