3 cylinder as uneven firing

[theaveng]

from wikipedia: "In a one, two, or three cylinder engine there are times when no power stroke is occurring. In a three-cylinder engine a power stroke occurs every 240 degrees (720° ÷ 3 = 240°). Since a power stroke cannot last longer than 180 degrees, this means that a three-cylinder engine has 60 degrees of "silence" when no power stroke takes place."

I never really thought of that.
I guess the electric generator helps dampen that unevenness.

[eq1]

Originally Posted by theaveng

...I guess the electric generator helps dampen that unevenness.

Actually, I recall reading somewhere that the electric motor pulses or something like that to smooth out the engine. Not crystal clear on that, though...

[Willie Williford]

It does basically smoothes out the engine at idle only.

Willie

[randomfire]

Really curious how the Geo Metro (also 3 cylinder) was able to handle the engine at idle. It doesn't have an IMA to help.

[Black_Angel]

Yeah I drive Geo Métro 90-94/Suzuki Swift 90-94 too And I can say that 3 Cylinder engine is somewhat stronger. But in checking the licence plate of my dad I see this little car only 775KG if my momery is good so this car is lighter that the insight in weight (852KG) even if this car is in steel. But yeah is true today this range of year, the car is always broke in front table frame support because of rust with time and road bump who finish to make crack the frame table support.

But is true is still possible to got Geo Metro 95-2001 who only got 70 pound more with an improve suppension because of a stablization bar. But yeah again with this car even if front table support is reinforce in body still finish to broke there but yeah I guess they could still have good one of this car of the market not too much attacked by the rust.

But finaly I can see that the Insight first remain more economical that this car who are rate : 37mpg (city) 40 mpg(Combined) 44mpg (Highway) I check Geo Metro 97 3 Cylinder 1L Manual in Fuel Economy

And Honda Insight 2000 Manual who is rated : 49 MPG (City) 53 MGP (Combined) 61 mpg (Highway)

So is true this car is week in power but if you drive more agressive you drop your gaz economie somewhat but is still more economical that a geo-Metro with a 3 cylinder who are very economic car for the time.

thanks for listening Iam happy to partcipate of this thread.

[aisbell]

The momentum of a heavy flywheel keeps a 3-cylinder engine spinning at idle even during the "silent" period between power strokes. A balance shaft could reduce the inherent imbalance of a 3-cylinder engine, but I don't know whether Suzuki's engine had one.

[theaveng]

Originally Posted by Black_Angel

Yeah I drive Geo Métro 90-94/Suzuki Swift only 775KG if my momery is good, so this car is lighter that the insight in weight (852KG) even if this car is in steel.

How on earth did they manage to make it so light? That implies the insight is carrying a lot of extra weight it doesn't need. It needs to be stripped like the Metro/Swift to be lightweight.

[samwichse]

Originally Posted by theaveng

How on earth did they manage to make it so light? That implies the insight is carrying a lot of extra weight it doesn't need. It needs to be stripped like the Metro/Swift to be lightweight.

The Metro/Swift was a deathtrap with basically no sound insulation .

Sam

[head-met]

When we were car shopping back in 1988, I looked at the Geo Metro 1st gen. I was drawn to it because it reminded me of my 1974 Honda Civic CVCC. Small, light, cheap, 12 inch wheels, with no frills. We ended up buying a 1988 Civic. One reason the 3 cylinder Geos didn't last is because those little engines had to have the crap wound out of them to get them to go. Top gear in a Geo was like 3rd gear in an Insight. Our insights aren't quick, but the Vtec allows low rpm cruising which equals a long unstressed life.

[theaveng]

Originally Posted by head-met

the Vtec allows low rpm cruising which equals a long unstressed life.

Except VTEC doesn't turn-on until ~3000 rpm. (You can feel the extra boost of power when it does.)