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VVTI

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    • Oct 29, 2006 2:14:21 pm
    anyone know where i can get the VVTI emblem

    • Oct 29, 2006 2:16:23 pm
    besides!!! ebay lol
    • Oct 29, 2006 3:28:40 pm
    japan?
    • Mar 05, 2007 7:37:00 am
    HIJACKING THREAD!:

    okay, so everyone knows by now how the tc's variable valve timing system (vvti) works. while it does share some characteristics with other valve timing systems, it is fairly unique. Eg. unlike Vtec, Vvti is constantly and progressively varying intake valve timing. whereas vtec "switches over" to the vtec cam profile at a set Rpm.

    however, during my course of time driving the tc, i've gotten pretty familiar with its powerband. While it is not a "set crossover point" I can clearly noticed a change in timing occuring right around 3500 rpms. Not only can you feel the difference in torque/hp, you can hear it as well.

    at 3300 rpms, the engine (intake and exhaust) tones and fairly subdued and average sounding. However, almost right as you hit 3500 the tone becomes noticeably more aggressive. An octave or so deeper, and more of the raspy growl commonly associated with evos or other turbocharged 4 bangers.

    part II:

    has anyone gotten a vvti controller and actually adjusted valve timing advance?

    i'd be curious to see the benefits of fine tuning the vvti. cuz its apparent that the system can be quite potential, and even with a few BPUs (my favorite term now) like intake and exhaust, you should conceivably be able to squeeze more power out through the range.
    • Mar 05, 2007 7:40:17 am
    Yes, the crossover is not very smooth. I notice the same around 3500 and a definate change at 5700.....my engine sounds like a VTEC from the header. I'll have to make a vid with someone in the car, but as soon as my needle pops 5500-5700, it sounds/feels like the engine opens up another level. I definately have the growl, or whatever you can call it, of a VTEC or something similar to it. It's quite nice
    • Mar 05, 2007 7:48:52 am
    yea i want one too
    • Mar 05, 2007 8:29:00 am
    My engine has a huge emblem written on the plastic valve cover .....that's enough show for me.
    • Mar 05, 2007 9:48:47 am
    Web wrote:
    Yes, the crossover is not very smooth. I notice the same around 3500 and a definate change at 5700.....my engine sounds like a VTEC from the header. I'll have to make a vid with someone in the car, but as soon as my needle pops 5500-5700, it sounds/feels like the engine opens up another level. I definately have the growl, or whatever you can call it, of a VTEC or something similar to it. It's quite nice


    yeah, up around 5700 it really starts to scream ( a higher pitched tone).

    but what i was referring to is the distint change for mild-aggressive valve timing at 3500. its not that its not smooth, its just that its very noticeable, eventhough there is not designated "crossover point" like vtec. you can hear the tempo and volume of the combustion pick up significantly and the tq/power output obviously begins to rise steeply at that point too.

    i'd love to see some accurate dynographs, both stock and BPUs.. anyone got one?
    • Mar 05, 2007 9:50:36 am
    idc as long as the thread gets used hahaha i think this was my first post
    • Mar 05, 2007 9:58:12 am
    aDelcoTc wrote:
    i'd love to see some accurate dynographs, both stock and BPUs.. anyone got one?


    Is there really such a thing?...haha


    But yeah, mine pulls a bit more around 3000-3500 and then again from 5500-5700........it's definately not a smooth transition.

    • Mar 05, 2007 11:20:53 am
    Haha, sorry, using thread to ask my own question as well:

    I know our cars have VVT-i, which is cool. But we dont have VVTL-i (likely cause its not made anymore, ha). But isn't the VVTL-i the same principle as the VTEC engines? (both have lift control)
    • Mar 05, 2007 11:30:34 am
    Mayo wrote:
    Haha, sorry, using thread to ask my own question as well:

    I know our cars have VVT-i, which is cool. But we dont have VVTL-i (likely cause its not made anymore, ha). But isn't the VVTL-i the same principle as the VTEC engines? (both have lift control)


    Kind of but it uses variable valve timing to force the lift at a higher rpm. VTEC is all of a sudden and VVTL-i is gradual. there is a slight jump when it kicks in (VVTL-i) but not as much as VTEC.

    • Mar 05, 2007 11:31:17 am
    I know exactly what Delco is talking about. The timing changes are most noticeable at highway speeds. You can keep the engine in VVTi by keeping revs around 3500 and maintaining throttle.

    If you coast for too long, the engine goes back to normal timing. You'll notice instant pull power when aggressive timing is kicked in.

    You can trick the ECU by tapping gas like you're going to pass someone and keep VVTi mode.
    • Mar 05, 2007 12:53:37 pm
    Web wrote:
    Mayo wrote:
    Haha, sorry, using thread to ask my own question as well:

    I know our cars have VVT-i, which is cool. But we dont have VVTL-i (likely cause its not made anymore, ha). But isn't the VVTL-i the same principle as the VTEC engines? (both have lift control)


    Kind of but it uses variable valve timing to force the lift at a higher rpm. VTEC is all of a sudden and VVTL-i is gradual. there is a slight jump when it kicks in (VVTL-i) but not as much as VTEC.



    just to clarify......

    vtec and vvti and vvtLi are both variable valve timing systems.

    vtec uses a solenoid to engage a different set of cam lobes at a Set RPM. Below that set point, the engine is working on a more subdued timing and fuel map. after vtec engages, valves open earlier, stay open longer (duration) i'm pretty sure and lift higher.

    vvti constantly and progressively varies valve timing throught the whole rpm range. ie. at low rpms, the valve timing is more subdued, at mid range, the valve advance is a bit greater, at high rpms the valves (intake only) open even earlier than mid range. However vvti does not alter lift or duration.

