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Smaller engine
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Author:  miniman82 [ Sat Nov 26, 2005 1:18 pm ]
Post subject:  Smaller engine

If you wanted to increase your MPG, one obvous way I haven't seen mentioned would be to either de-stroke the crank, or sleeve the block for smaller pistons to reduce engine size.

Author:  fordem [ Sat Nov 26, 2005 2:13 pm ]
Post subject: 

At the risk of pointing out the obvious, a smaller engine does not necessarily provide better mileage - ever wonder why you don't see SUVs with 1.0 litre 3 cylinder motors?

Author:  miniman82 [ Sat Nov 26, 2005 7:36 pm ]
Post subject: 

Are you saying a 5.7L Suburban gets the same mileage as a G10 powered Metro? :shock: I assure you, that is not the case. A smaller engine uses less fuel, and therefore gets better economy.

Quote:
ever wonder why you don't see SUVs with 1.0 litre 3 cylinder motors?

:shock:
Who want's to own an SUV anyway? I can haul more stuff while getting better MPG in my Mom's 4-banger Dodge Caravan. Plus, if I crank up the boost, I can wax Mustangs! :twisted:

Author:  fordem [ Sat Nov 26, 2005 8:51 pm ]
Post subject: 

Figured you'd miss the point :)

A small engine in a large vehicle will give you poor gas mileage and also have a limited lifespan.

Bottom line, don't expect to reduce the engine size and get better gas mileage with the same weight/size vehicle, also be prepared to lose performance.

BTW - Dodge Caravan = mini van = SUV = large kiddie hauler - all the same to me, a 1.0, 3 cyl ain't gonna move it.

Author:  miniman82 [ Sun Nov 27, 2005 1:41 am ]
Post subject: 

It's the same car, just with a smaller engine. Everything else remaining equal, if you reduce the diplacement of the engine, you also reduce it's fuel consumption.

I have not missed the point, you're shooting down the idea before honestly considering it's merits. You, therefore, have missed the point.

I think an 850cc (maybe less) engine would be enough to propel a standard weight Metro at 55 MPH, and gain a measureable increase in MPG. How much is the question. Yes, you will lose performance, but a Metro is hardly a performance vehicle. Performance is not the goal here, high MPG is.

Author:  fordem [ Sun Nov 27, 2005 1:29 pm ]
Post subject: 

Guess I'l have to spell it out - don't think I can find words of one syllable though.

Same car, same weight, smaller engine = engine works harder to move it.

Engine works harder, burns more fuel than than it would moving lighter vehicle, possibly more fuel than a larger engine would.

I am merely pointing out that the general assumption that a smaller engine will return greater fuel economy is a fallacy - those smaller engines usually come in smaller, lighter cars, which is the point that you are missing.

Having owned both the Suzuki Fronte SF360 and SF380, which are essentially the same body equipped in the one case with a 600cc 3 cyl engine, and the other an 800cc 3 cyl engine, I can tell you first hand where the differences lie.

Sure the 360 is more economical to operate - as long as you're operating it with one or two people - but put two more adults in the back - yes they'll fit, these things have surprising leg room and you're on the wrong side of the curve right there.

Oh - lest I forget, the 380 with two persons and the A/C is more economical than the 360 under the same circumstances - yes, A/C was a factory option ;) and in the Caribbean a very popular one.

Author:  Metro Muscle [ Sun Nov 27, 2005 5:01 pm ]
Post subject: 

I'm gonna be a jerk here and stir the pot up a bit..... :D 1.0l metro vs. 1.3l metro, similar weight but one has a smaller engine than the other. Which one get better fuel economy? :wink:

Author:  Lihtan [ Sun Nov 27, 2005 8:03 pm ]
Post subject: 

Metro Muscle wrote:
I'm gonna be a jerk here and stir the pot up a bit..... :D 1.0l metro vs. 1.3l metro, similar weight but one has a smaller engine than the other. Which one get better fuel economy? :wink:

If you didn't bring it up, I would have. Many vehicles are made on a variety of trim levels which includes a variation in engine displacement. Smaller engines do burn less fuel. When comparing the 1.0 vs the 1.3, the 1.3 tends to feel like it has power to spare, the 1.0 - less so. A 600 cc Metro would be an interesting vehicle, even less power than the 1.0, but much better fuel economy.

Few vehicles operate at the peak of their engine power. The extra reserve of engine displacement is only for driveability, and safety aspects like freeway merging. I don't see a problem with reducing displacement, although I would do a lot of weight reduction, and keep a nitrous bottle handy for freeways.

Oh and about minivans: Most minivans have a substancially lighter curbweight (~3000 lbs) than most SUVs (~4000+ lbs). Minivans deliver better fuel economy, better performance, and better utility than SUVs. I've owned a minivan before, and I'd happily buy another. You have to pay me to take an SUV. Minivans don't make the best daily drivers, but they do make economical work vans*, and will haul shittoads more than stuff than any of our little cars.

* economical compared to fullsize vans, pickup trucks, SUVs, or lost time due to repeated trips in a smaller car.

