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| Toyota Intake Technology; ACIS & T-VIS | |
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| Tweet Topic Started: Dec 7 2004, 05:54 PM (1,395 Views) | |
| jasestu | Dec 7 2004, 05:54 PM Post #1 |
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caffeinated...
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To clear up those acronyms ACIS is Acoustic Control Induction System and T-VIS is Toyota Variable Induction System. And if we want to create an acronym for this thread (Toyota Intake Technology) then it would be TIT. Still learning basics about my car I was looking around my stock intake system and noticed a plastic butterfly valve type arrangement in the intake system. It looks to be able to block off air from entering the ‘dirty’ side of the air filter chamber from the front scoop that pokes under the front of the bonnet. When closed the only entry point looks to be through the wheel arch via a small silencer box and coarse foam filter. Wanting to learn some more I searched the net for a while… Unfortunately I found nothing directly relating to this butterfly valve but instead found info on the aforementioned acronyms. Some good detail here: T-VIS Tech Discussion From what I can ascertain the RS200 must have one of these systems since it explains the “VVTi kick” (VVTi does not actually kick and is smooth) that we feel. Based on the link above it should be the T-VIS system, and not the ACIS, though the link does say the T-VIS was used on 3S-GEs for the US market, so do JDM Altezzas have it? So my search didn’t answer my original question as to how that valve in the intake works, and raised more questions about ACIS and T-VIS. However I do expect I can learn more about the valve by running the car at various conditions with the cover off the top of the intake (this does not diminish filtering integrity), as long as I can simulate the conditions required to actuate it without the car in gear… Damn the TITs.
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ex RS200 Z ed 6MT | Bay of Plenty, New Zealand | |
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| TranceManNZ | Dec 7 2004, 07:10 PM Post #2 |
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Paid-up Member
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Very nice post Look forward to your results
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| grahamd | Dec 8 2004, 12:22 AM Post #3 |
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Toowoomba, AUS
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Can email you a copy of the Lexus training manual on Variable Valve Control and Acoustic Control Induction System. Send me your email address for a copy. |
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Graham D RX350 Sports Luxury IS200 Sports Luxury with 2.5GT-T & Getrag 6 speed IS200 Sports Luxury Auto (Wife's car so no mods allowed) Suzuki GSX750-F No wonder the garage is full. | |
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| Sirnixalot | Dec 8 2004, 12:41 AM Post #4 |
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Paid-up Member
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When i took the scoop off to look at that flap i modulated the throttle by hand and it closed when i essentially "stepped" on the gas and opened when the throttle was released. It seamed a bit backwards to me so i disconnected the plug for the actuator. No ill effects occured. There is also a steel plate with rubber on one side bolted to the intake manifold. I assumed that was for sound deadening and took that off. All this wonderful technology and they add weight to cover up such a sultry sound. Graham...if you wouldnt mine could i get a peek at that info as well sirnixalot@gmail.com please
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| Damn you and your admin powers...damn you! | |
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| Twincams | Dec 8 2004, 05:19 AM Post #5 |
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i did a check... the flap will remain closed under all circumstances until the rpm hits around 4700 rpm... u could try holding your throttle at, say, 4000rpm and the flap will still remained closed, but once u bring up the rpm at whatever load or %throttle to more than 4700rpm, then the flap will open... so effectively, the only air channel provided for the engine to breathe for normal driving is the small circular opening to the left of the box... which explains why we always see a distinct circular dirty patch on our filter elements... my guess is that the car was designed for emission and economy benchmarking for high performance engines(chanced upon a website that stated so)... it makes no sense to restrict air into the engine, unless for those reasons, coz less air goes in means less fuel required + less emissions... just my views
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| Sirnixalot | Dec 8 2004, 06:53 AM Post #6 |
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Paid-up Member
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ahhhhh thats what its all about then
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| Damn you and your admin powers...damn you! | |
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| greeneyes | Dec 8 2004, 06:55 AM Post #7 |
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Targa Master
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There are distinct gains in having smaller intake manifolds at lower revs, giving the incoming air more inertia. But then they get too restrictive at high revs, so this is a good way of coping with both situations. Part of the reason rally/race cars run very poorly low down. Maybe the low end gain is harder to measure without a lot of dyno work & fuel measuring...?? Try it on & off a few more times Sirnix- keith |
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The Girl's KE70- http://www.rollaclub.com/board/topic/42407-the-girls-ke70/ How NOT to build a rally car- http://www.rollaclub.com/board/topic/64027...ld-a-rally-car/ | |
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| jasestu | Dec 8 2004, 10:23 AM Post #8 |
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caffeinated...
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Yes, definite advantage having more air velocity through the plenium/intake manifold at lower volumetric flows, which is what the ACIS and T-VIS systems are all about (as is my understanding at the moment). However, this restriction is before the filter chamber and wouldn't do anything to increase velocity through the plenium because the air will slow as soon as it enters that big chamber with the filter in it... Like you say Keith, probably hard to verify what the benefits of locking the flap open are without dyno and fuel monitoring. The ol' seat of the pants dyno just doesn't cut it with tweaks less than 10-20 bhp! I could try disabling the flap for a couple of weeks and then compare the fuel economy over three or four tanks of gas to test for any effect there... To summarise: My understanding (at the current moment) suggests that this flap is an economy thing and may actually be hurting performance down low, not helping it like T-VIS or ACIS. However, if everthing is sized correctly and the flap opens early enough in the rev range there should be no performance or economy effect at all, only a deadening of the sound and additional filtering at low speeds (when you're in smoggy Japan traffic?) since there's that extra bit of foam. The investigation (and my confusion) continues... |
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ex RS200 Z ed 6MT | Bay of Plenty, New Zealand | |
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| jasestu | Dec 9 2004, 05:43 AM Post #9 |
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caffeinated...
