S14 VTC vs. VTEC
S14 VTC vs. VTEC
OK newbie question what is the difference between the two cuz i am looking at the S14 SR20DETand my Brother in law Teg GSR owner says VTC is no where near as good as VTEC so ?????
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ItzGenX
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its based on opinion, both work on the same fundamentals just different "style". plus he might be a honda freak to say "vtec is better". power gains on vtec isnt exactly a big leap, but it does help somewhat. people who build great turbo honda motors usually buy a "vtec killer" cam--which disables the whole vtec feature, because vtec and turbo dont mix (word is that detonation occurs when a certain level of tuning is reached with turbo). basically both take the same standards just with different techniques. VTC and VTEC both alter the timing of the engine at a certain powerband to make lowend and highend power more beneficial to the user.
The difference is that Honda V-Tec uses both the intake and exhaust cams for DOHC models I am almost positive of this. But the VTC just does the intake cam. The Honda V-Tec is more powerful. I heard one person with a S15 swap on a 1995 240 say that he could barely feel the cam lobes switch or what you call VTC at stock boost. But when he upped the boost he couldn't feel it at all. So its not a huge deal. Also I heard that heavy racers disconnect it on SR20DET's.
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I H8 UR DSM
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they are similar...not the same....and neither is better than the other.:thinker search...
"vtc stands for Valve Timing Control.All that vtc does (on the S14 SR20DET) is that it advances the intake cam timing by 20 degrees (so that there is 21 degrees of overlap between the two cams). This system only operates when the engine is warm and under 5700RPM.
What this means in plain english is that it is a system that Nissan designed to increase midrange torque and give the motor more power where a daily driver needs it. Since the system doesn't engage past 5700RPM's, peak power is not affected by this. This is why some tuners prefer to not use vtc on high-power cars, because it's one less electronic gadget you have to deal with and it has no effect on peak power output.
In case any of you have doubt about what I've said, simply refer to a copy of the S14 SR20DET FSM. All this is explained on page EC-28
-alex"
http://forums.freshalloy.com/u...26662
http://forums.freshalloy.com/u...71497
"vtc stands for Valve Timing Control.All that vtc does (on the S14 SR20DET) is that it advances the intake cam timing by 20 degrees (so that there is 21 degrees of overlap between the two cams). This system only operates when the engine is warm and under 5700RPM.
What this means in plain english is that it is a system that Nissan designed to increase midrange torque and give the motor more power where a daily driver needs it. Since the system doesn't engage past 5700RPM's, peak power is not affected by this. This is why some tuners prefer to not use vtc on high-power cars, because it's one less electronic gadget you have to deal with and it has no effect on peak power output.
In case any of you have doubt about what I've said, simply refer to a copy of the S14 SR20DET FSM. All this is explained on page EC-28
-alex"
http://forums.freshalloy.com/u...26662
http://forums.freshalloy.com/u...71497
vtc is nothing like vtec. thing of ftc as valve timing change. vtec is a lift control set up. vtec is equal to added big performance cams, as the valve on a vtec will have three different lobes and rockers to choose from. vtc only has one lube and rocker. vtc takes the benefit of adjustable sprockets to a better level. vtec takes the benefit of a race cam to a better level. ivtec in the new hondas do both! fear not nissan fans, nissan also has a system that changes lift. they make three different models based on the sr20 actually. they call them neo vvl motors. they have the sr16ve. 175hp.then the sr20ve with 200hp. then the best! the sr20vet in the jdm xterra. 275hp. <---SOMEONE SWAP THIS INTO A S13 PLEASE. hope i was of some help. some of this is probably not exactly right, but should be very close.shaun
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I H8 UR DSM
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vtec is not good for turbos? please tell me you kiding right! yeah there are very few racers that use the vtec killer setup. As this make the car very unstreetable. As for the power issue. my b16a2 thats a 1.6liter with a drag 3 kit, wiseco pistons (8to1 compression), eagle rods, and hondata 3b setup made 259hp and 172 tq at only 10psi of boost with a stock head. and rember this is a 1.6liter. heres the dyno plot
In conclusion vtec is very god for turbos just as any cam with a higher lift is. and for the nissan stuff im not sure. but im learning. I would have loved to have given you a ride in my civic and we could play the "you grab the 10bucks from the dash before i hit 60mph and you get to have it, game" At 4500rpm i would have 4psi of boost and the second vtec kicked in at 4600rpm the boost would fly to 10psi instantly due to the more exhaust flow. jsut thought i would clean this up. And the vtec killer system was designed to remove more moving mass in the head by eliminating one set of cam lobes this is an all race setup.