Author:  fordem [ Sun Nov 27, 2005 9:14 pm ]
Post subject: 

Not having had the pleasure of owning a 1.0l Metro, I deliberately avoided that comparison, nevertheless, since you brought it up, can anyone give me mileage figures for a 1.0 and a 1.3 with four adults on board?

I'll also take this opportunity to point out, that in both the Fronte SF360/380 comparison and the Metro 1.0/1.3 one that the drive trains have been configured from the factory to suit the engines, which may not be an option if you're destroking an engine.

On the minivan/SUV score, we apparently have different opinions on where the dividing line between minivan and SUV lies.

Author:  suprf1y [ Sun Nov 27, 2005 9:21 pm ]
Post subject: 

Quote:
A 600 cc Metro would be an interesting vehicle, even less power than the 1.0, but much better fuel economy.

I doubt it.
At some point the motor will be in over its head, having to work too hard, and giving reduced fuel economy.
I think the 1.0 is just about at its limit, and probably over it, in the newer, heavier 95+ cars.

Author:  miniman82 [ Mon Nov 28, 2005 1:03 am ]
Post subject: 

I was thinking a 89 Metro, 5-speed of course. No A/C, just the bare minimums.

Author:  fordem [ Mon Nov 28, 2005 8:48 am ]
Post subject: 

suprf1y wrote:
I doubt it.
At some point the motor will be in over its head, having to work too hard, and giving reduced fuel economy.
I think the 1.0 is just about at its limit, and probably over it, in the newer, heavier 95+ cars.


My point exactly.

Author:  tuffcarguy [ Mon Nov 28, 2005 12:53 pm ]
Post subject: 

fwiw, i have the dreaded suv that everyone hates. 92 suburban, dont get too much bigger than that!! :lol: it was getting 10 mpg around town and about 17 highway. when i rebuilt the engine, i put together a stroker 383 cubic inch short block ( up from 350) and added a set of world products heads with 2.02 valves ( up from 1.74) along with a slightly bigger cam. milage went to about 15 around town and 23 highway!!!!

so my point is bigger doesnt mean less fuel economy, and smaller doesnt mean better. efficiency is the key.

Author:  bluelightning [ Mon Nov 28, 2005 2:44 pm ]
Post subject: 

:goodpost: Along the same lines, my cousin has an 80's style chevy truck. It came with a straight six, switched to a v8 and his fuel economy increased.

Author:  Vtek [ Mon Nov 28, 2005 3:45 pm ]
Post subject:  Re: Smaller engine

miniman82 wrote:
If you wanted to increase your MPG, one obvous way I haven't seen mentioned would be to either de-stroke the crank, or sleeve the block for smaller pistons to reduce engine size.


just wondering how do you de stroke an engine?

Author:  fordem [ Mon Nov 28, 2005 5:49 pm ]
Post subject:  Re: Smaller engine

Vtek wrote:
miniman82 wrote:
If you wanted to increase your MPG, one obvous way I haven't seen mentioned would be to either de-stroke the crank, or sleeve the block for smaller pistons to reduce engine size.


just wondering how do you de stroke an engine?


You can have a custom crank made with shorter throws, you can grind an offset into your existing crank and use undersize bearings - or - maybe if you're lucky you can find a different crank from the same manufacturer that will have suitable journal sizes and spacings - anyone know if the G13 & G16 cranks can be interchanged?

You will also need to get longer rods or deck the block to compensate, or you will probably end up with a very low compression ratio.

Author:  Darrell [ Mon Nov 28, 2005 9:39 pm ]
Post subject: 

Don't forget gearing too. That effects MPG.

Author:  HiTempguy [ Mon Nov 28, 2005 9:49 pm ]
Post subject: 

Well tuff, your increased mileage is more likely due to those 12 year newer in design heads and a better designed cam :wink:

Author:  miniman82 [ Tue Nov 29, 2005 10:45 pm ]
Post subject: 

I'm not aware of any production smaller cranks, so I would do it the same way the stroker crank in my VW was done-weld the journals, but offset grind the crank for shorter throws instead of longer. It would require rebalancing and different rods of course.

Wonder which would be cheaper- de-stroking, or block sleeving.
If you de-stroke, you machine the crank and get diefferent rods. If you sleeve it, you need different (probably custom) pistons, and the head gasket is likely to be a headache.

If I did it, I would likely opt for de-stroking, I know it's cheap to machine the crank, and rods wouldn't be a big pain either-not as big as one-off head gaskets and pistons. I guess if you had to, you could even skim a chunk off of the pistons crowns to get clearance, but the amount would obviously but limited.

Author:  Darrell [ Wed Nov 30, 2005 12:54 am ]
Post subject: 

What about using a motorcycle engine? 600cc

Wouldn't that be easier?

Here's an idea..... put a motor inside you engine compartment where the AC usually goes. Then turn on the motor whenever you want a little boost. Instant Hybrid!

Holly smokes! I just thought of that. I'm a friggen genious.

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