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EuroAccord13
26-02-2004, 05:26 PM
Ok it means intelligent but I read in a mag somewhere that the new gen i-VTEC kicks in at any RPM as long as the ECU senses a change in throttle response in a sense that when it thinks more power is required, the VTEC kicks in... can someone confirm or deny this? If it's true.. it seems to break the whole powerband thing and I don't think I will like it. :D

wynode
26-02-2004, 05:37 PM
LOL

It means it changes Cam timing.

i-VTEC engines have continuosly variable cam timing, but still only 2 stages of VTEC.

VTEC engines only DO NOT have continuosly variable Cam timing however.

Hence i-VTEC engines sense engine load and throttle position to adjust Cam timing, NOT when VTEC cuts in.

Kit
26-02-2004, 07:01 PM
LOL

It means it changes Cam timing.

i-VTEC engines have continuosly variable cam timing, but still only 2 stages of VTEC.

VTEC engines only DO NOT have continuosly variable Cam timing however.

Hence i-VTEC engines sense engine load and throttle position to adjust Cam timing, NOT when VTEC cuts in.


Hey Wynode,

I'm not sure I understand this, I know how DOHC VTEC engines work.
But what do you mean by continuously varying the cam timing?
cos there is still only 2 sets of cam lobes on each cam right?

Did you mean Ignition timing?



Euro, it wouldnt make sense to cross over to VTEC (that is the second set of cam lobes) at lower RPM cos each cam lobe will have peak power at different parts of the rev range, hence VTEC engines have 2 cam lobes: one for tractability at low rpm, and the other for high rpm power.
If you did two dyno power runs one with the low rpm cam lobe only, and one with the high rpm cam lobe. The factory VTEC crossover point is where these two power curves overlap.

Doing standard bolt ons won't change the point at where these power curves overlap. So contrary to popular belief, installing a VTEC controller and bringing in the VTEC cutover point earlier on in the rev range won't give you more power, cos at that point, the high rpm cam lobe is producing less power than the low rpm cam lobe!

I hope that makes sense.
sorry to blabble on, its hard to explain it in a short paragraph hehehe :)

Chris

wynode
26-02-2004, 07:05 PM
Kit,

Changing the cam timing is different to changing the valve lift.

Cam timing reffers to when the intake/exhaust valves open/close, not how much they open/close.

I suggest having a read of this (http://auto.howstuffworks.com/camshaft3.htm)

wynode
26-02-2004, 07:10 PM
OK that article isn't the best, but the relevant part is this:


Some cars use a device that can advance the valve timing. This does not keep the valves open longer; instead, it opens them later and closes them later. This is done by rotating the camshaft ahead a few degrees. If the intake valves normally open at 10 degrees before top dead center (TDC) and close at 190 degrees after TDC, the total duration is 200 degrees. The opening and closing times can be shifted using a mechanism that rotates the cam ahead a little as it spins. So the valve might open at 10 degrees after TDC and close at 210 degrees after TDC. Closing the valve 20 degrees later is good, but it would be better to be able to increase the duration that the intake valve is open.

Think of it as having automatically (ECU adjusted) adjusted cam gears.

McChook
26-02-2004, 07:35 PM
I honestly have never seen it written perfectly understandable. I know how it works in my head, but I doubt I could put it out in words, too much to remember, and what order do you put it all in....

That one however is one of the better descriptions

wynode
26-02-2004, 07:55 PM
Just for the newcommers, i suggest you read the following:

Cam shaft operation Basics (http://auto.howstuffworks.com/camshaft1.htm)

Its the start of the link above. You really need to understand the basics to get an idea.

Tofu
26-02-2004, 08:49 PM
yah....i-Vtec kicks ass.. :D

Kit
26-02-2004, 09:45 PM
OK that article isn't the best, but the relevant part is this:


Some cars use a device that can advance the valve timing. This does not keep the valves open longer; instead, it opens them later and closes them later. This is done by rotating the camshaft ahead a few degrees. If the intake valves normally open at 10 degrees before top dead center (TDC) and close at 190 degrees after TDC, the total duration is 200 degrees. The opening and closing times can be shifted using a mechanism that rotates the cam ahead a little as it spins. So the valve might open at 10 degrees after TDC and close at 210 degrees after TDC. Closing the valve 20 degrees later is good, but it would be better to be able to increase the duration that the intake valve is open.

Think of it as having automatically (ECU adjusted) adjusted cam gears.

hmmm just read that, so you were referring to the valve timing and not cam timing right?

cos i was wondering what you meant by cam timing.

Chris

VTEC16
26-02-2004, 11:08 PM
when are you guys going to learn???


THERE IS NO "I" IN TEAM!

:twisted:

w_civic
27-02-2004, 12:05 AM
hahahaha

wynode
27-02-2004, 01:22 AM
hmmm just read that, so you were referring to the valve timing and not cam timing right?

cos i was wondering what you meant by cam timing.

Chris

Variable valve timing and variable cam timing mean the same thing. The cams operate the valves.

