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Old 22nd January 2010, 01:56   #1
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Default Does engine size really matter?

Hi guys,

We the recent technological progress in automobile engines I begin to wander on the thought of this question.

One of the factors that influences a new car buyer is the size of its engine. However, there are many new engines on the block that are much smaller in terms of displacement but pump out much higher horsepower and torque.

Based on this premise, I question myself if one should really be bothered about displacement when comparing automobile engines.

Any inputs will be appreciated.
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Old 22nd January 2010, 02:49   #2
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I'm certain we have touched upon this topic earlier (about a year or two back?).

Does anyone recall / have a link?

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Old 22nd January 2010, 06:48   #3
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Agree that current smaller displacement engines can produce the (almost) same bhp, but they won't have the low end grunt. A minimum of 1200 cc is required IMO for a good bottom as well as top end. Anything less is a compromise!
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Old 22nd January 2010, 10:48   #4
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Theoretically speaking if all parameters are same a bigger engine with more displacement will produce more torque. Hence the engine will have better lugging ability.

A smaller engine can produce the same bhp at a higher rpm, however torque cannot be matched.

You can experience the difference by simply driving a 3 cylinder engine & 4 Cylinder engine. The power output might be the same but the torque characteristics makes the vehicle more ridable with lesser down shift.
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Old 22nd January 2010, 10:57   #5
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"There is no replacement for displacement." - Wolfgang Bernhard, Chief Operating Officer, Chrysler Group

You need displacement for low end torque. The only thing that provides massive torque at 1500RPM is displacement and electric traction.
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Old 22nd January 2010, 11:02   #6
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Depends on who the customer is. Going by the stats (of car sales), most people buy VFM cars. Engine displacement doesn't really matter there. Even people buying large (Accord, etc) cars, seldom buy the V6/3L variants.

Look at the bike sales, 100 cc rules. Pulsar has changed this to some extent but still people want bikes that have an FE of 100 kmpl.
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Old 22nd January 2010, 11:26   #7
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A 1.5 FI engine will be able to produce the same power and torque of a 2ltr NA machine. But if you fit a turbo on that 2ltr machine, it's power and torque will increase even more.

So under certain circumstances and engine tune, a smaller engine can be made to match a bigger one. But if both engines are similarly designed and tuned (displacement being the only diff), the bigger engine wins everytime.

But when you talk performance in general, its the whole package that matters. So unless you use an engine and chassis that work well together, using a bigger engine might not be of much use.

Shan2nu

Last edited by Shan2nu : 22nd January 2010 at 11:28.
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Old 22nd January 2010, 11:33   #8
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To see in practice the effect of engine size and torque, drive a bigger engine car and a smaller engine car. I do that quite often.
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Old 22nd January 2010, 11:51   #9
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Well the theory "there is no replacement for displacement" still holds good though not in the manner which the original author might have intended. With the advancement in technologies over the years, the engines have become more efficient, i.e. they are now able to produce more output from the same cubic capacity. A classic case in point would be the F8D motor powering the Maruti 800. In its original form(carburettor) it produced 37 bhp. When it got the MPFi treatment from Maruti, it produced 45 bhp. The very same engine where tuned for the erstwhile Daewoo Matiz could produce a whopping 52 bhp. I'm pretty sure Maruti could have done one up on the Daewoo but the 800's chassis gives up way before the engine does. Here we see that there is replacement for displacement is the sense that output can be upped without upping the cubic capacity. But if the same tecnologies are applied to an engine with a higher nad lower cc's, the one with the higher cc would have better output that the one with a lower cc, other things being equal.
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Old 22nd January 2010, 11:52   #10
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Quote:
Originally Posted by ImmortalZ View Post
"There is no replacement for displacement." - Wolfgang Bernhard, Chief Operating Officer, Chrysler Group
Couldn't agree more with this statement, I just made it my signature.

Rohan
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Old 22nd January 2010, 12:21   #11
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Quote:
Originally Posted by longhorn View Post
A classic case in point would be the F8D motor powering the Maruti 800. In its original form(carburettor) it produced 37 bhp. When it got the MPFi treatment from Maruti, it produced 45 bhp.
The M800 engine is still restricted to 37 bhp. It is only in the Alto avatar that it is upped to 45 bhp. (6 valves Vs 12 valves).
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Old 22nd January 2010, 12:41   #12
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Quote:
Originally Posted by Gansan View Post
The M800 engine is still restricted to 37 bhp. It is only in the Alto avatar that it is upped to 45 bhp. (6 valves Vs 12 valves).
Well there was this wolf in sheep's clothing called the Maruti 800 5 Speed MPi produced between 2000 and 2003. It came with the works within a budget - 4 valves per cylinder, aircon, 5 speed gearbox, MPFi, 45 Bhp engine and a rocking 22 kmpl mileage. It was the best iteration of the Maruti 800 ever produced on Indian soil. Maruti killed it in 2003 when it became too much of a competition for the Alto. In 2003 April they detuned the Maruti 800 to 37bhp in MPFi mode and again shod it with that crappy 4 speed gearbox of yore.

Last edited by longhorn : 22nd January 2010 at 12:44.
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Old 22nd January 2010, 13:16   #13
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Quote:
Originally Posted by longhorn View Post
In its original form(carburettor) it produced 37 bhp.
The specs sheet on my 97 800 specified 39.5 BHP as the output.Its a carb model.
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Old 22nd January 2010, 14:56   #14
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basically engine size is depend on the Stroke X Bore ratio required for definite power and torque i.e square ratio.over square etc,

to get the more power and torque from same engine size we need to help the stroke (displacement) by pushing more air with correct density (this done by Turbo) or by burning the fuel in better manner i.e more in percentage (partially don by turbo and partially by Fuel injection system )

Automobile manufacturer are happy to keep Engine size less including its packaging size also to get the excise benefit
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Old 22nd January 2010, 17:26   #15
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Hmm even I recall the A-Star Engine with less 1.0L cap having more power and torque than the 1.1L cap engine of WagonR and previour Estilo.
Doest this mean that pure change in technology has added more power to the engine or is there a drawback of some sort in the A-Star and current Estilo engines.
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