[SOS-cars] Re: stock aan and 7a cams
mlped at qwest.net
Thu Feb 12 01:18:44 EST 2004
Thats a great idea, but
. What exactly is a good cam for a turbo motor?
High rpm power? Low rpm torque?
Overlap, to do or not, & if so by how much?
At least with the 7A and all the other 20v NA 86.4mm stroke by 144mm rod
One would be dealing with the same piston accelerations and speed.
My impression is that aggressive cams whatever aggressive means, isnt
necessarily good in a turbocharger application. But Im certainly willing
to listen to arguments to the contrary.
I believe the Bentley publishes figures, and theyve recently been posted
either here or on the S-Car list, for acceptable compression test numbers
and maximum cylinder to cylinder variation. I think a compression test psi
reading will vary with (a) altitude; (b) condition of your starter and
battery; (c) throttle open or closed (its supposed to be open); oil temp and
As I recall, one key killer variable (i.e. what you DONT want to see) is
a great cylinder to cylinder variation.
Ah-ha, Bentley C 15-7
Compression pressures: 9.0 13.0 bar (131 189 psi)
Wear Limit: 7.0 bar (102 psi)
Max permissible difference between cylinders
3.0 bar (44 psi)
How to Check (Bentley C 15-6)
- Engine Warm coolant temp gauge @ 80 C° (176° F)
- Turn quick fasteners (arrows) on connector cover on rear of
engine compart bulkhead 90° to left & remove
- Mark and separate connectors -5 & -6 (to ignition coils)
- Remove cover with coils on cylinder head
- Unscrew all sparkplugs
- Check compression with VAG 1381 and adapter 1381/1
- Throttle valve fully open
- Operate starter until no further pressure increase is indicated
From: audibusdriver [mailto:audibusdriver at yahoo.com]
Sent: Wednesday, February 11, 2004 1:25 PM
To: SOS-cars at yahoogroups.com
Subject: [SOS-cars] Re: stock aan and 7a cams
I was looking at getting very aggressive cams with more lift and
duration. I found a supplier but I was looking at finding out what
stock is and go form there. I currently have a 7a exhaust cam and
it's nothing special. I want something to wake up the motor &
BTW does anyone know what the stock compression reading(psi) is with
the 9.3-1 comression ratio. I know mine is a little low and am going
to do a overhaul very soon, so that is why i'm looking at cams!
More information about the 200q20v