Is this a foruim for entusiasts? Or max power readers?! 8v/16v .... ... ...

[barkstar]

but is not the main reason

What is then? A 25 year old Mk1 1.8 GTi puts out about 115bhp and a 1.6 VW 16V with all singing and dancing injection and ignition puts out about 105bhp from your local showroom. So much for progress..... A suitably tuned VW 1.6 could push out well over 150bhp but would struggle to pass the emissions and fuel efficiency tests. That's why GM replaced the Red Top 2L 16V with the Ecotech and why the Ecotech is harder to tune because the ports and combustion chambers have been computer designed for fuel efficiency and emissions and so tuning shops have a lot less to play with.
Barkstar 

[VeeDubGTI16v]

the old engine does not consider emissions in the same way as the new one, as is the case with economy. the cars are also aimed at different markets, so the engine will reflect this. when the multi valve head was first designed it was for performance, not for better emmissions, therefore it is not the reason for multi valve engines, emmissions/economy etc are improvements on an existing design, not the reason for the design.

[VeeDubGTI16v]

i suppose the main reason is for efficiency

[Agreeable Slick]

Goodnight.

[Martz]

Yawn, boring. New topic please.......................................

Is a 20V better that a 16v