Smart ForTwo: 40 MPG Highway, But it Uses Premium

[ALephart]

More fuel for the fire.

http://blogs.cars.com/kickingtires/2...fortwo-40.html

Aaron Lephart

[ALephart]

Then I find:

http://en.wikipedia.org/wiki/Mitsubishi_3B2_engine

3B2-
Engine type Three cylinder, DOHC
Displacement 999 cc
Bore x stroke 72.0 x 81.8 mm
Fuel type Regular unleaded gasoline
Peak power 50 kW (68 PS) at 6000 rpm
Peak torque 92 N·m (68 ft·lbf) at 3000 rpm


I'm so confused over the octane rating.

Aaron Lephart

[SmartBob]

Yep, those are the firgures in the other mpg post. I don't have a problem using higher octane since our tank is only 8.5 gallnos and I will be adding bold-ons to boost the mileage. I STILL WANT MY SMART!

[lhoboy]

Has anyone seen the specs on compression ratio? I suspect it's high to get the 71hp/1000cc, and hence the need for higher octane.

[jonnysan]

Originally Posted by lhoboy

Has anyone seen the specs on compression ratio? I suspect it's high to get the 71hp/1000cc, and hence the need for higher octane.

Because I recently posted a response to it. I think it was with regard to the Brabus and the turbo it has making 86hp and the normally aspirated 71 hp engine having a higher compression ration due to it not having the added power created by turbo. I think the Brabus with 86 hp has 10:1 compression and the US model has 11.4:1. You would think that would be the other way around but as my memory can recall, the use of a turbo at the higher compression ratio of 11.4 may compromise the integrity of the engines lower end perhaps so they lowered that to be able to gain the benefits of the turbo. Not sure about this but it makes sense to me with my knowledge of engine design/building.
Fish will know for sure as he wrote the original post that I responded to.

[Old smart]

Rog..O. 11.4:1 for the 61PS and 71PS normally-aspirated gassers, and 10:1 for the 84PS and 98PS (Brabus) turbos.

BTW, the Brabus turbo is recommended to use 98 RON gas (about 94 PON here). Does Sunoco still sell 94 street gas?

[Old smart]

(Then I find:

http://en.wikipedia.org/wiki/Mitsubishi_3B2_engine

3B2-
Engine type Three cylinder, DOHC
Displacement 999 cc
Bore x stroke 72.0 x 81.8 mm
Fuel type Regular unleaded gasoline
Peak power 50 kW (68 PS) at 6000 rpm
Peak torque 92 N·m (68 ft·lbf) at 3000 rpm


I'm so confused over the octane rating.

Aaron Lephart)

The Wikipedia entry is probably correct, but the engine noted is the 3B20 which has only 8.8:1 CR, thus allowing the regular unleaded. Our engine is derived from the 3B2 family and is a bit different. I don't know what its current designation is, 3B21 maybe. Maybe just call it a 3B2x for now.

[Peddlecar]

I'm interested in the statement of mods to increase the gas mileage on the US car??

How about a new thread on mods that will increase the gas mileage, if we know them yet??

[2micro4u]

Originally Posted by Peddlecar

I'm interested in the statement of mods to increase the gas mileage on the US car??

How about a new thread on mods that will increase the gas mileage, if we know them yet??

Excellent I idea...I would like to know more about this aswell. Like could a Turbo, Brabus Exhaust, or air intake give better gas mileage and increase horse power . PLEASE PLEASE LET ME KNOW

[Old smart]

Doesn’t look like “Brabus-izing� is the key to better fuel mileage: the ’07 smart coupés Euro combined fuel mileages are 61PS – 60.1; 71PS – 60.1; 84PS turbo – 57.6; and 98PS turbo Brabus – 54.3 (all in Imperial gallons).

With fuel mileage such a deal in the U.S., you can bet that the smart designers have done everything practical to get the numbers up.