Flux

Can anybody share some real world examples and impressions of the effect of running the VAFC on an autox R? Outside of the tuning capability, I'm particularly interested in lowering the VTEC engagement (for obvious reasons on the autox course). What did it do for your times and the feel/balance of the car (were you always going in and out of VTEC)?

thanks.

Tweakmeister

if you tune correctly, the Vtec should engage when it is optimal to do so.

changing Vtec for say "low end" to something roadworthy "high-end" isn't going to help anything. it's when Vtec is seemless in the power band that it is best used.

jetydosa

My vafc isnt tuned yet, it was installed on sat and I autoxed on sunday, no tuning except lowering VTEC xover to 5200. I forget the name of the setting, the low-xover I think? Anyway that was set to 4800...so it was great! I didnt have to wait for the car to hit VTEC nearly as long, and as long as I was carrying decent speed through the corners, the car would never get below VTEC (4800). I dug it.

Tweakmeister

that doesn't mean you were making more power.

Fuuma0083

It will help as long as the rev range takes advantage of the larger lobes.

jetydosa

I agree, however the balance of the car seemed a bit better..normally I am in/out of VTEC throughout the run. With just lowering the VTEC down to 5200 the power delivery seems considerably more linear, no huge spike at 5800 anymore.

Just for the record though, I am dynoing the 17th and wherever the optimum point turns out to be that will be where I leave it.

1GreyTeg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Flux &raquo;</TD></TR><TR><TD CLASS="quote">Can anybody share some real world examples and impressions of the effect of running the VAFC on an autox R? Outside of the tuning capability, I'm particularly interested in lowering the VTEC engagement (for obvious reasons on the autox course). What did it do for your times and the feel/balance of the car (were you always going in and out of VTEC)?

thanks. </TD></TR></TABLE>

This is a good question that I was also curious about.

If seamless is what is looked for then why do some ECU's engage Vtec earlier IE: Mugen?

In theory, if you jumped into Vtec earlier wouldn't you make more highend power quicker? I understand that there can be TOO early and this a lag/bog, and I also understand that this all must be tuned on a dyno to be effective but, if all done correctly, and retuned to engage earlier where an autocrosser may take advantage of the big lobe quicker and maintain, wouldn't this be beneficial?

OR is the stock switchover optimal? "I find this a bit hard to digest."


Or are the 3 consumed Foster's oilcan's fueling my craziness?

Go Flux with some good questions and posts recently... (IE the rotor query.)

Art Vandeleigh

well ill throw my two cents in. here is what my dyno looked like before and after the vafc was tuned.



as you can see i lost the dip...my xover is set to 4700 rpm. But at the autox even before the vafc was tuned i was in vtec for most of the time anyway. I rarely got out of 2 gear...it was mainly switching from 2 nd to 3 rd for some of the faster track days. i would bounce off the rev limiter alot...but if i got into 3rd it would be too fast and i would get too hot in the turn.

I cant really say if my times dropped because of the vafc tune or if it was because of more seat time i was getting....HTH

i realy think it really also depends on how you drive.

1GreyTeg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Art Vandeleigh &raquo;</TD></TR><TR><TD CLASS="quote">well ill throw my two cents in. here is what my dyno looked like before and after the vafc was tuned.



as you can see i lost the dip...my xover is set to 4700 rpm. But at the autox even before the vafc was tuned i was in vtec for most of the time anyway. I rarely got out of 2 gear...it was mainly switching from 2 nd to 3 rd for some of the faster track days. i would bounce off the rev limiter alot...but if i got into 3rd it would be too fast and i would get too hot in the turn.

I cant really say if my times dropped because of the vafc tune or if it was because of more seat time i was getting....HTH

i realy think it really also depends on how you drive.

</TD></TR></TABLE>

Your numbers are almost identical to mine.

I personally would say just do a FD for quite a bit better lowend and midrange grunt but, that tosses you into SM right away for SCCA.

Oh well...

Thanks for your info.

Art Vandeleigh

im in stx now and i was planning on moving up to SM...i know there will be no way i could be competitive in this class...but what are you gonna do right??

I dont even want to get into the stupid scca classes

Black R

.....my current graph looks like Art's, except it makes even MORE midrange without sacrificing any low end by engaging vtec @ 3800. Tuned by yours truly on the dyno. I'm in vtec off the line, and don't come out of it till the finish gate.

It don't hurt my times, that's for sure!

(and yes, I'm in street mod)

1GreyTeg

Yep, I gotcha.

One of the first mods I did was the ATS 4.929 FD that threw me headlong into SM with very little stock experience. For local events in the past years I had a decent advantage but a few weeks back recently I ran a bigger more populated event and got murdered (a combination of my poor driving related to no recent seat time and of course a bunch of higher powered more developed cars.)

I totally believe that the R is competitive in the many classes that it runs in but, once you jump to SM, power is a neccessary mod of which I have virtually nothing done sans I,H&E.

But, on the roadcourse (my new love and passion) the FD is an awesome addition...

I guess it totally truely depends on your goals. Too bad the FD automatically bumps you to SM. But, I understand the rules wanting to equal the playing field and Not allowing any clear unfair modding advantage.

BlueTeg

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black R &raquo;</TD></TR><TR><TD CLASS="quote">.....my current graph looks like Art's, except it makes even MORE midrange without sacrificing any low end by engaging vtec @ 3800. Tuned by yours truly on the dyno. I'm in vtec off the line, and don't come out of it till the finish gate.
</TD></TR></TABLE>

I'd really like to see that graph and a list of your mods. I've never heard of a mildly modded integra gaining a broader powerband from engaging vtec that low. Interesting.

