junktionfet

It was a bit cooler this evening here so I decided it was time to G-Tech the car again to see what I could do. My best 0-60 was 6.71 seconds, which is noticeably better than my previous best of 6.88 seconds. I presume the difference may be due to a combination of things--engine now has synthetic oil, my driving might've improved a bit, and/or the engine is even "more" broken-in than it was. I took it up to an indicated 7400 RPM in 1st gear--about as high as I can go in 1st unless I want to accidentally hit the limiter.

Out of curiosity, I tried to see what I could do if I only brought the engine to 5999 RPM--keeping the engine on the "low" cam lobes only. My first attempt was an awful 10.60 (lousy shifts), however with only a few more attempts I got it down to 9.09. For some reason, my 1st-2nd shift at 5999 RPM was really difficult to pull off smoothly. 2nd-3rd was a breeze. With more work I could've possibly shaved a little more time off of that, but it was a silly exercise to begin with.

I don't know if that is typical, but in any event I find it amazing how much time the "high" cam lobes can buy 0-60, assuming that extra shift took an extra 1-1.5 seconds.

One can look at this two ways and be correct on both counts: The bulk of the powerband in the TSX is pretty uninteresting, but the last bit of the powerband is absolutely top notch.

It is times like these when I start thinking about Hondata's reflash. The power curves on their site illustrate how they squeeze a good deal more well-rounded power out of the engine by making better use of the cam profiles and such. That or a supercharger seem to be the only way to gain any really significant benefit at low and mid RPM.

godfather2

nice input

PWTSX

What mods do you have so far?


Thanks

Reach

Now, go get the reflash and try your tests again! The longer 'interesting' piece of the power curve makes up for the mundane first 4.8k rpms.

DAYTA

The Hondata reflash provides little to no gains in the lower RPM region. Where you start to see the gains are the mid to high RPMs, specifically between 5-6k where the stock powerband drops off drastically (most likely to enhance the "feel" of VTEC once engaged @ 6k).

I agree it'd be nice to stay in VTEC when shifting at redline. Personally, though, I'm waiting for a S/C. C'mon Red Shift...where's my boost???

junktionfet

It's stock except for the synthetic oil and the JTso-inspired airbox "de-ribbing" (removed the reinforcing ribs from the stock airbox). The stock resonators are still there.

I want to take that airbox thing a bit further (perhaps this weekend)--use my die-grinder as well as some fine sandpaper to really smooth it out inside. I doubt it does anything for power, but I figure I might as well go all out since I've already started it.

junktionfet

Man, I'd love to feel some boost--even just enough to fatten up the powerband at lower RPM. I think a little would go a long way in 0-60, assuming there were no traction problems.

Have any supercharged people logged 0-60 times in their cars? I'd be curious what they were.

bluesolara

is G-TECH really that accurate?

it can tell HORSEPOWER?!!?

sorry I have my doubts...and it gets the RPM fromt he cigarette lighter?

if all that is accurate to a dyno sheet...

I'm getting this!!

junktionfet

It gets its power from the cigarette lighter.

The G-Tech device has a timer and a solid-state accelerometer. If you are on level ground, you can pretty accurately determine 0-60 and 1/4 mile time and speed by using just elapsed time and "G force" registered by the accelerometer. In other words, if you know your rate of acceleration and the time that has elapsed, you can calculate your present speed, etc.

The G-Tech extrapolates horsepower by using the "G force" and the vehicle weight that you enter. The numbers depend on several variables, so you can't assume they are 100% accurate. However, in well controlled tests the G-Tech can get pretty close. For example, you can skew the numbers and get an abnormally high horsepower reading if you enter a ridiculously high vehicle weight.

rb1

It's all about hp and "area under the curve". From looking at some dynos, I think the torque output at 6000 RPM is down to about 150 or so from peak, which means about 170 hp at the crank, so you (1) only used 80% of the available peak hp, and (2) since you shifted early, you also sacrificed power in the next gear since the post RPM shift is now much lower than what is would be if you shifted at the redline.

aaronng

It's not about vtec. It's about having less area under the power curve if you shift at 6000rpm as when compared to shifting at 7400rpm. That area under the curve works out to be "work done".

junktionfet

Next time I'll disconnect the "VTEC" mechanism and load the ECU with the proper resistance so it thinks everything is still connected. Then I'll make a 0-60 to run, shifting at maximum RPM. How many people think my 0-60 time will suck under those conditions?

