Date: Mon, 20 Nov 2000 14:38:02 -0500
Reply-To: Robert Donalds <bostneng@FCL-US.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Robert Donalds <bostneng@FCL-US.NET>
Subject: Half lilley was Boston Bobs AMC rantings
Content-Type: multipart/alternative;
fellow vanagon types an the power hungry
The testing I have had done showed that I can greatly improve the
air flow threw the heads and
give the engine more torque threw the low end and mid power range. It
appears a majority high lift o gains in air flow came from the extra
valve and custom seat work (much more than just 3 angle valve job). The
testing did show clearly that the stock AMC heads don't flow very well
under .250ths valve lift. I am sure the stock head OEM heads have the
same flow characteristics. the total valve lift of the stock 2.1 intake
valve is .360ths at the retainer that's why the higher ratio rockers are
making a difference they increase the lift to around 450ths.
intake valve flow chart air flow measured in CFM
stock head on left ported and hp valve job heads on right
.050 lift 24.8 33.0
.100 lift 47.1 55.4
.200 lift 89.6 103.7
.250 lift 115.4 123.9
.300 lift 125.3 139.5
.350 lift 137.6 156.2
.400 lift 144.9 170.8
.450 lift 147.8 178.2
this is a huge gain in air flow as you can see the stock head at .450ths
lift doesn't flow as well as the reworked head at .350ths lift
I personally don't like the ratio rockers because I think they put more
side load on the already to short intake guides. reworking the heads as
you can see in the chart I have increased flow beyond the ratio rockers
but at lower valve lift with no decrease in reliability
The cam I have used in my test engine is the same grind as Robert
Lilleys its not a 3/4 grind and is only a tiny bit more duration this
cam would need the properly machined lifters to match the new lobe
profile
Other developments are that new performance swirl polished valves are
in and bigger valves are also in the works and due in at the end of
December. I plan to continue the next round of flow bench testing when
they arrive
I have one upgraded engine installed in a syncro with lilley style cam
and above mentioned head work its at my installers shop he tells me its
a big improvement in torque and he says there is less need to down shift
around town he called it the perfect upgrade for a syncro or westy he
also said that the acceleration compares to that of a 2 wheel drive van
with a fresh engine I am offering these upgrades the pricing however is
not yet complete.
updates as they happen
Boston Bob
.
[text/html]
|
Back to: Top of message | Previous page | Main VANAGON page
Please note - During the past 17 years of operation, several gigabytes of
Vanagon mail messages have been archived. Searching the entire collection
will take up to five minutes to complete. Please be patient!
Return to the archives
@ gerry.vanagon.com
The vanagon mailing list archives are copyright (c)
1994-2011, and may not be reproduced without the
express written permission of the list administrators.
Posting messages to this mailing list grants
a license to the mailing list administrators to reproduce
the message in a compilation, either printed or electronic.
All compilations will be not-for-profit, with any excess
proceeds going to the Vanagon mailing list.
Any profits from list compilations go exclusively
towards the management and operation of the Vanagon mailing
list and vanagon mailing list web site.