Lower VTEC to better suit road course racing

[skatepozer23]

Hey guys ive been out quite a few times to Motorsport ranch and Eagle Canyon in the DFW area.

My question is can i lower the vtec to say 5000 revs to better suite my driving. I know ill need a VTEC controller and possibly headers but is it possible with a stock car and a VTEC controller to lower the engagement point to 5000 and see better mid rev power?

Sorry if this is the dumbest question everrrrrrrrr!!!!!!!!!!!!

[turbosix]

nah, you could do that.

in all honesty you should save the money and learn to keep it 1,000rpm higher thou

[midwesta]

I have not messed with the VAFC much but yes this is doable.

But I think you can make it so the return crossover is set to 5k, so once you are in VTEC, it wont slip out until it goes below 5k.

So revving UP it hits VTEC like stock

but revving DOWN it falls out of vtec lower.

[MutantCheese]

I have the Hondata Toda Spec ECU reflash. I love it. vtec cross over is smooth and begins at 4200 RPM at full throttle and goes all the way up to 8500 RPM for the 2006+ AP2. Now, at around 5000 RPM the car is entering in the powerband. I don't have to wind out the engine at every shift to stay in the powerband either. IMO it's what Honda should have done from the factory. The stock Vtec "kick" is a gimmick causing usable power loss in the mid range.

[D1sclaimer]

It all depends on mods and what the car likes.

Immagine you have a 4th gen camaro(just for a point). Put in a huge cam like a MS4 cam. Your low end hp is now garbage but for mid range up to redline you have a really nice improvement in power.

Immagine a small cam. No top end power.

When you adjust vtec, you want to have it where the non-vtec and vtec points would cross. This will give you the low end power and the high end power.

[lonestarbuzz]

D1 - i've heard that cams don't do much. T6, CarGuy, Midwesta?

skater - i would save your money and only buy one header, since that's all we have.

[Honda007]

Hey Cheese hows the dyno sheet look, I've looked into similiar reflashes but I've heard the power curve dies earlier in the higher RPMs. Do you have a similar power curve to the stock ECU?
Sorry if the wording seems wierd. One of those days.

[Honda007]

Originally Posted by lonestarbuzz

D1 - i've heard that cams don't do much. T6, CarGuy, Midwesta?

skater - i would save your money and only buy one header, since that's all we have.

Your sorta right hear buzz. Cams generally just move the powerband around. i.e. Get more power in the top end but less torque/power in the low end. Generally power is not made by just adding a different set of cams.

[ZigZag]

What point does VTEC kick in in other models. I have had two Civics and an Accord and never had nearly the noticable feeling as when the S engages at 6k.

[Honda007]

Preludes were around 5200 if I remember correctly, most Honda's were around that area. The S I think has the highest Vtec engagement point. Honda did this so there would'nt be an abrupt power increase(or jump in the powerband), this is good when your taking a corner hard.

[MutantCheese]

This isn't my dyno ( I haven't dyno'd my car yet), it the test vehicle from Hondata

[Honda007]

I wish I had the funds, how much was the reflash? The torque curve looks a little wavy, but I like the HP curve and what I see gains wise. Shouldn't be making 240 to the Wheels though, unless they have other mods as well.

[MutantCheese]

The real gains are only in the midrange, but that's where the S suffers most. List price is $595, but you can get it as low as $535 or so if you shop around. BUT with the upcoming release of Flash Pro for $695, http://hondata.com/flashpro_s2000.html, the reflash my become obsolete.

[Honda007]

Originally Posted by MutantCheese

The real gains are only in the midrange, but that's where the S suffers most. List price is $595, but you can get it as low as $535 or so if you shop around. BUT with the upcoming release of Flash Pro for $695, http://hondata.com/flashpro_s2000.html, the reflash my become obsolete.

O thats a beautiful system there, mines MY04 no DBW.

[D1sclaimer]

You guys don't get what I said. I didn't say to buy cams.

When Vtec kicks in yo, its like a big cam. Your higher revs get more power. You can feel it right?

When Vtec is not engaged its like a small cam. Your lower revs have more power.

Thats why you want to set the Vtec crossover to where they would cross if you dyno with vtec set low and vtec set high..

[Honda007]

I got what you said, I was just explaining to buzz, and Im pretty sure he just got off tangeant there. I don't notice Vtec as much as other Honda's Ive driven for some reason.

[TheCarGuy2021]

Originally Posted by lonestarbuzz

D1 - i've heard that cams don't do much. T6, CarGuy, Midwesta?

