The Oldsmobile Connection

88delta88 · Joined: 09 Jun 2003 Posts: 2400 Location: Canada

I've been thinking about a device now for a while... I love the throaty sound you get when you replace a stock air box with a cone filter. What could a person do to make that sound LOUDER, or deeper?

I was thinking about sort of a ported enclosure. If tuned properly, would you not be able to get a louder, deeper tone out of the intake?

The other idea I thought of was making a cone to go over the cone filter ;-), sort of like a trumpet.

Any thoughts or input on this? This one's just for fun, no performance gains expected.

91parkave · Joined: 29 May 2007 Posts: 516

The only way to effectivley make a deeper sound under load from the intake is to increases the amount of vacum the engine pulls in. that would happen if you got a biger throttle body, ported your upper intake and/or cylinder heads, cams etc..... otherwise you'd be wasting your time with the trumpet and other external devices. BTW do you have a LN3 or LG3?

88delta88 · Joined: 09 Jun 2003 Posts: 2400 Location: Canada

91parkave wrote: The only way to effectivley make a deeper sound under load from the intake is to increases the amount of vacum the engine pulls in.

I dont agree. A stock air box can silence the sound through use of a tuned air filter enclosure (or resonator if you will). Through use of a differently tuned enclosure, one could change the sound characteristics of the intake. Much like a sub box is very important to the sound pressure level, and desired frequency target of the speaker.

How do you think a tuba can take a person's lips buzzing rapidly, and produce such a loud, deep sound? Or an antique record player... etc...

91parkave wrote: .... you'd be wasting your time with the trumpet and other external devices. BTW do you have a LN3 or LG3?

Wasting time, maybe. I'd actually prefer to think of it as an experiment. I'll probably have fun while I'm at it. I have the old LG3 in the delta.... But it still growls pretty nicely at WOT.

91parkave · Joined: 29 May 2007 Posts: 516

sorry i didnt mean to type waste of time in your case. I would start out with a longer pipe or a "dual chambered" intake utilizing 2 diffrent pipe sizes running to the filter. I wouldve tried this already but im in love with my current setup so...best of luck and post your results :P

andrewk · Joined: 18 May 2005 Posts: 1220 Location: Ames, IA

91parkave wrote: The only way to effectivley make a deeper sound under load from the intake is to increases the amount of vacum the engine pulls in.

Explain.

91parkave · Joined: 29 May 2007 Posts: 516

what is there to explain? the statment is pretty simple

andrewk · Joined: 18 May 2005 Posts: 1220 Location: Ames, IA

Quote: that would happen if you got a biger throttle body, ported your upper intake and/or cylinder heads, cams etc.....

How would any of this increase engine vac? And how does one port a cam?

91parkave · Joined: 29 May 2007 Posts: 516

andrewk wrote: Quote: that would happen if you got a biger throttle body, ported your upper intake and/or cylinder heads, cams etc.....

How would any of this increase engine vac? And how does one port a cam?

notice the comma before cam, all of things said above increase the volume of air into the engine

andrewk · Joined: 18 May 2005 Posts: 1220 Location: Ames, IA

91parkave wrote: andrewk wrote: Quote: that would happen if you got a biger throttle body, ported your upper intake and/or cylinder heads, cams etc.....

How would any of this increase engine vac? And how does one port a cam?

notice the comma before cam, all of things said above increase the volume of air into the engine

So an increased volume of air moving through the engine results in more engine vacuum? Hmmmmm.....

91parkave · Joined: 29 May 2007 Posts: 516

andrewk wrote: 91parkave wrote: andrewk wrote: Quote: that would happen if you got a biger throttle body, ported your upper intake and/or cylinder heads, cams etc.....

How would any of this increase engine vac? And how does one port a cam?

notice the comma before cam, all of things said above increase the volume of air into the engine

So an increased volume of air moving through the engine results in more engine vacuum? Hmmmmm.....

