Re: [DML] Re: Ported PRV Vacuum Ports

[Martin Gutkowski - DMUK <martin@xxxxxxxxxxxxxx>]

"quite a jolt" ? Not really because there's sod all TORQUE when you're 
not letting much air into the engine. Open the throttles more and MAP 
increases anyway. And the amount of advance is governed by the travel in 
the diaphragm - it ain't a huge amount.

Interetingly, the island turbo setup deliberately leaves the vacuum hose 
off the dizzy "because advance is bad". Well, dur - the diapragm is fed 
from the intake and won't budge if the intake is under pressure (boost). 
Bloody half-assed thinking there - reinstalled the vac solenoid on my 
friend's one and wouldn't you know it, bottom end pickup is vastly improved.

Martin

content22207 wrote:

> Don't have a throttle assembly in front of me, but if I remember
> correctly PRV ported vacuum ports are traditional slits. As the plates
> open, more of the slit is exposed, increasing the amount of vacuum
> allowed through. This is the way ported vacuum has been done for
> decades (carburetors).
> 
> The advantage of ported vacuum is it varies with throttle plate
> activation. DeLo simply takes off from the driver's rail -- 100% of
> whatever happens to be in the manifold at that time. Quite a jolt when
> the plates are only partially open.
> 
> Bill Robertson
> #5939
> 





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