Suprash Posted July 18, 2004 Share Posted July 18, 2004 I have a question concerning the butterfly inside the inlet chambers, because we noticed that the car really comes on full chat at 4k revs, and was wondering if there something was opening/closing. When we looked inside the inlet, there is a butterfly type thing, that stays open up until 4k which seems to cause the air to pass between chambers, and when you hit 4k revs, it closes causing more air to flow directly down into the inlet. Now we're wondering what happens if you jam that butterfly thing shut all the time, will it give it more kick below 4k. Hope someone can answer this.......... Quote Link to comment Share on other sites More sharing options...
dandan Posted July 18, 2004 Share Posted July 18, 2004 Just off to bed Ash, but I touched on this in the thread you posted up about modding the NA. Will reply tomoz. It's all to do with varying the intake runner lengths and volume to take advantage of pulse waves generated in the intake system as valves open and close creating pulses. The timing and direction of these pulses (if designed correctly) helps to force more charge into the cylinders at a given rpm. Typically (but not exclusively): - Short runner lengths: Pulse tuning effect occurs higher in rev range - Long runner lengths: Occurs lower in rpm range. - Longer runners help build greater torque at lower rpm's and short do the same at higher rpm's. NA supras have a variable intake system to try to allow benefit at more than one single point in the rev range. Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 18, 2004 Author Share Posted July 18, 2004 mmmm, interesting, cheers Dan So you saying that if we jammed it shut , then it would run like a dog lower down, and then be the same higher up in the rev range ????? Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 19, 2004 Share Posted July 19, 2004 Nas have a variable intake system???? That's news to me! How come in three years of Supra chatting this has never come up? I'm shocked. Quote Link to comment Share on other sites More sharing options...
Wez Posted July 19, 2004 Share Posted July 19, 2004 Originally posted by Darren Blake Nas have a variable intake system???? That's news to me! How come in three years of Supra chatting this has never come up? I'm shocked. MR2 turbos have them as well if I remember correctly. Quote Link to comment Share on other sites More sharing options...
Ian C Posted July 19, 2004 Share Posted July 19, 2004 Check under your bonnet and let us know, Darren -Ian Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 19, 2004 Share Posted July 19, 2004 The MK 1 MR2 definately had a variable area system. I'll have a check about. Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 20, 2004 Share Posted July 20, 2004 No mention of it here... Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 20, 2004 Author Share Posted July 20, 2004 The butterfly sits in the intake air chamber......... Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 20, 2004 Share Posted July 20, 2004 Can you post up a pic dude? Quote Link to comment Share on other sites More sharing options...
TLicense Posted July 20, 2004 Share Posted July 20, 2004 The Mk1 MR2's and ST185 Celica's definitely had T-VIS. Which effectively blocked air flow into 1/2 inlet valves at low speed. This gave you all the benefits of 8 valves low down in the rev range but opened up to 16 valve when you got past about 3000 rpm IIRC. I think what happens on the Supe NA is more to do with variable length intake rather than changing the number of effective vlaves though?? Regards Tony Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 20, 2004 Author Share Posted July 20, 2004 Originally posted by Darren Blake Can you post up a pic dude? Who ya talking to and post a pic of what mate Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 20, 2004 Share Posted July 20, 2004 Originally posted by Ashley Willis Who ya talking to and post a pic of what mate You sounded like you had an engine in bits. I was wondering if you could post up a pic of the butterfly valve? Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 20, 2004 Author Share Posted July 20, 2004 I did I havent any more, but I can.... Only have Microsoft paint here, so might knock you up a little drawing if I get chance..... Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 20, 2004 Share Posted July 20, 2004 Cool. There must be an external actuator too? I'll have to have a look under my bonnet tomorrow. Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 20, 2004 Author Share Posted July 20, 2004 mmm, this looks to scale Maybe my new design would flow better But you get the point, this is looking at from the gasket end of the inlet, so you have the 6 runners on the other side. Inside there is a circled disc that stays open (blue) until you hit 4k revs, this disc then shut closed (red) Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 20, 2004 Share Posted July 20, 2004 Can you tell what it is yet? So runners 1, 2 and 3 and 4, 5 and 6 have separate chambers in the plenum but they can be joined into a single chamber by opening the valve? Sounds similar to the multi-mode intake systems used on V6 engines where the plenums for each bank can be directly linked. I'm amazed that no one has mentioned it before. Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 21, 2004 Author Share Posted July 21, 2004 I think its runners 1,2 and 3 have one chamber and then 4, 5 and 6 have another chamber, that then can be joined into a single chamber by the valve........ A side veiw for ya...... Quote Link to comment Share on other sites More sharing options...
dandan Posted July 21, 2004 Share Posted July 21, 2004 Top quality Ash, You're not a draftsman by any chance are ya!! I thought the variable geometry inlet on the NA was common knowledge and like most NA stuff, unfortunately, it just never gets discussed. I don't think you've got anything to gain by fiddling Ash. If you were aiming for a balls out NA 300bhp engine then you might well junk the lot but that's a different story. Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 24, 2004 Author Share Posted July 24, 2004 What about throttle bodies, has anyone ever discussed this. Anyone ever used them on a NA...........the're supposed to sound mental........???? Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 25, 2004 Share Posted July 25, 2004 I meant to post up that I looked and did indeed find a vacuum actuator right where Ashley said it would be. Sweet! Quote Link to comment Share on other sites More sharing options...
lpher Posted July 25, 2004 Share Posted July 25, 2004 Originally posted by TLicense The Mk1 MR2's and ST185 Celica's definitely had T-VIS. Which effectively blocked air flow into 1/2 inlet valves at low speed. This gave you all the benefits of 8 valves low down in the rev range but opened up to 16 valve when you got past about 3000 rpm IIRC. I think what happens on the Supe NA is more to do with variable length intake rather than changing the number of effective vlaves though?? Regards Tony I know my last car....a Celica GTi (ST182) had ACIS...wich is..as i understand it basicly about the same as TVIS @lpher Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 26, 2004 Author Share Posted July 26, 2004 Originally posted by Darren Blake I meant to post up that I looked and did indeed find a vacuum actuator right where Ashley said it would be. Sweet! Darren, what does this mean then.......sweet I was right, sweet we can mod it ??????? Quote Link to comment Share on other sites More sharing options...
Digsy Posted July 26, 2004 Share Posted July 26, 2004 Sweet that you were right. If you make it either always open or always closed then either low down torque or top end power will suffer for no gain to the other. You might be able to play around with the switching point by running the actuator through a dedicated solenoid, but my guess is its optimised already. Quote Link to comment Share on other sites More sharing options...
Suprash Posted July 26, 2004 Author Share Posted July 26, 2004 Originally posted by Darren Blake Sweet that you were right. If you make it either always open or always closed then either low down torque or top end power will suffer for no gain to the other. You might be able to play around with the switching point by running the actuator through a dedicated solenoid, but my guess is its optimised already. Thats disapointing.........was hoping it was more of a Toyota thing for economy or emissions...... Quote Link to comment Share on other sites More sharing options...
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