cmnsnse

So the F20c is a great engine, can it still be improved?

On some other threads I had mentioned my concern about modifying the stock intake. Reasons were centered on the intake air velocity.

Since air must expand and contract to move sound, and sound is created by the expansion and contraction of air. The sound of the intake would mean that air is not flowing quite as well as it could. Being that the sound(and a great one at that) is created by air stopping and starting its flow. This sound is carried through the intake disturbing the airflow, all the way to the filter box that cancels out the sound.

When the valves open, the air is stretched as it accelerates and is sucked into the engine, and when the valves close it is then compressed as it slows down.

I feel that this disturbance can be almost eliminated by an active intake manifold, one with a small bladder that is controlled by a servo. Basically this would be along the lines of noise cancellation. The result would be a steady air velocity throughout the whole intake. But alass no intake sound

The volume of the manifold would increase slightly as the valves shut and decrease as they open, smoothing the airflow. Possibly enabling even greater volumetric efficiency, and therefore power output.

Should I stop thinking?

Ummm, Tell me what you think.

RT

what?

Schatten

I'm really not sure I follow you, but after working on many Mustang intakes, I can say there are different philosophies in gaining performance. There is the extrude honed path, which some say doesn't do much for the s2k, but it did wonders for the V8's. Larger, radical designed intakes, longer runners, small box type intakes - all made of different materials from sheet metal, CF, and even a few in composites.

I'm not sure which way you'd want to go with it, but I will say this, with the V8's when you'd SC them, you were better off with a box intake. Keep in mind I'm talking about fuel injected cars here, not carborated cars, where the length of the runners increase torque.

If you are thinking to improve the intake, port matching and polishing would be my first, and most economical choice - dremel works wonders for simple tasks like this - or even a small air tool with a carbide bit. Time consuming, but every little bit counts, right? I just hope you won't try this, go racing and come back and bitch cause you were protested against. <g>

I'm sure I'll get some flak and some will think - we're not talking V8's here - well, just trying to put in my two cents.

Bobway

Great thoughts, it's nice that some actually think once in a while. The part about air velocity when the valve opens and closes is pretty close. The runners are supposed to be 'tuned' for a specific rpm range, and I would assume that it is for high RPM in the S2000. When the valve closes though, you don't want to absorb the pulse sent back the the surge plenum; rather, the pulse is supposed to pressurize the plenum for the instant that the next valve opens, and thus provide an additional boost for that cylinder. Thus, the tuned length runners, short for high RPM (pulses close together) and long for low RPM.

So, the byproduct of the valve closing is used to enhance the next valve opening, and I think you would lose power in a system that would try to quiet this effect.

I don't know how the airbox works in helping the system though, Is it also pressurized by a ram air effect of some sort? Anyone run any pressure tests in the airbox at speed?

I think the best intake for the S2000 would be a nice tunnel ram sticking out of the hood, dual webers, and a pro-stock scoop. At least you might get some looks at a car show.

RT

What I'm not following is, if quite is faster, then why are all really fast cars so fvcken loud?

The Reverend

hehe... I think you got him on that one, RT.


I see what he was getting at, but Bobway's right that the noise is the effect of sort of pressurizing the intake manifold plenum and getting the air ready to cram in there.

Anyway, I've screwed with the intake design on this car enough that I've given up on trying to make a gain on it.

cmnsnse

Thanks for all the input everyone.

The type of system I was thinking about would not necisarily negate the effect of the valve closing within the manifold and in effect tune the runners to all rpm ranges, here's how.

Instead of that pulse backing up air through the TB to the airbox, It just backs up in the manifold, so there would still be a little of that effect. This would increase the efficiency of the intake up to the TB by improving the airs velocity by making it smooth.

The diaphram would not 'absorb' the pulse to a negative effect, because it would be pressing the air back into the runners also. Since what Im thinking of is an active system, its controlled by a computer and of course variable.
That means that you could tune it for all rpms, and if the sound is benificial (which I doubt, but it is designed into many new engine designs) can either be enhanced or negated.
Because sound and the disturbance is both positive and negative, like resonance, the diaphram would have the effect of resonance to help force the air into the engine while at the same time allowing the air comming up the line to be undisturbed.

The really fast cars are so loud because they went with such a big bang! Im really just talking about fine tuning this engine, I think it would still work with boost, but not to the same effect.

If you were to polish the intake, and if it did somehow lessen performance by changing the frequency it was tuned to this system would help big time.

Polishing of course smooths the airflow helping to increase the capacity of the intake, Im sure whoever does it, if they test it for flow charicteristics, tests with a steady flow and not pulsed.

I notice that the runners are slightly different legnths meaning that they must have tried to broaden the tuned frequency, and since the tuned frequency would be one RPM (while still having harmonic buddies), they tried to spread the effect anyway.

The 'harmonic buddies' just means that while its tuned to one RPM there are other RPM's that benifit but just not as well as the one.

I guess Id have to try it but I would need to have a small computer made, and a servo similar to what is used in a servo subwoofer. Hmm Ive got some time . . .

E30M3

...The type of system I was thinking about would not necisarily negate the effect of the valve closing within the manifold and in effect tune the runners to all rpm ranges, here's how....

Essentially, doing what you are describing has already been done and was patented long ago. Part owned by Ford.
Much more complex than you are describing. Can provide mild supercharging effects. And part throttle benefits too.

There are also several somewhat related approaches which are either patented or have even been produced using pulses from the exhaust to help the intake.

There are alos two main acoustic or air speed things taking place in a tuned manifold, both must be addressed for the best results.

Stan

cmnsnse

[QUOTE]Originally posted by E30M3
[B]Essentially, doing what you are describing has already been done and was patented long ago.

cmnsnse

I think I found fords thingy, done in '90