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Thanks Graham, looks like a good document. Seems to be the source of the diagrams used in the link I posted above. |
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ex RS200 Z ed 6MT | Bay of Plenty, New Zealand | |
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| CoffeeBoss | Dec 9 2004, 11:26 AM Post #10 |
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Location: Sydney, AU
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It's basically a variable intake system then. Many high tune NA cars seem to have them these days. They also have tuned 'lengths' on the intake. |
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| jasestu | Dec 10 2004, 05:41 AM Post #11 |
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caffeinated...
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Yeah, that's what I'd expect; I understand the principle of tuned lengths and resonant frequencies, but when you look at the shape and fins and stuff going on in that intake box, it’s clearly about dampening/preventing these waves rather than inducing them. If the flap was switching in and out a smooth chamber then yeah, perhaps then it would be doing resonate tuning, but the fact it’s opening another path into a convoluted route to the filter I figure its more about keeping the car quiet at low speeds and then opening things up a bit more when it’s really asked to go for it. I dunno, unless Toyota has gotten really clever and is able to map flows though such a tortuous path and have optimised the intake for resonance... |
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ex RS200 Z ed 6MT | Bay of Plenty, New Zealand | |
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| Twincams | Dec 12 2004, 05:37 AM Post #12 |
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according to a local jap tuner, he said the airbox was intentionally designed so that the induction waves will not be able to perpetuate so far into the intake system. this will allow intake flow to less likely be affected by intake length thus eliminates the need for variable tuned intake lengths in the system... so, hence the word 'acoustic' is used??? sounds logical to me as far as low rpm driveability is concerned, but for track driving where high rpm with minimum restriction is the emphasis, then i guess the airbox will then not be an optimum setup... wat do u guys think?
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| Serran | Dec 12 2004, 06:00 AM Post #13 |
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Unregistered
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hey twincams.. are you using an aftermarket computer? i tend to think that rpm is not the factor to consider when the flap opens. it would have to do more with fuel air map and/or ignition timing as now i do not feel the vvti "kick" since having an aftermarket computer tuned appropriately. forgive me if i haven't grasped the topic you guys are discussing.. i've come in half way through this thread. |
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| Twincams | Dec 14 2004, 04:19 AM Post #14 |
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hi serran, no i am using the stock computer with emanage as piggyback. yes, i thought so too initially, until i put the intake box in the passenger seat with all the vacuum tubes extended into the cabin(was quite troublesome,actually) and watched the flap open and close while the car was on the move... does your aftermarket computer support the dual vvt-i function? i suspect our vvt-i is working on dual mode only when the powerband comes in... else, during normal driving it operates on the intake only, just like the other single vvt-i models...just my guess... |
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| jasestu | Dec 14 2004, 06:30 AM Post #15 |
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caffeinated...
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Ya what? Now that's commitment to the cause! So you're confirming that it's only rpm that controls this flap? I'd love to get hold of a full listing of all the programs that the computer runs, it'd probably be more pages than I'd care to read, but would be nice to know some of what the inputs, setpoints and outputs are... |
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ex RS200 Z ed 6MT | Bay of Plenty, New Zealand | |
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| Twincams | Dec 15 2004, 04:03 AM Post #16 |
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actually there's no need to do that coz u can just rev the engine while standing in front of the engine bay and watch how the flap moves... else, u could get someone to rev and see exactly at which rpm point the flap opens as u watch it... m still trying to crack the jap code in the manuals... its been put to a stop recently due to other commitments... will try and pick it up again once i have the time
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| Serran | Dec 18 2004, 02:51 AM Post #17 |
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Unregistered
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back to one of jase's original questions.. no, the 3sge does not use tvis.. anyone else want to confirm this? |
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| greeneyes | Dec 18 2004, 08:13 AM Post #18 |
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Targa Master
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The tech page link above says the 3SGE does have Tvis, but I think they mean the MR2. I was puzzled as my engine certainly does not look like it has dual intake runners, unless they are cast into one cylindrical shape. So I figure you are right! |
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The Girl's KE70- http://www.rollaclub.com/board/topic/42407-the-girls-ke70/ How NOT to build a rally car- http://www.rollaclub.com/board/topic/64027...ld-a-rally-car/ | |
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| Serran | Dec 18 2004, 09:13 AM Post #19 |
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Unregistered
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yep yep i think they meant for the mr2
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| jasestu | Dec 18 2004, 04:27 PM Post #20 |
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caffeinated...
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I concur; the 5th generation 3SGE (a la Altezza) does not have TVIS. Nor does it have ACIS. And that flap in the airbox opens around 4700 rpm. That’s all my original questions answered… Except now I’m left wondering what causes the VVT-i kick that’s supposed not the VVT-i…
So I guess just the timing and fuel changes without the ACIS are enough to give the kick... |
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ex RS200 Z ed 6MT | Bay of Plenty, New Zealand | |
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Look forward to your results



1:03 PM Jul 11