[redgiki]

OK, not sure if this should go into the "mods" forum or the "MPG" forum, guess I'll put it into MPG for now, since that's what I'm trying to improve

I realize this has probably been asked before, but after hunting through numerous CVT threads, I couldn't locate this exact question.

The CVT has a lean-burn capable engine. Honda advertises their CVT Civic Hybrid as having a "lean burning engine" -- I would think they wouldn't do that if it just didn't work. Obviously, the Insight CVT is a different animal, but yet the underlying tech is similar enough that I'd think the CVT capable, on some level, of lean-burn.

For me, 50-60 MPG is still phenomenal, and I'm having a ton of fun driving the most fuel-efficient automatic transmission hybrid on the planet. And getting down around 54.9 LMPG (winter driving, 20-40 deg Farenheit in a "stock" configuration, averaging around 56 MPG per tank) because I can't resist blowing away other cars off the line in "S" mode. And yet... I'd still like to figure out, if there's any physical way to do it, how to kick a CVT into lean-burn. One would think it could work! I can routinely drive the auto on straight & level ground at about 55 MPH with the FCD pegged to around 75 MPG, the RPMs right around 2500, and maintain speed.

So my question is: is the lack of lean-burn an electronics thing on a CVT? Is it just not allowed? Is it a difference with the cats? Or, could it be, that if some steps were taken to expand the lean-burn window, that a CVT could achieve lean-burn statistics within 10-12 mpg of the manual transmission?

As it is, I plan on seeing just how high I can drive the lifetime MPG (55.1 when I got it, 54.9 now as I've been learning the car over the last 1,000 miles). The "achievable" LMPG highs for CVTs, as of this writing, are all around 58-62 MPG, while the "achievable" LMPG high for manuals are around 80-85 LMPG. There have *got* to be some ways to drive the CVT's mileage up

Mods planned after I've figured out what I can get out of the CVT under "normal" conditions:
* Warm air intake
* Blocking radiator
* 50 PSI per tire (gotta wait for spring on this, 50 PSI on icy roads is scary, factory 38 front/35 rear is MUCH more grippy on Utah roads in the winter)
* Remove front license plate (not required in Utah anyway, but how to cover up those ugly holes!)

Of course, weekly washes, high-gloss wax, and the all-important right-foot-control figure in there too

But before I go so far, I really need to figure out if it's even physically possible to kick a CVT into lean-burn using any combination of mods and right-foot control. If the tallest ratio of the CVT isn't as tall as fifth gear on a manual, it may be a lost cause. Maybe I'll have to be a trailblazer and figure out what it takes, or fail spectacularly. It would be nice if there were a little light on the dash that said "Lean Burn" so you could tell, really, when you're there!

Anyway, my random ramblings. From the lifetime MPG database, it seems the "sixty-five at sixty-five" ideal is mostly a dream for us CVT owners, but I'd be overjoyed to get close! And I'm enjoying the crap out of my little Insight. I was stuck in traffic just one day so far, and was excited to be in an automatic instead of a stick shift...

 

[Rick]

I think the lack of lean burn is in the software somewhere which would have to be reverse engineered. But also there's the fact that you have a different engine all together than the 5 speed. The compression is different. I haven't looked in to specifics, but there might be other things missing too, though you do have the nox converter. I think the best way to get lean burn on a cvt would be to do a transmission swap from a 5 speed, but that would be more work and cost more that it's worth.

As far as your other mods you have planned yes those should help.

 

[Tim Maddux]

http://www.hondacars.com/models/specifi ... me=Insight

Note that at some point Honda dropped the "Lean-Burn" notation from the "Multi-Point Fuel Injection" line of the Insight specs. I noticed this about a year ago. Before that time, the "no lean burn in CVT" was widely reported by dealers and posters to Yahoo! but not officially represented by Honda on any specs.

I agree with Rick that the lack of lean burn must be software/firmware controlled, and that otherwise the engine/exhaust are the same. In addition one would expect the CVT transmission to put some drag on the engine. This could be enough to keep you out of lean-burn mode even if the car would allow it. It doesn't take much -- I put 185/60 R14 tires on my 5spd and it makes it noticably more difficult to stay in lean burn while cruising.

On the plus side, the lack of lean-burn means much lower smog-forming emissions from your CVT. So enjoy!

 

[3509]

bump

I know this is an old thread, but in another thread about parts from japan, someone mentioned that the 1999 japanese version had a lean burn feature. Maybe a chip replacement?