Executive Summary
Sorry it has taken so long for an update on my "ultimate performance header" and exhaust system but the title says it all <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> the peak gains with just the headers and exhaust installed (no other changes, not even tuning!) were 53RWHP and 49RWTQ and yes, this is with the CAT's removed, however, this is through a complete semi-quiet exhaust system with tailpipes out to the rear of the car!!! The other killer is that I was way rich on the dyno (~11.8-11.9 A/F at high RPM!) so there was more power to be had if I could have just leaned it up a bit! The before numbers were through 2-1/4” real dual exhaust with CAT’s and DynoMax mufflers (324/315 RWHP/RWTQ) compared to 377/364 RWHP/RWTQ (no other changes!) with complete street exhaust and I picked up another ~4.5HP with the Shaner TB to end the Dyno session at 381/364 HP/TQ.

For those that need the details!
Quick recap on the headers since most people probably already forgot about them here are the header technical spec's:
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• <font size="2" face="Verdana, Helvetica, sans-serif">32" overall primary length</font></li>
• <font size="2" face="Verdana, Helvetica, sans-serif">the first 12" are 1-3/4" 16 gauge mild steel tubing</font></li>
• <font size="2" face="Verdana, Helvetica, sans-serif">balance of tubing is 20" long 18 gauge 1-7/8" mild steel tubing</font></li>
• <font size="2" face="Verdana, Helvetica, sans-serif">merge collectors neck down to 2-3/4" OD with 3-1/2" OD outlets</font></li>
• <font size="2" face="Verdana, Helvetica, sans-serif">two welded in O2 bungs (one for primary O2 sensor and one for Wide Band O2 dyno use so it will normally be plugged)</font></li>
• <font size="2" face="Verdana, Helvetica, sans-serif">stock LS1 A.I.R. fittings welded in place</font></li>
• <font size="2" face="Verdana, Helvetica, sans-serif">0.400" thick header flanges from PACE</font></li>
• <font size="2" face="Verdana, Helvetica, sans-serif">0.375" thick 4 bolt 3-1/2" diameter collector flanges (custom cut on an Abrasive Water Jet)</font></li>

<font size="2" face="Verdana, Helvetica, sans-serif">Here’s a pic finally after the Jet-Hot2000 coating
<img src="http://home.earthlink.net/~bzdel/LS1HeadersC2.jpg" alt=" - " />The exhaust system behind these headers consists of dual 3-1/2” pipes mated directly to the 3-1/2” merge collectors and travel approximately 27” each into a Dr. Gas “X” pipe and then after exiting the “X” pipe the exhaust transitions down from 3-1/2” to 3” dual pipes entering (2) 3” dia. DynoMax Super Turbo mufflers and finally over the axle via 3” tailpipe GN/TR exit style behind the rear tires. This view shows the pipes between the collectors and mufflers
<img src="http://home.earthlink.net/~bzdel/LS1HeadPipe.jpg" alt=" - " />

I welded in flanges behind the “X” pipe and actually created a 2nd “front pipe assembly with two Carsound 93009 cats ” (3” diameter instead of 3-1/2”) so that I can bolt this in once every two years for emissions testing <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> This pic shows a comparison between the two units <img src="http://home.earthlink.net/~bzdel/LS1HeadersPipeComp.jpg" alt=" - " />

And so what why else do I call this the “ultimate LS1 exhaust system”? Take a look at the ground clearance (almost 5” at the collector flanges and my car is lowered almost 2”!!!) Check out how the crossmember protects the exhaust form being the lowest point!
<img src="http://home.earthlink.net/~bzdel/LS1HeadersGCrv.jpg" alt=" - " />

The baseline run that I made (run #14 on 5-4-02) was done the day before I took the car out of service to begin the exhaust work so that I would have a good baseline to measure performance from. Run #19 was the best run with the “exhaust only” change and run #21 was with the Shaner ported TB installed (the TB gained ~4.5HP more in peak power over and above the header only numbers). I tried changing the A/F in LS1_Edit PE tables (took out 15% fuel at WOT) but was only successful in pulling fuel out to 4600RPM for some reason. Originally it was all at ~11.8 to 11.9 A/F throughout the RPM band but the peak power numbers really didn’t change much.

