Compression ratio misprint?

[oilman930]

The UK smart brochure has the compression listed for the 71 hp engine version as 11.4:1. The turbo equiped engines (84 hpand Brabus versions) are listed as 10.0:1

The US smart brochure has the compression ration listed for the same 71 hp engine as 10.0:1. I think the US brochure is a misprint. Can anyone confirm a possible misprint?

[spdickey]

You will find the correct tech specs here:

http://www.smartusa.com/smart-car-te...fications.aspx

[Fredvon4]

oilman930

The North American motors are the lower compression but non turbo versions

This is what got us all excited about just bolting on a turbo...sure wish it was that easy...

[24-42]

Originally Posted by spdickey

You will find the correct tech specs here:

http://www.smartusa.com/smart-car-te...fications.aspx

The compression is not included in those specs.

[oilman930]

Why I question a drop in compression is that the power output of the US and Euro spec non turbocharged engines are the same. Going from 11.4:1 to 10.0:1 would cause a big drop in power output.

I have to check to be sure but I think the 61 hp euro version engine in the pure also has a compression ration of 11.4:1.

Why lower the compression ratio for the US market? Something is not right.

[Fredvon4]

Wer have different fuel formulations and different environmental controls (programing in the ECU)

RON 91 is readily available 93~94 is not

In a small 3 cylinder motor the difference of 1.4 is not that much

We do not know if we have different cam profile or timing...this can/will effect the dynamic compression ratio

The 11.4:1 or 10.01 are the static (calculated) compression ratios for comparison they are interesting but do not mean much...

dynamic compression ratio is what the engineers determine the fuel needs from

On my Harley Vtwin 1340cc motor I can dramatically change the dynamic compression ratio with a cam change to higher lift, longer duration, and different timings

Calculated 9.4:1 is still true mathematically because I did not change bore, stroke, or combustion chamber volume... but running she will need slower burn (higher octane) fuel