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crossflow heads

To: mgs@autox.team.net
Subject: crossflow heads
From: wzehring@cmb.biosci.wayne.edu (Will Zehring)
Date: Fri, 28 Jun 1996 09:26:06 -0400
Todd M. et al.:

I can, if you really want it, theorize for hours on the virtues and vices of 
a crossflow head.  None of it would be based upon experience or knowldege, 
so I'll pass.  OTOH, it is my understanding, gathered from readings and 
conversations, that the crossflow design is superior.  It improves HP output 
on the B-series engine, the Ford Kent engine (in the Morgan) and is well 
known on the famous Jag XK engine.  The hard core reasons, as I say, are 
obscure to me.  The *hypothesis* that it has to do with gas flow seems 
appropriate, as the head is, largely, regulating gas flow, in the form of 
fuel/air aerosols and exhaust.  Ports can be larger as one side of the head 
doesn't have to accomodate both intake and exhuast.  Hence, carb throats can 
be larger as well.  Fuel/air flow is enhanced and a greater "charge" can be 
delivered at each intake stroke.  I imagine cooling passages can be better 
spaced as well.  When you think about it, the single side head that is 
standard on the B-series engine is awfully crowded on that side, and awfully 
empty on the other.  

The principal drawback to that design on the B-series is that if the intake 
is on the passenger's side and your carbs leak, they will leak onto the 
distributor and/or the starter motor.  A friend has the original "HRG" 
crossflow on his B-series engined TVR Grantura MkIII (God, I WANT that car!) 
and he complains only that its hard to reach the distributor.  The head is 
equipped with twin Delorto carbs.  I understand this was a MAJOR hassle with 
the crossflow DOHC head that Chapman put on the Ford engine in his Elan and 
Europa.

I'm quite interested in the new head, but am also quite unwilling to be the 
first guy on my block to try it from the fellow who is promoting them.  He 
makes claims about its performance enhancement and superior cooling 
properties.  I'm not saying he is wrong at all.  I'm just saying I'd like a 
second opinon from someone who is not profiting from their sale.  Once I've 
heard the good word from someone else, I'd seriously consider it.

Will Zehring


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