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VTEC VVTI and turbo's question

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    #1

    VTEC VVTI and turbo's question

    ok i was arguing with a friend about vtec and vvti technologies and its use with turbo's..he got a 1jz-gte swap in his lexus is 300..and said he didnt want the vvti or whatever toyota calls their version of vtec

    i was like it just opens the cam lobe further why would this create a problem with a turbo setup

    i dont see any problem with turbo charging a vtec motor... or any other variable cam lobe profile technology and the addition of boost

    i dunno correct me if im wrong...
    Tags: None
    #2
    The high lobe on VTEC cams has high lift (good for turbos), long duration (good in moderation) and a lot of overlap (bad bad bad for turbos). The reason overlap is bad is because the intake and exhaust valves are open at the same time...this is good on an N/A motor, because if the header is designed right, the exhaust pulse will "pull" the intake charge through, making the engine breathe better...

    On a turbo motor though, the intake charge is pressurized, so if you have the exhaust valves open with the intake valves open, the intake charge will go through w/o being burned.

    Now if your homeboy has a VVTi system, that is basically an ECU controlled cam gear on the intake side, which only changes overlap...so for him to make the most power, he'd either want it programmed to act over a limited range, or go for a motor w/o the feature at all.

    Hope that helped.


    Originally posted by lordoja
    im with you on that one bro! aint nothing beat free food and drinks any day of the week, even if its at a funeral

    Comment

      #3
      Originally posted by gloryaccordy
      The high lobe on VTEC cams has high lift (good for turbos), long duration (good in moderation) and a lot of overlap (bad bad bad for turbos). The reason overlap is bad is because the intake and exhaust valves are open at the same time...this is good on an N/A motor, because if the header is designed right, the exhaust pulse will "pull" the intake charge through, making the engine breathe better...

      On a turbo motor though, the intake charge is pressurized, so if you have the exhaust valves open with the intake valves open, the intake charge will go through w/o being burned.

      Now if your homeboy has a VVTi system, that is basically an ECU controlled cam gear on the intake side, which only changes overlap...so for him to make the most power, he'd either want it programmed to act over a limited range, or go for a motor w/o the feature at all.

      Hope that helped.
      yes makes sense... thanks glory accordy mauve paintjob FL
      .. i guess the best bet would be to lower your vtec or vvti point with a vafc before boost threshold happens.. and then ''disable it'' if thats possible ??? after boost threshold..this would be good im guessing on applications where you are using a bigger turbo

      Comment

        #4
        Originally posted by 93EXaesthetic
        yes makes sense... thanks glory accordy mauve paintjob FL
        .. i guess the best bet would be to lower your vtec or vvti point with a vafc before boost threshold happens.. and then ''disable it'' if thats possible ??? after boost threshold..this would be good im guessing on applications where you are using a bigger turbo
        Yea...matching everything up to capitalize on making boost over as wide a rev range as possible is the idea. But the main thing you really wanna do is minimize overlap. That is why turbo cams have ok duration and crazy lift, as opposed to the crazy duration and lift of an N/A cam.


        Originally posted by lordoja
        im with you on that one bro! aint nothing beat free food and drinks any day of the week, even if its at a funeral

        Comment

          #5
          Most people that go boost hate the VVTI system and/or try to get rid of it or get around it. Me and my buddy are still figuring out what type of program to run on his GS. We got the turbo and everything still debating what program to use to tune the damn thing.

          The New-ish Ride
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          Comment

            #6
            i personally think the whole boost with VTEC is an internet myth. iv yet to see a non-VTEC motor make more power than a VTEC motor under boost (assuming everything else is equal of course)

            Owner of https://theclunkerjunker.com

            Comment

              #7
              Originally posted by Accord R33
              i personally think the whole boost with VTEC is an internet myth. iv yet to see a non-VTEC motor make more power than a VTEC motor under boost (assuming everything else is equal of course)
              It's not the VTEC system, just the overlap....the additional lift, duration, and head flow overcomes that one factor.


              Originally posted by lordoja
              im with you on that one bro! aint nothing beat free food and drinks any day of the week, even if its at a funeral

              Comment

                #8
                Originally posted by Accord R33
                i personally think the whole boost with VTEC is an internet myth. iv yet to see a non-VTEC motor make more power than a VTEC motor under boost (assuming everything else is equal of course)
                same here.

                and no, overlap is not bad, bad, bad. it is good, to a certain point.

                its all personal preference on where the power wants to be made in the power band.

                CrzyTuning now offering port services

                Comment

                  #9
                  Originally posted by d112crzy
                  same here.

                  and no, overlap is not bad, bad, bad. it is good, to a certain point.

                  its all personal preference on where the power wants to be made in the power band.
                  i like the sig, jose. LOL

                  Comment

                    #10
                    Originally posted by mondojackal
                    i like the sig, jose. LOL
                    dont tell me she got implants now.......*sigh*
                    "You don't have to be a Phi Beta Kappa to know not to strip-search a girl who is accused of stealing change,"

                    I did gagoogity that girl. I gashmoigitied her gaflavity with my googis. And I am sorry.

                    Comment

                      #11
                      has anyone in his situation had some cams made/re-designed and adjusted
                      the gears ( with gears) so there is less over lap? that way you would get the best of both worlds.
                      Life is wide, limitless. There is no border, no frontier ~ Bruce
                      My Page!

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