ok....i know that people always say that vtec causes a dip in mpower.....most of them have DOHC....now....since i have a SOHC.....the only vtec i have utilizes the intake...meaning more air comes in....and of course fuel maps are changed....now....if i activate earlyier say 4500taht will give me more air coming in....until i hit my redline...7200.....but since my turbo is smaller (tdo4) if i set the vtec higher say 6000...i can get that extra boost....when my turbo is running out??? anyone? kinda complicated .....TIA :

 

I read it 3 times.... and I still don't get it??

 

Hmm.......try explaining that a little more clearly.

 

whats "V-TEC?"

 

Variable Valve Timing and Lift Electronic Control

they get VTEC out of that phrase

 

ok one more time..

in the SOHC vtec motor, vtec kicks in at 5500 rpm from factory....which utilizes the intake valves..

if i adjust my VTEC so that it kicks in at 4500 rpm...the turbo is fully spooled by then..then i have the motor in VTEC all the way to my 7200 redline...... or i can

adjust my VTEC to 6000 rpm......so that the turbo is fully spooled for about 3000 rpm....and since my turbo is small and has littlee top eend...i can have my vtec give me that extra top end boost.....

i dont know which one to choose...any ideas???

do u get it? lol

 

I think what he meant was that since his SOHC utilizes only the intake valve side, if he sets the x-over point higher with his turbo setup...will it introduce more "air" into his engine once his small turbo runs out of steam up top. Get it?

Basically, once his turbo peaks at higher rpms...can he set his x-over point a little higher to add more airflow to get more gains up top?

Personally, I think the turbo you're talking about is plenty enough for the 1.6L SOHC. How much boost were you planning on running? If it's a low boost application, then there's no need to change x-over points...that turbo should pull all the way to redline. But if you're planning on going over 15-18psi, you might want to check into a bigger turbo...and a highly reinforced block. Good luck either way.

 

there u go.exactly what i mean...
im planning on boosting 8 psi daily....and like 11 at the track......

 

Set it low. That way you have that power throughout the powerband. If you set it too high, you are wasting precious time that you could be using it. If you set it too low, the VTEC and turbo will conflict, and you will bog out. The TD04 kicks in and fully spools before 3000rpm right? If so, then a 4500rpm VTEC activation point should be perfect.

 

so 4500 would be an ideal cross over point...now when a "certified profesional" tunes my VAFC and the vtec point is at 4500...the ecu is still on a non-vtec fuel map right? so what happends when the vtec fuel map is activated...? when they tune my vafc will they compensate for that????

 

the vafc can tune that

 

cool...thanx...

 

ya your wrong...vtec in a sohc comes on at 4800rpms. 5500 is the vtec switch in most of the b-series.

liam

 

in reality it kicks in at 5600 rpm......but 5500 same thing....dont know what motor ur talking about...

 

Maybe for the Z6, but the Y8 comes on at about 5600rpm indicated. As for where to set the VTEC X-over, I personally use 5000 rpm for VTEC. Set it too low and you WILL feel a loss in power, I know I did. 5K seems to fit just fine

 

ditto... never felt it kick in... so i guess my GSR doesn't have it..

we should call it "placebo" instead of "vtec"... ahhhhh the illusion of power..

 

ya your wrong...vtec in a sohc comes on at 4800rpms. 5500 is the vtec switch in most of the b-series.

liam

I have a D16Y8 with an AEM CAI. Ever since the CAI has been on the car I clearly hear an increase in sound right at 5500rpms. VTEC on my D16Y8 is 5500rpms.


[Modified by 97CivicFerio, 7:49 PM 1/2/2002]

 

Instead of guessing where the X-over should be set, why not have the "certified professional" set it based on the dyno results? Thats really the only way to get optimal results from moving the engagement point.