Hey everyone. I've been a longtime fan of the Japanese super car: the 3000GT, the Supra, the 300ZX, and the MR2. What I want to bring up today is torque. The above cars had loads of torque and they had it at the low end. Japan's new cars, such as the Integra, the RSX, and the S2000, have just measly amounts of it. I blame this primarily on the VTEC system. Acura's homepage describes VTEC has "generous low-rpm torque and awe-inspiring high-rpm horsepower from the same engine." Now, does that seem to anyone else to be a bit false? The RSX has 142 lbs-ft of torque at 6000 RPM. I've driven an Acura Integra GSR, and those things have hardly any torque at all...only 115 lbs-ft, despite that massive 170 HP. And the ultimate mockery of low end power is the S2000...despite its accolades of "120 hp per liter!" this supposedly potent engine belts out 153 lbs ft at 7500 RPM. The Germans-specifically Audi and VW-put a ton of torque into their cars, and they perform better at lower RPMs. So, for me at least, that leaves 2 questions:
1-How can people claim that VTEC offers both low end and high end power?
2-Wouldn't it be better to do away with VTEC and bring back the Japanese supercars I described above?

I'm a Honda/Acura fan, and I hope these questions can be answered.

Thanks Guys


MarkDavid

 

Not really related, but a good read on what horsepower and torque really mean and how they are diffrent. http://vettenet.org/torquehp.html

 

Yes. I believe VTEC causes world hunger as well.

 

Honda engines lack torque because they are relatively small displacement, N/A, and have 4-cylinders, not because of VTEC. All of the "Japanese super cars" you mentioned are either turbo, 6-cylinder, or both.

 

Honda engines have a comparatively long rod to stroke ratio. While this allows high revving, it also moves the powerband up.


All the cars you described have turbos. Turbos make torque.

 

Yeah, Mark, you are seriously disillusioned. Who told you that VTEC is going to be the downfall of torque? Let's put it this way.

Acura RSX-S with i-VTEC: 200HP/142 ft-lb
Acura RSX-S without any form of variable valve/timing system: Probably less than 170HP and 140 ft-lb (with a peaky torque curve)

If a Corvette had a system like VTEC, it would achieve higher horsepower and torque ratings while having better fuel efficiency on the low end (without using the 400 RPM 6th gear). I don't know if you understand engine mechanics at all, but VTEC changes the cam timing. This allows cam timing on the low end that provides for torque and on the high end that provides for horsepower. Here's the RSX Type-S engine on the dynograph, it's fairly obvious where VTEC kicks in by following the horsepower curve. That torque curve is as flat as a V8's.



VTEC has almost no cons to it, unlike forced induction or large displacement. Porsche uses a VTEC-like (VarioCam) system on their 3.6L flat Six, as does BMW (VANOS) on most of their engines, including their inline sixes, V-8's, and I think their latest V-12 for the 7 Series.

 

yea, ummm if it werent for vtec, the engines would have even less low-end power.

the whole point of vtec is to preserve low end torque while allowing for high end power by having 2 distinct cam profiles. vtc further helps by changing the timing to maximize torque output.

 

Generally VTEC engines are destroked in comparison to their non-VTEC counterparts of similar displacement within the Honda range. Shorter stroke means less low RPM torque and since the motor isn't on the hot cam yet the breathing isn't that great either.

 

The only way low-displacement engines like the B-series motors can make power is by revving it high. Take the B16A for example. It's practically gutless before 6000 rpm. After that it just screams. VTEC is nothing more than a system that extracts more power from high-rpm driving, while retaining the economy-friendly characteristics at low rpm.

 

hmm, just in case it means something, my non vtec engine with nitrous makes a hell of a lotta torque at around 60kph, the plot on my dyno sheet almost gets vertical. and god it feels good