Hi all!
I'm new to the forum and only 3,000km on my TW GE8.
I'm wondering if any of u fitfreakers can answer my question~~
I kinda feel the vtec going off around 5100 to 5500 rpm range or I'm just completly wrong!! Where is the vtec line?? Please educate ur fellow forum nub!!! Thanks!!!

 

5400 is when VTEC activates.

 

Thrushold?

 

I think he means threshold

 

Technically with i-vtec it activates in four stages (nevermind I was watching the k20 ivtec video). The first 3 stages are changes in the valve overlap and number of intake valves open. It's based more on engine load than rpms. The 4th stage, the one you are probably thinking of, activates between 5,300 and 5,400 and it is the vtec cams kicking in.

 

Thanks for the information! I never knew that vtec activates in four stages. DAng!

 

It depends on the type of VTEC really. The VTEC mechanism in the newer L15 doesn't deactivate valves or activate them at certain points. All 16 valves are always in play at all times.

 

its ivtec!

 

I would seriously like to understand how the L15 i-Vtec functions in my 2010. The info I've been able to gather supports this, but 5400RPM seems mighty demanding. The "i" in the i-Vtec is for 'intelligence', this relates to the timing advance/retard of the engine.

Problem is there seems to be little hard documentation on the engine in my 2010. Most of what I see is slightly more 'generic' and broad in scope/explanation.

 

The i allows the cam to rotate to different degree settings based on engine load and RPM. I don't believe it has the full 50 degree phasing like the K20, I thought it was more like 30 degrees, but I could definitely be wrong so don't quote me.

I don't really think the 5400 activation is demanding, but I'm sure with tuning and a lowering of the activation point more mid-range will be seen. Honda has done a nice job on the tuning aspect, but of course it was set for a broad range of drivers and conditions and should be able to be improved upon.

I will say that the newer L15 is a world better than the older L15. Only when tuning options become readily available will the true potential be seen with this motor and I don't mean by boost, strictly staying meka-tuned (NA).

 

So the first I do is quote you_

Cam is spinning like a banshee. When the hi-lobe on the lifter is engaged it's locked in, no varying anything. This changes the valve timing by changing its 'open' duration. Thoughts are that this is around 3400RPM or 5400RPM. Engagement is activated by an oil pressure controlled switch. On/Off.

However, the "i" in i-Vtec allows for continuously variable timing, I take this to mean the ignition timing is varied based on engine load demand among other parameters and is controlled by the ECU across all ranges.

Do I have this wrong??

 

I think this has been posted before, but it's always a good read.

Honda Media Newsroom Release: 2009 Honda Fit - Powertrain

The 1.5-liter i-VTEC engine - powerful, torquey performance at all engine speeds
The newly developed 1.5L i-VTEC engine delivers both spirited driving performance and outstanding fuel economy. The two-stage i-VTEC system varies intake valve timing and lift between low- and high-speed settings, while valve overlap is optimized for low, medium and high speeds to achieve a significant improvement in breathing efficiency. The result is power and torque to spare, regardless of engine speed, along with outstanding fuel economy. By comparison, the previous generation's VTEC system effectively deactivated one of the two intake valves per cylinder, creating a swirl effect that enhanced torque below 3400 rpm.

 

I've seen that before, thanks - it is a very good read. I lost it and it's found.

To quote:The low to high setting is when the 'Vtec' locks in. The valve overlap has been redesigned from that of former engines to optimize performance.

This is the engine in my FIT.

Still not seeing when the lock in occurs.

 

Woah! I swear I watched a honda educational video about the new ivtec engines using the 'swirl effect' too.

LOL NEVERMIND! I was watching the ivtec k20 video

I guess the ivtec k20 does one valve operation and the l15a7 does not.

Yea... the 2 camshafts should have been an obvious sign http://www.youtube.com/watch?v=UEtm2y1yXnI

you can see the 3 stages of vtc and intake valves. the 4th stage would be the vtec cams.

 

You ever see anything on the v-tec switch?