VTEC engage, b4 stock or after???

[Streetwise Performance]

VTEC engages at about 4500 rpm on b16a motors, don't know for other motors.

Some tuners prefer to get Vtec sooner, while others choose to delay Vtec until higher rpms. However, neither choice has any effect on HP.

I did get some info that mentioned Vtec engagement at a higher point like 5000 rpm gives a better driving experience because the engine is revving faster and when bigger cams kick in, the driver truly feels the torque shift as opposed to a smooth transition at stock 4500.
I personally like this idea because all the drivers said that the cars were more fun to drive. However, I'm willing to learn some more about this issue.

What do other TTuners have to say???

[cdx2k1]

I'm a Honda noob so don't bash me Honda boys...don't the K series engage @ around 5,000?Atleast that what I read somwhere and I think that's what you're talking about...maybe it's reference to the K series in general being a...

better driving experience because the engine is revving faster and when bigger cams kick in, the driver truly feels the torque shift as opposed to a smooth transition at stock 4500.

Or maybe the drivers like the more aggressive shift @ higher RPM over the smoother one @ 4,500 which could make it more fun to drive..I'm just guessing here..

[flatline]

^or maybe he's referring to changing the engagement point with a vafc/ hondata/ e-manage or some other EMS system, thus altering the stock torque curve, in an attempt to increase torque numbers

[cdx2k1]

I know the K's with i-Vtec can do that but I don't think that B's can

[crazybalhead]

B16's engage around 5200-5500, not 4500 (unless is an automatic which I don't know much about)

But the only reason to change the VTEC point is if you make significant changes, AND you have a dyno to see where the HP and Torque curves need some smoothening out to produce overall better performance.

Other than that, leave it alone.

[Big Z]

It would be a bit foolish to alter your VTEC point such that torque is lost.
The VTEC point was set so as to obtain the most toque as possible.
And what Crazy said.

[pete]

I think it's more 5800 rpm VTEC comes in.

[civcdrvrinwrx]

i believe vtec engagement is 5200-5400 depending on the oil pressure and which b16a u have.

but i disagree that vtec engagement being shifted cant improve horsepower. It depends on where your torque and hp curves cross. this will only vary depending on the mods done to intake and exhaust. I have proven that shifting vtec engagement earlier to where i had the most torque did increase hp noticeably. but most importantly u need to accomodate this earlier enagement with fuel. Hence a standad vtec controller may not help hp if u cant increase fuel at that point. vafc or hondata units do have a vtec unmatch where u can accomodate the change in vtec.

[kes_vtec]

^^ on point.... on a stock motor with a few bolt-on, moving ur vect point if can't control the fuel or timing will not help.
most ppl like to move the vtec point up in the rpm so they can "feel" vtec come in...
what does this mean...
say ur vtec point is 5400 and the dyno shows Tq is 100 and and HP is 140
and at 5800 tq is 110 and hp is 149
if you move ur vtec point to 5800
u will get a "harder pull feel" than at 5400, but from 5400 to 5800 you will not feel the tq with was there before as the will show some thing like 130, so u still feel that small pull but not like you will at 5800...
NOW
if u have EMS and a dyno, what i can do is try to bring ur vtec poin as low as you can
how say at 5200 after playin with timing and fuel u got 112tq that will be alot better..

[Val]

if you change ur cams, to higher performance cams, should you then change your Vtec point?

[flatline]

u'd have a different torque and HP curve with changing cams. Plus remember they have different grinds of cams. Hopefully with a change like that, u'd already be tuning them one time on the dyno with EMS and cam gears, because you'd be needing more fuel, so it makes sense to see how different VTEC engagement points affect your output

[DrunkenMaster16]

I think it's more 5800 rpm VTEC comes in.

5500 - 5200 normal for manual B16's

had my sir tuned to 5200 - 8400, starting to miss my dual cam

never got the actual dyno figures from the previous owner but what was done before made alot of power, and with minor upgrades to that I was feeling 3 - 8 more hp and a touch more tq

B16a2 manual cams, stock block, stock B16a internals, Y21 tranny, ACT stage 2 clutch and lighten'd flywheel, 2.5" free flow to a DC5R ehaust.. thats about all the mods done over time.

I believe hondata, but couldn't find any mods to the ecu and the previous owner/ tuner was allready in canada.

[Val]

feeling 3 - 8 more hp

how you felt that?

[X2]

stock cams and stock head/intake manifold.... shifting vtec engagement point is useless.


Honda engineers are not idiots...they put the stock engagement point there for a reason... the reason is that the Vtec cam duration and lobe seperation is DESIGNED to work with the stock engine geometry. Changing the engagement point will lose you power, but you will FEEL the engagement more since there will be a larger jump in power when you switch to vtec later in the band. In either case, vtec is designed to provide a smooth transition. The only reason they changed it with the K series was to get people to stand up and notice. Observe that they had to make accomodations for this higher rpm engagement by incorporating a dual stage intake manifold, which you will notice, is lacking on the B16.

Dropping the engagement point on a stock setup will just about never yield power.

[DrunkenMaster16]

feeling 3 - 8 more hp

how you felt that?

lets say an educated, under-exagerated guess

[X2]

^^ Yeah.... I can vouch... my butt dyno is FINELY tuned.

