The D17 VTEC controversy (solved).
02-25-2005
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The D17 VTEC controversy (solved).
For a long time there has been a debate on this over the D17A2 VTEC.
Some people say it is a regular VTEC that engages at 4500RPM
And there are others that say it is a VTEC-E that kicks at 2500-3000RPM
Well I did a lot of research and tore apart my engine to prove my point (and to do some other things that I will post in the DIY section)
This is it this is the FINAL ANSWER
We have VTEC-E that kicks at 2500
I use to think that are VTEC kicked at 4500 until I read up on it. I went to Honda and copied all the cam profiles and tore apart my engine to come up with this answer.
Here is a link to my old post on VTEC all Photos are there. Look at page 3 for the smoking gun.
Here is a link to honda that says d17's have VTEC-E http://www.hondanews.com/CatID2015?m...asc&archives=t
http://www.7thgencivic.com/forums/sh...1&page=1&pp=15
http://www.7thgencivic.com/forums/sh...1&page=3&pp=15
Some people say it is a regular VTEC that engages at 4500RPM
And there are others that say it is a VTEC-E that kicks at 2500-3000RPM
Well I did a lot of research and tore apart my engine to prove my point (and to do some other things that I will post in the DIY section)
This is it this is the FINAL ANSWER
We have VTEC-E that kicks at 2500
I use to think that are VTEC kicked at 4500 until I read up on it. I went to Honda and copied all the cam profiles and tore apart my engine to come up with this answer.
Here is a link to my old post on VTEC all Photos are there. Look at page 3 for the smoking gun.
Here is a link to honda that says d17's have VTEC-E http://www.hondanews.com/CatID2015?m...asc&archives=t
http://www.7thgencivic.com/forums/sh...1&page=1&pp=15
http://www.7thgencivic.com/forums/sh...1&page=3&pp=15
Last edited by caorndorff; 04-21-2005 at 03:03 AM.
02-25-2005
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Wow.. thats alot of work to prove a point, good job. I always thought my car surged with a tiny amount of power at around 2800 rpms, perhaps this is my VTEC kicking in. I can hear my engine make a different sound also when this happens.
02-25-2005
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Rep Power: 787 I knew ex had vtec-e already it says right on the honda site when I priced my 02 civic.
Now this is getting crazy. Vtec still kicks in at WOT right? Just at lower rpms?
Now this is getting crazy. Vtec still kicks in at WOT right? Just at lower rpms?
02-25-2005
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Rep Power: 0 VTEC hits about 2500-2800 full throttle. Or about 3000 if it is half throttle. It has to hit at least at three; otherwise you will suffocate the motor (because only one valve is open).
02-25-2005
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well ... that's what -I've- been saying since the beginning ...K20a3 vtec is the same as our vtec ... the only difference is that we have only one cam. vtec engages at 2200 rpm under hard throttle, up to 3000 under light throttle. same as the k20a3 ... http://www.hondata.com/techk20general.html
if you check out their vtec cam, it looks very similar to our vtec cam
02-25-2005
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Originally Posted by aznboysrfr
well ... that's what -I've- been saying since the beginning ...K20a3 vtec is the same as our vtec ... the only difference is that we have only one cam. vtec engages at 2200 rpm under hard throttle, up to 3000 under light throttle. same as the k20a3 ... http://www.hondata.com/techk20general.html
if you check out their vtec cam, it looks very similar to our vtec cam
That is an excellent picture. Our rocker arms are situated the same. The rocker on the left simply cracks open to prevent fuel puddling behind the valve.
02-25-2005
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Rep Power: 787 If I set the vtec engagement point to 2800rpms with a vafc, will it still only engage at wot and when the engine is warm, oil pressure high enough, etc? So it's safe to do?
02-25-2005
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Originally Posted by gearbox
If I set the vtec engagement point to 2800rpms with a vafc, will it still only engage at wot and when the engine is warm, oil pressure high enough, etc? So it's safe to do?
02-25-2005
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Originally Posted by 4drcivic2k1
Suffocate the motor?
http://www.leecao.com/honda/vtec/sohcvtece.html
02-25-2005
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Originally Posted by caorndorff
As long as you have proper fuel tuned in, you will be fine.
Yup it's been tuned on a dyno, just wanna make sure setting to a certain point won't hurt. You know I tried to set the vtec point hi one time like 4500k rpms and the car wasn't feeling so good between 3-4k rpms. Maybe that's what you mean by suffocating.
02-25-2005
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Rep Power: 787 I set my vtec to 2800 rpms and if I'm acelerating slowly from a stop to around 3200rpms, I feel a power increase as soon as the vtec light turns on at 2800rpms. It's like pressing the gas more even tho I'm not. But it is noticable to me.
02-25-2005
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Originally Posted by caorndorff
Honda is so tricky with there stock ECU tuning that because of tuning alone that is why the Integra GSR makes all its power at high rpm’s, why did they do that you may ask. Because too many consumers complained about torque steer at low rpms for the first year of its production.
BTW, our EX's do not get the gas mileage of HX and DX models solely because of our ECU tune
Besides, there's a few points you really can't explain.
Ok... so if you say we have VTEC-E that engages at 2500 RPM... What causes the change in sound at around 4900 RPM indicated?
