What is the factory vtec engagement ? At 5k right?
Has anyone lowered theirs with V-AFC? Good Results?

 

This topic has been cover many many times before.. Try doing a search on it i gaureentee you that you'll find alot on this topic

 

I did a search on 'vafc' before I posted and didnt really find anything except someone saying that they did a 4600/4500 switchover

 

I spent a good amount of time looking this mod up Faz, and was going to get one, but in the end everything I found said it looked really cool, but that gains if any were minimal at best, maybe a couple of horses if that. Most could not tell of any gains and dynos didnt show naything. Also many had problems with check engine lights and other problems after changing the switch point. Talked it over with Jens at Park Ave, and he said the same thing. So in the end I passed on it.

 

Yeah, I think it's just cause it looks cool. I'm thinking of getting one, just cause of the coolness. But I would also like to gain some HP out of that $300 thing. Is it even a wise idea to lower the RPM of when VTEC kicks in?

 

When I got my VAFC, the Acura dealer told me VTEC engages at 5300 RPM, when tuning the VAFC, 5300 was confirmed. We lowered the VTEC engagement to 4400 RPM (you lose lots of gas BTW), and did end up gaining 6HP to the wheel.

 

ahhh, how much gas do you lose? What else can the V-AFC do?

 

faz, I have the V-AFC, I got it tuned on a dyno by a pro tuner with a lamda meter etc, and we only gained like 3hp and 2ft/lbs with it...we set VTEC engagement at 4800 RPM because that created the smoothest curves....almost 2 straight lines...
If you're going to get the supercharger, the V-AFC is useful, if not, don't bother, our fuel systems are running at 90% efficiency at a bare minimum...

 

Did lowering your VTEC engagement point cause the engine to "jerk" at that RPM instead of transitioning smoothly into the VTEC profile?

 

it does more than that like it tunes fuel and air mixtures

 

Tuning the VAFC made my power curve much smoother. If you can search on Dyno charts, I posted mine way back then. You could see like 147HP all the way up to like 5200 then bam, it jumped up to like 197HP. After tuning, the curve was more consistent and didn't get "turbo" effect anymore, and gained like 6HP to the wheel.

 

Hmmmm.....So far...it's just small gains...but making the curve more constant. The V-AFC would be more helpful on forced induction...correct? Either way, I'm getting one cause it has a cool blue face plate.. :p hehe

Hmm, daverman, have you ever heard about such a "jerk" before? Or are you just assuming that it might happen for lowering the VTEC profile?

 

I've come across many jerks before... oh, you're talking about VTEC.

If you recall, the VTEC switchover point was chosen at the RPM at which the power curves of both cam profiles meet. In other words, both low-RPM and high-RPM cam profiles should produce exactly the same power output at the switchover point. Otherwise, you'll feel either an sudden gain or loss of power when the profiles switch over, and hence: jerk.

 

oh..hahaha.....i see. It appeared no one has complained about it before..yet.