16v or 8v turbo?

[jfolkson@optonline.net (Jan Folkson)]

> okok, heres what i mean.
>   by running lower c/r, you can run higher boost, meaning the engine draws in
> more (mass) of air
> on each stroke. the lower c/r means lower multiplication of the absolute
> pressure coming in, so
> since the lower c/r engine is multiplying by a lower factor, there is a lower
> peak cylinder pressure
> in the lower c/r engine (with the same level of boost). the peak cylinder
> pressure is usually the
> limiting factor.
>   a (stock) 16v with ~5 lbs boost has approx the same peak pressure as an 8v
> with ~15 lbs boost.
> this is where the ~5 lbs limit comes from for stock 16v turbos. yes the 16v
> may be flowing better,
> but the 8v is still getting much more mass of air (and fuel) in the cylinder
> per stroke (due to the
> much higher intake pressure).

Doesn't lowering the c/r make for more of a lag before the turbo kicks in
though.


- Jan Folkson  http://www.janfolkson.com
NYC

'86 16V
'99 Passat GLS 1.8t
'00 Beetle GLX 1.8t

"Gravity, it's not just a good idea...it's the law!"