-We do not have secondaries in our intake manifolds (correct me if I'm wrong there, I'm assuming we don't)
-We do not have two VTEC solenoids for both a 2500 RPM profile change AND a 4900 RPM profile change
-Nothing else in our engines, besides a profile change, can cause the sound change. There is little or no power difference because there is not supposed to be. VTEC activation was never meant to kick you back in your seat; it was designed to be a smooth transition, as it is in our cars and all other grocery getter Hondas.
WHY is this such a mystery?
We've known what our camshafts look like for a while.. a few people on this forum actually tore into the engine and put in regrinds before they put on wHaCk bling-bling body kits and chromed wheels
Anyhow, you can see from the camshaft: one intake valve is open all the time, the other is slightly opened to avoid charge puddling... When VTEC activates, the second intake valve opens to the height of the first intake valve until the pin is released and VTEC is "deactivated".
Where did you find this 2500 RPM number?
02-25-2005
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Originally Posted by caorndorff
VTEC hits about 2500-2800 full throttle. Or about 3000 if it is half throttle. It has to hit at least at three; otherwise you will suffocate the motor (because only one valve is open).
02-26-2005
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Rep Power: 787 I don't believe the set rpm either. It also depends on how far you press the gas. I've seen it engage anywhere from 2200rpm to 3000rpm. It varies with throttle, although it's only supposed to engage when the gas is floored. I'm confused.
02-26-2005
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Rep Power: 0 I just got a v-afcII for my 01 civic ex does anyone know why my check engine keeps coming on and why the engine bogs at 4000 RPM its killin me I get get it right help me out
02-27-2005
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Originally Posted by psychotic_z
Sorry bro... for a statement like this and a few others from your other "SOHC VTEC Explained" thread, I don't buy it...
BTW, our EX's do not get the gas mileage of HX and DX models solely because of our ECU tune
Besides, there's a few points you really can't explain.
Ok... so if you say we have VTEC-E that engages at 2500 RPM... What causes the change in sound at around 4900 RPM indicated?
-We do not have secondaries in our intake manifolds (correct me if I'm wrong there, I'm assuming we don't)
-We do not have two VTEC solenoids for both a 2500 RPM profile change AND a 4900 RPM profile change
-Nothing else in our engines, besides a profile change, can cause the sound change. There is little or no power difference because there is not supposed to be. VTEC activation was never meant to kick you back in your seat; it was designed to be a smooth transition, as it is in our cars and all other grocery getter Hondas.
WHY is this such a mystery?
We've known what our camshafts look like for a while.. a few people on this forum actually tore into the engine and put in regrinds before they put on wHaCk bling-bling body kits and chromed wheels
Anyhow, you can see from the camshaft: one intake valve is open all the time, the other is slightly opened to avoid charge puddling... When VTEC activates, the second intake valve opens to the height of the first intake valve until the pin is released and VTEC is "deactivated".
Where did you find this 2500 RPM number?
BTW, our EX's do not get the gas mileage of HX and DX models solely because of our ECU tune
Besides, there's a few points you really can't explain.
Ok... so if you say we have VTEC-E that engages at 2500 RPM... What causes the change in sound at around 4900 RPM indicated?
-We do not have secondaries in our intake manifolds (correct me if I'm wrong there, I'm assuming we don't)
-We do not have two VTEC solenoids for both a 2500 RPM profile change AND a 4900 RPM profile change
-Nothing else in our engines, besides a profile change, can cause the sound change. There is little or no power difference because there is not supposed to be. VTEC activation was never meant to kick you back in your seat; it was designed to be a smooth transition, as it is in our cars and all other grocery getter Hondas.
WHY is this such a mystery?
We've known what our camshafts look like for a while.. a few people on this forum actually tore into the engine and put in regrinds before they put on wHaCk bling-bling body kits and chromed wheels
Anyhow, you can see from the camshaft: one intake valve is open all the time, the other is slightly opened to avoid charge puddling... When VTEC activates, the second intake valve opens to the height of the first intake valve until the pin is released and VTEC is "deactivated".
Where did you find this 2500 RPM number?
03-02-2005
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Rep Power: 244 So if VTec engages at 2500ish rpm then my VTec is always engaged except in 1st from a stop. At each shift my rpms are around 3K so therefore VTec never disengages? I must be missing something...
03-02-2005
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Originally Posted by bobsagator
So if VTec engages at 2500ish rpm then my VTec is always engaged except in 1st from a stop. At each shift my rpms are around 3K so therefore VTec never disengages? I must be missing something...
Where VTEC engages on these motors is generally worthless to even try to change, because it does very little in terms of power gains.
03-02-2005
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Rep Power: 787 I'm tried changing it a few times, and the car always feels like something is wrong. I say just let it do what it's supposed to.
03-02-2005
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Originally Posted by 4drcivic2k1
A lot of people are missing something, so don't feel bad.
Where VTEC engages on these motors is generally worthless to even try to change, because it does very little in terms of power gains.
Where VTEC engages on these motors is generally worthless to even try to change, because it does very little in terms of power gains.
bobsagator... Yeah, don't feel bad - there's a crap load of technical misinformation all over this forum that people spread daily. The VTEC engagement isn't at 2500 RPM, either.
In general, take what you read here with a grain of salt.
