My B20 setup,

84.5mm JE piston (Combustion Tested all 4 cylinders 380 psi)
1mm oversize valves (Ferrea)
Combustion chamber bored to 84mm
Skunk2 stage 2 camshaft
Skunk2 Mainfold bored to 74mm to match with 74mm TB
RDX 410cc injectors
Manley Rods 89mm stroke
Tri-Y Header straight thru to 2.5"
Hondata ECU S300
MSD ignition System (External Coil)
Fuel Reg (3.5 bar) and 255 fuel pump
6" to 3" Blitz open pod filter

I have tuned my car 2 times on dyno and twice having the same problem.Before Vtec the torque is 23kg/m but when vtec opens at 5700 the torque drops to 22kg/m and down to 20kg at 8500.

This is not normal as all cars i have tune will have a increase in torque at least 1- 1.5kg/m torque then it will drop at high end.

Currently, i only managed to tune 230hp on crank.But when you try the car the vtec area sucks and very lag.

I have tried different cam timings on the dyno but all did not work.My cam timing was dial in at Exhaust advance 3.5 and intake advance 1.I even tried to retard intake and still the same.

On tuning part i have increase ignition timing up to 44 degrees at 7500 to 8500.Surprisingly, there was no knock but power does not increase and the weird thing is 410cc injectors not enough for my car, duty cycle was at 93%.

Can someone give a advice on this why on the vtec zone power drops?
I have really ran out of ideas, everything on the car is normal and drives very good on the low end till 5000rpm, in fact very torquey.

 

I have used those cams in more than one setup and they ALWAYS loved timing at intake +2, exhaust -1. There is also usually a dip in transiton ay vtec because of the big difference between the non vtec and vtec lobes for these cams. You just need to tune the transition properly to eliminate the dip. Also 44* timing is toooo much if you ask me, especially AFTER your MBT (mean best torque), which I guarantee is before 7500rpm. If power does not increase after added timing, then take it away until it just starts to lose power and then add .5* at that point. Hope this helps.

 

tuner cams like overlap.. lots of it. Start @ +2/3 on intake and -2/-3 on exhaust.

 

my old s2s2 liked +2intake -2/-1exhaust on 3 different motors.

 

im at +3 and 0 on my tuner 2 im thinking of changing to +2 -1 to see what it does

 

I have tried all cam settings but still the same.
Could it be due too combustion chamber is too big and can't make power on vtec?

All my AFRs are in the 13 to 12.

I have another car which having same cams but with 86mm piston CR13:3 with obx ITB.combustion chamber 84mm cam settings exh +3 int +2
the car made 260 with almost 27kg/m torque.

Could it be my car is running 74mm and not enough on the intake for the vtec ??

 

Maybe some different on my cams, I attached the specs of this cams.

Lift @ 0" lash : 0.485(12.3mm)
Intake 37 BTDC
49 ABDC

Lift @ 0" lash:0.466(11.8mm)
Exhaust 61 BBDC
21 ATDC

For the intake is set at 95 and exhaust is 110.

In fact the cam settings came up to int +2 and exh +3.5.

Can anyone advise more, I really thinking is due to Without ITB and chamber is too big.

Would be advisable to bolt on a stock b16 head with these cams and try?

 

All cam settings will NOT net the same power! That is IMPOSSIBLE! Are you actually using a dyno or just changing them and driving the car to see which one "feels" different? There is also a big difference between 13-12 afr's, as I try to flatten my afr on 13.2 from about 3500rpm to redline. I also had a head with 84mm chambers when using these cams, and that didn't affect my performance one bit. Don't bother with the degree spec for these cams as they are relatively small and should not cause any damage unless you get wild on cam setting. Degreed specs are just a starting point for when you get to the dyno and start playing to see where the motor "really" likes it.

 

where do you live?

 

Hi,

I did all degree settings on the dyno, but all these settings have a drop in torque when vtec opens.

From 3K rpm my torque is 23.3 kg/m until vtec no increase in torque and drops to 21 kg with 240 hp.

Does a faulty distributor cause this problem?I have no check light on my ECU.

 

Try moving your Vtec engagement point up to 6000 and see if it has any effect on that dip.

 

if doing the dyno pull, its pretty easy. move vtec ultra low; do a pull. move vtec ultra high;do a pull. overlay the graphs and see what RPM you come up with for best VTEC engagement.

There will be some harmonic changes at engagement, but this should get you pretty close.

Matt

 

My calculations from your lobe centres says that you have advanced (good for low end power) your cam.by 7degrees, maybe thats why you have nothing in the upper range.