davo-cls

it was based on throttle position rather than a set RPM? I would rather it kick in at WOT at any speed/RPM for more immediate power and response than waiting for 3800RPM (when it does work) .

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'01 CLS #4055 Red/Parchment-all the goodies

mrdeeno

probably not.

the reason for the 2 stages is the "supercharging" effect. The effect is dependent on the resonating characterisitic of the way air is sucked into the engine...and the resonating characteristic is dependent on engine speed (rpm).

i did a report on this in college on the plymouth prowler (it has the same type of system). i looked at acura's website concerning the 'type-s' and they are a little inaccurate (probably just so most people don't have to think too much about it), but i'm too lazy to expand on this.

gabe, care to expand on this?

frederix

I think the second stage opens so that when VTEC kicks in the engine has enough air for the more aggressive valve timing, lift, and duration. The Integra GSR also has a dual stage intake manifold but the Integra Type R does not. The Type R just has a larger single stage intake manifold. I think that is one of the reasons why the GSR develops peak torque sooner. I had a Ford Taurus SHO that had a dual stage intake manifold. It has six separate butterfly throttles for each runner in the intake plenum. The engine was a 3.2L 24V DOHC V6. At low RPMs, only two valves per cylinder and one stage of the intake were used. At higher RPMs, four valves per cylinder and both stages of the intake were used.

EricL

Acura is using Helmholtz resonance tuning. I was originally looking around at some noise quieting methods for the air intakes was screwing around with some old Acoustics books. Then I ran into some class note (on the web from a grad. level auto engineering class). One of the class outlines contains notes on "Helmholtz" supercharging effects.

There is also a reference from a very smart "Honda" tuner who mentioned the natural supercharging effect. The pulse timing of the respective cylinders "change" with engine speed, not air intake position. The air mass moves at a given speed, so the pulses from the alternate banks of cylinders produces a "boost" or natural supercharging effect at a particular speed. The speed of sound is relatively fixed (changes with pressure/altitude to some degree), so the pulse timing that is good at low speed is NOT the same that is good at higher speeds.

There is a Porsche version of this system that uses 3-modes. I forgot where the picture is, they use a similar system in one of the engines, but it has 3 different modes vs. our 2.

So, the engine speed determines the "switch-over", not the mass flow.

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Silver 2001 CL-S with NAVI

• Mud guards
• Wheel locks
• Toyo T1S 235/45ZR17-97W* Proxies on 17x8" SSR Competition wheels (48lbs less than stock)
• Kevlar/SS Brake lines w/Brembos?
• Comptech headers & sways
• Silver AEM CAI
• 9 coats of Zaino magic

EricL

the Acura Cl-S system is different...

Your talking about the different length runners and/or keeping the ram charge up by changing the "effective" port/intake size.

Low speed still gets good cylinder charging due to narrow runner. High velocity means, high pressure of air to fill cylinder and increased torque (or hp.. whatever). At higher velocities, more air is needed, so bigger equivalent port is needed. Air can now move at same or higher speed in the larger diameter port thus reducing restriction (and pumping losses) at high speeds while maintaining good air mass flow.



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Silver 2001 CL-S with NAVI

• Mud guards
• Wheel locks
• Toyo T1S 235/45ZR17-97W* Proxies on 17x8" SSR Competition wheels (48lbs less than stock)
• Kevlar/SS Brake lines w/Brembos?
• Comptech headers & sways
• Silver AEM CAI
• 9 coats of Zaino magic

mrdeeno

the rl has a 3 stage one...i wonder why they didn't give us a 3 stage like the rl? probably wanted to save like $200 or something.

EricL

Good question -- do you have the goods on that one?


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Silver 2001 CL-S with NAVI

• Mud guards
• Wheel locks
• Toyo T1S 235/45ZR17-97W* Proxies on 17x8" SSR Competition wheels (48lbs less than stock)
• Kevlar/SS Brake lines w/Brembos?
• Comptech headers & sways
• Silver AEM CAI
• 9 coats of Zaino magic

mrdeeno

yeah, the one we have is basically a different principle than the integras.

i use to use the term "runners" instead of "manifold" to describe our system which confused some people a while back 'cuz it's the wrong word.