The keyword is valve timing as opposed to valve lift

UR2L8
27-02-2004, 11:48 AM
I read somewere and I think it was from OzHonda, that the new DC5 R ECU is the smartest ECU in the world, because it can change its lift control or something depending on air temperature, engine temp, engine rpm and some other crap (crap=good). Meaning that as a result of this it has the best emision controls but can sacrifice performance.

ginganggooly
27-02-2004, 12:00 PM
i dunno about that... i reckon bmw must have some pretty fancy schmantzy stuff.

they incorporate variable cam phasing and manage to get by without a throttle body, instead using some sort of variable intake valve lift control to regulate airflow. afaik it's a totally new system of valvetrain design.

it's all ever so complicated for simpletons like myself :P

Boost
27-02-2004, 12:34 PM
you can pack as much as you want in an ECU not just hondas as long as you have sensors to give inputs and the ECU prpgrammed to do what ya like. There are other ECUs out there with heaps more intell. than the honda.

ginganggooly
27-02-2004, 12:39 PM
i think the intelligence is more in the software behind it...

wynode
27-02-2004, 01:46 PM
i think the intelligence is more in the software behind it...Yes.

Basically the ability to detect outside conditions (such as load and driver input via the TPS) and to adjust engine performance to suit.

Porche use a technology called Vario cam where the Cam shaft slides such as to give a smoother transition from low cam to high cam. Maybe thats what you are reffering to as opposed to BMW's Double Vanos.

LUD02C
27-02-2004, 10:55 PM
yah....i-Vtec kicks ass.. :D

VVT-i KICKS ASS

Oh wait, this is a honda forum, Go i Vtec

EuroAccord13
28-02-2004, 12:43 AM
Doing standard bolt ons won't change the point at where these power curves overlap. So contrary to popular belief, installing a VTEC controller and bringing in the VTEC cutover point earlier on in the rev range won't give you more power, cos at that point, the high rpm cam lobe is producing less power than the low rpm cam lobe!

I hope that makes sense.
sorry to blabble on, its hard to explain it in a short paragraph hehehe :)

Chris


I heard about the VTEC controller issue too, the factory setting is tuned for optimum performance in the VTEC engine. But then again, if controllers don't work, why are people still buying and Apexi still making them?

I've ordered one already... and my friend has it on his already and the car not only response with more grunt on the lower end but definately more linear delivery of HP....


I AM CONFUSED!!

McChook
28-02-2004, 12:57 AM
CAPS LOCK WARRRIOR TIME

VAFC'S ARE USED MOSTLY TO TUNE THE MOTHER****ING AIR:FUEL RATIO, NOT TO PLAY WITH THE GODDAMN HI CAM ENGAGEMENT POINT

****ing sick of the same shit being said about VAFC's. ****ing noobs, ****ing read up, don't be a dipshit

/rant over

Delete or censor if you must, but I am so sick of the same dumb shit being posted about what is pretty much a good product for its money. People who spread uninformed crap are pains in everyone's asses

EuroAccord13
28-02-2004, 02:17 AM
I don't know if it was being directed at me...

Sorry dude IF I have offended you.. I'm just trying to find out things but if it's the sort of forum that people get worked up just because I'm a F***king noob and dipshit.. then I'm sorry, I'm in the wrong forum to learn..

Have a Nice Day... Nice knowing all of you...

Good night...

eknine
28-02-2004, 08:51 AM
EuroAccord13 don't worry abt it mate....ppl just come to whore<laffz>
it be good if everyone try the search function a lil within the forum , i'm only saying because there may be info somewhere...and well like most we are all lazy to read thru all and wants on-demand power like we want from our cars...so since we drive VTECs, we don't really have on-demand power...so i guess on-demand infos something do crack an egg on repeated Q&As....

just hang around and soon you will breeze thru the culture, but what do i know...i'm the jack of post whores<kekekekeke>

Kit
28-02-2004, 10:38 AM
CAPS LOCK WARRRIOR TIME

VAFC'S ARE USED MOSTLY TO TUNE THE MOTHER****ING AIR:FUEL RATIO, NOT TO PLAY WITH THE GODDAMN HI CAM ENGAGEMENT POINT

****ing sick of the same shit being said about VAFC's. ****ing noobs, ****ing read up, don't be a dipshit

/rant over

Delete or censor if you must, but I am so sick of the same dumb shit being posted about what is pretty much a good product for its money. People who spread uninformed crap are pains in everyone's asses

My post was in regards to the Field's VTEC Controller.
that does has the ability to change the VTEC crossover point.

Euro. Vtec controllers are useful when you pop open the engine and you start playing with cams and such where the characteristic and the powerband of your engine starts to change, then the stock VTEC crossover point may no longer be the optimal point of crossover.
:)

Regards,
Chris

eknine
28-02-2004, 10:43 AM
changing the Vtec x-over point it not the be it or end all, there are still alot for consideration........ohhh well nvm <kekekekeke>


when are you guys going to learn??? :twisted:

VTEC16, mate lend me the above ?...if you have any objection,will return it back to u so you can get +1 post :D :D :D :D :D :D