You've got the picture. More cam, more compression. The 300+ cams work
well though from 4000 to 6500 or a little more in these old time engines and
generally it is the cylinder head breathing and combustion shape that stalls
out the power much over that number.
----- Original Message -----
From: "Larry Young" <cartravel@pobox.com>
To: <fot@autox.team.net>
Sent: Sunday, December 30, 2001 7:39 AM
Subject: Engine Simulation & Cams
> As a new member, I've been spending a lot of time going through the
> archives, but it's a slow process. A few questions:
>
> Has anyone run an engine simulator on TR3/4 engines? It seems like a
> good way to dial in cams, compression, etc. It is a fast and cheap way
> to experiment, and an excellent tool when used in conjunction with a
> dynamometer. I played around some with Engine Analyzer. I could get
> close, but really need some flow bench data to do the job right. Has
> anyone published flow data for these engines? I'd like to use the
> simulator to look a cams. I have a gut feeling that about 90% of
> modified engines are overcammed (too much duration). My TR3A (ex Jeff
> Wilt/Bob Kramer) has about 10.5:1 compression and a 304 degree duration
> cam. I saw Greg Solow's post which recommends cams based on compression
> ratio. Usually the cam duration is tied to the RPM range where you want
> power. From what I read, these crankshafts tend to let go with
> sustained operation around 6500 RPM. So why would you ever want to run
> a 300 degree cam which produces power at 4000 to 8000 RPM, when you
> could run a 290 degree cam which produces power at 3000 to 7000 or even
> a 280 degree cam that produces power at 2500 to 6500?
> Larry Young
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