Bryan;
Actually we are in agreement. A good dyno test will give both the BHP &
torque curves over the full RPM range of the engine. Once that is known,
you have the info you need to do a comparison or determine the best
gearing, etc.
So far I haven't seen any A-B comparison data presented on header
performance re: stepped tubes, conventional tubes, anti-reversion
devices, etc. Comparing data from different engines on different dynos
is not very helpful: most magazine articles don't do good comparisons if
they present any data at all.
Regards, Neil Tucson, AZ
-----Original Message-----
From: Bryan Savage [mailto:basavage@earthlink.net]
Sent: Tuesday, March 09, 2004 12:12 PM
To: Albaugh, Neil
Cc: land-speed@autox.team.net
Subject: Re: Stepped Headers
Neil,
The problem I see with the dyno test is it only yields one piece
of power information.
As Dave has said (I hope I get this right) what is important is
the way the horse power curve fits between the transmission's
shift points. An engine that would go like hell with a 6 speed
might be a dog with a 3 speed.
Example: A formula Ford engine will produce maximum power
with a four into one header. It will go faster on a road race
course with a 4-2-1 header which produces a lower but
broader power curve. To me, the only race peak HP
always wins is the dyno race.
A 1,000cc motorcycle with a 6 speed and high power
to weight is quickest with 4-1.
Sooo ... I think I need to find the best header for my
application .
CFD ?????
In looking at some headers made to fit real tight areas, I wonder
how the actual behavior of the fluid flow and the shock waves
could be predicted or modeled. I would be surprised if current
CFD models would be of any use. It's looks like it's just too
chaotic to describe mathematically.
Bryan
Albaugh, Neil wrote:
>List;
>
>It seems to me that a series of dynamometer tests could settle this
>"stepped header" question once and for all.
>
>Regards, Neil Tucson, AZ
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