Hey guys,

I'm a new forum member and virgin Civic owner (03 EX 5spd manual.) I bought the carfor my daily commute of100 miles which is about 96 miles of interstate. Igenerally drive between 70/80 mph @ 3500/4000 rpms. It seems pointless for the revs to be this high since the engine still has plenty ofuumph at this speed. Doesn't this just cause unnecessary engine wear (and noise) for the way I'm using the vehicle?

My goal is to keep total cost of ownership to a minimum. Mpg, maintenance$, repair$,and extending thelife as long as possible are the way. I'm getting about 35 mpgand I'm happy with that and I plan to drive the car until the wheels fall off.

Does it make sense to gear the car up to reduce the rpms? What would be the least expensive way to do this, differential, gears or different tranny all together? How much and can I do the mods myself? (I'm mechanically competent but the only tranny I've been in was on a dirt bike.) What would this mod do to mpg's, seems like it would help?

 

Smaller engines need to rev higher. Im pretty sure honda geared it perfect because civics are economy cars so they are meant to save as much as possible

 

cyberx32, While I agree with you in general terms, engineers make a lot of compromises in the designs because cars are used in so many different services. Also, government ratings are calculated with a certain driving profile. Engineers design machines to optimize some "figure of merit," a model of how the machine will be used andcriteria it must meet within that model.

My car will have 95%+ of its miles at about 75mph.Honda probablydid not engineer EX for least cost of ownership in this scenario since it's out on the edge of the bell curve. For example, such a car may have less thanenjoyable drivability in stop-and-go city conditions which my car will hardly ever see.

 

Well i dont know too much about that, but by what your trying to say, sounds like you will need to take apart the transmission and install a different top gear. Maybe someone else here would know if thats even possible to do.

 

Who cares if the rpm is at 4000 crusing. Youre still getting 35 mpg and acar that will outlast any other car out there. Theres no extra wear from it crusing at 4000rpm. Its meant to be able to drive safely all the way up to redline.

 

oh and just to put it out there, if you drive at 60 mph, you will get better mileage.

 

my 95 civic crusies at those speeds at that rpm. I get damn good gas mileage and have over 250K miles on it. i wouldnt even touch it. If you think about how much that is gonna cost to get done and it really wont make much difference. IMO i wouldnt touch it

 

I believe dx/lx transmissions are geared higher... but personally, I'd just keep the ex transmission you have. Spending how much money on a used transmission and doing that much work (pulling the whole engine to get to the transmission) just for the sake of lowering the cruising rpm's seems a little much. Not to mention what that would do to resale values.

 

good point. when on hwys, being in the top gear uses less gas than going through a city at 30 mph.

 

The cool thing is that, even though you're at a higher RPM than many cars, you're getting great mileage. The issue with gearing it down more to decrease RPMs would be that you're throttle position would be greater, which would more then likely use more gas. I've found that if I'm driving around town doing 50, I get better mileage in 4th then 5th, even though the RPM is higher. Just some food for thought, but I'd stick with the stock gearing.