Small engines vs the Big Engines

11 Sep 2016

This is just a general question. People always shout the disadvantage of large vehicles being gas guzzlers because of their large-displacement engines. So I thought: Why not swap in a smaller engine modified with enough grunt to match the existing larger engine? At least it won’t eat up as much gas. But then, this suggestion is rejected with the cited reason being that the small engine cannot pull the car’s weight around like the big ones do. Excuse me?! If they have the same amount of power and torque, why does the size make the big guy better? Someone please explain ASAP.

Comments

Gas consumption is directly related to the weight of the car. A small engine will have some better effiency because of heatloss. (large engine more heatloss) larger engines with same effect as a smaller engine will last longer = better.

You claim it will last longer but WHY will it last longer? That’s my question

Larger engines won’t have more heatloss, the heat doesn’t have much do to with the engine size, by the same logic a bigger engine would likely dissipate heat better when thinking of convection, which is good, not bad.

But yeah, larger engines generally need to be under less stress to make the same power, so should be slightly more reliable.

it’s also about how linear the power delivery is, a bigger engine will typically have a more linear power delivery which is more usable in a big car or truck pulling around all that weight

If u put a small engine in a large car you are constantly going to have to accelerate hard and rev high just to take off normally. Lots of fuel consumption and wear on engine

Strangely, what you might find is that a smaller engine tuned to match a big lazy engine gives very similar fuel economy. One of the reasons big engines #tend# to be less economical is they tend to be less developed. However, a bigger engine will have more internal friction (bigger bearings, more piston ring area and so on). I dont think that big engines or small engines last longer, but it is true that the smaller high power engines tend to be more stressed.

So you say small vs big with same power will give similar fuel economy and the small engine will mostly be stressed. What about, for example, a large engine with 385 hp vs a small engine with 500 hp?