Future lean burn engine swap into 7th generation Civic sedan? CRX HF, HX?

[Ecky]

The HX engine would get you part of the way there, but taller gearing helps a ton. I wouldn't want to discourage you from trying it! An engine swap of the same generation, which use the same mounts and nearly the same harnesses, isn't too bad. You could likely do it yourself with a harbor freight engine hoist over a weekend, even if you're not familiar at all.

That said, I did the timing belt on my previous car. Belt itself was something like $70, plus I had to get a special tool for holding the crank pulley still. Hardest part of the process was getting the damned crank pulley bolt off, after that it was just following a step by step manual.

[mpg_numbers_guy]

So I would have to replace with the HX engine and tranny. Plus convert my automatic into a manual. Sounds like a lot of parts, expense, and expert know-how required. Unless there would be a way to take my current transmission and modify it to match the gears of the HX transmission to go with the HX engine?

I've heard too many horror stories from people changing their own timing belts to attempt to do that lol.

[Ecky]

Well perhaps I should put it this way: Neither alone will give the full benefits, but either would be of benefit.

I would think replacing a transmission with one that has taller gears would be easier than taking a transmission out, disassembling it, rebuilding it with a custom gearset, and reinstalling it.

I believe the ECU in your car needs to match the transmission type though, which is to say, you could not pair a manual transmission HX computer with an LX automatic transmission.

Oil Pan 4 probably points out the cheapest best solution though - replace the computer with a custom one. Modders do this all the time, so they're relatively inexpensive and well understood. By replacing your factory ECU with an aftermarket one (e.g. Hondata) you can then take it to a tuner, who can program lean burn and perhaps different (better) shifting behavior into your existing engine and transmission. A custom computer would also allow for an automatic transmission with an HX engine, if you so desired.

[oil pan 4]

Just going to lean burn and changing nothing else can get you a 10% to 20% boost in fuel economy.
If all you do is swap in the lean burn engine and ECU all you should expect is no more that 20%.

[mpg_numbers_guy]

Originally Posted by Ecky

Well perhaps I should put it this way: Neither alone will give the full benefits, but either would be of benefit.

I would think replacing a transmission with one that has taller gears would be easier than taking a transmission out, disassembling it, rebuilding it with a custom gearset, and reinstalling it.

I believe the ECU in your car needs to match the transmission type though, which is to say, you could not pair a manual transmission HX computer with an LX automatic transmission.

Oil Pan 4 probably points out the cheapest best solution though - replace the computer with a custom one. Modders do this all the time, so they're relatively inexpensive and well understood. By replacing your factory ECU with an aftermarket one (e.g. Hondata) you can then take it to a tuner, who can program lean burn and perhaps different (better) shifting behavior into your existing engine and transmission. A custom computer would also allow for an automatic transmission with an HX engine, if you so desired.

So I take it that the increased MPG of the 7th gen HCHs is less due to the electric assist and more due to the lean burn and taller gearing?

True, but both sound like one heck of a challenge lol.

Are you saying I can have the ECU computer reprogrammed for lean burn and to somehow make the manual tranny work as an automatic?

Originally Posted by oil pan 4

Just going to lean burn and changing nothing else can get you a 10% to 20% boost in fuel economy.
If all you do is swap in the lean burn engine and ECU all you should expect is no more that 20%.

A significantly greater than 10% improvement for just one mod. wistfull look

[19bonestock88]

Originally Posted by mpg_numbers_guy

So I take it that the increased MPG of the 7th gen HCHs is less due to the electric assist and more due to the lean burn and taller gearing?

True, but both sound like one heck of a challenge lol.

Are you saying I can have the ECU computer reprogrammed for lean burn and to somehow make the manual tranny work as an automatic?

A significantly greater than 10% improvement for just one mod. wistfull look

The HCH1 also has a much smaller engine(1.3L) making much less power than your 1.7L...

You may be able to use Hondata to reflash your ECU and add in lean burn at cruise and alter shift points of your trans, which *could* gain you between 10 and 20 percent... an HX swap, while more involved, could gain you a little more...

The HX manual trans has better gearing than your auto does I imagine so the trans alone would get you something...

[Xist]

People compare changing from automatic to manual to sex changes. Swapping engines, building a custom wiring harness, and having a custom tune installed very well may be easier.

[mpg_numbers_guy]

Originally Posted by 19bonestock88

The HCH1 also has a much smaller engine(1.3L) making much less power than your 1.7L...

True. Almost seems like the hybrid system does nothing for the fuel economy.

Originally Posted by 19bonestock88

You may be able to use Hondata to reflash your ECU and add in lean burn at cruise and alter shift points of your trans, which *could* gain you between 10 and 20 percent... an HX swap, while more involved, could gain you a little more...

Sounds like a much easier solution...how complicated is it? Cost estimate?

Originally Posted by Xist

People compare changing from automatic to manual to sex changes. Swapping engines, building a custom wiring harness, and having a custom tune installed very well may be easier.

Lol, does sound like a good comparison. If only there was an "easy" way to drastically increase MPG...but if there were then automakers would most likely already be implementing it.

[Ecky]

Originally Posted by mpg_numbers_guy

True. Almost seems like the hybrid system does nothing for the fuel economy.

For the most part, it doesn't. I have it unplugged in my Insight right now, running on gas only until I can get a replacement part for my IMA battery. Fuel economy is virtually the same, except in some stop-and-go situations, which are rare where I live. What's different, however, is that the 0-60 time is just about doubled. The hybrid system allows for the use of a smaller, more efficient engine than you could otherwise put in a vehicle, because it would be dangerously slow.

Originally Posted by mpg_numbers_guy

Sounds like a much easier solution...how complicated is it? Cost estimate?

Probably $5-700? The Hondata ECU plugs right in where you old one was, but you need a tuner to program it.

Originally Posted by mpg_numbers_guy

Lol, does sound like a good comparison. If only there was an "easy" way to drastically increase MPG...but if there were then automakers would most likely already be implementing it.

Pretty much. It helps to look at where the losses are.

Aerodynamics - A smaller car with a tapered rear end improves highway economy. People are increasingly buying larger, more boxy vehicles, despite more aerodynamic cars sitting next to them on lots.

Weight - Smaller, lighter vehicles improve city economy, since it's less mass to accelerate and stop. People want larger, heavier vehicles.

Transmissions - Manuals are less lossy than autos (usually). Nobody wants to shift gears, manuals are disappearing.

Engines - Smaller engines have less internal friction, and smaller parasitic losses. People want faster cars, and are buying bigger engines.

Tires - Narrower, lower rolling resistance tires improve economy. People want more grip for safer, higher speed cornering, and buy bigger, stickier tires.

~

Hybrid systems address a lot of these things, for various reasons. You can have a smaller engine without sacrificing power. You can have an automatic transmission with low losses (read about Toyota's planetary gearset in the Prius). You can use batteries to capture some of that energy lost in braking a heavier vehicle. You can get rid of some of the more lossy components in cars, such as alternators. It doesn't solve the aerodynamics or tire problems, but it helps.

[California98Civic]

Not only will the HX/EX Seventh gen engines and transmissions bolt up to one another, there is a chance that the manual Gen 1 Insight and the Gen 1 Civic Hybrid manual transmissions will too. See the manual transmission specs link in my signature file below. But the HX/EX swaps are painlessly simple within the 7th Gen.