[Fot] Racing rod design

[MadMarx]

Hi Brad,

 

we are just discussing the shape pattern, not the manufacturer. The failed rod came from Scat.

Your link is leading to a Chinese rod.

 

Cheers

Chris

 

Von: Fot [mailto:fot-bounces at autox.team.net] Im Auftrag von Brad Eells
Gesendet: Donnerstag, 23. Juli 2015 02:06
Cc: FOT
Betreff: Re: [Fot] Racing rod design

 

Are these the Ebay rods that have been discussed?

 

http://www.ebay.com/itm/Connecting-Rods-for-Triumph-TR3-TR4-Forged-Conrods-Con-Rod-158-75mm-ARP-Bolts-/131562025540?hash=item1ea1b53244 <http://www.ebay.com/itm/Connecting-Rods-for-Triumph-TR3-TR4-Forged-Conrods-Con-Rod-158-75mm-ARP-Bolts-/131562025540?hash=item1ea1b53244&vxp=mtr> &vxp=mtr

 

Any thoughts? The price is certainly attractive...

 

 

Brad

 

On Tue, Jul 21, 2015 at 12:24 PM, MadMarx <tr4racing at googlemail.com> wrote:

Hi Guys,

 

After my engine blow at the last race and a rod in two pieces I investigated about rod design.

 

In US forums I found an interesting opinion:

 

H-beam rods are for low rev high torque engine (turbo, compressor)

I-beam are for medium torque engines with high revs

 

As engineer I agree with this statement. On high revs the rod shaft gets bended back and forth by the inertia caused by the rotation.

I could imagine that the sharp sides of the H-beam rod will create a crack after a while because the stiffness for bending along the rotation axis smaller than with an I-beam rod.

That means to me that the fatigue resistance is smaller on an H-beam rod at high revs.

With high revs on a long stroke engine I mean 6000+.

 

The manufacturer of the broken H-beam rod was Scat.

 

I think next time I order an I-beam rod from Scat.

 

What do you think?

 

Cheers

Chris


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Brad Eells

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