has anyone had any probelms with this? If you look on Apexi website in the questions and answers section, it says that the vafc wont work in 4 cyl accords because they use a different type of vtec and it makes the car hesitate at like 5000rpm. i called them and they did verify this. i also noticed there are a lot of 4 cyl accord with the vafc. does anyone have a problem with thiers because im planning on getting one.

one more thing, what is stock vtec engagement on 94 accord ex

 

No problem at all. In fact, there's a number of people in this forum that have one.

 

I have a 96 Accord 4cyl and it works fine, however, Apexi is right cause if you set the vtec x-over to about 5k or so, the car just takes forever (hesitates) to get to the x-over. I have mine set lower then 5 but I forgot what I have it at right now. On top of that I have an automatic. I think w/ the auto you will have this problem just set the x-over lower. The 5speeds don't have a problem at all I believe. I know that the car is getting enough fuel too cause my air/fuel gauge shows that the car dumps really rich when gettin closer to the x-over. So fuel is not a problem. I think it is just the tranny.... I can tell you that I ran my car at the track w/ the setup: V-AFC, AEM CAI, DC Headers, Greddy Exhaust, Magnacore Wires, Denso Plugs, Full Body Kit, full interior, (remember Auto Four Door EX) and I got a 16.5. I ran a 17 flat all stock. Just my experence.

Hey what's sup DunReit. I talked w/ you for a lil at the BBQ down in Reston, but I forgot to ask you what your settings were. But then again u have summmmm ummm HaHa LoL Gas.

 

it worked for me when i had mine before it got jacket, it worked fine

i miss having my cut-over at 3500 ='(

 

What is jacket?

**Edit** nevermind, I think you meant jacked. Duh to me.


[Modified by Big James, 8:58 AM 5/20/2002]

 

yeah jacked

 

After i hooked mine up it would bog at 4k.. felt real shitty.. after lowering x over to 3600 it ran fine..

96sohc 5 speed


[Modified by unltdacc12, 4:45 PM 5/20/2002]

 

Yeah, if you have it set at 4K, then when VTEC engages, the power jumps significantly (17whp for me). At 3500 the transition into VTEC is much smoother...

 

yes, the point of setting the crossover to the point where the hi and low cams are making the same power, sudden jolts and increases are not good for the driveline

 

why vtec crossover point set so low? just curious how that helps?

 

please read my above post:

its not just this but its all about arrea under the curve and the lo cam wont make any more power than the hi cam will at this point....speed is area under the curve......

 

It works fine in my 6th gen coupe.

What some people don't realize is that on the 6th gen I4s, VTEC is variable. It can kick in as early as 2300rpm, or as late as 4000rpm. That is why, on the VAFC, the lowest VTEC can kick in is 3100 rpm. On 6th gen, this actually causes a LOSS of power. I have the VAFC hooked up but I didn't connect the VTEC control, I left that to the stock ECU.

 

Hi. Umm, you have a SOHC so where do you get "hi and lo cam" from? The SOHC VTEC Accords vary timing by the valve opening/closing. There are low and high speed engine operation that dictate different VTEC profile, but just a single cam.

Or were you referring to the DOHC VTEC engines?

 

me 2, sniff

 

Just dont connect the VTec controller part. Many 6th gen f23a4 lost power due to VAFC because during the cam switchover there was a power dip and then surge.

this is an untuned VAFC on a F23A 4 banger coupe:


while this is a tuned one:


both are from LDYKLLAs dyno runs.
Make sure you get the thing dyno tested and tuned. They really dont add much HP unless you have forced induction and are experiencing fuel starvation. having a low Vtec engagement point seems fun, but it punches in harder because your car is actually bogging more at the start and then kicking harder at the crossover point. Not best for performance

 

SOHC VTEC enguages a high performance cam on the intake side to increase air and fuel flow into the combustion chamber. So there are infact different cam lobes but not different cam shafts. Misa aka SOHCArchangel was refering to the cam lobes

 

Hey. Ok, thanks for clearing that up. I forgot that some people shorten to say "cam" when they mean "cam profile". Later.

 

im not sure you read the whole thread, those who had it set at 3500 or around that have NO surge in power because the changeover is perfectly seamless, and again i steress the point of correctly tuning the crossover is to the point where both cams are making the same power

 

The 3500rpm threshold has been dyno-proven on two separate occasions on my car, at least once on Misa's, and I'm sure on other people's as well.

 

yes, and but then again this just all goes to show that.....

OBD-II CARS ARE USELESS PAPERWEIGHTS!!!!!!

 

I'm not sure what cars you two have, but I was there when LDYKLLA dyno tuned his VAFC. If you look at the second dyno plot, the red plot is the untuned (all settings at 0), while the blue is the A/F tuned (with a wideband O2 sensor).

You can see that in the red plot, when the VTEC x-over was set to like 3700 there is a huge dip. Even with the tuned plot, where the VTEC x-over was set to the lowest possible on the VAFC which is 3100rpm, there is still a dip. You can tune the x-over so they are smooth, but that would mean killing the power either by leaning or richening the fuel on the hi-cam profile so that it doesn't give you as much power when it switches. This is not what you'd probably want. What the surge is indicating is at that VTEC x-over pt, the hi-cam makes more power than the low cam, and VTEC x-over can be "further" lowered... however, this isn't possible on the VAFC. This is how it is couple of the 6th gens that I've seen with VAFC. It might be different with early gens.

Here is my dyno tune of the VAFC. You can see that on my 6th gen, VTEC kicks in around 2300, where the small dip is. Note that I tuned the A/F to a perfect 13.5 ratio all across the whole RPM band.

 

So Shaggs2Dope, what are your best settings after being dynoed and everything. Where is your vtec x-over and fuel settings set at? So you made a total about 144 horses to the wheel? That is pretty good since your car is rated at 150 fly wheel.

 

Time to find a scanner ASAP...

 

GODDAMNED CANADIENS!!!!!

but the above rise is sharper than your dyno plot




john, scan your dyno plots please

we have 5th gens thank you very much

which means our 145 whp translates to about 182 crank hp

 

The dyno charts are actually in my car, but I don't have a scanner at home, nor a functional one here at work.