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Ulev 5spd vs Sulev CVT.

2417 Views 9 Replies 6 Participants Last post by  BLUEBUG
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 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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80 Posts

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.

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