    VVTLi alters valve timing AND increases lift . VVTLi also has a "Set" rpm that it engages the other cam profile at, like vtec.
    • Mar 05, 2007 12:57:47 pm
    Orin wrote:
    I know exactly what Delco is talking about. The timing changes are most noticeable at highway speeds. You can keep the engine in VVTi by keeping revs around 3500 and maintaining throttle.

    If you coast for too long, the engine goes back to normal timing. You'll notice instant pull power when aggressive timing is kicked in.

    You can trick the ECU by tapping gas like you're going to pass someone and keep VVTi mode.


    and to clarify, the engine/ecu is ALWAYS "in" vvti.


    what you're referring to (i think) as far as coasting and "tricking the ecu by tapping the gas" is more related to throttle position.

    due to the drive by wire system, its easier to program the ecu for Hi throttle and low throttle settings.

    ie. there are different fuel/timing maps for "Hi throttle" and "low throttle" situations.

    if you are coasting for a while, the throttle position will likely dip down to low or mid throttle. When you Step on it, the ecu jumps to Hi throttle, which does result in a almost immediate burst of torque due to the more aggressive timing and fuel correction settings.

    hope this helps.
    • Mar 05, 2007 2:13:24 pm
    Web wrote:
    aDelcoTc wrote:
    i'd love to see some accurate dynographs, both stock and BPUs.. anyone got one?


    Is there really such a thing?...haha


    But yeah, mine pulls a bit more around 3000-3500 and then again from 5500-5700........it's definately not a smooth transition.



    whats the redline on the tC?? because how much after u feel it pulling from 5500-5700 do u gotta shift at?
    • Mar 05, 2007 2:41:27 pm
    Red line is around 6200-6500. so that last little boost is mainly to maintain speed i guess.

    On a slightly diff topic, anyone notice how the TC is not really tuned for WOT. the engine only seems to benefit from it on 1st and 2nd gear
    anything beyond that and the engine just kinda bogs regardless of how on point your shifts are.

    I've found that if i WOT 1st n 2nd then use only 80 to 85% throttle for all the other gears and you can maintain the most power and pull through out the entire band.

    I'm hooking up a simple narrow band gauge and single wire narrow O2 to
    my second bung to see what the CPU does at WOT. I bet it runs the engine rich as hell...
    • Mar 05, 2007 3:36:17 pm
    eXecLusIvE05 wrote:
    Web wrote:
    aDelcoTc wrote:
    i'd love to see some accurate dynographs, both stock and BPUs.. anyone got one?


    Is there really such a thing?...haha


    But yeah, mine pulls a bit more around 3000-3500 and then again from 5500-5700........it's definately not a smooth transition.



    whats the redline on the tC?? because how much after u feel it pulling from 5500-5700 do u gotta shift at?


    Yeah, at 5500 when it kicks in hard that just gets me to about 6200 and i shift. By the time the next gear catches and the torque transfer occurs between the clutch and flywheel down to the tires, i'm only back down to about 5K rpm so I lose almost nothing.
    • Mar 06, 2007 5:48:21 am
    as far as the redline, yeah approx 6200. on a stock tc, power starts to die off after 5500. probably mostly due to restrictive intake and exhaust systems. during the course of modding, i've noticed that opening up the intake and exhaust tracks has seemed to allow a more complete pull all the way to redline.

    also, i'm pretty sure, but need someone else to confirm, but i think that Toyota's throttle systems never actually reach "Wide Open Throttle". Pretty sure that even at Full Throttle applications (gas pedal pushed all the way down), the throttle body butterfly valve is only 75% open.
    • Mar 06, 2007 6:02:28 am
    aDelcoTc wrote:
    as far as the redline, yeah approx 6200. on a stock tc, power starts to die off after 5500. probably mostly due to restrictive intake and exhaust systems. during the course of modding, i've noticed that opening up the intake and exhaust tracks has seemed to allow a more complete pull all the way to redline.

    also, i'm pretty sure, but need someone else to confirm, but i think that Toyota's throttle systems never actually reach "Wide Open Throttle". Pretty sure that even at Full Throttle applications (gas pedal pushed all the way down), the throttle body butterfly valve is only 75% open.


    Well, peak power is gained at 5700 on many dynos for stock tCs and yes....as you open the intake and exhaust up a bit, the power seems to be steady up the power band. I do have a more "even" pull though my power band with my setup as compared to when it was stock.

    I did read somewhere a while ago that there was a discussion about the DBW system on our tCs. When idling, the butterfly is at about 15% and WOT it's only about 80-85%...there's no true WOT on this setup.
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