V-TEC

N/A build discussion
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By suspendedHatch
- Sun Jul 01, 2007 2:24 am #12779 Adjusting the VTEC (or VTEC-E for that matter) crossover point using the stock cam and cam gear results in only one thing: a loss in power.

VTEC-E is a completely different system than VTEC and you will not want to use a VTEC ECU on a VTEC-E motor.

VTEC-E runs on 8 valves until about 2500 RPM and then it switches to 16 valves. This results in better low end power than on your standard 16 valve motor.

VTEC motors run all 16 valves all the time. They have the low cam lobes optimized for low end power. This would normally result in a huge power drop off in the mid-high (4500+) RPM. This is the point at which VTEC activates and the valves switch over to a higher lobe with different timing and duration optimized for top end power. Essentially VTEC is like having two intake cams in one (and two exhaust cams on DOHC VTEC motors). A low end cam and a high end cam.

At low RPMs you want a small air passage so that the air flows quickly. At high RPMs you want a large air passage to allow a higher volume of air and you can rely on the motor to pull in air at a good speed.

Referring to VTEC "popping" or even caring about the VTEC sound over the actual power output is rice, pure and simple.
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By chnzgoofball
- Sun Jul 01, 2007 4:05 am #12780 great write up!!! :thumb:
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By ChicagoMike
- Sun Jul 01, 2007 1:16 pm #12787
suspendedHatch wrote:Adjusting the VTEC (or VTEC-E for that matter) crossover point using the stock cam and cam gear results in only one thing: a loss in power.


I completely disagree. And here's an example why.......

A kid brings in his 2000 civic si and wants his Hondata s100 installed. No problem, we put him on the dyno. Mess around with his fuel charts for a lil while and manage to grab him 6hp to the wheels. Thats not terrible for not doing any other mods. Then we're like f*ck it, lets bump his VTEC x-over to 6000rpm.................Bam......and extra 3hp popped up, and he didnt loose anything down low in the RPM's. We pushed it a lil further, 6200 RPM x-over......bam........another 1hp.

Thats a total of 4hp just by messing with when VTEC hits. 10hp gain on the day just by installing the s100.

And yes, on stock cam and cam gear.
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By teal_dx
- Mon Jul 02, 2007 3:35 am #12845 so you raised the vtec crossover, along with adjusting the fuel curve. thats cool, and some fine tuning :thumb:

But I see the ricers on H-T all the time asking about using a manual vtec switch to make it engage at 4000ish rpm. That is what not to do. Maybe there's some kind of cam out there that could benefit from a lower vtec engagement, but if you've got a stock or motor with just basic bolt ons, don't lower your crossover to make your engine "pop into vtec sooner" or "stay in vtec longer"
And manual vtec switches are a bad idea as well. Just buy the right ECU :thumb:
That has nothing to do with the original post, just had to rant a little :)
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By suspendedHatch
- Mon Jul 02, 2007 6:32 pm #12881 I get my information from Scott Fox (I don't expect anyone to know him, but I would hate to say "my friend sez...". He's a factory trained AEM tuner, and he commonly tunes MOTEC, FAST, HALTEC and whatever other crap people bring in. He tells me that changing the VTEC crossover point from stock w/out changing the cam or cam timing only results in a loss of power. I believe him over anything I read on the internet.

I think you may have introduced some error into the equation when you altered fuel/ignition settings. I also don't have any respect for Hondata. In any case, I could be wrong. But I wont be changing my VTEC crossover point unless my car is on the dyno.
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Re: V-TEC

By -EJ1- COUPE
- Mon Jul 02, 2007 8:11 pm #12897
AddictiveAllMotor wrote:
hatchiespank wrote:i have a d15z1. i was wondering on how i can make my v-tec pop harder for more power. i am just now sure on how i can do this. can any one help?


I'm not trying to be an ass, but, If you want a good VTEC crossover....get a B series.


dont listen to him get an H series :lol:
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Re: V-TEC

By Hereg6
- Mon Jul 02, 2007 8:24 pm #12901
hatchiespank wrote:i have a d15z1. i was wondering on how i can make my v-tec pop harder for more power. i am just now sure on how i can do this. can any one help?


Why don't you just get a cam
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Re: V-TEC

By dogfight
- Tue Jul 24, 2007 5:51 pm #16737
Hereg6 wrote:
hatchiespank wrote:i have a d15z1. i was wondering on how i can make my v-tec pop harder for more power. i am just now sure on how i can do this. can any one help?


Why don't you just get a cam


:thumb:

By JDM michael
- Fri Aug 17, 2007 12:42 pm #20206 great lil write up there,


ITS VTEC NOT V-TEC :x
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By bietelboer
- Sat Aug 25, 2007 4:29 pm #21107
teal_dx wrote:yup, thats the main reason they sound meaner when they crosss over.

SOHC you gotta listen for it.


B-series are loud indeed but, have you ever listend to d15 with a vtec head? man thats awesome! no b-series can beat that 8)
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Re: V-TEC

By weaponr82
- Fri Aug 31, 2007 7:09 pm #21833
H22+LSD-EJ2 wrote:
AddictiveAllMotor wrote:
hatchiespank wrote:i have a d15z1. i was wondering on how i can make my v-tec pop harder for more power. i am just now sure on how i can do this. can any one help?


I'm not trying to be an ass, but, If you want a good VTEC crossover....get a B series.


dont listen to him get an H series :lol:


Sweeeet. :thumb: I got 197 to the wheels on my H by screwing with the fuel and vtec. Basic crome chip and tune with a totally stock engine. Oh and whoever said the b16 has loud crossover has never heard a fully trumpeting H. I took a kid for a ride the other night and he never wanted to get back in the car! I looked at his face when it kicked in and just laughed at him...maybe its because im crazy that he didnt wanna get back in?
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By weaponr82
- Fri Aug 31, 2007 7:19 pm #21836 Hey wait is 197 for an H good? I just saw people on HT talking all sorts of crap about hp numbers....oh wait its HT, my bad. Everyone there has stuff better and faster than you. Sorry Im spaming. Long day

Re: v-tec pop

By jer
- Sat Sep 08, 2007 1:03 am #22667
hatchiespank wrote:so your saying that the popingof the v-tec isn't that loud on a sohc? so what if i get a p28? could i do it that way? one more thing. wht do you think about APC parts?

Theres a reason why APC went bankrupt..enough said. If you REALLY want a loud crossover, SOHC or DOHC upgrade to a more aggressive cam. Ive found from driving si's, SIR's and gsr's that the B series definitely have a louder crossover especially with a short ram on there.
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By suspendedHatch
- Wed Nov 07, 2007 5:14 pm #28865 The D15Z1 doesn't have any aftermarket cams available. Any modification to the VX throws the ECU way off and the car will buck madly. Even just I/H/E. So you will have to do something for engine management first.

The reason for this is because Honda tuned the ECU to run the VX lean at the bleeding edge. A few 10ths of a point leaner and the fuel doesn't ignite. When I experienced this (caused by a small vacuum leak) it felt as though I was stomping and dropping the clutch repeatedly. But when I gave it heavy throttle it ran okay.

Best solution with a VX is either to swap motor/tranny/ECU, or get a standalone.

I'm replacing my VX engine with an OBD2 JDM D15B. This motor has both VTEC-E and VTEC. I'm running it with an AEM EMS. This way I'm staying true to the VX VTEC-E, retaining the 45+mpg, and getting ~130hp too.
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