Strictly Technical, Balancing X4:
“Thanks for your comments but we have been developing this engine for 10 years and we have laid out the engine that way for a reason. 1st: as I before mentioned the output shaft would not be able to deal with the torque if it was the balance shaft. 2nd: being a development engine, the balance shaft is located at the top for ease of changing the balancing when modifications are made.”
The 1st is wrong: When a shaft of 70mm diameter is eccentrically cut to create the one 1st order counterbalancing weight of the X4, the resulting shaft is more strong than a 50mm diameter shaft, which is by far more strong and inflexible than what is necessary to pass half of the total inertia and combustion torque of the X4.
Even in case Revetec needs counterbalancing shafts of more than 70mm diameter, the “intermediate” synchronizing gears between the two shafts can be of larger diameter than the one third of the big spur gears: each balancing shaft has two spur gears, the primary one is meshed to its mate big spur gear at a 3:1 ratio, the secondary one is meshed to an equal secondary spur gear secured to the other balancing shaft. The secondary spur gears can have diameter larger than the 1/3 of the big spur gears and still the output shaft to rotate once per piston reciprocation.
The 2nd is true if Revetec thinks it is preferable to load the engine with additional bearings, shafts and spur gears only to “change the balancing when modifications are made”. I was wrong to think I had heard everything.
It’s up to Revetec to use additional balancing shafts. But the justification is not convincing.
Strictly Technical, the thrust loads:
”The thrust loads on the bearings are deflected into the opposing cam. If you modelled our assembly and a conventional engine and you performed an analysis on the assemblies you will find that 36% of a conventional engine's load transfers to downward force on the crank, and our assembly only has 11% downward force on the shaft (the balance is converted to rotational forces by the opposing cams.”
The thrust loads: Based on their animations, the X4 Revetec arrangement, compared to the Boxer Revetec arrangement, has the two rollers of a piston in a significantly longer distance. This means significantly increased thrust loads. These two rollers push the two tri-lobe cams. If the two tri-lobe cams were on the same plain, the thrust loads would be zero. But as the two tri-lobe cams are in a significant offset from each other, the reaction of the cams to the rollers create a significant pair of forces that tends to rotate the piston about the cylinder axis. If you leave the piston free into the cylinder, it will rotate. To keep it from not rotating, a wall is necessary to provide an opposite pair of forces. This is the thrust load. This is what has to be compared to the thrust loads of the conventional. With a con-rod to stroke ratio of 2:1 in a conventional, the thrust load to the vertical load is 25% at 90 deg after TDC and only 12.5% at 30 deg after TDC. What is this ratio in case of X4 at 90/3 deg and at 30/3 of the tri-lobe cam?
Strictly Technical, Revetec rev limit:
”Our engine failed in India due to a damaged cambelt spocket in transit. This intern caused the cambelt to fail at which time the valves hit the pistons at 4,600rpm. Due to the huge momentum mass of the diesel dyno, the output flange shaft cracked when the engine stopped suddenly. The valve stems were in a "S" shape but there was no damage to any other components, such as cams bearings etc. Which proves the strength and reliability of our internals. This failure had nothing to do with our technology either so your comments are just blowing in the wind. Our engine performs well upto 6,000rpm currently and our new engine has a safety factor of 4.5 at 6,000rpm. That means it is 350% over engineered.”
After the failure of the Boxer Revetec engine in India / Mahindra on September 2006, and according Revetec’s Directors Announcement: “it is expected that the further testing will take place the next 3 – 4 months” (3 to 4 months sounds too long if the basic mechanism of the engine was unaffected).
It is now more than 4 months.
Did the tests of the Boxer Revetec completed, or the whole “Boxer Revetec” project is “phased out” (canceled) for the sake of the X4 arrangement?
And if someone had to sent from Australia to India ten people with a single engine to test, or five people with an engine to test and a “back up” engine “in case …” , or twenty people without any engine at all, I think the “back up” engine “selection” is the reasonable one.
Strictly Technical “the long connecting rod”.
“Yes, the higher the conrod ratio, the higher reving the engine. Standard car about 1.55:1, EVO 1.65:1, F1 engine about 2:1 and so on. I have performed tests with a sine wave cam and it does not perform or breathe at lower RPMs.
If you were to put some decent breathing on the Patakon engine you will find that it will continue to perform better at even higher RPM's. But remember that the higher the RPMs the more fuel you are using to achieve the output. “
The fact that Revetec failed to make a “long connecting rod” engine to breath efficiently at low and medium revs is completely different than to accept as a physical law that a “long” connecting rod conventional cannot breath efficiently at low and medium revs”.
Pattakon’s 354 cc single cylinder Harmonic engine (it is like a conventional with a connecting rod to stroke ratio not only 2:1 -like F1-, not only 10:1, not only 100:1 but infinite) provides on the flywheel more than 3 Kp*m of torque at 3.000 rpm, with only one intake and only one exhaust valve. This, according Revetec, is called “inefficient breathing”!
Is it necessary anything more to prove that Revetec’s theory for the long connecting rod is wrong?
Revetec’s “law” that relates the breathing efficiency of an engine to the connecting rod length is as wrong as it gets. The plot on which this Revetec “law” was based, proved – beyond any doubt - mistaken on previous posts.
Formula 1 engines use very long con rod to stroke ratios (2:1 or more) because it is impossible for them to use shorter: the two pistons (100mm diameter with 40mm stroke) hit to each other if short connecting rods are used.
It is a strictly geometrical subject, it is also a strictly simple subject.
In my previous post I was wondering whether there is a car with a Revetec’s engine on it for tests. From Revetec’s reply, it seems there is not. It seems that “all the money” (hopes) are now on the X4 airplane model.
I am the last to blame Revetec for trying. They try.
But it is not a good sign when Revetec’s posts are full of “high school level” mistakes.
I wish to be true that Revetec X4 is designed with a 4.5 safety factor at 6000 rpm (whatever Revetec means by this). After all this would be great for the future of Pattakon’s GRECO. But . . .
Strictly Reality:
“If you want to pedal your engine Manolis, start a topic on it! Don't be scared.
I've seen the video of your engine spiting and spluttering, oh yeah...and the one of a tacho. Where is one we can see an engine in a vehicle driving or running on a dyno. I'd like to see it for my own interests. Can you email me a video please?
Thank you for your comments Manolis, I have enjoyed reading them.”
I think Revetec will enjoy better driving than reading.
For the video A1.MOV at http://www.pattakon.com/vvar/OnBoard/A1.MOV (the one with the tacho of the Honda Civic), it seems Revetec doubts for its authenticity.
So:
The car is on a public road with the driver and a passenger.
With the first gear it goes to 9000 rpm where the rev limiter is set.
With the second the same.
At 7500 rpm with third the gas pedal is released because the car was dangerously approaching other cars going slower.
Does Revetec think this video is too good to be true?
If yes, Revetec has an invitation to come in Athens to make a video himself, any time. In case Revetec will see less than what the video shows, his airplane tickets and 1st class Hotel in Athens will be paid by Pattakon.
But instead of Revetec, Pattakon prefers Mahindras’ R&D director to come in Athens and drive the cars himself. Tickets and Hotel prepaid by Pattakon.
Or even better both, Mahindra and Revetec are welcome.
If Revetec or Mahindra have a representative (or a friend) in Athens, he can also confirm that the cars and the engines exist, and that 9000 rpm is nothing special, any place any time.
Thanks
Manolis Pattakos
Originally Posted by hightower99
)
Reply With Quote
