vtec vs. vanos

[LtWacko@xxxxxxx]

<< Anyway,
>From what I understand, VANOS only boost low end torque, and makes the
torque curve flatter. But max figure remains practically unchanged. Sorry if
I didn't make this clear in the first email.

On the other hand, VTEC provides low end torque, AND some high end torque
and higher HP.

The VTEC sounds superior to me.



Michael Ting >>

That did it.  Now to clear things up a little.  Modifying both cars (and 
others) in my business, I became a little familiar with them.

Honda's (I don't like to call them Acura's -- marketing crap) started with as 
much torque as bearable in a high revving motor.  In order to develope that 
torque, the valves had to be small enough for bottom-end power, but barely 
big enough for top end breathing.  Basic engine design concept common for ALL 
manufacturers.  

BMW's took a different approach (but not by much).  Bigger valves than most 
manufacturers dare for a production car.  BMW's breath well at high RPM.  
Even the low tech M20 motor, 2.5 TWO valve motor from 87-91, would pull 
motors of twice it's displacement above 100 MPH (poor Mustangs and they have 
215hp on the BOTTOM end) in stock form.  The HONDUH motors of TODAY are weak 
above 80 MPH.  Now BMW's with a great Top-end suffered on poor off the line 
performance (the slush boxes were even worse than the 5-speeds).

V-Tec, which opens a larger set of valves at higher rpm, gave the Honda 
motors more breathing capabilities.  Hence, the higher HP at higher RPM's.  
(note:  an engine is an air pump, not a gas burner.  the more air you move, 
the more HP you make.  ie. turbocharging and supercharging are fun!)  V-Tec 
gave the Honda, the small valves it needed for low-end torque AND the big 
(open) valves it needed for top-end HP.

VANOS, which essentially does the same thing for BMW, gave the BMW the 
smaller valves it needed for MORE bottom-end power, but only a slight 
increase in top-end power because it already had larger valves to begin with. 
 Another quick note.  The early non-vanos 24-valve motors of BMW had more 
aggresive cams than the later VANOS ones.  The valves are also bigger on the 
early versions.  These are some reasons why you don't see a big HP jump from 
the '92 to the '93 vanos version on the top-end.

Now we have two motors that are drivable in broad RPM ranges.

Venture above 100 MPH and you will see which motor has more umph between the 
Japanese and the German counterparts.  Anyone can make a car fast 0-85 MPH 
(Lexus).  Bahn stormers are for real players.  Stock motors only of course.  
I love it when people spend money to make their cars faster  8-)

To give Honda some credit, their engineers invented the idea of the two 
different valve profiles in their motorcycle racing program.  It was only a 
matter of time before they mated it to an automotive engine.  Others have 
improved on it.  BMW's Double-VANOS, even Nissan has a superior system (200SX 
SE-R's really rock stock and in heavily modified Naturally Aspirated 
versions.  Just no rich nuts with heavily blown versions like the Honda 
crowd.  Otherwise they would be just as fast or faster.)

I hope that I am not being Biased in anyway.  Just stating some engineering 
facts (I hope.  I am not an engineer.)  Honda modifying is now 80% of my 
business.  We do a lot of headwork, turbocharging and supercharging.  Another 
note.  Try not to touch a BMW head unless you really, REALLY know what you 
are doing.  Many people screw them up.  The BMW engineers did an amazing job 
for a piece that is mass produced.  There is a lot of room in the Honda motor 
for improvement.

Don't be loyal to manufacturers for superiority (the import crowd is famous 
for that).  Stick to the facts, the numbers will take care of themselves.

Now about the handling and brakes...

Rodney

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