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Carillo: Two-piece con rods claimed to boost low-end engine torque by 30%
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A new take on the Atkinson cycle…?
This is nonsense. The outcome is no different than moving the piston pin down and shortening the rod.
This adds mass and increases side loading, while adding unnecessary parts.
Maybe there's an angle benefit, like a slip yoke eliminator? Maybe there's less power wasted from basically trying to push the piston into the side of the cylinder wall?
My sixth grade teacher told me something that seems to make since. More so today then back them.
He said Bill, don’t believe anything ya hear and only half of what ya see.
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You'll get a parking violation and a maggot on your sleve.
Really?
Draw it out on paper and get back to us
As a guys who's done a lot of crank work. I'm intrigued to say the least.
This design should show the biggest gains when lubricated with snake oil instead of dino blend.
It's funny they tout their design requires more spark lead; as if that's not a tell tale indication of efficiency loss.
Be sure to read the entire article. Whoever wrote it is knowledgeable, and right on the money in their criticisms:
"While Transcend is confident, many are not convinced, particularly given the current lack of third-party testing and the paucity of results presented by the company. The two-piece con rods are heavier than standard items, creating additional inertial forces that will increase substantially as the engine revs faster, so there's a good chance that even if there are low-end gains, they might come at the expense of high-RPM horsepower.
And the design would also appear to create extra lateral force on the pistons, since the lower pivot point and shorter main arm make the angle between the con rod and the cylinder bore even greater. Not only that, but the distance between the main gudgeon pin and the new, lower pivot now effectively appears to become a torque arm that'll amplify the forces making the piston want to tilt.
So Transcend will certainly need to prove its con rods do what they say on the tin, and that they can do it without increasing engine wear."
Well I don't know what my drawing will do for you if you can't tell from the video they posted.
The skirt takes all the side load of the extreme rod angle, plus the moment from the pivot being moved so far below the bottom of the skirt will cause the piston to tip.
If it adds weight, it will kill revs.
Thats just Mathematics.
All I see is a short rod and a lower piston pin height. And that could be done with one wrist pin instead of two by redesigning the piston. Why add more parts to the rotating assembly?
None of the naysayer commentators have drawn it out on paper to realize the benefits
Please explain the benefits.
The shorter rod once past TDC has a faster break angle against the crank center, giving it more leverage
This also allows for the timing to be advanced, unlike the long rod that dwells longer and would cause it to knock
There's nothing that needs to be drawn out; it's very simple. It's an unnecessarily complex short rod, low rod stroke ratio engine. All else equal, a lower rod stroke ratio causes the piston to dwell longer around bdc, giving the effect of higher "dynamic compression". This is where their low rpm torque gains are coming from. Higher compression can be achieved easier via traditional means, without the many inherent drawbacks this design brings with it.
It might seem that way, but the "increased leverage" occurs over a smaller crank angle, so it cancels out over the entire cycle.
Also, a design that requires timing to be advanced is not a good thing. That's negative work, and an efficiency loss.
So you did not watch the video then
Where the wrist pin drops down inside the crank counter balancers
In between the balancers is just enough room for the rod
How do you propose to attach the rod wrist pin / piston then
Pit Row
Don’t the OEMs play with all these different piston geometries already? I have to imagine after half a century of trying to eke out another percent of performance, there isn’t a 30% torque increase just laying around with a simple change like this.
Wouldn’t a shorter rod and a lower piston pin do exactly the same thing? Without an extra pin, an extra chunk of connecting rod and two of whatever the stabilizer things that mate to the bottom of the piston are called?
Seems like complication for the sake of complication. I’m surprised Carillo is involved. Does anyone else think the secondary rod segment doesn’t look like something built by the same company as the primary rod?
This is what the Deegans were hiding at Loretta’s!!
Watch the video
The piston is already as small as it can be, watch when the counter balancers come around, and with that the standard rod is as short as it can be
This way they keep the piston as small as it can be and use a rod that is much shorter
They are thinking well outside the box
Is it different than moving the wrist pin lower on the piston? I am having a hard time seeing how it doesn’t increase the rocking force on the piston.
Watch the video
The wrist pin is as low as it can be now
The diameter of the counterweights on the crank can be much larger with this gizmo, which gives a lighter crank more flywheel effect, but adding 4 more reciprocating parts and their weight to each cylinder doesn’t seem to be a good trade off.
Who knows, maybe it’ll work? I’m thinking not, but I’ve been wrong before.
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I’m a little slow on the uptake, does mx251 want me to watch the video?
let’s make the bikes look cool, then we can worry about cam shafts and con rods
Get rid of the upper wrist pin and the bumpers and build that extra geometry into the piston. Two-piece style if the lower needs to be steel due to size/strength constraints.
They seem to have gone out of their way to design this in the silliest way possible.
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