EDIT: In fact, I think I'll try that this afternoon...

RaCeR4LiFe022

DO IT ! lol im saying 9-11s

vidgamer

Wouldn't a better test be to force VTEC on at a lower RPM? I did this on my previous Honda, and it made a noticeable difference, all by itself. VTEC controllers are kind of pricey, but if you have the knowledge on how to force the ECU to work correctly... hmm.....

(Has anyone tried to use a VTEC controller on our car? If it was possible to get a wiring harness so that I wouldn't have to hack into the stock ECU harness, I might be tempted....)

JTso

iTrader: (2)

Here is the adapter wire harness. Now go do it.

http://www.boomslang.us/vafc2.htm

aaronng

VAFCII works. But, there is no point lowering your VTEC point unless you have done changes to the fuel and ignition mapping such that your final tune would benefit from a lowered VTEC point.

vidgamer

$150!

vidgamer

I would be surprised that there would be no benefit. Have you tried turning the high-cam on without adjusting the fuel (air) map?

How do the VTEC controllers do anything with the ignition timing? Do they indirectly affect it by playing games with the throttle?

vidgamer

I should add that I had a VTEC controller on my Prelude, and the more I think about it, it was a hack then, and is still a hack. It may not be a real safe way to go.

So, if the controller plus cable cost almost as much as the Hondata, I'd say it's better to look into the Hondata. In the latter's case, they definitely can modify the ignition timing...

aaronng

There is no benefit unless you want a bigger dip in your torque curve. Devices like the VAFCii allow you to adjust the fuel maps as well so that you can take advantage of the ability of altering your VTEC point. VTEC controllers do not do anything to the ignition timing. That's why instead of advancing your timing at high RPM, with greater fuel it retards timing instead because the VAFCii is tricking your ECU into thinking there is more air going in and will try to avoid a lean condition by adding more fuel and retarding timing.

TSXnTEX

i have yet to feel anything "vtecky" in my 07 automatic. Had the car a month. should I KNOW when it kicks in? How?

DAYTA

How do you know? Redline it...

VTEC kicks in @ 6k RPM with a stock ECU, so unless you've revved the crap out of your car already, you haven't felt it yet. However, I'd advise against hitting VTEC until you've logged a few hundred miles on the engine to allow sufficient break-in.

TSXnTEX

never redlined it yet....got over 2k on it. I guess its ready!!

rb1

It's a little extra "kick in the pants" that comes on right at 6000 RPM. (e.g. Whoa! Where did that come from?)

I'd rather they engineered it so it was imperceptible (it needs to come on a little earlier in the powerband, say around 5500), but they didn't ask me...

TSXnTEX

So i can't still feel it in my automatic? I mean, how do you redline it if its an automatic?

jlukja

rb1

If you floor your car (and I mean floor it ), it should shift at the redline.

I have an MT, so I don't know the AT specifics, but I think you can also take over shifting yourself, but just flooring it until it shifts should work.

'06 Arctic

I let my dad take out my '06 MT this past weekend with my brother for a quick spin. I think he thought he screwed up my car when he V-TEC'ed it. After alittle prodding I got it out of him that he had it up to 110 and didn't realize it was a 6spd, I got a new Momo shiftknob for the b-day. After I explained the V-TEC to him, he was pretty impressed. Truthly, I still get alittle surprised when I hit. What a difference from driving a grand am to an Acura.

junktionfet

If manifold pressure is at or near atmospheric and there's no airflow measuring device (like an airflow meter or mass airflow sensor), how is the ECU supposed to know there is more air entering the engine? Typically at wide-open throttle the O2 sensor input is no longer used to calculate injector duration. As a result, air density calculations would be nearly identical.

