[Arizona480]

Hard to hear the revs in the first part with that music playing.

[oldman]

Originally Posted by JaxChris

An oval and a circle with the same perimeter length do not have the same area. Therefore when a circular pipe is reshaped to an asymmetric form, it is no longer at its' optimum flow rate.

For visual reference, let's look at the perimeter of 12 feet using 1x1 blocks.



Notice that changing from 3x3 (pseudo circle) to 4x2 (pseudo oval) drops area from 9 sqft to 8 sqft. The area is the opening of the pipe. We haven't changed the outside circumference. In this example, you can imagine this was 3" diameter pipe. By flattening it you have dropped the flow rate by 11.2% (8/9 = 0.8888r).

Nobody said the crushed area is an oval. The bottom half is almost a semicircle of 3.4" diameter, the top half is not flat but indented (concave) .2 to .3 inches from horizontal and forms an inverted bow where it sharply tapers to the far sides (the two end points of the half circle bottom). I gave a reasonable eyeball calculation. It is NOT the same size.

You are comparing a square to a rectangle. This does not reflect the reality of comparing a oval (need to know the radii of the ends but definitely less flow area) to a circle (down 15 to 20% because you are loosing parts of at least 4 block due to rounding). Meaning it is not 9 blocks to 8 more like 9 blocks to 7.2 blocks. Hold on, I'll do the calc for square to circle below so don't go name calling me as a square xenophobe. The real pipe is not an oval pipe, it is crushed and that crush is about 1.6 on the edge in vertical height and 1.4 is in the middle. You are losing substantial internal flow volume. even though your surface area is constant. So 9 to 7.2 blocks is a 20% reduction in area, not chump change.

Now that we have put the oval part to rest, that square blocks don't reflect oval pipe and internal area is down 16% (see below), and that we all did this mental gymnastics with the LS1. All mitigated by the fact we are looking at a flatten circle, NOT an oval pipe like the LS1.
http://ls1tech.com/forums/generation...ood-round.html


Your square is 12" perimeter, with the exact same amount of steel a circle would be PI Diameter = 12 solve 3.82" the surface area of a 3.82" pipe is 11.45" sq So basically the circle is down .5"sq on 12" sq Square or 1 in 24 or 4%. While above the oval is down 20%. The total delta is 16%

But now the mental gymnastics is at an end cause the pipe ain't square and the crush pipe ain't oval. Meaning of all this if GM went from an circle to a nice oval flow would be down 16%. Which BTW is not "the same". But GM did not do this (they did on the LS1), the simply crushed the pipe leaving a semi circle on the bottom and concave top.

I did a napkin calc here at 33%
http://www.camaro6.com/forums/showth...=476521&page=3

Nutshell, you say 11% ideal
I say using your model 16%
reality is we don't have an oval pipe, my eyeball and napkin say 33%

take hubris out of the equation and we get the average of 11, 16, and 33 = 20%

Now we will NEVER have to address it again, flow area is down....


I did like your model, I assume your were not around for the LS1 oval pipe wars.

[shags]

fk that sounds good.. the prices are crazy

[oldman]

Originally Posted by shags

fk that sounds good.. the prices are crazy

My muffler guy told me $75 bucks I supply the pipe. I can do it home for free but I'm LAZY. Agree unless you are doing long tube headers, I would not even look at the rest of the exhaust.

Heck I have long tubes and offroad pipes and still have not looked at the rest of the exhaust... just saying.

IMO best bang for the dollar is the flowmaster mufflers out back at $550 ish. I should say the best sound bang, cause I don't know how much any of these systems from primary cat back offer in terms of HP. say a few to 10 HP.

[gdgraph]

Yeah, I have an automatic too so she'll only rev up to 4,000 before the fuel cuts out so it's not as loud as a full rev would be anyways.

If you wanna hear it rev without the music check out my Instagram (@gdgraph) I have a video there without the music, it'll be the video with the side profile of the car if you are trying to find it.

Originally Posted by Arizona480

Hard to hear the revs in the first part with that music playing.

[gdgraph]

Yeah, it's expensive especially with the AFM & NPP valves. I saved a little money by getting it "used"... well technically it wasn't used but I bought it off someone that ordered it and changed their mind about installing it so I got it at about 40% off!

Sounds amazing though, worth every penny to me, and the videos don't do it any justice compared to what it sounds and feels like in real life.

Originally Posted by shags

fk that sounds good.. the prices are crazy

[shags]

Originally Posted by oldman

My muffler guy told me $75 bucks I supply the pipe. I can do it home for free but I'm LAZY. Agree unless you are doing long tube headers, I would not even look at the rest of the exhaust.

Heck I have long tubes and offroad pipes and still have not looked at the rest of the exhaust... just saying.

IMO best bang for the dollar is the flowmaster mufflers out back at $550 ish. I should say the best sound bang, cause I don't know how much any of these systems from primary cat back offer in terms of HP. say a few to 10 HP.

agreed i did a muffler delete and it sounds great for now until i do long tubes in a few months

[shags]

Originally Posted by gdgraph

Yeah, it's expensive especially with the AFM & NPP valves. I saved a little money by getting it "used"... well technically it wasn't used but I bought it off someone that ordered it and changed their mind about installing it so I got it at about 40% off!

Sounds amazing though, worth every penny to me, and the videos don't do it any justice compared to what it sounds and feels like in real life.

i agree it sounds amazing.. i might buy the mid pipes for 600 and add my own mufflers i just don't know what yet

[gdgraph]

It's the Borla Mufflers (axleback) that makes the sound (exhaust note) though, and guarantees that you won't have drone vice an alternate brand.

Originally Posted by shags

i agree it sounds amazing.. i might buy the mid pipes for 600 and add my own mufflers i just don't know what yet

[gdgraph]

Wanted to throw up a recent sound clip I captured with a car mounted GoPro right by the exhaust tips, gives a more realistic depiction of how it sounds on the outside, probably as close to real as you can get (sounds most realistic on computer speakers especially if you have a subwoofer).

SOUNDCLIP

[HyperBlu2SS]

Thanks for the post gdgraph! Thinking of getting the 60610 x pipe as well. Do you have any clearance issues in the "crushed pipe" area?

[gdgraph]

Hey no problem! No, there were no clearance issues at all. Only time you may run into clearance issues is if you had a convertible because you have those extra support braces that come across the back in that area.

Originally Posted by HyperBlu2SS

Thanks for the post gdgraph! Thinking of getting the 60610 x pipe as well. Do you have any clearance issues in the "crushed pipe" area?

[TheAbyss]

Originally Posted by gdgraph

I recently installed the Borla S-Type axle-back w/NPP (11924) and the car sounds great. I wanted to get some better flow through the x-pipe and get rid of that hideous "crushed" section of the stock exhaust so I got the Borla x-pipe w/ mid-pipe set up (60610).

This system goes from a few inches behind the secondary cats and matches up with the Borla Axle-back systems while also maintaining the AFM valves. I'll post some videos if anyone is curious how this set-up will sound!

Sound Clips:

Start up, Revs, Drivebys, Inside, Outside

Outside by exhaust tips

Thanks for the link! I am wondering if you hear more pops and crackles with the mid pipes/xpipes supplied by Borla

I have Borla Atak axleback but want more crackles.. I drive a manual and I can get it to pop often during a cold start but then its gone.

[MPLJR1222]

Nice review!