which variable valve control system is ur favourite?

[jadotch]

go here
http://www.hotrocker.com/

It has nothing to do with the cam, but instead the rocker-arm ratio which is being changed. Basically a the rocker arm is hollow with an adjustable pedistol in the middle that changes positions during a certian RPM adjusting the the lift of the rocker arm. They make them for Chevy V-6's and 350's as well. I am sure it is not the best VVA, but it is a good simple solution for push-rod engines that can be added to virtually any pushrod. And it does effect lift, which only Ferraris and Honda's do. They actually used a similar VVA in some WWII aircraft engines.

[crxman]

I was wondering who first came up with the variable valve technology in a production car? I thought in was Honda around 1991 in there NSX, but someone has told me that was wrong, he says it was ford and chevy a long time ago. Note he is a Ford fan so i dont beleive much he does say.....

And what is the best "bonus" achieved from variable valve tech, for example
x Liters = y hp compaired to
x Liter(With Variable Valve Tech) = y hp plus how much?

[jcp123]

not a fan of vvt, it's too complicated and new-fangled for me, and i regard it with a fair amount of suspicion with regards to relaibility. but i picked the toyota vvti, my mom drives a van with it and after 5k miles the vvti still works.

[PerfAdv]

Reliability wise, I drove a Integra GS-R for 163+K miles and it still had 220 psi in all 4 cylinders, when I had compression tested. The beauty of VTEC or any other variable valve system is that the lower-profile lobes for low speed operation actually put less strain on the valvetrain. Only when the revs climb do the more radical lobes cause longer duration and higher lift. Economy down low and power up high. Before, normal use cars were always a compromise leaning towards economy and the hot-rodder could be picked out by his lopey idle. Both compromising either for high or low, but no more.

I vote for VTEC

[jcp123]

Ah, I see, but by the reliability I had meant more like the electronic controls for it. The mechanicals are no sweat to build utterly reliably.

[PerfAdv]

Ah, I see, but by the reliability I had meant more like the electronic controls for it. The mechanicals are no sweat to build utterly reliably.

In the almost eight years I had the VTEC Integra I never had an issue with the VTEC. I went through 2 clutches, a few brake jobs, several sets of Yokos and Pirellis, and the distributor assembly was the only mechanical failure. The VTEC system was completely invisible, never needing any attention. Only other thing that needs regular attention are valve adjustments. Having solid lifters they require adjustment every 15-20K miles.

[jcp123]

That's not too bad then...and I hear ya on the solid lifters. They're a PITA, though if set properly I've heard some can go upwards of 50k miles. But we digress.

[KnifeEdge_2K1]

i heard somewhere that BMW's valves are organised as 1 exhaust valve/3 intake valve. can anyone confirm that? which manufacturer do u think will be the first to come up with a 5 valve, direct injection, twin spark engine with each valve individually controlled by computer?

... the head would weigh more then the block crank and pistons combined ..

[gtrjazz]

VVT,VCT lets not get mixed up .My preference would be the electrically controlled Hydraulic system by Lotus.

[fpv_gtho]

... the head would weigh more then the block crank and pistons combined ..

and thats supposed to deter people from doing it?

[jcp123]

and thats supposed to deter people from doing it?

well sorta, i mean you don't wanna raise the center of gravity in a car. DOHC already does this pretty badly, i think carmakers probably shy away from this because it adds even more to the head. but who knows...

[NSXType-R]

No VVT system is better than Honda's VTEC system in my opinion.

[Guest]

whsat is it with you and dead threads?

[PBB]

Subaru's system is AVCS (Active Valve Control System).

[KnifeEdge_2K1]

Honda's is one of very few cam changing systems that accomplishes both changing the timing and the lift profiles of the cams, toyota's ivvt-l is another
none of the other listed systems can do this, so its a tossup between toyota and honda, id prefer honda just because most of honda's systems make a bit more power per litre then comprable toyota systems