Exhaust theory

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rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

Exhaust theory

#1

Post by rlaggren » 11 years ago

Here's a link to a couple pages about how/why exhaust systems work and help an engine breath. It says some interesting things about the relative importance of the exhaust system vs. other tuning improvements in getting more from a particular engine. Also note the possible use for a "resonator", positioned a certain distance aft of the collector but before any mufflers - it terminates the tuned length so that whatever comes after that (mufflers) doesn't mess up the tuning of the headers and secondary pipe(s).

http://www.superchevy.com/technical/eng ... page1.html

Cheers, Rufus
82 Maxima wagon

windsock
Posts: 144
Joined: 11 years ago
Location: zu ui umop

Re: Exhaust theory

#2

Post by windsock » 11 years ago

rlaggren wrote:Here's a link to a couple pages about how/why exhaust systems work and help an engine breath. It says some interesting things about the relative importance of the exhaust system vs. other tuning improvements in getting more from a particular engine. Also note the possible use for a "resonator", positioned a certain distance aft of the collector but before any mufflers - it terminates the tuned length so that whatever comes after that (mufflers) doesn't mess up the tuning of the headers and secondary pipe(s).

http://www.superchevy.com/technical/eng ... page1.html

Cheers, Rufus
Will have to read that linked information a few times to interpret it relative to the LD28. What does it mean for optimising a pipe size for the diesel engines?
Good roads lead to bad fishing.

rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

#3

Post by rlaggren » 11 years ago

What does it mean for optimising a pipe size for the diesel engines?
Nothing particular... <g> It's the concepts that I'm looking at. Although, it may mean that that resonator next to the tranny was doing something - as I recall the LD exhaust manifold actually has some shape and had a 3-2-1 form. A turbo may throw all this out the window because it probably evens out any pulses pretty much - puts the breathing upgrade ahead of the cyl instead of behind...

You can take the "breathing" calculations for the Datsun gasser 6 and use that as a starting point (lots of info on those engines); probably we're just interested below about 4500rpm. The diesel valve timing must be different and s/b available in the FSM to compare. I figure it's more "conservative", less overlap than the gasser builds, so any exhaust tuning would have less affect. But I found the relative importance of _any_ exhaust tuning vs. intake tuning most interesting.

Rufus
82 Maxima wagon

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