SUPRA-JDB Posted January 16, 2009 Share Posted January 16, 2009 hi, just a quick question, i own a J-Spec 3.0 N/A 1995. when accelerating hard it pulls well then at around 5000 RPM its asif their is some sort of VVTI or VTEC cut in, as you get a second influx of power. although i thought only the later spec engines had VVTI?. anyone shed abit of light on this? Quote Link to comment Share on other sites More sharing options...
dandan Posted January 16, 2009 Share Posted January 16, 2009 Is your clutch slipping? Quote Link to comment Share on other sites More sharing options...
Animal Posted January 16, 2009 Share Posted January 16, 2009 Until someone with proper knowledge comes on and shows me up; I think it's to do with the fancy plenum chamber that was an innovation at the time. When you get to 5k RPM, something mysterious and arcane happens, giving you another boost of power. It happens around 3.5k RPM too. You don't have to understand it to enjoy it. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 16, 2009 Share Posted January 16, 2009 Variable intake length, a butterfly valve opens to change the plenum volume, to aid resonance tuning at a higher RPM, and vice versa. Toyota have long been advocates of it. Quote Link to comment Share on other sites More sharing options...
SUPRA-JDB Posted January 16, 2009 Author Share Posted January 16, 2009 nice one. all sounds good to me. cheers for help. . . Quote Link to comment Share on other sites More sharing options...
Animal Posted January 16, 2009 Share Posted January 16, 2009 Cheers Chris, I knew it was plenum-related, but couldn't find anything with a search. Quote Link to comment Share on other sites More sharing options...
ilicos Posted January 16, 2009 Share Posted January 16, 2009 Don't forget that the N/A produces it max HP output at just over 5K revs. I also have an N/A and get the same response from mine. Quote Link to comment Share on other sites More sharing options...
supra_aero Posted January 16, 2009 Share Posted January 16, 2009 Mine does this too, I thought something was up but if its normal Quote Link to comment Share on other sites More sharing options...
bigbloodyturbo Posted January 16, 2009 Share Posted January 16, 2009 5k also see's a large increase in ignition advance with the stock n/a ecu, this is what limits the amount of boost you can run when you go na-t as that advance causes det over 10psi, i would guess it might have a noticable effect when n/a also. Quote Link to comment Share on other sites More sharing options...
Supra-Brett Posted January 16, 2009 Share Posted January 16, 2009 Variable intake length, a butterfly valve opens to change the plenum volume, to aid resonance tuning at a higher RPM, and vice versa. Toyota have long been advocates of it. I thought it was variable cam timing ? (sure ive seen that in the toyota manual), or is that teh same as your fancy wording above ? My N/A does this also by the way, but mine at about 4.5K. Quote Link to comment Share on other sites More sharing options...
miko_supra Posted January 16, 2009 Share Posted January 16, 2009 I thought it was variable cam timing ? (sure ive seen that in the toyota manual), or is that teh same as your fancy wording above ? My N/A does this also by the way, but mine at about 4.5K. no, just a wee valve. Quote Link to comment Share on other sites More sharing options...
paul mac Posted January 16, 2009 Share Posted January 16, 2009 (edited) Variable intake length, a butterfly valve opens to change the plenum volume, to aid resonance tuning at a higher RPM, and vice versa. Toyota have long been advocates of it. yep celica's use it to, short intake runners make good top end at the expense of bottom end and vise versa link to T-VIS http://en.wikipedia.org/wiki/T-VIS and http://en.wikipedia.org/wiki/Acoustic_Control_Induction_System Edited January 16, 2009 by paul mac (see edit history) Quote Link to comment Share on other sites More sharing options...
Aero-M Posted January 16, 2009 Share Posted January 16, 2009 mine is from 4k upwards. Quote Link to comment Share on other sites More sharing options...
Supra-Brett Posted January 16, 2009 Share Posted January 16, 2009 mine is from 4k upwards. Is that you in your avatar ? Quote Link to comment Share on other sites More sharing options...
Aero-M Posted January 16, 2009 Share Posted January 16, 2009 is that you in your avatar ? no! is that you in yours? Quote Link to comment Share on other sites More sharing options...
Dan8 Posted January 16, 2009 Share Posted January 16, 2009 do they need adjusting some how to keep them in tune such as a threaded bar and lock nut & can you change when it kicks in is there a tolerance are measurement to set it to Quote Link to comment Share on other sites More sharing options...
Digsy Posted January 16, 2009 Share Posted January 16, 2009 5k does sound a bit high. Mine comes in at 4 / 4.5k The further away from the intended switch point you are the more you will feel it. In theory you could make the changeover completely un-noticable, but Toyota like to make you experience it. There may be something very slightly up with your variable intake system, such as a lazy valve or something similar. Quote Link to comment Share on other sites More sharing options...
dani_r Posted January 17, 2009 Share Posted January 17, 2009 I've always wondered what that feeling was! I didn't realise it was plenum related! I used to have a Prelude 2.2 Vtec and when the Vtec kicked in you really felt it! Real nice engines. Then I got the Supra and had that 'kick' effect, but never asked questions, just enjoyed it! Quote Link to comment Share on other sites More sharing options...
bigbloodyturbo Posted January 17, 2009 Share Posted January 17, 2009 I've always wondered what that feeling was! I didn't realise it was plenum related! I used to have a Prelude 2.2 Vtec and when the Vtec kicked in you really felt it! Real nice engines. Then I got the Supra and had that 'kick' effect, but never asked questions, just enjoyed it! The kick in a prelude is the vtec at 5k2, that changes the cam lobe to a more aggressive one with more lift and duration at a certain rpm(5k2 in the case of the H22) the prelude will also have what the na supra has though, which is two sets of intake runners, in the prelude it is controlled by vacuum and changes before vtec at about 4k something, it doesn't really make a performance change in the prelude, it just changes the sound, you do notice a huge difference when you disconnect the vacuum hose from the actuator though as it looses all the low end as would the supra probably. Quote Link to comment Share on other sites More sharing options...
Supra-Brett Posted January 17, 2009 Share Posted January 17, 2009 no! is that you in yours? Yes, im a car. Cars are very capable of typing on a keyboard Quote Link to comment Share on other sites More sharing options...
dani_r Posted January 17, 2009 Share Posted January 17, 2009 The kick in a prelude is the vtec at 5k2, that changes the cam lobe to a more aggressive one with more lift and duration at a certain rpm(5k2 in the case of the H22) the prelude will also have what the na supra has though, which is two sets of intake runners, in the prelude it is controlled by vacuum and changes before vtec at about 4k something, it doesn't really make a performance change in the prelude, it just changes the sound, you do notice a huge difference when you disconnect the vacuum hose from the actuator though as it looses all the low end as would the supra probably. Good to know Quote Link to comment Share on other sites More sharing options...
steady_dave Posted January 18, 2009 Share Posted January 18, 2009 Yeah this happens in mine, and is extremely acentuated (sorry if my spellings off there) by the fact that i'm sure from 3k to 4.5k the car doesn't accelerate as hard as it was doing before however I still have the 1st Cat on so could be to do with that! Quote Link to comment Share on other sites More sharing options...
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