Difference between 8v and 16v?

What is the difference between an 8 valve engine and a 16 valve one? Sorry! I don't know much about cars and engines. 16v is better than 8v right?

And what is the difference between for example 8v and v8? I know that v8 is more than probably a super car and 8v is an every day road car, but regarding the engine what is different? I presume the v must stand for something different whether it is before or after?

If you were to buy a car though, and your only choice was between two cars that were exactly identical except for the engine, what would you choose between the following:

1.4 L 16v engine

or

2.0 L 8v engine

Which one would you choose?

John

Reply to
John
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Reply to
SteveH

8 valves.

HTH

-- JackH

Reply to
JackH

As per, the resident unhelpful numpties have been first to answer. First of all, apart from the obvious first answer of "8 valves", 16 valve engines tend to flow gasses more easily (there are a few exceptions to the rule, however). Rather than having 1 big giant inlet valve (to let air and petrol in to the cylinder) and 1 big giant exhaust one (to let them out once burnt), manufacturers have decided that 2 slighter smaller valves flow better, and more efficiently. This usually equates to higher power output, and lower fuel consumption from the 8 valve counterpart.

A V8 engine is one that has 8 cylinders (8 pistons) and is arranged in a V format. Basically, if viewed from the side, there are two banks of four cylinders diagonal from each other. This is the same with V4 (rare), V6 (common) V8, V10, V12 etc etc. You also get I4, and I6 engines, basically meaning that all the cylinders are in a straight line. Inline engines tend to make for greater refinement and less vibration when revved hard.

The most common engine found in a standard family car is an I4, and nowadays, with 16 valves (4 valves per cylinder).

For power, the 2.0 8 valve, for fuel economy, the 1.4 16v. Double valves does not mean double power (i.e a 1.4 16v isnt like a 2.8 8v), just that it works slightly better.

Reply to
Sandy Nuts

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Reply to
Tony Bond (UncleFista)

looke here

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specifically here
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and here
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Great pages.

Reply to
Tim S Kemp

As has been said the difference is 8 valves that could be the difference between

2 and 4 valves per cylinder or between a 4 cylinder and an 8 cylinder engine (the yanks were at one point big on putting 16v on the back of some of there V8s as a marketing exercise because of the belief that a 16v must be faster.

Without knowing what the engines are it's hard to say, generally 4 valve per cylinder engines tend to be a bit more revy and have a bit less torque due to the lower gas speed caused by more valve area. Generally though given the choice above I'd take the 2L 8v as it will pull better lower down.

Reply to
Depresion

As per usual Steve a *useless* response, was it worth replying? *But* a nice short link that worked, so not all's lost :)

Lordy.UK

Reply to
Lordy. UK

Who knows, you did it anyway so there's no real point in asking.

Reply to
Lordy.UK

..or rather that they can fit four small valves in the space of the combustion chamber with a larger area than they could fit two big valves. Also the smaller valves are lighter and thus can travel at a higher speed without the need for excessively strong valve springs.

Reply to
adder1969

Neither.

Any 2L 8v is an old tug by today's standards.

1.4L 16v is a shopping trolley.

Really needs a compromise 1.7L or 1.8L 16V VVTi so you get a gain in top end without too much loss of bottom end.

This shows how for a same size engine 4valve/cylinder improves top end WITHOUT reducing bottom end power. Bottom end just feels weak due to top end gain. Better fuel economy at higher power demand, not much change at low load.

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If you aim for same power by having a smaller engine as you have suggested then you do lose bottom end power. Reduction in botton end performance gives big gain in economy if you are willing to accept the reduced performance. A 1.4L 16V even with VVTi is way too small to match a 2L 8V. It may not get any better mpg as you will be in a lower gear and running higher rpm to get the same performance as the 2L 8V.
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Whole report at (it's big 2Mb).
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Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Reply to
Peter Hill

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