Exhaust temperature?

Within the next month, I will begin working on a new project car.
The base car will be a 2 door, 95 neon with a SOHC 2.0 with a 5 speed.

One of the questions that I have been kicking around is exhaust
temperature requirements. Is a cooler exhaust temp better? With a
completely home made exhaust system (manifold and piping cut, bent and
welded in the back yard garage), temp is one factor I am looking at
now. I know in theory, the cooler the exhaust, the denser the volume of
gases traveling through the piping.

I bit of history behind the project:
The car is as mentioned, an stock 2 door 95 Dodge neon. The car
currently has approx. 445,000km on it, with the body is considerably
good shape ( two minor surface rust spots on hood and passenger door).
Gross weight is approx. 2640lb with a full tank of gas, and 12" sub in
an MDX box.
The car IS still running and driven to this day, but will be replaced
when the new Jeep comes in.
The reason for using this Neon as a base is that I own it, owe nothing
on it, and allows for the $1500 needed to buy another base car, to be
spent on components and beer.

This project is currently in the planning stages, but this exhaust
question has been kicking around in the back of my mind, so I figured
that I would ask.
The ultimate goal is to build a fast/light car, with as stock as
possible appearance. (All replaced body panels will be painted to match
the original color.

The major item on the block right now is the engine selection. The 2.0l
is solid, but why work on a car, that will be, in the end, a Neon with
bult-ons.

Any other considerations or ideas welcome as this is still in the
planning stage.

Thank you,
Mike
mlawrenc(at)gmail.com

mike wrote:

> One of the questions that I have been kicking around is exhaust
> temperature requirements. Is a cooler exhaust temp better? With a
> completely home made exhaust system (manifold and piping cut, bent and
> welded in the back yard garage), temp is one factor I am looking at
> now. I know in theory, the cooler the exhaust, the denser the volume of
> gases traveling through the piping.

On this type and size of engine, exhaust temp should be in max around 400°C.
Another aspect are the speed of exhaust gas, and should be keeping in mind.

Depending of skills in this "backyard garage".

Regards,

Ralf
--
www.omnibusclub.de
Erfinder des Abgasturboladers Dr. Alfred J. Büchi: "Die Abgase,
deren noch inne-wohnende Energie bis dahin vergeudet wurde ..."

The reason for asking about exhaust temps is the new piping that is
going to be installed is being cut, and bent by my father inlaw.
One of the guys in our group brought up the thought of using a sort of
heatsink idea. (we are mostly computer/electronic engineers).
The thought was, to use a strip or two of light gauage copper, mounted
vertically on the exhaust piping that runs down the center of the car.
This should work simular to a heatsink, with minimal weight added.
The idea is that the cooler the exhaust running through the piping, the
more we can push out.

Any comments or suggestions?

Mike
mlawrenc(at)gmail.com


Ralf Ballis wrote:
> mike wrote:
>
> > One of the questions that I have been kicking around is exhaust
> > temperature requirements. Is a cooler exhaust temp better? With a
> > completely home made exhaust system (manifold and piping cut, bent and
> > welded in the back yard garage), temp is one factor I am looking at
> > now. I know in theory, the cooler the exhaust, the denser the volume of
> > gases traveling through the piping.
>
> On this type and size of engine, exhaust temp should be in max around 400°C.
> Another aspect are the speed of exhaust gas, and should be keeping in mind.
>
> Depending of skills in this "backyard garage".
>
> Regards,
>
> Ralf
> --
> www.omnibusclub.de
> Erfinder des Abgasturboladers Dr. Alfred J. Büchi: "Die Abgase,
> deren noch inne-wohnende Energie bis dahin vergeudet wurde ..."

Typical nonsense I'd expect from a bunch of EE's that don't know
anything about how a car runs.

For a modern computer controlled car the factory designed
exhaust system has a certain amount of backpressure in it.
The engine computer's fuel curves are designed with this
exhaust system's backpressure characteristics. Keep in mind
that backpressure varies depending on RPM and also to
add to the fun the exhaust system has a sweet spot in it
where at a certain rpm the system resonates and what
actually happens is that the exhaust system sucks the exhaust
out of the cylinder at that point.

The end result of bending up a exhaust system that does
indeed have lower backpressure and a different resonance
in it, and making absolutely no other changes to the engine
computer, is absolutely no increase in power, and a decrease in
fuel mileage. However, a lot of people that try this ****
it up and end up creating an exhaust system that is more
restrictive, so not only does mileage goes down, so does
power. Unless your father in law has a mandrel bender in
his garage, your going to end up with a worse exhaust system.
Mandrel benders actually stretch the tube as it bends, a
mandrel bend maintains the same ID as the pipe, throughout
the bend. A mandel bend is actually weaker and thus they
are only used in air and fluid flow piping, NOT in frame bending.

There's lots of guys out there who have equipment for bending
up frames, and figure they can also make exhausts. Wrong!

Ted

"mike" > wrote in message
oups.com...
The reason for asking about exhaust temps is the new piping that is
going to be installed is being cut, and bent by my father inlaw.
One of the guys in our group brought up the thought of using a sort of
heatsink idea. (we are mostly computer/electronic engineers).
The thought was, to use a strip or two of light gauage copper, mounted
vertically on the exhaust piping that runs down the center of the car.
This should work simular to a heatsink, with minimal weight added.
The idea is that the cooler the exhaust running through the piping, the
more we can push out.

Any comments or suggestions?

Mike
mlawrenc(at)gmail.com