Vtec Actuation point


D'janiero

D'janiero

Active Member
Joined
Jul 17, 2007
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Hey peeps,

Whats your opinions on adjustting the vtec actuation point on the ek9's?

Ive looked on a few forums and spoke to a few tuners, and its 50/50. Some say leave it where it is, as honda put it there for a reason (optimum performace etc) while others say you can lower it, as long as you have supporting mods.

I've experienced vtec at a lower actuation point in my friends sir crx, and I was pretty impressed, out of all the vtecs I've been in so far. He only has simple mods - mani, zorst, cai and vafc. He moves the actuation point, lower down in the rev range for racing etc, and claims to feel a noticeable difference.

What do you guys think, leave it where honda left it, or bring it in lower in the rpm range?
 
D'janiero said:
Hey peeps,

Whats your opinions on adjustting the vtec actuation point on the ek9's?

Ive looked on a few forums and spoke to a few tuners, and its 50/50. Some say leave it where it is, as honda put it there for a reason (optimum performace etc) while others say you can lower it, as long as you have supporting mods.

I've experienced vtec at a lower actuation point in my friends sir crx, and I was pretty impressed, out of all the vtecs I've been in so far. He only has simple mods - mani, zorst, cai and vafc. He moves the actuation point, lower down in the rev range for racing etc, and claims to feel a noticeable difference.

What do you guys think, leave it where honda left it, or bring it in lower in the rpm range?
Click to expand...
50/50 is the only thing you can hear actually about vtec crossover :)
My opinion though this is an unecessary if not a risky mod :( Just to tell you something that I know. The EK9 makes about 125 bhp just before vtec is enabled at 6200 rpm, and within fractions of a second it makes 175 bhp at 6200 rpm, and the rest hp until 8000 rpm. The reason why Honda has put vtec there is because this is the point where vtec becomes most efficient. In case you place it for example at 7000 rpm you will feel a stronger kick but it will be too late. In case you drop it at 5000 rpm, you will feel a weaker kick but you get some extra power from the engine earlier. In case you drop it even more, there is no power to take advantage and most probably you are gonna damage your engine or it will wear out fast. Also, I'm not sure if you loose peak hp as well when you lower it but this is the impression I have.
And V-AFC is not a simple mod, its a piggyback device that controls some important engine parameters such as fuel, air, but basically is a crap and EK9 ECU gets messed up with this.
If you just need more power, start modifying your car with aftermarket parts, there is no reason really to alter vtec crossover. :nice:
 
Yeah, thought just as much:). Just after seeing how well the above combo worked on my friends rex, thought I'd see if would be a cool setup on the ek9.

Thanks for the info:nice:
 
My mate had A vtec controller on his EK4 civic and he had the vtec point at 4000rpm. when he put the car on the dyno it showed A noticeable dip in hp at this rpm which could be seen clearly on the print-out. They told him this was due to the vtec point been to low in the rev range something to do with compression I think?? Anyway he set the actuation point back to standard engage point and he got a much better hp result throughout the rev range and also there was hardly any dip in hp when vtec did engage. In the end he took the controller out and sold it. So from what I have seen I wouldnt change the actuation point. If engaging vtec at lower rpm's would produce higher hp then im sure honda would have set the actuation point lower dont ya think!:D
 
vtech6000 said:
My mate had A vtec controller on his EK4 civic and he had the vtec point at 4000rpm. when he put the car on the dyno it showed A noticeable dip in hp at this rpm which could be seen clearly on the print-out. They told him this was due to the vtec point been to low in the rev range something to do with compression I think?? Anyway he set the actuation point back to standard engage point and he got a much better hp result throughout the rev range and also there was hardly any dip in hp when vtec did engage. In the end he took the controller out and sold it. So from what I have seen I wouldnt change the actuation point. If engaging vtec at lower rpm's would produce higher hp then im sure honda would have set the actuation point lower dont ya think!:D
Click to expand...
See what I mean?? You are running high danger of causing engine malfuctions. But 4000 rpm?? That's insane!! I hope his engine runs ok now after the vtec restoration :nerv:
 
when you change vtec you have to change fuel and ignition accordingly, unelss you have the ability to change all 3 parameters together its pointless.
 
ManosEK9 said:
See what I mean?? You are running high danger of causing engine malfuctions. But 4000 rpm?? That's insane!! I hope his engine runs ok now after the vtec restoration :nerv:
Click to expand...

Im gonna see can i get a hold of his dyno sheet from when the vtec came in at 4000rpm and I will scan it and post it up so people can see the dip in hp it caused. Its shocking :shocked
 
Hi,

Wana check with everybody if i have a EK4, and if i installed a ek9 cams + ek pistons. Can i run with stock ek4 ecu with vafc? or i am better off running on my stock ek4 ecu? or better still save up n buy an emanage ultimate?

Anyone with experience?

Also can anyone tell me wat's the code for EK9 stock ecu (did a search but cant find any)

thnks in advance.
 
yeh, I agree that the original vtec point is best. It seems that the combination of the engine likes it there at 6k rpm. Better to just increase redline to 9k to get a bit more powerband. Dropping it to 5500rpm is better though, but only with correct tuning then you won't see much of a dip, power then builds up more earlier by the time you hit 6k. I've seen it on a dyno.
 
I agree with the points made in this thread about leaving the Vtec point where it is u should never put your vtec too low u will hurt your engine.. but I think I would make my Vtec kick in at about 5700-5900 rpm just like the itr. it would not affect the performance that much and u would get a better jump off the line in 1/4 mile races. especially if u r racing against another ctr with a stock vtec point:lol:
 
There is power to be had right before the changeover. To fix this, get the car on a dyno with an programable ecu (not vafc, something like hondata, crome, or other standalone) and do a run with just the primary cam by setting vtec at like 9000 rpm. Then do a run with the secondary cam by setting it at something like 2000 rpm. Look at the dyno sheets, find out where the powerband between the two is the same or near the same. It could be for example @ 5400 rpm. Set the vtec changeover at that point, and you have achieved a more progressive powerband and have actually gained more power in that small RPM window.
Might I add that VAFC does work fine in the right hands, its just not the best way to change the fuel map. It is just a piggyback device.
 
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