Originally Posted By: 92saturnsl2
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Also, I don't see how my OHC dyno graph example is apples and oranges?
I guess I just don't see where I made the statement that OHC engines only produce power up top. Again, you're reading between the lines something that's not there.
But I'm not.
You stated:
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With its torque down low and its midrange pull
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thus would benefit from a wide torque curve, with peak torque at lower RPM's, typically what you get from an OHV design.
This implies exactly what I said it implies: The myth that OHC engines don't make power down low. That's why I mentioned it.
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I never included low end torque as any of the three primary reasons I like pushrod motors. The reason for that is that it's not an advantage-- If you want an OHC engine with gobs of low RPM torque, they're out there. It's all in the design.
But you did mention it twice in the post. Again, it wasn't the focus of my discussion with you, but I mentioned it because you did.
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My last truck, an Supercharged Nissan Frontier made 248 ft-lbs @ 2000-2800rpm, yet had no power up top. This completely contradicts your inference that I believe OHC engines are high-strung and only make peak power at high RPM.
No, it just completely contradicts your reasoning for mentioning what you did in the OP. I didn't say you "believed" anything. I simply played off the statements made and mentioned that there was a myth about OHC engines making no torque.
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The fact that an internet myth exists is wonderful but irrelevant.
It's completely relevant, particularly since you mentioned it in entrance line of your original post.
I don't see why this is such a big deal?
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I wouldn't be posting on this forum if I didn't welcome discussion on the topic. Frankly I don't care whether or not you agree with me. We're both aware how quickly these types of topics turn into a mud slinging contest. When the first post out of the gate intends to discredit and prove me wrong, it's easy to view it in a hostile light.
I don't think I came off hostile at all. I do however think you are coming off as hostile right now.
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The BMW example you gave is a poor one for this purpose. You're comparing a state of the art, high-compression V8 with dual variable valve timing, individual throttle bodies, and a host of other advancements to run-of-the-mill pushrod motors where one of the primary considerations is cost.
No, I compared a state of the art DOHC V8 that was as you described to a SUPERCHARGED pushrod V6 with a roots-type blower, which are known for making oodles of power down low. My point was to illustrate that this kind of torque could be made with an N/A DOHC engine when one has the ability to control valve timing. Ford is now doing the same thing with Coyote.
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That's about as productive as comparing GM's best pushrod motor to Ford's 4.0L SOHC V6 and using that as the basis for pointing out the pros and cons of each.
No, it would be like comparing the LS7's torque output to that of the Ecoboost. Which heck, might even be a worthwhile topic to explore.
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Ultimately, I'm not even sure why you are so stuck on proving that OHC engines make power down low, as this was never a point that was argued, and as such is an exercise in futility.
Then why did you mention it twice in the OP?
And you've obviously not read the rest of my contributions to this thread as that is far from the crux of my argument, as my discussions with chevyboy delved into the topic of power delivery, design and displacement, all of which are certainly relevant to where an engine makes power, regardless of the type of valvetrain setup it has.
