240Z, 260Z, 280Z (S30) Forums Dedicated to first generation ZCars

Exhaust?

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Old 10-19-2002 | 08:48 PM
  #3  
Bleach's Avatar
The Evil Twin
 
Joined: Mar 2001
Posts: 9,296
From: Seattle, WA
Re: Exhaust?

The exhaust tone, produced by the engine itself is not relative to the number of cylinders but to the air capacity of each cylinder.
The 4 cylinder L20b (found in 70s datsun trucks and cars) has a larger capacity per cylinder than the L28 found in the 280ZX. Therefore it will sound much deeper than a striaight six given the same exhaust system. A 1.8L Harley Davidson motorcycle only has 2 cylinders, but each one is about 900cc so it sounds really deep. The L20b has 500cc per cylinder and the L28 has 467cc.

Cylinder size, exhaust manifold, pipe size, and muffler style effect the sound that leaves the car. here's what I think about them in general.

Headers are louder than a cast iron exhaust manifold, but not nessisarily deeper.
The larger the pipe size all the way back, the louder and deeper the sound.
Certain mufflers can make an L28 sound like a fart can. My stupid Flowmaster almost does that to my Z.
Straight-through design mufflers have a much more deep and rastpy sound at idle but are much louder at higher RPM.

I heard a very nice sounding 240Z that was deep at idle and not very loud at all inside the car and outside. It had a 2.8L engine, cast iron manifold that was ceramic coated. It used a 2.5 inch pipe through a resonator and then through a straight-through design Dynomax muffler in the rear.

Using a resonator near the front of the exhaust system decreases the noise that goes out the back of that resonator. Therefore less soundwaves are vibrating around the remainting pipe. You gain some extra quietness by having a resonator up front. Also, dual exhaust is much louder. When all the air flow and noise from each exhaust port flows together into one pipe, somehow they cancel each other out a little and produce less noise.

Old 10-21-2002 | 09:38 AM
  #8  
Bleach's Avatar
The Evil Twin
 
Joined: Mar 2001
Posts: 9,296
From: Seattle, WA
Re: Exhaust?

Ya, that's another good point. Higher compression and a performance cam changes the sound because it increases the intensity of the explosion inside the engine.

Old 10-21-2002 | 09:52 AM
  #9  
Spudz's Avatar
Registered User
 
Joined: Mar 2002
Posts: 646
Re: Exhaust?

An L motor with a large cam and header sound similar to
a V8 at Idle, but when rev have an exhuast tone of their own.
I really like the sound of a nice running L motor.

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