------------------------
anything that allows the engine to pull more air in before the throttle plate
yes.........cams with a bigger overlap, head porting, bigger valves, bigger intake manifold bigger TB. so yea..............

andrewk · Joined: 18 May 2005 Posts: 1220 Location: Ames, IA

91parkave wrote:
anything that allows the engine to pull more air in before the throttle plate
yes.........cams with a bigger overlap, head porting, bigger valves, bigger intake manifold bigger TB. so yea..............

Would result in more air moving thru the engine, not more engine vac. Increased valve overlap leads to a decrease in vac. which is why you see many people with big cammed engines move away from vac. boosted brakes, as the engine is not capable of producing enough vac. to power it.

And how does any of that, with the exception of the throttle body, pull more air in BEFORE the throttle plate?

91parkave · Joined: 29 May 2007 Posts: 516

andrewk wrote: 91parkave wrote:
anything that allows the engine to pull more air in before the throttle plate
yes.........cams with a bigger overlap, head porting, bigger valves, bigger intake manifold bigger TB. so yea..............

Would result in more air moving thru the engine, not more engine vac. Increased valve overlap leads to a decrease in vac. which is why you see many people with big cammed engines move away from vac. boosted brakes, as the engine is not capable of producing enough vac. to power it.

And how does any of that, with the exception of the throttle body, pull more air in BEFORE the throttle plate?

they move away with a bigger cam because at IDLE they dont produce enough vacum, under load is another story, which is what were talking about.

andrewk · Joined: 18 May 2005 Posts: 1220 Location: Ames, IA

91parkave wrote: andrewk wrote: 91parkave wrote:
anything that allows the engine to pull more air in before the throttle plate
yes.........cams with a bigger overlap, head porting, bigger valves, bigger intake manifold bigger TB. so yea..............

Would result in more air moving thru the engine, not more engine vac. Increased valve overlap leads to a decrease in vac. which is why you see many people with big cammed engines move away from vac. boosted brakes, as the engine is not capable of producing enough vac. to power it.

And how does any of that, with the exception of the throttle body, pull more air in BEFORE the throttle plate?

they move away with a bigger cam because at IDLE they dont produce enough vacum, under load is another story, which is what were talking about.

You couldn't be more wrong. As the throttle opening increases, load increases and manifold vacuum decreases. The more duration and lift you give an engine, the vacuum decreases proportionally.

91parkave · Joined: 29 May 2007 Posts: 516

really? so youre saying under load vacum decreases? so then what do you call the increase of air flowing into the engine? i always thought that was vacum :roll:

andrewk · Joined: 18 May 2005 Posts: 1220 Location: Ames, IA

91parkave wrote: really? so youre saying under load vacum decreases? so then what do you call the increase of air flowing into the engine? i always thought that was vacum :roll:

You might find this article helpful-

http://bankspower.com/Tech_SecrettoMakingPower.cfm

The entire article is good, but these paragraphs specifically-

bankspower wrote: Suppose you have a 300-cubic-inch gasoline four-cycle engine. Most of you know how an engine works, but as a simple review, a four-cycle engine has an intake stroke to draw the air/fuel mixture into the cylinder as the piston moves down the cylinder bore, followed by a compression stroke during the following upward movement of the piston. These first two strokes occur during one revolution of the crankshaft (see Fig.1). On the next revolution of the crankshaft, the power stroke occurs as the air/fuel mixture burns pushing the piston down. The following upward movement of the piston is the exhaust stroke. Two revolutions of the crankshaft, four distinct cycles – it’s the basic Otto-cycle piston engine.

By its very design, this means our 300-cubic-inch engine takes in 300 cubic inches of air every two revolutions of the crankshaft. Now here’s the interesting part. It does this whether the throttle is open or closed. But wait, you say. The engine takes in more air when the throttle is open. And while it is true that more air mass flows into the engine when the throttle opens, the engine’s size, or displacement, never changes, so the only actual difference is the density of the air that fills that displacement.

When the throttle is closed, very little air mass flows into the engine, so that small amount has to expand to fill our 300 cubic inches. Thus, the air will be of very low density. As the throttle opens, more air mass can flow in to fill the engine, and the density will increase. This is often called the “charge density”.