[6pack] Connecting Rods with Relief Holes

[Chuck Arnold and/or Kathleen Kelley]

Added FOT to this string -- sorry for those it is a duplicate.  Wanted to
try to equate the hp number I just got of by car from a DynoJet chassis
dyno with the numbers from "back in the day".

Found a great article at :
http://www.hardtail.com/techtips/hpexplained.html

to net it out, as it were:
HP before 1972 in US was a gross figure -- engine dyno, no accessories.
After 72 SAE HP is engine with accessories -- about a 20% parasitic loss
(net SAE)
When you factor in rear wheel through drive train with a standard tranny
you lose 15% more.

My racing TR6 was measured at 172 on the dyno [and running rich] with PI,
hottest cam I can get, lots of head work and a Pacesetter exhaust maifold
to 2.5" pipe with racing muffler [am putting in  a Goodparts header before
racing next year].  Using .15 for parasitic loss instead of .2, I get about
202 SAE Net HP and a wopping 238 using 1970 gross SAE values.  I seem to
recall in one of KAS books they were getting around 240 HP on the engines
-- and there gross versus net were probably the same as thee were no
"accessories" on the race engine.  That seems about right also -- I should
pick up some HP with the header and leaning it out and I run about 12.5:1
compression.  Think Kas was around 14:1.



On Thu, Dec 20, 2012 at 8:58 AM, Robert M. Lang <lang at isis.mit.edu> wrote:

> On Thu, 20 Dec 2012, Richard Seaton wrote:
>
>  I'd suggest,If not going over 150hp, then the stock rods will be fine.
>>
>
> Don't forget the factory CP cars were 150 HP in stock form.
>
>  I thought I read the late rods were better??? I must be mistaken.
>>
>
> I've had some lengthy discussions with JK Jackson about this and he was,
> adamant that early rods are the better choice.
>
> I believe the reason that the early rods are better is that they don't
> start out with a huge stress riser drilled into the rod at the spot where
> the stresses all converge.
>
> But I've been wrong before.
>
> ;-)
>
> rml
> ------------------------------**------------------------------**
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> Bob Lang              Triumph TR6!!            |  This space for rent
> Former NER Solo Chair                          |
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-- 
Chuck Arnold and Kathleen Kelley