Is there a VVT-i controller like the Vtech Controller?
04-02-2004, 03:46 PM
#21
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Originally Posted by jackmott
vvti control the phase timing between when the intake and exauhst valves open.
this way you can get 0 overlap at low rpms and some overlap at higherrpms, optimzing fuel efficiency and make the powe band flatter.
vtec actually changes the lift of the cam at a specific rpm. This allows them to use a low lift setting at lower rpms for better low rpm power and fuel efficiency, and a big cam at high rpms for maximum power production.
from a pure horsepoower production standpoint, a vtec system is going to have more potential all else being equal. Being able to 'switch' to a huge lift cam at high rpms is a huge win. Simply changing *when* the intake and exauhst valves open is a bit more subtle.
anyway, could aftermarket control of vvti be useful? I wouldn't expect so on a near stock engine, when you floor the gas pedal it likely goes to optimum horsepower settings.
I wouldnt expect a vtec controller to be useful on a stock honda either.
this way you can get 0 overlap at low rpms and some overlap at higherrpms, optimzing fuel efficiency and make the powe band flatter.
vtec actually changes the lift of the cam at a specific rpm. This allows them to use a low lift setting at lower rpms for better low rpm power and fuel efficiency, and a big cam at high rpms for maximum power production.
from a pure horsepoower production standpoint, a vtec system is going to have more potential all else being equal. Being able to 'switch' to a huge lift cam at high rpms is a huge win. Simply changing *when* the intake and exauhst valves open is a bit more subtle.
anyway, could aftermarket control of vvti be useful? I wouldn't expect so on a near stock engine, when you floor the gas pedal it likely goes to optimum horsepower settings.
I wouldnt expect a vtec controller to be useful on a stock honda either.
04-02-2004, 04:49 PM
#22
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0 overlap at least on the exhaust side(kinda stupid to use vvt-i on just the intake tho) is very bad for n/a cars. It decreases lowend torque. But Im not sure the effects on the intake side, seems like it might do some good. I would not call the ECM thinking for you a good thing because it thinks on terms of stock setup which when your looking at this kind of thing your most likely not stock. I'd much rather have a motor like the one in my stealth where the timing is advanced and retarted based on knock counts. Even then I can override it. Anyone think of a timing controler. They do exist Apexi makes one but might yeild some control. But any controler will just be masking the problem. Someone needs to dump the code from the ECM onto a computer and go thru it redoing some stuff thats wrong. I know someone dumped the code on a 95 vr-4 spyders ECM and it was all assembly type of code. So reprograming it shouldn't be a major problem. With current technology most cars come with flash programmable ECMs to that may make it easier. Just some food for thought. I can't wait to get my scion so I can poke around and test some stuff.
04-02-2004, 09:10 PM
#23
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Location: Houston, Texas
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Iamslow, your post reveals that you are a bit confused.
you are confusing ignition timing with valve timing.
0 overal on the exauhst side is a statement that doesnt make sense. the meaning of valve overlap is when bost valves are open. you cant have overlap on just one side.
your stealth is changing IGNITION timing based on knock. (when the spark plugs fire)
VVTI changes VALVE timing. (when the valves open up)
VETEC changes valve LIFt (how FAR the valves open up)
got it?
and 0 overlap is goood for low rpm power. you know how people idiotically post here all the time about have exauhst that is TOO free flowing causing a loss of low rpm power? This used to be (somewhat) true on cars that had lots of valve overlap at low rpms. But it much less of an issue on a car with variable valve timing. there is no overlap so you don't need backpressure.
you are confusing ignition timing with valve timing.
0 overal on the exauhst side is a statement that doesnt make sense. the meaning of valve overlap is when bost valves are open. you cant have overlap on just one side.
your stealth is changing IGNITION timing based on knock. (when the spark plugs fire)
VVTI changes VALVE timing. (when the valves open up)
VETEC changes valve LIFt (how FAR the valves open up)
got it?
and 0 overlap is goood for low rpm power. you know how people idiotically post here all the time about have exauhst that is TOO free flowing causing a loss of low rpm power? This used to be (somewhat) true on cars that had lots of valve overlap at low rpms. But it much less of an issue on a car with variable valve timing. there is no overlap so you don't need backpressure.
Originally Posted by iamslow
0 overlap at least on the exhaust side(kinda stupid to use vvt-i on just the intake tho) is very bad for n/a cars. It decreases lowend torque. But Im not sure the effects on the intake side, seems like it might do some good. I would not call the ECM thinking for you a good thing because it thinks on terms of stock setup which when your looking at this kind of thing your most likely not stock. I'd much rather have a motor like the one in my stealth where the timing is advanced and retarted based on knock counts. Even then I can override it. Anyone think of a timing controler. They do exist Apexi makes one but might yeild some control. But any controler will just be masking the problem. Someone needs to dump the code from the ECM onto a computer and go thru it redoing some stuff thats wrong. I know someone dumped the code on a 95 vr-4 spyders ECM and it was all assembly type of code. So reprograming it shouldn't be a major problem. With current technology most cars come with flash programmable ECMs to that may make it easier. Just some food for thought. I can't wait to get my scion so I can poke around and test some stuff.
04-03-2004, 01:00 PM
#24
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Join Date: Sep 2003
Location: Covina
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HKS does make VVT-i controller, BUT it's a complete kit with cam shaft and ONLY for 1JZ-GTE or 2JZ-GTE ENGINES ONLY.
http://www.hks-power.co.jp/products/...on/valcon.html
this is the product, even though it's for different toyota, its good to know VVT-i is controllable, if you spend enough money into it.
http://www.hks-power.co.jp/products/...on/valcon.html
this is the product, even though it's for different toyota, its good to know VVT-i is controllable, if you spend enough money into it.
04-17-2004, 01:54 PM
#26
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Join Date: Dec 2003
Location: Groveland, FL (Orlando)
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Originally Posted by kagero79
HKS does make VVT-i controller, BUT it's a complete kit with cam shaft and ONLY for 1JZ-GTE or 2JZ-GTE ENGINES ONLY.
http://www.hks-power.co.jp/products/...on/valcon.html
this is the product, even though it's for different toyota, its good to know VVT-i is controllable, if you spend enough money into it.
http://www.hks-power.co.jp/products/...on/valcon.html
this is the product, even though it's for different toyota, its good to know VVT-i is controllable, if you spend enough money into it.
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