So, I took the dyno charts on vtec.net, and calculated the torque available at the rear wheels at road speeds in 100 rpm increments. No keep in mind these dyno show much more power at a give engine speed in 04 than 03...but 04 is done at 8000.

What the results show is that in the lower years, 04 is a head for 2/3s of the time, and 03 a head for 1/3. The area under the curves are similar at the time of the 1-2 shift in the 03. and with the 04 gaining a little on each successive gear. At street speeds (gears 1-3 with a 1-2 and 2-3 shift) they should be nearly equal. At an autocross, the extra flexiblity of the 03's extra vtec rev range may be an advantage.

On a race track, where speeds are always above the 2-3 shift, the advantage passes to the 04. The faster the track, the bigger the 04's advantage.

Now if only the 04 had a decent rev range...

 

thats interesting

 

One thing I would have liked to see is a dyno sheet after a shift at the redline. Does the '04 stay in the VTEC after the revs drop to 5300 on a 1-2 shift. If there was a delay before it came off. If it said, I was at the redline and now I am still at wide open throttle, so I will stay in VTEC, there may be more torque/power under the curve than the TOV dyno sheet shows. But not enough to overcome the 03's rev range.

At 5300, 1 HP = 1 ft-lb torque, at 9000 1 HP = 1.7 ft-lb torque.

 

My '04 does not come out of VTEC from 1st to 2nd gear if I shift at redline. It keeps going like a bat out of hell.


Kris

 

We need a dyno graph of that. Unfortunately I'm not sure how. The dyno test was done in 4th gear. That won't do it. And I, while I'm not sure, I think the dyno can't handle the torque in first gear. It may be able to simply since the S2000 is much less powerful, or at least has less torque than such monsters as 400 in^3 V8s and Supra TTs.

 

The MY04 does not drop out of VTEC when shifted 1->2nd at redline.

Stays right at ~6000 or so and keeps going!

 

The MY04 does not drop out of VTEC when shifted 1->2nd at redline. Stays right at ~6000 or so and keeps going!

That does not seem correct. If the '04 S2000 reaches 38mph in 1st and 59mph in 2nd, and the redline/cutout is at 8200rpm, then you will land at 5300rpm from the 1st to 2nd gearchange at 8200rpm.

It does not really matter what the tacho says, as this is derived from the gearing and the redline (and nothing else). There's probably a little bit of 'slip' in there but we're still talking about landing at around 5500rpm.

The pre '04 S2000 lands at 5,900rpm (ie. at 6,100rpm with the same given 'slip') and that is with extra 800rpm to play. The '04 has to always land lower unless the gap between the 1st and 2nd gear is dramatically narrowed.

 

So the question becomes:

Does the '04 stay in VTEC down to 5300?

Not on the TOV dyno sheet, but they started from low revs. Does it respond differently after a shift? We are talking about a fraction of a second here, but an important fraction of a second.

 

David NJ

I asked that very question of my mechanic (he works almost entirely on Porsches and Jags, but is very knowledgable about all exotics/specialty cars)
and he claims that once you are in VTEC and within a few hundred rpms of redline, it will NOT drop out of VTEC until the gas is let out for a "significant period of time". ie. there is a delay...so even if the 04 drops below the engagement rpm, it will remain engaged as long as you are asking the car to get on it!

He claims this is not an uncommen scenario for any car running some sort of variable valve timing, whether it be a honda, toyota, porsche etc.

I am not claiming this to be fact, just what I have been told.

 

I know for a fact that when I shift from 1st to 2nd at redline I'm in Vtec right away. No waiting for the cams to switch, it's already there.

I'm not watching the Tach when this happens (cause I'm driving . ) but I know I'm no where near 5300rpms...gotta be 6K plus.