Exactly what are the technical differences of the two variable timing systems?

 

Just go to http://www.leecao.com/honda/index.html

This website explains all the different v-tec systems

 

so is iVTEC the 3-stage VTEC?

 

iVTEC vaires the timing too. On the RSX Type S the exhaust has VTEC as well as the intake.

That would be my guess on the 3 stages...timing, intake and exhaust.


[Modified by Spade, 3:37 PM 10/15/2001]

 

in simple terms, here :

forget about 2 and 3 lobe cam operation ... the fundamentals are the same, different lift and differnt duration when VTEC lobes switch (we say VTEC kick in) ...
a regular VTEC uses a static cam timing where we generally have cam sprockets that never adjust as the engine is spinning (this is also the same even if you have adjustable cam gears, you adjust them but only change static timing as opposed to while motor is spinning.

iVTEC actually has its own adjustable cam gear (on the intake cam anyway) which "adjust the sprockets" by the ECU for every RPM for +50 degrees at crank to -50 degrees at the crank. The advantage is you see a high torque output on the motor at very low RPMs and it goes across the RPM band to redline (jumps higher when cam lobes switch) .

This is the advanced way of adjusting cam gears which is what we do now with the old vtec motors when we adjust the cam gear settings to give a compromise in the mid-to-high end RPM band. So for example we have a setting like +2/-2; the iVTEC has +6/-5 @ 1Krpm, then +7/-6 @ 2Krpm then +24/-15@ 7KRPM and so on ...

Greg

 

ingenious! STANDARD!!!

 

now the question is this: what will be the next evolution in VTEC technology? hmmm....

 

vtec4gs is right,

I forgot that the site I gave didn't explain the new i-v-tec. Another important thing to mention in that the base model RSX, only the intake cam is being adjusted and the exhaust cam is fixed. But in the type-S, the intake is continusouly adjusted while the exhaust cam is like a standard v-tec cam that has one longer duration setting.

I think that the 3-stage vtec will make it to the states in the next couple of years in the base model civics.

How bout no cams at all? All selonoids? Who knows.

 

speaking of continuously variable Honda innovations... didn't Honda produce a continuously variable transmission for a specific Civic model in the mid 90s?

 

Maybe not the next VTEC generation . . . .

But I'm sure in the not too distant future, we'll see completely cam-less valve trains. Solenoid activated, completely computer controlled. Infinitely variable timing & lift on the intake & exhaust. Not only infinitely variable, but NO valvetrain losses. Very sweet. . . . .

Although, I wouldn't be surprised if BMW comes out with it first, they've been working on it for a while now. From what I understand, the major obstacle is developing solenoids that are reliable/fast enough.

 

Actually, I'm pretty sure the RSX only uses VTEC and VTC on it's intake cam, the Type S uses VTEC on both cams and VTC on the intake cam.

 

Very interesting stuff... so does anyone have more info on this possible form of future drivetrain (cam-less valvetrains)... anyone have the low-down on BMWs R&D on this innovation? (All those childhood days of playing with Legos are coming back... fun with mechanical engineering!!!)

 

The base RSX uses VTEC just like all B series motors. Both base and S have variable cam timing on intake cam.

The reason for the hp difference between the base and the Type S are different pistons(compr.), better flowing exhaust and intake manifolds.(not sure if intake mani. is different now that I think about it)

 

I think a german company- porsche maybe- was looking into using electrical solenoids for a valvetrain- It would be awsome and have endless possibilities- you could basically have endless valve timing/lift/duration combinations at any speed. No physical cam- the ecu is the cam. (what daemione was saying- maybe it was BMW- I can't remember)

The civic HX in 96 came out with the CVT and lean burn Vtec-E engine.


[Modified by fixhondas, 1:15 AM 10/18/2001]

 

Sorry but unless you've gone and opend up a K20 yourself, I think I'll take Honda's word over yours. The base RSX does NOT use VTEC in the tradtional sense. Rather, it's actually more of a VTEC-E whereby, one of the 2 intake valves per cylinder only open slightly (on the D16Y5 Civic HX, the second intake valve doesn't open at all till engaged). At a certain rpm, the secondary rocker is linked to the primary to open the valvles fully. All the while, VTC is being used on the intake cam to adjust cam timing, the exahust cam remains untouced and is no different than any other B18B motor on the exahust side. The Type S on the other hand does operate like a B-series VTEC engine, plus the added benefit of VTC manipulating the intake cam timing.

 

And before you jump to disargee, this is quoted directly from Honda:

"In the 160-hp RSX, the VTEC modulation of i-VTEC works on the intake valves exclusively, using a 2-rocker arm design. At lower rpm, the second intake valve opens only partially, creating a desirable swirl effect in the combustion chamber. At higher rpm, both intake valves open fully, for quicker, easier breathing and full power output. In the 200-hp RSX Type S, an exclusive 3-rocker-arm design operates on both the intake and exhaust valves, developing incredible low-end torque and high-end power. At lower rpm all valves open to a lower profile that changes to a higher profile, with a longer duration, at higher rpm. In both engines, i-VTEC is designed to get not only the best results at a given rpm level, but the best performance possible from each individual engine revolution."

 

where did u find this? i've been trying to get this kinda info from honda and they dont even tell u that the rsx has 3 lobes..

 

I foget who's theory it was (one of those old smart guys), but it's the old "the simplest answer, is usually the correct one". I went right to Acura.com and looked up the RSX. In part of the description of the motor, there's a hyperlinked "I-VTEC", I just clicked it and it give you a breakdown of what i-VTEC is and how it applies to the K20's. BTW Waffles was right, the intake mani's are different for the RSX and Type S. The RSX usused a B18C1 style "dual runner" design, and the Type S uses a single runner (per cylinder) which is shorter and fatter than the base RSX. Ala B18C1 vs. B18C5


[Modified by VTC_CiViC, 12:27 PM 10/18/2001]

 

educate the uneducated.... what is K20?

 

K20C is the current engine series used in the Acura RSX and new Honda Civic Si.

 

So what's my non-vtec motor? Prehistoric??? I can't believe you're calling regular vtec oldskool.

 

I'm not calling anything prehistoric or oldschool, but there's new technology... and dated technology. VTEC has been around for like how many years!? And I do't mean commercialy available (since the '89 Integra XSi/RSi), I mean since Hodna used it in racing back in the 70's n' stuff.

 

k20A is the rsx base and new si engine. The k20c is the type s engine.


And thanks for the information on the difference. I thought I read what I said in something, but I was obviously wrong, however I DO know they have different pistons and exhaust and intake manifolds.

for the direct quote. Very informative.

 

Great thread

 

no K20B eh? hmmm....

so how VTEC differs technically from VVTI, VAMOS, et cetera?