Re: Engine design question

[Alexei M Voloshin <Alexei.M.Voloshin-1@tc.umn.edu>]

Why not go with a VTEC type system and keep two of the four valves closed 
at low RPM and then open them up at high rpm. After all, the technology 
is over 15 years old.

Alex

On Tue, 1 Oct 1996, Andrew J. Speer wrote:

> I think this was discussed a few months back, so you might want to check the
> archives.  Audi decided on a 2 valve engine (after manufacturing DOHC 4
> valve I5s for quite some time) for a little known, but very good reason: 2
> valve engines produce better torque in the low to mid rpm range where a
> driver spends over 90% (with the exception of several q listers) of his
> time.  A flat torque curve is far more important for everyday driving than
> top-end power.  A 4 valve engine breathes better at higher rpms and can thus
> generate more power, but at the expense of decreased low-end torque (ever
> driven an Acura? you'll know what I mean).  Make no mistakes about it, the
> Audi 2.8 is a sophisticated little mill.  It sports a variable intake
> manifold (interesting article in this month's EC) and the latest
> Bosch-Motronic fuel management system.  Come springtime the 2.8 engine gains
> a new 5 valve head, and variable intake timing to solve the
> lack-of-low-end-power conundrum.  Even so, power increases to 193 not 300 so
> you haven't missed out on that much unless you live for skirting that rev
> limiter.
> 
> 
> Andrew Speer.
>