Most liked posts in thread: Can someone explain compression ratio?

Don't see how the compression ratio of a motor would ever become irrelevant or outdated in the design process or in tuning and Modding it.... 2 cents

 

In case anyone should think I am not qualified to make the posting above, I should like to go on record with the large number of tokens that I have collected from the top of corn flake packets, which I believe trumps all other certificates (including my two masters degrees and all those badges I got in the Scouts).

 

Please don't discount the countless hours spent polishing my cars in the driveway along with the untold time spent studying in Google.....

2cents

 

For the most part the average consumer doesn't care about Compression Ratio's, Bore and Stroke and all that more esoteric information. It seems like they mainly want to know if their iPhone will connect and if they can text while driving.

Companies that have pushed the envelope with more efficient engines will use that in marketing but it is far from the focus of the marketing efforts.

That's my take on the matter.

 

I think the point in the ads is that a higher compression ratio gives more efficiency - it also can lead to higher N0X emmissions and the aforementioned pinging (or pinking, as it used to be called) to get there the mfr's are using all sorts of tech including variable valve timing, forced induction, direct injection, exhaust gas recircualtion and on and on.....

And I thank and applaud them for it!

Doing so has given more HP and a corresponding huge bump in fuel economy - two things that in the past did not go hand in hand.

However, compression ratio is just one peice of the puzzle, and the one they've chosen to highlight.

Back in the day, if you could run 10:1 on the street (using ethyl of course) you were doing pretty good. But the rich mixtures required made gas mileage in the single digits - and the car ran so rich you couldn't stand behind it for the fumes. But she went like the clappers!

Now adays 10:1 is "normal".......

But it all may become moot if MBZ gets their variable cylinder size engines in production, as the comp ratio will change with the cylinder volume.....