I have no firsthand experience with aftermarket cams on this car but I haven't heard of a cam that does more good than bad yet.

[skatepozer23]

Too bad i have an 05. That hondata toda header flash is exactly what i want

[D1sclaimer]

Alright Honda007.

I got bored and made some MSPaint pictures to help explain it to the others as its a little confusing if not familiar with cams.

[philiam]

You get better results with gears.

[S2nasty]

so does eny one know what this magic number where points cross (rpm)

[TheCarGuy2021]

Originally Posted by D1sclaimer

Alright Honda007.

I got bored and made some MSPaint pictures to help explain it to the others as its a little confusing if not familiar with cams.

Your logic isn't quite right. What you're comparing are different cam lobe profiles. Changing the VTEC activation point has nothing to do with lobe profiles, it just changes the point in which the VTEC lobes are activated.

The ONLY benefit from lowering your VTEC activation RPM will be a very slight bump in power from 5000-6000 RPM (assuming you lower the activation point to 5000 RPM). The VTEC lobe is still exactly the same as before, so under 5000 RPM and over 6000 RPM power will be exactly the same as before.

[turbosix]

car guy... i get where dis is going.

the pre-vtec cam, one would THINK.... would be the perfect <6000rpm cam for low rpm torque and gas mileage

the aft-vtec cam, one would THINK.... would be perfect for a 120hp/l >6000-9500rpm motor

so one could come t the conclusion that honda made the pre-cam to work great at idle-5900rpm and the post-cam to work 5900-9500rpm


no? it would make PERFECT sense for the cams to slightly overlap and have completely different power curves

[TheCarGuy2021]

Originally Posted by turbosix

car guy... i get where dis is going.

the pre-vtec cam, one would THINK.... would be the perfect <6000rpm cam for low rpm torque and gas mileage

the aft-vtec cam, one would THINK.... would be perfect for a 120hp/l >6000-9500rpm motor

so one could come t the conclusion that honda made the pre-cam to work great at idle-5900rpm and the post-cam to work 5900-9500rpm


no? it would make PERFECT sense for the cams to slightly overlap and have completely different power curves

Correct, however they cannot overlap, here is why.

Take a look at this picture I marked, disregard the arrows.


Yellow=non VTEC camshaft lobes
Green=VTEC camshaft lobe
Blue=non VTEC rockers
Red=VTEC rocker

At low RPM when VTEC is not engaged the yellow lobes are opening/closing the valves through the blue rockers. The red rocker is free to pivot however it wants as it isn't fixed to the assembly, therefore the green lobe is not doing anything.

At high RPM when VTEC is engaged a pin slides through the red and blue rockers (by oil pressure) interlocking them, allowing them to move as a fixed assembly. Now that the red rocker is fixed, the higher lift, longer duration green VTEC lobe is now the ONLY lobe controlling both valves at the same time.

So there can be no "overlap", either the non VTEC lobes are "on" or the VTEC lobe is "on". No in-between. All one is doing when changing the VTEC activation point is changing when the cam switches over.

[S2nasty]

When i said overlap im thinking of a dyno like when the non vtec cam stops making more power than the vtec cam does at low rpms would be the rpm youd need to set vtec i think..... no thats if you tested the vtec at like 3000k rpms and tested it as stock then overlay those dynos and where they meet in power X should mark the spot.

[MutantCheese]

Originally Posted by philiam

You get better results with gears.

I have been researching this as it was my next mod. While straightline acceleration will increase with gears, you will be shifting more often and this is undesirable for track and autocross.

I am still contemplating gears as my next major mod, but haven't decided if I want 4.57 or 4.77 gears. More research is necessary. I understand that 4.77 gears will limit your top speed to around 125 miles per hour also.

[gomarlins3]

Originally Posted by MutantCheese

I understand that 4.77 gears will limit your top speed to around 125 miles per hour also.

135.


I have 4.77's and I rarely have to shift more often then other S2000's without them on autoX courses. Yes, it will depend on the course set up, but I MUCH prefer being able to pull out of EVERY turn quicker than MAYBE having to shift an extra time occasionally.

[MutantCheese]

Thanks for that info Gormlins3. I'm seriously thinking of gears. So you have an AP1. What do you think would be the difference, if any, for an AP2 with the 4.77 gears? Or should I consider the 4.57 gears instead?

[gomarlins3]

Originally Posted by MutantCheese

Or should I consider the 4.57 gears instead?

