VTEC has an actual power spike within the RPM range if u strap it on a dyno..VVT-i doesnt have a power spike..but it depeneds on where the VVT-i is actually felt, it has more pick up at a certain RPM..ive felt it at about 3800-4000 RPM on the tC
VTEC engages a rocker arm extension and makes a small cam act like a large cam which is the sudden engeagement. i-VTEC does the same only it adds VTC (Variable Timing Control) which advances or retards the intake cams timing.
VVT-i is basically like hondas VTC...it is constantly adjusting the intake cams timing. VVTL-i is the same thing as i-VTEC, it adjusts the intake cam timing and the has "lift" which makes the small cam act like a big cam at a certain engagement point
yes the vvtl-i is better then the vvt-i. with the vvtl-i you would get more power depeneding on how the car is geared. BTW i was just thinking if the S2000 has 2.2 Lt engine and it makes 240 hp i just wounder how much hp would come out of 2.4 vttl-i. I'll stop now cuz i'm starting dream again.
I had the Matrix XRS with the vvtl-i. Lift was great! Hitting 6200 rpm and shifting around 7800 - 8100 was a blast. You definately felt it.
But...I personally like the tC's power around the 3800 - 4000 range.
Not sure which is better. What I do know is that the tC is 2.4, not 1.8 (as in the vvtl-i engines) and it's just as fast 0-60. Our car has tremendous potential and pushing 280 - 300 hp shouldnt be a problem with this engine (without sacrificing reliability)
Wow, I love this [email protected]#t. I think the 2.4 has more torq which I like. the 1.8 has to be peaky, You would have to have a manual to get the most. I think i'm getting of the subjuct but hey, Its all what you like not what someone said is the "Best".
Probably the best read on variable-valve timing can be found here: http://www.streetracersonline.com/articles/camshafts/3.php
the main difference you are going to find between Honda's variable valve and toyotas is that Honda has variable valve timing on both the intake and exhaust valves while Toyota's is only on the intake valves. This make's Hondas setup superior as far as performance gain and fuel economy. The other main difference is that Honda's variable valve timing kicks in after a certain amount of rpm while Toyotas is continuously on. Although Honda's 2006 Civic is now continuously on also.
A properly designed variable valve timing setup wouldn’t be noticed at all. It should be keeping the power evenly across the entire power band. You can defiantly feel the spike in power when VTEC kicks over, but is that necessarily a good thing? I don’t think so, where is the power before the spike.
From what I understand, varying the valve timing doesn't make as much of a difference at lower rpms, which is why Honda's varying valve system hasn't until very recently been kicking in until you reach a certain rpm. I'm not sure which rpm but I'm sure it's well below 5k.
i've been meaning to post this for a while. I am quite familiar with vvti and vtec, and variable valve timing systems in general. i know it is said that, our vvti does not "kick in" like vtec. While it is true, vvti is a progressive system as opposed to "on/off" functionality of vtec, where separate/specific cam lobes are actuated at a certain rpm....
i've noticed that while its not an "on/off" function, our vvti certainly does "pick up" or "kick in" (if you want to call it that) right around 3000-3500.
eg. one of my favorite things to do (and best aspects of the car imo) is to cruise at hiway speeds in 5th... pull even with cars, at about 3000rpms, then gun it and pull away pretty easily (for top gear acceleration, its pretty quick) what i notice is that, at 2900, i can barely hear the engine's intake tone at all. Once the tach hits 3000, i can start to hear a soft "whur" of the intake. As the rpms climb from 3000-4000 a very distintive throaty intake tone is head, and the motor really starts to pull significantly harder.
if i let off the throttle a bit, the engine tone quiets back down to be totally inobtrusive again.
this is one of the few features i like about the dbw, when coasting at a steady rpm, you are able to make such slight throttle % changes, so you can really control your engine speed, and thus, have better control over your acceleration/deceleration and MPGs.
but i really get great enjoyment from both the tone and feel of the engine once it hits 3000. for a 4 banger, its certainly a peppy motor. I am so giddy to find out what it will do with some hi compression JE pistons and 93 octane in there!
btw, i have a modified custom intake system, removed silencer, removed charcoal filter element, K&N drop in, heat coated intake tract, Cool air fender extension-fake grill inlet. imo, my engine intake tone sounds EVo-ish (kindof, like an evo's little brother) around 3000-4500
it'd be great to get a vvti controller and have the agressive timing start even earlier, as i feel the power is a bit lacking below 3000. anyone do this???
It isnt just when or how it engages either, it is how it works. VTEC and VVTI are two totally different concepts. VTEC uses higher lift at higher rpm (which is where the other cam lobes come into play) while VVTi only changes the timing of the cams (allowing more valve overlap at higher rpm) but still using the same cam profile. This means that valve duration and lift stay the same.
There are variations of VTEC that also affect timing, while there are versions of VVTi (like VVTi-L) that affect lift as well as valve overlap.
In reality, they (either system) dont necesarrilly allow more performance per se. They allow decent performance while still providing economy at the same time.
And yes, that was some serious thread revival.
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