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| 300WHP Supernatural 3.XX Coming Soon! (Page 29/54) |
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La fiera
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NOV 21, 07:02 PM
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Blacktree
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NOV 22, 12:11 PM
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Nice 
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pmbrunelle
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NOV 22, 03:35 PM
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Your videos are getting better, but it is hard to hear you speak. I had to make the volume very high, then when the music came on, it was blasting.
What does it mean when you say you calculate the camshaft duration based on the rod/stroke ratio?
Is this a La Fiera secret-sauce calculation, determined over years of finding what works?
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La fiera
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NOV 22, 08:29 PM
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| quote | Originally posted by pmbrunelle:
Your videos are getting better, but it is hard to hear you speak. I had to make the volume very high, then when the music came on, it was blasting.
What does it mean when you say you calculate the camshaft duration based on the rod/stroke ratio?
Is this a La Fiera secret-sauce calculation, determined over years of finding what works? |
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I know, sorry you couldn't hear me properly. That is everyone's complaint. As far as the secret sauce I can say it is something like that.
I take EVERYTHING into consideration when designing a cam. People say camshaft designing is a black art, not for me. It is just common sense.
I don't built my engines to make HP, I build them to make torque. And since HP is a mathematical calculation of how fast that torque is delivered, the HP would find its place if you build engines to produce the highest torque per cubic inch. That would also give you an idea of how efficient and effective the engine is using the air/fuel mixture to make power.
You got a PM. Read it and I'd like to hear your thoughts on it. I did that approach year ago on an engine without knowing (by mistake) and after doing a lot of research on why that engine was so powerful I came across this.
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sourmash
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NOV 22, 09:06 PM
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I turned on the close caption and it said something about a lobster and a celebration. Was it a Rock Lobster?
I think it turned 6 degrees of extra duration into a six year celebration. I'm not sure what a "narrow lobster handle" might be though.[This message has been edited by sourmash (edited 11-22-2020).]
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La fiera
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NOV 23, 07:39 AM
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| quote | Originally posted by sourmash:
I turned on the close caption and it said something about a lobster and a celebration. Was it a Rock Lobster?
I think it turned 6 degrees of extra duration into a six year celebration. I'm not sure what a "narrow lobster handle" might be though.
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LOL!! Narrower lobe center angle is what I said. I know, it's all my fault! I'll see if can find a microphone that works with my Iphone.
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sourmash
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NOV 23, 08:22 AM
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Ok, lol, I should've gotten that. It's looking ver-nice.
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Blacktree
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NOV 23, 02:09 PM
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| quote | | Originally posted by pmbrunelle: Your videos are getting better, but it is hard to hear you speak. I had to make the volume very high, then when the music came on, it was blasting. |
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I had the same problem, when I started making videos. To balance the audio, I had to crank up the microphone gain quite a bit. There should be a setting for that in the voice recording app. I also had to turn down the volume on the music. You can do that in the video editing app.
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pmbrunelle
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NOV 23, 08:29 PM
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You did publish the title of the paper in your video, so you could share it here for other folks to read.
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So there are perhaps four aspects to consider with the quick-return:
1. With a certain amount of air/fuel mixture in the cylinder, how can the most work be performed on the piston face? The is is called the indicated work. The study you refer to only analyses this aspect of the engine performance, so it's a bit incomplete (not the big picture). Also, it's only computer simulations, so who knows how good those are? The paper did not mention if they adjusted the (simulated) spark advance for different values of offset; I think that optimum spark advance could change.
My personal feeling is that quick-return is not good to maximize indicated work on the piston.
Ideally, to reduce the load on the crankshaft during the compression stroke, the spark should be delayed as late as possible. Then, at TDC, the spark should light the mixture, and the mixture should completely burn, causing the pressure to rise. Then, the piston should move down from TDC, ideally once combustion is complete. This is the ideal. In practice, we seek to have the mixture burn fast, and the spark is advanced relative to TDC; this gives a compromise between negative work on the compression stroke, and positive work on the power stroke.
With quick-return, could the piston start moving down prematurely, preventing the pressure from getting high and pushing down hard on the piston?
2. At the start of the intake stroke, as the piston moves down, this movement kick-starts the movement of the slug of air inside the intake runner. In your engine builds, this seems to be a key factor to success. The quick-return could have a large payoff due to this.
3. Side load on the piston is affected by offset. Since this is for racing, if the engine wears out a bit faster, I don't think you have to worry about that. This doesn't look like a 100 000 km 5-year warranty kind of project.
Side load can cause friction. Friction in the engine is why power available at the flywheel is less than indicated power.
4. Assuming that your racing class limits the displacement, you cannot verify compliance with the normal formula:
number_cylinders * crank_stroke * bore * bore * pi / 4
You can use the formulas in the paper to find your true displacement.
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General remark: On the big-bore 60° V6 models such as LZ9, the piston bores are offset (away from the camshaft) by 1.5 mm (I think that's the number). I don't know if the piston pin is centered in the piston. Anyway, if the ECM uses the same tune for both banks, then that means that 1.5 mm shift is not significant.
The piston motion is the same for these two scenarios:
Pin centered in piston, bore offset
Bore centered, pin offset in piston
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ericjon262
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NOV 24, 01:44 AM
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OEM's have been offsetting piston pins for years to better balance the thrust loads on the cylinder walls.
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