The trick with compression is that you want to achieve a dynamic compression
ratio of 8:1 on all Healey engines. If you raise the static compression on an
engine you must use a longer duration cam, i.e. rally or race. If you use a
such a cam the dynamic compression is lowered and you will be fine. It's quite
straight forward to calculate the dynamic compression. You don't consider the
complete stroke (static) rather the remaing stroke after the intake valve has
closed. If you calculate with different cams you will see the difference and
that with longer duration you will get a lower compression. I build both 3000
and 100 engines with 300 degree cams for road use, without hesitation, pingin
or run on.
Magnus Karlsson
BorC%s Motor Corporation AB
Husbondegatan 36 B
507 60 BorC%s
Sweden
Phone +46-(0)703-933349
www.concourshealeys.com
13 jan 2011 kl. 16:23 skrev "Thomas Willig" <twillig@ruda.de>:
> Hello,
>
>
>
> I am in the process of rebuilding the engine of my 100. In order to get
> some more punch from it, I am thinking about fitting DW forged pistons
> with an 9,5:1 compression ratio. You all know that if you talk to three
> people (all of them not A-H 100 owners) you will get at least four
> different opinions. Statements given were:
>
>
>
>
>
> "You will get detonation at this compression rate"
>
> "You will loose all smoothness of that engine"
>
> " A motor with that CR is only drivable on the track"
>
> "You will have to buy three head gaskets every year"
>
>
>
> I am aware that most of this is probably nonsense, but... maybe..??
>
>
>
> I guess there must be experienced folks on the list who are running
> engines with a 9,5:1 compression ratio. Please come forward and share
> your experiences and thoughts with me.
>
>
>
> Regards
>
>
>
>
>
> Thomas Willig
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