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Discussion Starter #1
Ok this is maybe a stupid question but I am going for it:

Why is there an emissions level difference between a CVT and a 5 spd ?
Does the CVT has leanburn or not ?
What is the exact difference between the 2 engines without
the cvt or 5 spd gearboxes. I don't have a clue.
I know that leanburn exhaust gasses are more "dirty" compared to non-leanburners due to the fact that the combustion is not optimal compared to non leanburners.
In this http://www.insightcentral.net/KB/faq-cvt.html#Chart part I see that the engine compression ratios are 10.8 to 1 (5spd) and 10.3 to 1 (CVT). I tought that for a leanburn engine, the ratio is about 22 to 1.
So as I have to say: What is it ?
 

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Your right on that, the CVT is geared more towards emissions, the 5 speed towards mileage. I think the difference in the compression ratio is in the head. No lean burn on the US CVT that's for sure; however, if you look on the Japanese Honda site (using a translating program) they show both of theirs as 10.8:1 with both transmissions so in theory they have lean burn CVT's, and *maybe* if someone imported a Japanese ECM you could have a lean burn CVT here. I've looked at a couple CVT Insight's and they still have the NOX catylst there, which is primarily to hold back the NOX emissions while in lean burn. Not sure what you guys get in the europe market.

Still, those who have had emissions tests all I can remember hearing about blew in sub SULEV levels.
 

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According to the service manual, for the 2005 car there are the following differences between the M/T and CVT versions. This is just in the specifications, which doesn't say anything about a different intake manifold, for example, or a different engine control computer code version. That you would have to find out by looking at the part numbers, checking it by comparing the actual parts.

Anyway, according to the service manual, the following are different:
- compression ratio (M/T: 10.8, CVT: 10.3)
- brake pad size
- radiator size
- battery size

There is also an additional oxygen sensor in the M/T cars. There may be a difference in the brake fluid pressure sensing system. Maybe a few other things like cam timing.

Note that the differences in some of these specs is tiny, and really only matter in a high production volume car. It's common, for example, to use slightly different brake pads between similar models of a car, and then have a single repair part that is shared between models. All that proves is how highly tuned the car manufacturing business is...
 

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Discussion Starter #4
Is it not so that lean burn ratio is about 22 to 1 ? So 10.8 to 1 is normal " burn" .
In Europe we do only have the 5 spd ---->lean burn. In the Uk I think it is the same.
So actually the CVT is a non-vtec-e, because leanburn (5spd) requires a vtec-e. This must be difference is it ?
 

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Windmill:

I may be wrong, but it sounds like you are mixing up compression ratio with the air to fuel ratio.

Our Insights have a compression ratio somewhere around 10.8:1, the manual transmission cars are a little higher and have lean burn. The CVT compression ratio is 10.3:1, and for most, no lean burn.

The manual transmission engines air to fuel ratio will vary from 14.7:1 all the way to 25:1 (which would be extreme lean burn).

Now for the part I'm not sure about: Most CVT Insights do not have lean burn capabilities. I have heard on this forum that the Japanese CVT's do lean burn.

In any case the lean burn engines are not as environmentally clean as the CVT engines.
Lean burn = hotter combustion temperatures = more nitrous oxides.

Regards,
 

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Discussion Starter #6
Yes hawkGT647, I mixed it up ! Now I understand, sorry.
I didn't know that air to fuel ratio will vary from 14.7:1 all the way to 25:1.
I tought it was a fixed ratio. And yes lean burners are more poluting.
The only question that will remain is why does Honda made the CVT's non lean burn ? Both engines output performance are almost the same, even the high Californian emission standards are ok for the lean-burners so why Honda didn't ?. Is the CVT so much more "work" for the Insight's little engine ?
Mmmm I am gonna take a look in the maintenance manual or I can Find something difference in the engine's head.
 

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The CVT is probably made as a SULEV car because there is a goal at Honda to have low emissions. It's not all about fuel economy...
 

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Discussion Starter #8
Dougie said:
The CVT is probably made as a SULEV car because there is a goal at Honda to have low emissions. It's not all about fuel economy...
That's true.
 
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