What’s really amazing is the overall gains by this combo…..between 3000-6000RPM the average torque gains were a staggering +47.6 RWTQ!!! The HP gains were just as astounding between the sweet spot of 4600-6500RPM (where my M6 operates) where it averaged +48.3RWHP!!!

And for those of you who really don’t understand performance exhaust technology and criticized this combo before it was even tested (oh, oh, it’s too big!)…..how does a gain of +47RWTQ at 3000RPM sound!!! Needless to say this thing absolutely annihilates the tires in first AND 2nd gear from a roll as high as 35MPH in 2nd gear

Soooooo....I am very pleased knowing more power is still to be had when I get it leaned up a bit. The really cool thing is that my new 381/364 RWHP/RWTQ are through a complete semi-quiet street exhaust....NOT THROUGH A CUT-OUT!!!!

And lastly for those requiring more precise facts and data, here’s the dyno comparison below:
<img src="http://home.earthlink.net/~bzdel/dyno8-5.JPG" alt=" - " />

<small>[ August 05, 2002, 09:58 PM: Message edited by: John B ]</small>

 

John, I'm mucho impressed. That is a hell of a job to tackle.

I'm curious as to how you decided on your header parameters. diameter , length to step, step diameter. merge collector shape. etc. etc.

I've been very tempted to have Burns set up a merge collector-megaphone setup for my dynatechs. But I figure this might be a little pricey.

anyways...job well done amigo!

Larry

 

Wow <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> those are impressive <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />

Are you going to mass produce those LTs? If so, how much are they going to run?

 

Great job!! It's nice to see hard work pay off. I can't wait to get a garage. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

ERic

 

Very nice job! <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Like Larry, I was wondering how you decided on tube sizes, lengths and other specs?

John

<small>[ August 05, 2002, 09:13 PM: Message edited by: XLR8NSS ]</small>

 

Very impressive numbers, and very nice work on the exhaust system as a whole. Those headers are awesome looking. I don't think there's room under an f-body to duplicate your design, but there's a lot to be learned from it nonetheless.

I've toyed around with the idea of building my own headers before, but I just don't know if I'd really be up to the task or not...

Anyway, great work!!!

 

That looks like an excellent setup, John. Goes to show what good research and some hard work can get you <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Absolutely beautiful work John! You get two thumbs way up for crafsmanship <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> The only thing I would like to point out that is even after your 50+ rwhp gain, you still have 380 rwhp which is by no means higher than other similarly setup B1 cars. I put down 395 rwhp through cats and non-stepped 1 3/4 headers, Y-pipe etc, and over 400 rwhp when I removed the cats. This leads me to believe that your previous setup of dual 2.25" pipes (was there a crossover? Any pics of the old setup?) was worse than stock. I could be way off base, but thats just my observance. Again, John you impress me with the beauty and thought you put into your work! Your exhaust will only shine more as you get heads, more cubes etc... <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" />

 

Thanks all for the extremely complimentary feedback! It was certainly a lot of work but like anything else....you get what you put into it and trust me....I have a lot of blood sweat & tears into this project!

As for the design spec's, I had a professional class racing engine builder (has build many NHRA class record holders) in Oregon give me the design parameters based on my input of cam spec's, compression, cylinder head flow and proposed TQ & HP curves. He actually recommended a triple step until I told him that I wanted the exhaust system optimized for the street through mufflers and would sacrifice low end torque for top end power to try and kill some of the wheelspin on the street. He definitely knows his stuff!

As for mass producing these, unfortunately for 99.999% of you these were engineered specifically for my G-body so reproducing them wouldn't really help anyone other than fellow engine swappers but you could certainly duplicate the results based on the design parameters!

TrahnZam WS6, thanks and I realize that this power level isn't greater than other set-ups, however, as everyone continues to point out, each motor is different and I must point out that these headers and exhaust were not designed to be optimized for a cam only car, they are specifically designed for a cam and heads motor. It just really amazed me that they gained as much as they did across the board knowing that they are optimized for high flowing exhaust ports which aren't installed yet.

