American race cars (formerly - OT: new car advice)

[Robert N. Eaton]

Bob Holtzman wrote:
> On Tue, 22 Nov 2005, Mike Garfias wrote:
>
>   
>> Robert N. Eaton spoke forth with the blessed manuscript:
>>     
>>> Mike Garfias wrote:
>>>
>>>       
>>>> Two small valves weigh more than one single one. 
>>>>         
>>> Not really. Think cube-square law.
>>>       
>> Yes, really.  you're failing to take into account the weight of the stem.
>>
>> Two valves = two stems 
>>     
>
> How about thinking weight per flow area? You will still be rev limited but 
> should make more power at the revs available because you're moving more 
> mixture.
>
>   
What I was thinking, and I apologize for not stating it, was that the 
valves should be redesigned proportionally in all dimensions such that 
the head area is 1/2 that of a single valve. This being the case, each 
redesigned valve would weigh/mass 1/4 as much as the larger valve. Valve 
springs would be proportionately lighter, both in mass and pressure. 
Thus the reciprocating mass of each valve, being on the order of 1/4 
that of the larger valve assembly, would allow a substantial increase in 
rpm without valve float.

One caveat. The small valves might have to open wider in so as to allow 
increased flow (just how much I don't know.) In this case, the valve 
stem might have to be a little longer, adding mass. However,  the 
lighter valve springs would allow greater valve motion before 
compressing coil to coil.

All in all, light multi valves allow higher rpm and greater volumetric 
efficiency than two large valves per cylinder, as the Miller, 
Meyer-Drake-Offenhausers did at Indianapolis. Even though the big Offy 
wasn't a high revver (long stroke, frightening piston speed,) its 
multi-valve pent-roof head lent high volumetric efficiency to a very 
tough, rugged engine, which made it supreme at the Brickyard for 
decades. The small Offies and Millers spun like hell and developed 
amazing power for their size.

It has been only in the past decade or so, that race proven developments 
for engines have filtered down to production cars. I only wish more of 
them were in American designed vehicles. I realize that NASCAR has 
developed pushrod technology to the limit, but I really wish they would 
let the Northstar engine race. Although it would take a couple of years 
to sort out,  I really think it would show those good-ol-boys how.

Now I'll shut up. Sorry for the long OT.

Bob Eaton