Ferrari Mailing List: Re: No Ferrari content - hobbs switch

[LarryT (l02turner]

Hi James,
   How do you know the switch activates at 4psi?   I assume you know that 
because you bought one  with a set point of 4psi?  (just trying to get a 
feel for the history of the problem).

    Also, the Hobbs/Honeywell website 
http://content.honeywell.com/sensing/hss/hobbsparts/products/pressureSwitches.asp
has a warning about using the switch with the polyimide diaphram with water 
and suggest using their
switch with theTeflon diaphram.   They also have a Technical Help email 
address.

(BTW, the set points are listed as 1 psi for 2 of the switches and 2 psi in 
2 others & 4 psi in 2 others.  All their other switches are set at 10psi or 
greater so none of those are probably installed in your car.)

   Having said all that, I would think it would be preferable to put a 
pressure gauge near the switch so you;ll know where it is opening.  You 
never know when the set point drifts - I would think too much  pressure 
might damage the engine?  Jegs and Summit point raceway both carry a large 
number of AN fittings and pressure gauges.  I would think you'd prefer to 
know exactly how much pressure the Hobbs switch is using.

   Alternately, you may get an answer at the most popular Porsche email 
discussion list in the world ;-o  www.rennlist.com has a forum and an email 
discussion list which you can join and ask as many Porsche questions as you 
wish - would love to see you there -     BTW, I know there are some others 
there who have installed supercharging on their 911s.

Sorry I wasn't able to provide a proper answer -

Larry T (67 MGB, 74 911, 78 240D, 91 300D)
www.youroil.net for Oil Analysis and Weber Parts
Test Results http://members.rennlist.com/oil
PORSCHE POSTERS!  youroil.net
Weber Carb Info http://members.rennlist.com/webercarbs
.

----- Original Message ----- 
From: "James V. Cunningham" <vikelj [at] comcast.net>
To: "Larry Turner" <l02turner [at] comcast.net>
Cc: "The FerrariList" <ferrari [at] ferrarilist.com>
Sent: Saturday, January 26, 2008 2:04 PM
Subject: [Ferrari] No Ferrari content - hobbs switch


> I just put water injection on my supercharged Porsche 911.  I have a
> hobbs pressure switch which activates the water injection at 4 psi of
> boost.  Since I only make about 6 lbs of boost, I would like to
> reduce the pressure required to have the hobbs switch engage.  I know
> that I am supposed to turn the adjustment counter clockwise but by
> how much.  Do you turn the adjustment a full turn for each psi or do
> you turn it less and by how much.  Any help would be appreciated.
> Jim
>
> James V. Cunningham, Esq.
> 410-625-7400
> http://home.comcast.net/~vikelj/page3.html
>
> _________________________________________________________________
> To unsubscribe or modify your subscription options, please visit:
> http://lists.ferrarilist.com/mailman/options/ferrari/l02turner%40comcast.net
>
> Sponsored by BidNip.com eBay Auction Sniper
> http://www.BidNip.com/
> and F1 Headlines
> http://www.F1Headlines.com/