Before I start, sorry for all of the questions and much needed corrections!
I will place my thoughts in red.

I'm about to configure my exhaust system. I have already purchased a decent
set of Hooker Competition Series headers.

1 5/8" x 30" primaries, 4 to 1 collector (3 inch):

http://gmthunder.com/tino/hookers.jpg


In the linked photo, you will see a diagram of my proposed exhaust system
for daily drives and racing apps..
http://gmthunder.com/tino/exhaustcalcs.jpg
http://gmthunder.com/tino/collectortune.jpg

Questions for Race Tuning:

http://gmthunder.com/tino/collectortune.jpg

Using a 5800 RPM power peak as my estimate and shift point of about 6200 RPM, here are the values I have calculated:

Exhaust Valve Frequency (at 5800 RPM) = 48.3 Hz

Wavelength (1888 ft. per second in gas at 400 degrees Celcius) = about 39 feet.

4 to 1 collector: 48.3 Hz x 4 = 193.2

Tuned Collector wavelength = about 9.7 feet

1/4 wavelength = about 29 inches collector length, or 2.5 feet.

During racing conditions with open headers, if I connect a 2.5 foot pipe to my
collectors, will I be close to the tuned frequency @ 5800 RPM?

I plan to dyno test a few lengths of pipe, but I want to get close with my
math before I begin cutting.

Is there some sort of telescopic pipe used to tune collectors on the dyno?

Will fabricating a 3 inch pipe with a tight fitting sleeve which can slide to
lengthen the tuned point be effective for dyno tuning, or will the slight step
throw my results (sleeve on the outside)?

My hope is to gain the most power across 4000-6000 RPM during tuning
for shifting purposes.

Questions for Daily Drive Tuning (using the following diagram):

http://gmthunder.com/tino/exhaustcalcs.jpg

When figuring H-pipe position, do I want to locate the mid point of the pipe at the specified length…or
the edge of the H-pipe opening? Does it really matter for street tuning?
I believe the mid point of the H-pipe diameter should be located at the tuned length position of the collector.

What is going to determine the pulse reflection – the H-pipe, or the reducer position?
I believe it will be the H-pipe.

Should I place the sweet spot of the H-pipe where I normally would cut the tuned point for the race
setup, or closer to the collector where the pulses are strongest?
I believe to position at the tuned length will be most effective

For mufflers, I plan to select a straight through design with a combined flow of at least 1000 CFM.

I’m not set on any brand, but I’ve read good things about Magnaflow. Any other suggestions?

I don’t mean to come across as “Mr. **** Tech Wannabe”, but a couple of
inches in error in many places can add up for the worst I’m sure.

 

Holy cow. That's mostly way beyond me. <neatly throws big pile of technical papers in trash bin and claps hands together a few times to clean the dust off>

Here's what I've found from experience.....

Open headers: Start with an extension of about 12-14" in length and go longer from there. Somewhere around 18-24" you'll probably like the results. I don't ever remember going out to 30" or more, but who knows- see what works best on your combo.

Nobody makes a variable length pipe that I'm aware of, but YOU could. Any custom shop could give you 2 pieces of 3" pipe such that one will just barely slide over top of the other- then you could telescope it and LIGHTLY clamp it down using a regular exhaust clamp, extending it 2" at a time between dyno runs. Just long enough to do your dyno runs- not what you're actually going to race with.

X-pipe..... you put it where you can fit it. That means the crossover portion will almost always go directly under the tailshaft of the tranny. You might have a few inches to play with one way or the other, but not much. Sacrificing ground clearance for a few HP is no fun at all.

 

Thanks Damon. I know there aren't many people on this board that can
answer questions like this, but I'm glad you have the experience to reply.

Hopefully I'm not making this more difficult than it should be. The math is
more for my own interest and to get in the 'ballpark' before I purchase lengths
of tube.

I realize theory and math will only take it so far; I do plan to dial-in the system
on the dyno and track.

If anyone else has some input, don't be shy. I'm not looking for exact figures,
I am just grasping what I've read and want to apply it to my car.

 

LOL here...but perhaps I took that WAY out of context.

 

Geez Jon, I've turned five shades of red!

Nope I'm not gay...that was strictly an exhaust system refernce

 

Absolutely no offense intended. It's just my (some folks say) warped sense of humor.

Don't overthink the street exhaust system. Listen to Damon.

Even Nextel Cup cars have to sacrifice some pipe lengths for a better fit in the chassis. I would concentrate on fit into the chassis, minimizing exhaust flow restriction and acceptable muffling downstream of the headers.

Good luck.

 

I have program that Larry Meaux sent me to figure out exhaust system lengths and diameters that looks really good. If you want to test out what you are thinking, I'd have to plug a bunch of specs into it but from what I have seen it's really close to giving you the correct length pipes for the system.

Bret

 

Thanks Bret. I would be interested in checking that out.

How would I go about getting this program?

Jon,

Thanks for the laughs. This forum tends to be a little dry
and impersonal at times. It's nice to see a good sense of
humor.

 

You would have to buy it from Larry. e-mail me and I'll run some numbers for ya.

Or Download PipeMax here, it's $20 so it's not going to kill ya.

Bret

 

I'm getting a headache looking at all of those numbers!

I wouldn't know what to do with such an eloborate program. Does it come
with an engineering degree?

If you don't mind, I'll throw some values your way. It would be interesting to
see how close the crude math comes to the PipeMax software.

Let me know what info you need.