4 valves better than 5
Oct 25, 2003 | 05:25 AM
#3
Red Rider
Honda, accept nothing less!
Honda, accept nothing less!
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4 valves better than 5
Can't remember what the principle is, but two small valves are more efficient than one large valve. That is why the modern engines have 4-valve heads (two intake and two exhaust). Yamaha tried to do one better, and added an extra intake valve. If two is good, three is better, I guess????????
Oct 25, 2003 | 09:25 AM
#4
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4 valves better than 5
there is no advantage and there is no disadvantage. see every engine needs to breath differently. some engines will produce more horsepower with 5 valves where others can produce more with 4 valves.
Oct 25, 2003 | 11:28 PM
#5
Trailblazer
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4 valves better than 5
Originally posted by: Ridley
it's all about velocity. 5 valves offers the same volume as 4 valves, but the charge comes in at a higher velocity, increasing efficiency. Unless your running boost, 5 valves will always be better. Hence the yz450f making 2 more hp than the CRF450(dirtbikes) [img]i/expressions/face-icon-small-wink.gif[/img]
it's all about velocity. 5 valves offers the same volume as 4 valves, but the charge comes in at a higher velocity, increasing efficiency. Unless your running boost, 5 valves will always be better. Hence the yz450f making 2 more hp than the CRF450(dirtbikes) [img]i/expressions/face-icon-small-wink.gif[/img]
Oct 27, 2003 | 12:05 PM
#7
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4 valves better than 5
Originally posted by: Ridley
Ok, here's the link. And next time someone says the CRF is better, make sure they can see how the yfz makes more power almost EVERYWHERE. I also like this graph, because it shows how the moto 440's engines actually are compared to either the yamaha or honda. Enjoy [img]i/expressions/face-icon-small-wink.gif[/img]
YZ450 vs CRF 450 Dyno
Even guestimating the yfz and trx horsepower at this time is pointless. However, when both are brought up to race specs, you could expect them to closely mirror the above dyno's, especially the yamaha since it's the same motor. Who knows what honda's will make, but I would imagine it would be less than the CRF in peak hp, but maybe a little more down low with the longer stroke. Also, from what I've seen, both motors respond about the same to pipes, and the yammy retains the 2 hp advantage(actually, the yammy gains a little more from a pipe). I wouldn't worry about getting smoked Amsoil. It will come down to the rider no matter which one you choose. 2 hp isn't a whole lot either way.
Ok, here's the link. And next time someone says the CRF is better, make sure they can see how the yfz makes more power almost EVERYWHERE. I also like this graph, because it shows how the moto 440's engines actually are compared to either the yamaha or honda. Enjoy [img]i/expressions/face-icon-small-wink.gif[/img]
YZ450 vs CRF 450 Dyno
Even guestimating the yfz and trx horsepower at this time is pointless. However, when both are brought up to race specs, you could expect them to closely mirror the above dyno's, especially the yamaha since it's the same motor. Who knows what honda's will make, but I would imagine it would be less than the CRF in peak hp, but maybe a little more down low with the longer stroke. Also, from what I've seen, both motors respond about the same to pipes, and the yammy retains the 2 hp advantage(actually, the yammy gains a little more from a pipe). I wouldn't worry about getting smoked Amsoil. It will come down to the rider no matter which one you choose. 2 hp isn't a whole lot either way.
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Oct 27, 2003 | 09:15 PM
#10
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4 valves better than 5
I was talking about the peak generated HP .. yz = 49, crf = 47.6 .. diff = 1.4
The honda makes it at a fairly lower rpm too (at least in this scale) .. what do the torque charts look like? Where does each produce it's peak torque ?
I'm not bashin the yammi, nor propping the honda .. both are wicked machines as stated earlier .. and I dont' own either as you can see by my sig .. just going on what I'm reading from the charts .. l8r's all!
The honda makes it at a fairly lower rpm too (at least in this scale) .. what do the torque charts look like? Where does each produce it's peak torque ?
I'm not bashin the yammi, nor propping the honda .. both are wicked machines as stated earlier .. and I dont' own either as you can see by my sig .. just going on what I'm reading from the charts .. l8r's all!
