Engine Rebuild.. Fuel Economy?

[brucey]

Either way, top gear should like, idle the engine. And mines revving to nearly 3,000 rpm at 70 mph!

[getnpsi]

A little extra tq down low almost always helps. There are people changing the engine from a 1.3 to a 1.6L in the festiva/aspire (same engine design) and report almost no change. If I choose to rebuild an older engine I would like to think the new tolerances are a lil better, and would opt for some polishing on the components to reduce friction. that way you can have your mpg's under 3000rpms, and a little more fun above that mark when you choose.

[Blue07CivicEX]

So, that would explain why the civic can go 0-40 pretty much in the blink of an eye but at 70mph it's revving 3k. Bah! damn car oh well it's still not a bad little rig, it'll do.

[Shawn D.]

If one is going to the trouble of a rebuild that includes the rings, one should look at "zero gap" rings such as Childs & Albert or Total Seal. Blowby is supposedly reduced dramatically. FWIW, I have the C&A rings in my '57 Chevy (there were too many factors changed in that engine when I rebuilt it to say what contribution the C&A rings have).

[bhazard]

Originally Posted by brucey

Either way, top gear should like, idle the engine. And mines revving to nearly 3,000 rpm at 70 mph!

Not necessarily, at idle speed your engine most likely doesnt make enough power to cruise at 30 mph...

Obviously cruise rpm is gonna be lower on a big diesel or v8 gas engine. My buddys olds toronado used to cruise 55mph at like 1200 rpms. Kinda like a train... just glug glug glug down the road.

[Volones]

Originally Posted by Blue07CivicEX

So, that would explain why the civic can go 0-40 pretty much in the blink of an eye but at 70mph it's revving 3k. Bah! damn car oh well it's still not a bad little rig, it'll do.

My '95 Mazda MX-3 has a similar gear ratio at 70mph, and I'm getting closer to 40mpg average per tank every day. I'd expect there's quite a bit of tranny changing you could do to your Honda though.

[Blue07CivicEX]

Originally Posted by Volones

My '95 Mazda MX-3 has a similar gear ratio at 70mph, and I'm getting closer to 40mpg average per tank every day. I'd expect there's quite a bit of tranny changing you could do to your Honda though.

Yeah, I actually ran a test today driving 300 miles at 65mph I posted the results on my build thread, little better top gear probably would help but the current tranny isn't as bad as I thought.

http://ecomodder.com/forum/showthrea...ions-2994.html

[Bror Jace]

"Bror, I think you have your engines mixed up because 427 to 454 was a pure stroke increase."

Thanks for the fact check. I'm guessing it was the 396/402 to 427 change instead.

[hunkybizkit]

boring an engine out actually increases the stock compression ratio a bit as well... a nice little bonus.
keep it under 60 you will get great mileage

[Blue07CivicEX]

Alrighty, so today I figured out why my 5spd civic has such a high rev at highway speeds. The auto civic has MUCH lower rev, at 74mph (10 mph faster) the auto is at 2400rpm's where the 5spd is at 2800 at 65mph. The reason for this is because cruise control can't shift down to go up hills in a 5spd. Therefore it needs higher revs and more power to be able to climb hills without lugging and requiring a shift where as auto's will just downshift up the hill. If this fact is well known maybe i'm just a slow learner, I wish my civic had the same high gear as an auto though but in my manual.