You have a habit of changing the scenario. You're talking about tuning ingition timing/maps/whatever, or combining a VTEC engagement change with other mods. That's not what I said which you opposed. And as a side note, Honda's "main concern" for the S was not creating exceptional fuel economy. You don't hear reviewers of the S saying "MAN that is an amazing car with a great community following of owners due to Honda's focus on fuel economy."

I will agree with you on your opposing view that on an S2000 with only a VTEC controller, that a gain can be made by lowering the engagement, only when I see you do it. I would expect no more than .2-.5 peak horsepower at MOST, with potentially an overall loss as a result of smoother engagement due to having the VTEC brought in too early. That's my opinion till I see you prove it otherwise.

Go slap on a VTEC controller and tune the hell out of it until you've got the max power out of it. I'm confident wagering a decent sum on this.

 

Lowering VTEC alone will not make power. You need to tune your A/F in conjunction to make power.

 

Ok, I'll try focus on the scenario at hand. Changing the Vtec point alone will show minimal gains without tuning. I would hope that the OP would incorporate a VAFC with the Vtec controller, IF he decided on that route of tuning. I think most do that anyway.

As far as my gas mileage comment goes, I'll try to be more clear. I think that Honda did their best to optimize the daily driving "rev range", without engaging Vtec. If that ment waiting a few hundred rpm more before switching cams, only to loose a few hp, then I think they'd do it. It makes those epa numbers 20/25 instead of maybe 18/25. Not that it would have kept most from buying the car, but maybe a few.

 

Its a 3rd party PnP adapter or something. There is someone on the FI boards that has it running in his car which is an 06.

 

I think it was Autowave, they made a custom adapter to run it on an 06.

 

Fair enough! I'll agree on both of those points

 

[QUOTE=MikeyCB,Sep 25 2007, 09:27 PM]Fair enough!

 

Thanks for all the info guys. From all the comments I gather that what I would be looking for is a ECU refresh or V-AFC. I don't want to just lower the VTEC engagement. What I was thinking was that the better flowing intake and exhaust in conjunction with tuning the air/fuel and passably VTEC engagement may yield more power.

I had assumed that the VTEC engagement was set based on ideal engine conditions such as RPM and air/fuel flow, etc. and taking into consideration fuel consumption, emissions, performance and drivability. My assumption could be completely wrong as I am after all assuming. But if my assumption is correct, the increase in intake and exhaust flow may allow for a slightly earlier VTEC engagement while maintaining the factory "balance" Honda provided. Under the same assumption more "balance" could be attained by tuning the air/fuel.

Regardless of how wrong my assumptions are, it sounds like this mod is relatively expensive and often requires a S2000 tuning professional with a dyno (even more $). It sounds like this is a mod that would be more beneficial for someone who is going to heavily modify their S2000 (like FI). Is there a cheaper option for me? Maybe something easier that works right out of the box?

Back to the test pipe, I went on a 1000 mile business road trip this week (had to drive to Dallas). I drove mostly highway but some city too and I drove pretty heavy footed with the AC on. I topped off, reset my trip and drove 324 miles before topping off again. I divide the total miles since the last top off by the total gallons added during the current top off (3 clicks) and got 29.4MPG the first time. The second tank was about 60% city and I went 319 before the next top off. Using the same method I got 28.1MPG. This was all with my CAI and TP.

The times before I drove about 90% city and was getting 22-24MPG but that was before the CAI and TP mod. I will report my heavy city MPG with CAI and TP as soon as I burn through a few tanks.

So far so good though. No CEL, no backfire, no loader (only deeper) and only a slight increase in noticeable fumes.

 

Good job reporting back! Glad to hear you're getting good hwy mileage, it'll be interesting to hear how it compares to your city mileage.

The reason there isn't an "out of the box" solution is that there are too many variables of component combinations, differences in the engine (though greatly reduced by today's manufacturing processes), and even other things like distance above sea level as a factor.

Tuning by a pro is the best way to see some power gains by customizing your engine program to most efficiently and effectively consider all these diffierent variables. It's not cheap and I haven't done it myself, but eventually I'll put some money out and grab an AEM EMS and get it tuned properly. That's the plan for now, at least, but who knows if I'll end up F/I or whatever and tune then.

Apparently the "learning" nature of our ECUs causes the changes being made by the VAFC to be eventually learned and compensated for, putting you back to the original ECU program. The EMS does not suffer this kind of problem from the reading I've done.

 

Well actually now that I actually see that you have an 05MY... the reflash from Hondata isn't even an option. Its for the 06'+ DBW cars. So yeah, unfortunately the only quality option is AEM, as MikeyCB stated above.

Also Hondata just released their programmable ECU for the 00 - 05 crowd. Its basically a version of the K-pro designed for the S. Its standalone management and all it requires is a laptop and USB connection. You do however have to replace some sensors on the car with different MY S2k sensors, approx. $300+/-, but in the end I think it will be in the running with AEM as the best tuning solution for the S.