In conclusion vtec is very god for turbos just as any cam with a higher lift is. and for the nissan stuff im not sure. but im learning. I would have loved to have given you a ride in my civic and we could play the "you grab the 10bucks from the dash before i hit 60mph and you get to have it, game" At 4500rpm i would have 4psi of boost and the second vtec kicked in at 4600rpm the boost would fly to 10psi instantly due to the more exhaust flow. jsut thought i would clean this up. And the vtec killer system was designed to remove more moving mass in the head by eliminating one set of cam lobes this is an all race setup.
i don't see where someone said vtec wasn't good for turbo. but ironically, i think that vtec isn't that great for turbo. here is why...the overlap on the intake and exhaust valves. boost is going in the intake valve, and since the exhaust is open at the same , boost goes straight back out. not what i would call an efficient turbo setup. now the actual extra lift isn't so bad. but the longer duration would cause the overlap problem. i don't mean to be mean, but 259hp seems kinda low. with10psi of boost with standalone and a built motor. i have a few friends with b18 non-vtec motors running 10psi and making 290hp. lets play that $10 bill game in my car at 22psi with nitrous on! i'm just playin :0)shaun
when was the last time you raced a civic under 4grand????Never even at the track from a stand still my car launchs at 5800rpm and never drops below that the whole run. Sound like you have never drove or raced with a turbo b16.Even under normal driving my car may be under 4grand in first for a mili second then its above 4000rpm most of the time. it helps when the red line is at 8200rpmAlso the reason the hp is abit low for 10psi is cause its 8to1 compression. Im sure your friends LS was at least 9to1. The motor was built to take 400hp with no probs and we were shooting for 350hp at 18psi of boost. however after the first tunning section that put the car at 259at 10psi i felt no reason to go back. 259hp is crazy in a FWD and thats the reason i sold the car. I wanted a RWD a the nissan seems like the best route. Im not hating or anything 90 percent of the major turbo honda racers out there cant all be wrong. It has been proven many times that a vtec honda makes more on boost. Or why would my boys b18 turbo have picked up 45hp when we put an b16 head on it. The compression is still the same it just now has vtec. Ever riden in a b20/vtec turbo? Im telling ya the vtec helps.oh need more info check this out a b16 bored and built to a 1.7liter that put out 500hp and 320tq. its a good threadhttp://honda-tech.com/zerothread?id=311514also jemil118 i used to have a 91 300xz nonturbo and man what a waste of money. What good is a N/A 3.0v6 when it has to pull a boat load of weight. True the cars look very very nice but they are slow as hell. thats why i sold mine. I looked at a 300zxTT but i did not want to ever have to work on it as im sure you have found out on yours with the super lack of space under the hood. so now i got a 92 240 for 500bones and im gonna jump on the sr20det bandwagon. Gotta love RWD though Im not trying to argue here but find any vtec honda that makes good power and pull the plug on the vtec sel. and see what happens. i promise you it wont make anymore power or we would all be doing it
Also pampadori could i see some pics of your car as you link does not work. Im interested not in a negative way as i am now doing a 92 240sx myself. thanks
Also pampadori could i see some pics of your car as you link does not work. Im interested not in a negative way as i am now doing a 92 240sx myself. thanks
VTEC is relatively simple system (ignoring i-VTEC) - at a given RPM, if the correct conditions are met (throttle position, oil pressure, engine temp, IAT), a pin engages a taller rocker, and switches the cam profile.
