Originally posted by: Flyermax2k3
Originally posted by: cr4zymofo
Originally posted by: SampSon
Originally posted by: Thegonagle Oh, so much mis-understanding about VTec. And I don't care any more. Suffice to say, because it's akin to having two camshafts to switch between on the fly, they can tune one for good low-end torque and/or efficiency, and one for maximum performance. That's why the V-Tec versions can have more high-end horsepower plus better low-end torque, yet give up nothing in the way of fuel efficiency as opposed to the standard versions. People who really understand engines and see in their heads how V-Tec works are able to appreciate what a fvcking ingenious system it really is, even compared to other VVT systems. (Ever heard of someone swapping the camshaft for one with different performance characteristics? That's what V-Tec does automatically as you drive.)
You mean cam lobes don't you, not the shaft?
No, he meant the shaft (the lobes are machined with the shaft, you can't really "swap" the lobes, but you can grind it), and people do swap out cams for higher performance cams. They do gain performance when doing so, but gives up fuel economy. VTEC would give you that performance at certain RPM range, and also give you better fuel economy when it's not utilized, so it's almost like swapping out cams on the fly, if you can imagine that.
Eh, wouldn't it be more accurate to say "cam profile" than "camshaft"? It's not as though you're actually changing the cam(s) for another type of cam, just the lift and duration at certain RPMs. There's nothing special about Honda's VVT system, especially not compared to say BMW. BMW's Vanos system beats the pants off of VTEC, i-VTEC, or any other "TEC" Honda wants to come up with, period.
😉
What I meant is that it's
like having two camshafts in one, because it allows the engine to switch between two different cam profiles depending on what's most appropriate for the RPM it's running at. And it's ingenious because it's simple, reliable, and available on a $16K (US) car.
An advantage VTEC has over many other systems is that when it "kicks in," because the valves run off an entirely different cam lobe, that cam lobe can have different timing, lift,
and duration. Mere variable camshaft phasing varies the timing, but
not lift or duration. (For an analogy to cam "phasing," think of twisting a distributor to adjust spark timing.)
Granted, there are other systems out there that do these things now, and Honda's i-Vtec now adds variable cam phasing to the regular "two camshafts-in-one" Vtec system, but in my mind, that takes nothing away from the ingenuity of the original Vtec system.
And did I mention that Vtec is mechanically simple, and has proven itself to posess exemplary reliability? (Oh yes, I did.)
🙂