On Wed, 30 Nov 2005, Gene Holtzclaw wrote:
> I would like to know from those who know much more than I ever will, what
> connecting rod is best if you are attempting to build the ultimate street
> driven TR6 engine?
The best rods are Carillo. Period. All the top racers run them. They are,
however, just this side of insanely expensive at $333 _each_ when I last
checked.
The stock rods are pretty good unless you build a lot of boost and/or
compression (like more than 12:1 c/r or more than 9 or 10 pounds of
boost)... if you follow the Kastner recommended methods for
polishing/lightening the rods, they will be stronger still. Just don't
take off too much material to lighten the stock rods or you're asking for
trouble.
There are two alternate forged rod companies out there that are worth
looking at, Pauter and Sainz(sp). A lot of the vintage crowd is tiring of
the ex$pen$ive Carillo offerings, and have started using Pauter. They are
NOT Carillo, but they are affordable. I tried talking to Sainz a while
back and had a less than memorable experience, as I had trouble getting
return calls, but if you can get those rods they seem to be closer to the
Carillo with the beefy H cross section.
With either the Carillo or Pauter, you loose a LOT of mass at the big end
and this is a good thing when it comes to doing less stress on your crank.
You can lighten the stock rods well more than 30 grams at the big end with
proper lightening, but you do give up strength. However, for a boosted
engine, you should sacrifice high end ultimate revs for strength... so I'd
suggest full prepped stock rods that are polished, lightened and
end-to-end balanced. You'll put probably $150 to $200 per rod to get
there. Otherwise, try the Pauter/Sainz and then Carillo if you have the
dough.
> FYI, I am supercharging my engine. I am having my
> crankshaft lightened considerably. I would like to buy the lightest, most
> durable rod available. Also does anyone know what the stock rod weighs so
> that I may compare it to what is offered. Can I lighten my rods and expect
> them to be durable?
See above.
As regards to lightening the TR6 crank, I would advise against it.
Instead, you should get it balanced and then plasma nitrided to make it
stronger. The TR6 crank flexes quite a lot at the peak harmonics and this
leads to stress cracks (and worse). Lightening the crank does not add
strength which is what you need. Interestingly, Kastner et al discovered
that be ADDING weight to the TR6 crank they could make it less prone to
cracking. So, balance the crank and get it nitrided. that's the right
thing to do.
Regarding the rods, like I said - if you want the best, Carillo.
Otherwise fully prepped stock rods, then Pauter/Sainz and then Carillo.
And for a boosted motor - don't skimp. The crank and rods take a real
beating and if they fail, they'll take EVERYTHING with them.
regards,
rml
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