Just curious to know how S2K owners shift the first two gears ???
I don't mean casual driving, rather when you want to pull away from a stop as quicly as you can.
In my AP2 I've gone to the max in 1st @ 8,000 rpms. (35 mph) then in 2nd to redline @50 mph.
Do you think shifting earlier, say 25 mph then second to 50mph is an advantage?
Thanks!

 

If the car is still making power right up to when you shift then there is no advantage to shifting earlier.

 

And I can shift mine at 9k

 

Same here.

 

Keep in mind the engine is on the economy cam up to 6000 rpm so to get VTEC power you need to be above that.

A nice table I downloaded from this site (I think) shows that 6000 rpm in 1st gear corresponds to 29mph (AP1 engine)/28mph (AP2 engine) and 44/42 in 2d. The trick is to get the engine on the high power cam as quickly as you can and keep it there if possible (and it ain't possible between 1st and 2d). At 35mph in 2d gear you're on the economy cam. Downshift if you want some power right away, otherwise you to wait until you build up to 42/44 mph.

Specifically for the AP2 engine/gearbox in the original post: At WOT the car will engage VTEC at 28mph (6000 rpm) -- yes, it takes that long. Rev limiter is 8200 rpm and 38mph in 1st gear. Shift to 2d and the rpms will immediately drop below 6000 (due to the gearing) and you won't get back in VTEC until 42mph. Shift at a lower speed and it just takes that much longer to get back on the high power cam. Almost needless to say but lowering VTEC has great benefits.

I really wish I knew where this chart came from as it shows how lame the 6000rpm VTEC is for max acceleration (as well as lame altogether!). Accounting for human delays in shifting the engine will fall off the VTEC cam at WOT for sure between the 1-2 and almost invariably between 2-3 shifts.

Once in 3d gear and higher the top speed in the lower gear and VTEC in the higher gear is no longer a problem but you still have to rev the tits off the engine with the OE VTEC set point.

-- Chuck

BTW fuel cutoff rev limiter is 8900, not 9000rpm on the AP1 engine.

 

I read somewhere that the AP1 was supposed to rev over 9k but Honda decided to keep it conservative. Not sure how true that is....

 

Rounding (and trivia) is the name of the game.

The AP1 engine is supposed to be 2000cc too. But, alas, is only a measly 1997cc. It will certainly "rev to 9000" but it ain't getting any fuel (in stock tune) once it hits 8900.

The AP2 displacement ain't 2200cc either but merely 2157cc but it will rev to 8200rpm before fuel cutoff in stock tune, not the 8000rpm AP1 fanboys insist on listing.

-- Chuck

 

What? Who? Fanboys? Exaggerate? No.

 

If that's your aircraft you've trumped every S2000 ever made. A buddy has a "cottage" on Lake of Bays, Ontario, exactly 200 statute miles from my former house just south of Cleveland. Ignoring pesky things like customs that's 2 hours by float plane and land next to their dock. Road miles? 440 and roughly 7 hours drive. Somewhere north of Toronto my wife could tell by my stare I was hallucinating and considering selling my infant daughter to gypsies and buy the aircraft.

-- Chuck

 

@Chuck S , once again: the redline of the F20C engine found in the AP1 cars is 8,800 RPM. The rev limiter / fuel cutoff is 9,000 RPM. So those cars can indeed rev to 9,000 RPM. For clarity, the F22C engines found in the AP2 cars have a redline of 8,000 RPM and the rev limiter / fuel cutoff kicks in at 8,200 RPM

The other part of the story in this discussion that @robb alluded to is where in the RPM range these engines are making their power. In the F20C those gains continue until 8,300 RPM when the power begins to drop off. In the F22C engine found in the AP2 cars, max power output is reached at 7,800 RPM before it starts to drop off.

Each of these engines are capable of reaching higher RPMs. However the engineers at Honda set the rev limiters where they did to preserve the engine’s life. They based this in part on the speed that the pistons are traveling within the cylinders. Even at the limits that Honda set, the piston speeds reached in these engines are amongst the highest in the world for production engines (despite the difference in the RPMs, the max piston speed achieved in both engines when the rev limiter kicks in is the same). Just as VTEC engagement can be lowered in the RPM range, there is also the possibility of increasing the RPM level where the rev limiter kicks in. But the more time the engine spends in that newly opened range of high RPMs, the sooner the engine is likely to fail.

Lowering the RPM figure where VTEC engages is also subjecting the engine and drivetrain to additional stress not fully accounted for by the engineers. The impact this might have on engine longevity will only be fully known as these cars get older and rack up hundreds of thousands of miles. You pays your money and you takes your chances. In either scenario some are bound to get luckier than others.

As far as when to shift in these cars for max acceleration from a dead stop is concerned, your best bet is to test various shift points for yourself, in your own car. I’m going to guess that your launch technique will play a much greater role in the acceleration you are able to realize than your respective shift points will. Up to a limit that is (in either case). Sadly it seems that the drivetrain in these cars including the differential in particular is not as bulletproof as the engines themselves when properly maintained.