BlueTeg

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tweakmeister &raquo;</TD></TR><TR><TD CLASS="quote">if you tune correctly, the Vtec should engage when it is optimal to do so.

changing Vtec for say "low end" to something roadworthy "high-end" isn't going to help anything. it's when Vtec is seemless in the power band that it is best used.</TD></TR></TABLE>

Well put James. I was taught that the correct way to tune your vtec crossover was to set the VTEC controller so that the VTEC switch is at 7000 rpm. The dyno pull will be done almost entirely on the non-VTEC lobes. After reviewing the dyno sheet you find the highest rpm point at which the hp dies on the non-VTEC lobe. Go 200 rpm before this point and that is the ideal VTEC switchover point.

VTEC is just the car switching to a different cam lobe for better breathing/power in the higher rpms. The bigger lobe doesn't necessarily mean more power.

Unsung

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tweakmeister &raquo;</TD></TR><TR><TD CLASS="quote">if you tune correctly, the Vtec should engage when it is optimal to do so.

changing Vtec for say "low end" to something roadworthy "high-end" isn't going to help anything. it's when Vtec is seemless in the power band that it is best used.</TD></TR></TABLE>

Very well put. Once your car is optimially tuned, it's quite obvious that lowering your crossover isn't going to have a benefit. Just get it tuned and call it a day.

Asahi

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tweakmeister &raquo;</TD></TR><TR><TD CLASS="quote">that doesn't mean you were making more power.</TD></TR></TABLE>

Based on his modificatiosn and previous tuning I have done I set it at 5200 which does tend to net more power at the cross over. It is difficult to make the Xover seemless with a VAFC but we will tune it soon to verify proper VTEC point and to get the fuel settings off 0%

Trey

Asahi

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black R &raquo;</TD></TR><TR><TD CLASS="quote">.....my current graph looks like Art's, except it makes even MORE midrange without sacrificing any low end by engaging vtec @ 3800. Tuned by yours truly on the dyno. I'm in vtec off the line, and don't come out of it till the finish gate.

It don't hurt my times, that's for sure!

(and yes, I'm in street mod) </TD></TR></TABLE>

Ken you racing this coming Sunday? I will be there in Street Mod as well. My VTEC is at 3800 too BTW but this seems to be a function of the header.

jdmspoonitr

iTrader: (1)

Everyone with a nearly stock R and a VAFC that I have seen tune, seem to be smoothest around 4500 rpm switchover.

My car was no different. I just lowered the crossover and leaned out the areas that were too rich and that's all.

GokuSSJ4

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jetydosa &raquo;</TD></TR><TR><TD CLASS="quote">My vafc isnt tuned yet, it was installed on sat and I autoxed on sunday, no tuning except lowering VTEC xover to 5200. I forget the name of the setting, the low-xover I think? Anyway that was set to 4800...so it was great! I didnt have to wait for the car to hit VTEC nearly as long, and as long as I was carrying decent speed through the corners, the car would never get below VTEC (4800). I dug it.

</TD></TR></TABLE>

lower the vtec point dont mean anything unless you dyno and see where the car makes power , like mine is set at 7500rpms ...

Asahi

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Spoon1 &raquo;</TD></TR><TR><TD CLASS="quote">

lower the vtec point dont mean anything unless you dyno and see where the car makes power , like mine is set at 7500rpms ...</TD></TR></TABLE>

I means something when you know what the modifications will do to the car and an approximate range. We are smarter than to say this is how it will stay without dyno proof but lowering the limit is common on most stock cam setups. One of the few setups I have seen the crossover be that high on is Jun 3's.

Flux

7500 VTEC engagement - wow, that is the highest I have ever heard of.
I am going to be getting a VAFC in the hopes of finding that extra bit of power and smoothing out the power delivery. Should be extremely valuable on the autox course I think.

So is lowering the VTEC simply making power delivery smoother or is it making more power available sooner in the rpm range?

jdmspoonitr

iTrader: (1)

Look at Art's graph. The dip you see before 6000 on the stock graph is the dip that will disappear after you tune it. Not only will you gain 10-15 whp in some of the mid, but you won't feel vtec anymore, only hear it. Trust me it's sweet as hell. I gained in the same spots as Art. So you have smoother power delivery and more power earlier.

The only downside I see is getting worse gas mileage due to me going above 4500 and loving it.

Black R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueTeg &raquo;</TD></TR><TR><TD CLASS="quote">

I'd really like to see that graph and a list of your mods. I've never heard of a mildly modded integra gaining a broader powerband from engaging vtec that low. Interesting.</TD></TR></TABLE>





Run 4 is without vafc tuning. AEM CAI, hytech header, and 2.5" mandrel bent custom exhaust w/ stock p73.
Run 7 is with vafc tuning of the fuel, but stock vtec crossover (5600).
Run 21 is with some more tuning, and lowering of vtec crossover to 3800.

timing is 16 degrees for each, stock cam gears, stock fuel pressure.

nEoMuGen

VTEC has little effect on autox. Especially with lowered untuned crossover points, it just makes your car rev up slower.

96dc2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueTeg &raquo;</TD></TR><TR><TD CLASS="quote">

I'd really like to see that graph and a list of your mods. I've never heard of a mildly modded integra gaining a broader powerband from engaging vtec that low. Interesting.</TD></TR></TABLE>

You haven't seen George's (Knighton) graph? VTEC is 3500.