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FW: Cylinder Bore

To: "'Healey Forum'" <healeys@autox.team.net>
Subject: FW: Cylinder Bore
From: PG <britishcars@shaw.ca>
Date: Thu, 09 Nov 2006 20:22:38 -0800
To follow up on my previous email, here an email I received today from a
fellow in Arizona that I have been working with to benchflow and design the


Again, I thought it might be interesting to many of you.


I am relatively new to the list, so if this is taboo, please let me know.






Assuming you went from a stock bore to 88.9 mm bore and keep a 10 to 1
compression ratio, ran a muffler, used the DW 278 cam, and both heads flowed
the same. You would get


Stock 2.9 liter

171 ftlbs at 4952 RPM

179 Hp at 5899 RPM


3.311 liter

195 ftlbs at 4107 RPM

179 Hp at 5184 RPM


Torque is larglely driven by displacement and compression ratio. Horsepower
is primary driven by cylinder head flow. In real life the 3.3 liter would
make 4.2 more horsepower because there is less friction at lower RPM.


If the head and manifold flow real strong we may need this trick to keep the
engine RPM below the critical 6000 RPM point.


Note I would leave at least one overbore left. Its a real bummer when you
have an engine you like that needs to be rebuilt and you have to either
resleeve the block or buy a new one.


Cheers Jim

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