That SiR was making at least 10hp over a stocker.... everywhere... it was quick... damn shame she's gone...

[Val]

exactly how does approx 10 hp feel?

I'm trying to gauge how much of a difference the lightened crank pulley gave me

it feels like when I take off the A/C

[DrunkenMaster16]

3 - 7 hp then is a good range, maybe more... I know a guy who just changed his... claims 8 or so right thru his power band and afew tq.. 2 - 4?

minor mods can make little differences that count when done right and work well together.

Note nothing is sure unless its dyno proven.

[X2]

Val... trying to guess what 10hp feels like on the butt dyno is heavily dependant on the weight of the car and secondly on displacement and/or stroke...Even then, it's guesstimation at best....but an educated guess can be right on the money despite what many say....

Note nothing is sure unless its dyno proven.

Hell...u seen me make dyno predicitions !... how accurate have I been in the past ?

Just keep in mind that HP is a derivative of torque... so you actually need to guess how much torque is really being gained, then figure a HP estimated based on that.

But how do u do it ? If I could explain that... I'd write a book and make some $$ off the ricers that can't afford a Gtech....

[SR]

stock b16 manual is around 5700

[Val]

hmm I hear what u are saying.

I realise we hijacked the man's thread.

I am tired of ppl bugging me to get a VAFC cause they say it's just like a "boost controller for VTEC".
Should I run over such ppl?



leave the forking VTEC point where it is on a stock car, Honda engineers are smarter than you

[X2]

leave the forking VTEC point where it is on a stock car, Honda engineers are smarter than you

Ya heard ?!?!


Funny thing is most people buy the VAFC solely to alter vtec when they can't make $0.02 worth of power on their setups by doing so.... BUT the real value of the AFC is to allow you to fine tune your fuel maps (which honda was a bit conservative on to allow for tanks of bad gas, high ambient temps,etc...) so as you lean it out in some areas, you tend to make more power than stock.... something easily accomplished with a VAFC and a wideband...

[Val]

so as you lean it out in some areas, you tend to make more power than stock.... something easily accomplished with a VAFC and a wideband

something I'd like to look into someday, when I can afford it lol.
I think as I have the short ram air intake, and as the catalytic converter is removed that the increase in air-flow would make a tweak on the VAFC all that much better. What you think?

[X2]

Any change u make can be enhanced with tuning....

Minor stuff like an intake and muffler will be handled by the ecu over time tho.... but the ecu typically errs on the cautious side.... so an afc would allow you to get more ''aggressive'' in tweaking the fuel map.

But as always... tuning is the key.

Back OT.... unless you change an intake manifold or cams or do headwork or drastically change compression or cam timing... leave ur Vtec where it is !!!

The previous opinion is that of X2 and you may do whatever u want, but X2 is prolly right.... (Ah... bring on the haters.)

[civcdrvrinwrx]

X2, i have gained hp by changing vtec engagement, with the vafc 2 on the d15b sohc 3 stage vtec. But i had to increease the fuel map for the vtec unmatch alot. hence losing economy. my curve before vafc showed the most torque between 4600 and 5600 rpm and the stock 3rd stage vtec or wild cam engages at 6200 rpm. i brought it in at a convenient point between the highest torque . the torque plus the fuel map allowed for more hp. but i still have to tune the fuel maps per rpm on the dyno. maybe i can let u look at my dyno chart some time and u can help me tune the fuel maps

[kes_vtec]

well like i say, if you can play with it...
PLAY WITH IT...

if you on the dyno...

it will not kill to move it around, and you will learn at the same time...


if ur not on a dyno, and all you doin is aming at a AFR, leave the forking VTEC point where it is.

[Silvermike]

ANA_sole, i wanna see them dyno charts too bro

[civcdrvrinwrx]

silver mike what settin u have for sensor no. and vtec no. in car select (this is in your etc display) since i interfere with it i gettin an engine check. or is it the fuel map causin dat. pm me if u want

[X2]

X2, i have gained hp by changing vtec engagement, with the vafc 2 on the d15b sohc 3 stage vtec. But i had to increease the fuel map for the vtec unmatch alot. hence losing economy.

That has to be done anytime u change engagement point to below stock and the reason your fuel economy will suffer is that you are running a sohc engine and your cam overlap is not designed to engage that low.... you are blowing fuel and intake charge out your exhaust ports. (I assume the car does alot more *pax*pax*pax* when u lift off the throttle right ?)

my curve before vafc showed the most torque between 4600 and 5600 rpm and the stock 3rd stage vtec or wild cam engages at 6200 rpm. i brought it in at a convenient point between the highest torque . the torque plus the fuel map allowed for more hp

Just as above, the 3 stage vtec is designed purely for economy and the lift and duration of the cam is engineered to engage high... you SHOULD be seeing your highest torque levels while in vtec or right before. (1 wtq in the midrange is worth more than 2 whp in topend)

but i still have to tune the fuel maps per rpm on the dyno. maybe i can let u look at my dyno chart some time and u can help me tune the fuel maps

Please post em... I'd love to look at the before and after to see where you are making this power. (but I don't tune other ppls cars)

[DrunkenMaster16]

^^ don't even tune your own.. yet