So iwith more air entering the engine, the overall air-fuel ratio simply wouldn't be as rich as it could/should be. Additionally, the ignition timing may actually be too advanced since a larger air/fuel charge calls for a drop in advance relative to engine speed. I suppose you could cancel this requirement by chilling the intake air charge since a cooler dense mixture typically requires advance in order to light and burn thoroughly. This gets complicated in a hurry.

The A/F ratio debacle is one of several situations where a fuel injection system with an airflow meter or mass airflow sensor is superior. With a device to measure airflow, the ECU can accurately figure out the air density entering the engine per stroke without having to know about how the engine has been tuned. This of course gets thrown out the window if the engine exceeds the measuring ability of the airflow meter or mass airflow sensor, but ignore that for now

MAP dependent systems are incapable of elegantly dealing with any changes in aspiration. If you alter the engine, you must tell the ECU about it. In the case of the TSX, this is where some reprogramming of the ECU is needed.

Long story short, dropping the VTEC point without completely reprogramming the ECU yields a poorly tuned engine.

vidgamer

Maybe it's completely different with the TSX, but at least on the Prelude, getting the high-cam to kick in a bit sooner made a big (positive) difference.

I'm with RB1... it should kick in at, say, 5500 instead of 6000... But like I said, even though I did the VTEC controller in the past, I don't like the hack approach. But if I could do it for cheap, I'd probably give it a shot coz it would be like easy power.

And as for getting to redline, if you're not used to these high-revving Honda engines, you gotta get used to the idea of, well, revving high! No point on worrying about adding power if you don't take it to the redline at all....

vidgamer

I thought OBD2 engines are supposed to adjust according to the O2 sensor. Even when the sensor is turned off at WOT, it should still use the information it figured out when it wasn't at WOT. Not that I really know anything about it.

junktionfet

While in open loop mode the ECU will rely on the long term fuel trim data it has accumulated, but that won't help much when you have it floored and you've configured VTEC to engage at a lower RPM than normal

vidgamer

Why wouldn't it help? When in closed-loop mode, you've also told it to engage at a lower RPM, so it should be used to the idea that it needs more fuel.

Worked great on my Prelude, at any rate. (I still think it's a hack, but I was willing to live with that. ) As the VTEC gets more complicated/sophisticated, perhaps the ECU is even more difficult to deal with, so past performance is not a guarantee of future success, as they say.

aaronng

Probably uses throttle opening % together with the MAP and engine RPM.

There isn't any more air entering the engine. The ECU is tricked into thinking there is more air entering the engine. So the intake charge gets more fuel than is normal and should therefore be used with addition timing advance as engine speed increases (because it is rich, the charge burns slower and there is less time to do so at high RPM).

Hondas/Acuras have usually used MAP sensors only. The new 1.8L R-series engine in the Civic uses both an AFM and MAP sensor. One Civic here had just the Apexi short ram pod and with the stock ECU, was running slightly lean at particular points in the RPM at full throttle. In this case, it needed some form of ECU control to maximise output.

That's the point of using kpro/s100/s200/reflash.

Agreed 100%

junktionfet

Oh wait, you're talking about that aftermarket thing--the VAFC whatever, right?

The context of my discussion was about manually engaging "VTEC" with no other changes to engine management. In such a situation, I thought you were implying that the ECU would somehow automagically know there's more air entering the engine. I know that it would be absolutely impossible for the ECU to know that, so my question to you was somewhat rhetorical. I think we got our contexts confused.

junktionfet

To be precise, I said it wouldn't help much. There is never a point at which you'd be at wide open throttle, 5000 RPM (or whatever), VTEC manually engaged, and the O2 sensor trimming the A/F ratio. It goes without saying that those conditions are quite different than half throttle, 5000 RPM (or whatever), VTEC disengaged, and closed loop mode. Just think about what's happening with the VTC (especially the EGR functionality), ignition timing (which is more advanced at part throttle), etc. The long term numbers it produces would not be nearly enough to assist the ECU in figuring out what to do if VTEC is manually set to engage at a lower RPM.

Tsx6363

i thought fuel cut off hit at 7300.. is it different with hondata?

jlukja

Yes, the hondata reflash raises the fuel cutoff from 7300 to 7600.

Tsx6363

SS mode, duhh