VTEC is an on/off proposition - you're either on the VTEC lobe, or you're not.
Since cams have been the bane of tuners everywhere since the invention of the piston engine (a cam tuned for fuel economy provides unacceptable performance, and performance cams give bad emissions and fuel economy, etc), cam timing has always been a compromise between many objectives.
VTEC (and other forms of variable valve timing) are a partial answer - by allowing the cam to contain a second profile, an engine that provides great economy and good emissions results can also provide a burst of top end power.
VTC is different from VTEC - while VTEC revolves around a secondary cam profile (which can be anything the person who cut that cam wants it to be), VTC is cam PHASING.
Cam phasing involves tilting the cam on direction or another to effect a gradual increase or decrease in lift or duration. Infinitely more subtle than VTEC, VTC has no solid changeover point, as the ECU should be constantly varying the cam phasing dependant on driving conditions and driver input.
The reason most tuners disable variable systems such as VTC, VTEC, i-VTEC, VVT-i (and the -L variant) is simple. Tuning these systems to work with aftermarket parts is simply too big a job for not enough results. You may gain 5-10hp with a well tuned system, but the time and results for tuning a given setup on a variable system (which takes engineers, physicists and more than you want to know in time and money) is equal to years and millions of dollars.
Manufacturers do it because a) they have the resources, and b) they're tuning a setup for millions of engines. A tuner would have to tune for each individual setup. See my point?
As to which is better, well neither - they do completely different things completely differently.
i-VTEC is the most advanced VVT system on the market right now in a car under $50,000 - at that point, Porsche's Variocam and Variocam Plus and BMWs VANOS, Double-VANOS, and DME (Direct Motor Electronics) slap around the stuff we can afford.
They all feature infinitely and stepless variable valve timing, cam phasing, and ignition timing.
VTEC is an on/off proposition - you're either on the VTEC lobe, or you're not.
Since cams have been the bane of tuners everywhere since the invention of the piston engine (a cam tuned for fuel economy provides unacceptable performance, and performance cams give bad emissions and fuel economy, etc), cam timing has always been a compromise between many objectives.
VTEC (and other forms of variable valve timing) are a partial answer - by allowing the cam to contain a second profile, an engine that provides great economy and good emissions results can also provide a burst of top end power.
VTC is different from VTEC - while VTEC revolves around a secondary cam profile (which can be anything the person who cut that cam wants it to be), VTC is cam PHASING.
Cam phasing involves tilting the cam on direction or another to effect a gradual increase or decrease in lift or duration. Infinitely more subtle than VTEC, VTC has no solid changeover point, as the ECU should be constantly varying the cam phasing dependant on driving conditions and driver input.
The reason most tuners disable variable systems such as VTC, VTEC, i-VTEC, VVT-i (and the -L variant) is simple. Tuning these systems to work with aftermarket parts is simply too big a job for not enough results. You may gain 5-10hp with a well tuned system, but the time and results for tuning a given setup on a variable system (which takes engineers, physicists and more than you want to know in time and money) is equal to years and millions of dollars.
Manufacturers do it because a) they have the resources, and b) they're tuning a setup for millions of engines. A tuner would have to tune for each individual setup. See my point?
As to which is better, well neither - they do completely different things completely differently.
i-VTEC is the most advanced VVT system on the market right now in a car under $50,000 - at that point, Porsche's Variocam and Variocam Plus and BMWs VANOS, Double-VANOS, and DME (Direct Motor Electronics) slap around the stuff we can afford.
They all feature infinitely and stepless variable valve timing, cam phasing, and ignition timing.
ItzGenX wrote:with the s14 personally i would put the motor that BELONGS in the chassis, meaning the S14 motor (doesnt cost too much extra). putting a motor that is older then the car usually makes me feel funny. that's just me though.
true, but consider extra $1000 getting S14 motor may upgrade your turbo
