-----Original Message-----
From: Mark Anderson [mailto:mark@928intl.com]
Sent: Saturday, December 21, 2002 6:11 PM
To: 928
Subject: [928] RE: cam lift question


Here is the cam info you requested


           intake lift    exhaust lift   intake duration     exhaust
duration
78/79 	.435			.395			227			216
80/82		.396			.350			216			206
80/83 usa	.435			.395			215			203
80/83 euro	.472			.432			223			215
84/86 euro	.472			.432			228			219





-----Original Message-----
From: tom falkenberg [mailto:shaaark89@hotmail.com]
Sent: Sunday, December 22, 2002 9:34 AM
To: 928
Subject: [928] RE: cam lift question

jay,
i have lift numbers for the 85/86, s4, gt, and gts that i got from phil 
threshie and you're right.  the gt cams and the 85/86 cams are virtually 
identical.

85/86
int dur 253 int lift .393 exh dur 236 exh lift .353
s4
int dur 236 int lift .354 exh dur 223 exh lift .314
gt
int dur 258 int lift .393 exh dur 236 exh lift .353
gts
int dur ?   int lift .374 exh dur ?   exh lift .334

hmmmmm....

tom falkenberg
89 s4 shaaark
88 s4 track car
87 s4 not supercharged anymore
91 gt (barney)




-----Original Message-----
From: Neil Forn [mailto:axiomatic99@netscape.net]
Sent: Tuesday, December 31, 2002 7:05 PM
To: 928
Subject: [928] RE: cam lift question


Thanks to those who responded to my cam lift and duration questions.  I
finally degreed out the cams on my 81 US.  The numbers I finally arrived
at are; 270 degrees with .396 lift.

I have interpolated my measurements from my car to the other 16v cams
below.  It is not guaranteed accurate but should be a reasonable
approximation.  These numbers make sense and support what everyone has
always supposed: that we have quite mild cams in our cars.  Even the 84
euro cam is quite mild. It ‘s really only one step up from a standard
stock grind.  There is so much untapped potential in these engines!

   		intake lift  	 intake duration @ 1mm 	intake duration absolute
78/79 	.435				227				281
80/82		.396				216				270
80/83 usa	.435				215				269
80/83 euro	.472				223				277
84/86 euro	.472				228				282

Neil Forn

from: Brad Orr


Hi Neil,
This is a rather late reply, but I didn't see any list responses
subsequent to this post that dealt with your questions.
 
The duration numbers being quoted at 1mm lift is not unusual....
manufacturers of aftermarket performance cams for North American
V8 engines commonly use a .050" lift reference from which duration
figures are measured.  As 1mm = .03937" the "Porsche" numbers would
show a couple of degrees extra duration on both the opening and
closing values, but could still be related to camshafts for other
V8 engines using the .050" figures.
The reason duration is measured with the valve already "unseated" is
because the cam manufacturers have found that there is very little
appreciable flow until the valve has exceeded this lift.
 
I don't know the lobe center angle for any of the 928 cams, but this
could easily be determined with a camshaft (with degree wheel mounted)
in a "V-block fixture" or a lathe and two dial indicators - one riding
on an intake lobe and one on an exhaust lobe.  Maybe I'll get around
to this one day in the future.
 
You can adjust the camshaft timing on the 4.5 liter engines *IF* you
change your timing belt and gears to the "updated" later-style belt,
sometimes referred to as the "high torque" belt/gear assembly that
started in 1983 on the later 4.7 liter engines.  The cam gears on the
later setup allow adjustment of a few degrees, unlike the early 4.5
liter parts.
Get ahold of Mark Anderson at 928 International to inquire about
used gears ("new" is, of course, expensive.... and NOT necessary as
the rubber belt does not wear the gear teeth rapidly!).  Tell Mark
I sent you, we are good friends.
 
Hope this helps,
 
Brad Orr
'78 euro  5 speed