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Discussion Starter · #1 ·
well i was on my way into philly last night and im getting on the onramp for 76. Well anyway i usually have fun on the onramps by gettin up to like 100 right when im actually getting on the highway. I then slow down to about 10 mph over the speed limit usually but this s2000 saw me cruising on the onramp. Anyway we play around for a little not really racing but more just goin pretty fast. We get next to each other and slow to around 65-70 and he guns it. Well i wasnt really thinking and im in 4th and didnt have time to downshift to 3rd and i figured if i downshifted i would just have to shift in a second anyway since were already around 70. So i start in 4th under 4k rpm and hes pulling just barely on me....and as i near 5,500 i gotta let off and get behind him cause theres a car in my lane. Well he beat me...but he really didnt..... :? ...cause he never raced again and if i could have started out of 3rd i would have demolished him. even if i didnt start in 3rd and the race continued a little longer i would have killed him.
 

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Discussion Starter · #3 ·
yeah they are pretty nice. I went and pretended i wanted to buy one just to test drive it and they are pretty nice. no torque whatsoever. its like that feeling i get when i floor is in 5th gear before the turbo spools going like 50 miles per hour. and that feeling is anywhere before like 4500 rpm in 3rd gear on the honda. Once you get goin though its fun. But it is soo tiny, not my kinda car
 

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Ya woulda whooped on him had you both gotten a fair rolling start. I've beaten two or three. V-TEC or not they have a veeeerry narrow powerband. About 190 horses to the wheels, and they weigh roughly 2800 lbs. Still quick, last one I beat was more than a little suprised to read the Saab badge from behind.

Adrian~
 

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how exactly does the V-Tech thing work?
 

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Ok here's how v-tec works ... but first there are two kinds and they aren't the same.

v-tec stands for one of two things depending on the model ...

"Variable valve Timing Electronic Control system" --- This is low level v-tec ... the S2000 has high level ...

"Variable valve Timing and lift Electronic Control system" ---- this is the upper level v-tec.

The first one works like the variable timing on BMWs with a worm gear in the cam sprocket which allows them to vary cam phase timing.

The second one has essentially three cam lobes for every two valves. It runs a rocker setup. The outer two cam lobes are the emmissions/low rpm cam lobes. At a certain RPM, or by electronic signal, hydraulic pressure is sent down the rocker rails to the rocker arms in the v-tec system, and instead of the outer two cam lobes controlling the valves, the center lobe takes over for both of those valves. (Two intake, or two exhaust whichever the case may be.) This is the high rpm cam lobe.

Because the high RPM cam lobe is essentially emmissions exempt (cars are not required to meet emmissions at full load and high RPM) ... it's tuned VERY aggressively. In fact that's one of the major problems with v-tec tuning ...

In the S2000 the high RPM cams are tune SO WELL stock that the exact backpressure of the exhaust system is tuned into the cam. It's so sensitive and precisely tuned that owners of S2000s who go out and buy upgraded exhausts generally lose between 5-15 horsepower at the wheels because they've thrown the engine out of tune. It has to do with valve overlap and subsequent fueling.

Another problem with V-tec is that because it uses a rocker system it's very un-reliable at RPM beyond the factory limit. 8,000 RPM to you and me sounds like a lot, but twin cam racecars frequently get above 12,000 RPM ... this is where the additional valvetrain inertia of the rocker arms can cause retainer falure. Valve retainer failure is one of the most common catastrophic afflictions to v-tec racers.

Also because of the additional inertia if you lighten the rotating mass of the engine too much vibration caused by high valvetrain load can snap timing belts, throw belts off the gears, and snap chains. A good setup with direct cam-over-valve lifters will (if properly tuned with high RPM cams) outperform v-tec.

V-tec is great for high performance street cars, low displacement drag cars, and economy cars, but not practical with larger engines, or pure-bred racecars.

Adrian~
 

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Alright so when people with accords put a full 3" exhaust on their car they are really just lowering the HP?
 

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Well it's not QUITE that simple. Firstly the Accord usually has the first sort of v-tec. Also an Accord is not tuned nearly as well as the S2000 ... the lowering of hp is something pretty much only the S2000 has a problem with. Though some of the other Hondas see a only a small improvement with an exhaust.
 
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