There is a difference in the tranny gear ratios in 1st-4th with the AP2 tranny, so I am not sure how much 4.77's would help you over 4.56's, especially for autoXing, sorry.

Hopefully there is someone more educated on AP2 tranny's and rear gears on here that can contribute.


**EDIT**

According to this, you will shorten your gears considerably (as I did in my AP1). Whether that works for you in relation to the types of courses that are set up at your local autox's or not is up to you.

http://www.turnzero.com/technical_re...ear_calculator

If I have done the correct calculations, my 2nd gear will go to ~54 miles per hour. An AP2 will go to ~47 miles per hour with 4.77's. That's pretty short by most autoX courses I have been on.

4.56 on an AP2 will go to ~51 miles per hour. Tire and wheel size makes a difference as well.

[MutantCheese]

In my dream world, I would have a stock diff and a 4.77 gear diff to swap back and forth as desired. That would be sweet. Anyone want to donate an AP2 rear end to a good cause? Namely, me?

[turbosix]

Originally Posted by TheCarGuy2021

Correct, however they cannot overlap, here is why.

Take a look at this picture I marked, disregard the arrows.


Yellow=non VTEC camshaft lobes
Green=VTEC camshaft lobe
Blue=non VTEC rockers
Red=VTEC rocker

At low RPM when VTEC is not engaged the yellow lobes are opening/closing the valves through the blue rockers. The red rocker is free to pivot however it wants as it isn't fixed to the assembly, therefore the green lobe is not doing anything.

At high RPM when VTEC is engaged a pin slides through the red and blue rockers (by oil pressure) interlocking them, allowing them to move as a fixed assembly. Now that the red rocker is fixed, the higher lift, longer duration green VTEC lobe is now the ONLY lobe controlling both valves at the same time.

So there can be no "overlap", either the non VTEC lobes are "on" or the VTEC lobe is "on". No in-between. All one is doing when changing the VTEC activation point is changing when the cam switches over.

i did not mean physically overlap. i meant the power curves overlap... which they would, if you dyno'ed the car with vtec disabled, then found a way to do an entire pull on the big cam.

the big cam probably idles like crap and makes no power down low. the little cam probably runs out of steam around 6000rpm, considering after 6000rpm it is disregarded anyway.

we are saying the same thing just in different ways..

[TheCarGuy2021]

Gotcha, misinterpretation.

[D1sclaimer]

Originally Posted by turbosix

i did not mean physically overlap. i meant the power curves overlap... which they would, if you dyno'ed the car with vtec disabled, then found a way to do an entire pull on the big cam.

the big cam probably idles like crap and makes no power down low. the little cam probably runs out of steam around 6000rpm, considering after 6000rpm it is disregarded anyway.

we are saying the same thing just in different ways..

That is exactly what I meant.

[wgrandmont]

Originally Posted by MutantCheese

I have been researching this as it was my next mod. While straightline acceleration will increase with gears, you will be shifting more often and this is undesirable for track and autocross.

I am still contemplating gears as my next major mod, but haven't decided if I want 4.57 or 4.77 gears. More research is necessary. I understand that 4.77 gears will limit your top speed to around 125 miles per hour also.

I don't think gears will help you in an autocross. I have an 07 an 1st is too low and 2nd I hit the rev limiter on longer straight aways. If you changes gears I would be interested in how you feel it worked for you.

[Jim21680]

That's funny, I would think the complete opposite (as long as you don't go too extreme with the ratio).

I've never autocrossed, but it seems like a lot of small, tight turns, with fairly short straight-aways. With a lower gear in the diff, I would think being able to pull out of slow-speed corners stronger would be a huge advantage. Maybe I'm wrong (I'm guessing it depends a lot on the course).

[wgrandmont]

No question the course makes a difference. I do relatively better on the short courses. On a short course I launch in 1st. Then try to pick a spot to up shift that is not while in a corner and before I hit the rev limiter. From that point on it is faster to stay in 2nd and just drive the car. On some longer courses I hit the rev limiter in 2nd and need to use third. Usually though it is still just best to leave it in 2nd. The S2000 would probably be untouchabe if it had the VTEC torque as a flat torque curve from say 3000 RPM or if the car ahd been upgraded to about 300 HP. The S2000 is still competitive, but it is getting harder in stock configuration.

[MutantCheese]

My toda spec reflash gives me vtec from 4200-8500 RPM ....Gettyup!