When I started this project I had a paltry 288/300 RWHP/TQ and have gained almost 100RWHP without cylinder head work since so the 2-1/4" duals (without cross-over) may have been a bit weak. I believe that with the proper A/F that I too could be pushing 400RWHP (my 3.73 8.5" could cost me a few dyno HP though) with cam only but honestly believe that my biggest gains will be when I install my Stage II MTI heads since this is ultimately what this exhaust system was designed for so now I'll be gunning for your best with SII heads & B1 cam through mufflers/tailpipes (and no cheatin' cut-out!) <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

By the way, what was that number....in the 430's? And I must say, your power levels are killer! Congrats!

<small>[ August 05, 2002, 11:44 PM: Message edited by: John B ]</small>

 

OH MY GOD!!!!! That is what I call a gain! Those heads are gonna really shine when install them! Not for nothing John, have you ever considered manufacturing those headers? I'd be the first on line to buy a pair! <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

Great work! Hotrodding at its' finest.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by John B:
<strong>I believe that my biggest gains will be when I install my Stage II MTI heads since this is ultimately what this exhaust system was designed for so now I'll be gunning for your best with SII heads & B1 cam through mufflers/tailpipes (and no cheatin' cut-out!) <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

By the way, what was that number....in the 430's? And I must say, your power levels are killer! Congrats!</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">442 rwhp and 421 rwtq, not with a B1 but still on stock tuning, 17x11 rims and 315s, no cooldown etc. Good luck! <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Most impressive!

Reallly looking forward to your results with tuning and heads.

While the neck down at the collector really looks trick, I don't understand it's purpose. Would you explain why neck down to 2.75 then go to a larger primary etc?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">have you ever considered manufacturing those headers? I'd be the first on line to buy a pair!</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks for the flattery Mike but I just don't really have the time to try something like this...too many projects and commitments....maybe when I retire someday and need something to keep me busy <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">While the neck down at the collector really looks trick, I don't understand it's purpose. Would you explain why neck down to 2.75 then go to a larger primary etc?</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">99 Black Bird T/A, the theory here is that when the four header primary tubes merge together, there is a flow disruption created and a loss of exhaust gas velocity with the typical 3" or 3-1/2" collector size. This will cause a loss of torque!

The reduced size of the merge collector accounts for the fact that only one cylinder fires at a time therefore only that cylinder needs to flow through the 2-3/4" reduced size at any given moment (that's why this isn't a bottleneck!).....since the correct exhaust flow volume for all 4 tubes (in my case with 1-7/8" primaries) is ~3-1/2" pipe, the merge collector outlet must be increased to 3-1/2". The easiest anology here is to think of a merge collector as an exhaust venturi where it actually increases exhaust velocity thus inmproving the header's ability to scavenge. There you have it!

An now, TrahnZam WS6, back to you....I don't know how in the heck you expect me to top 442 rwhp and 421 rwtq <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> So.....three questions for you....1)what was you max numbers with B1 through mufflers, 2)what is your best track MPH through mufflers, and 3)what was the full weight of your car at the track running through mufflers?

Knowing this data gives me a better opportunity to "best" your real world numbers <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

That really kicks a$$!.

Looks like the hard work is paying off.

 

Ya man thats crazy work.. to bad the car aint a F body tho.. i'd like to see someone do the duals,headers and lowering on my car. Good work

 

Super nice John!!!!! When are you going to be at the track? I can't wait to see/hear it.

I finally got my headers on. I gained over .3 in the 1/4ml, with wheel spin. I'm still on street tires. My new best is 12.84 @ 110.7! With drag radials, I believe 12.6 are possible.

I designed the Y pipe myself. Ryan K, did the welding. I'm also making removable cats and off-road sections. I finished cutting all the lengths and angles yesterday. I'm just waiting on the clams. I'll be using the same style clamps as the removable cats on the FLP's.

It also looks like I'll be ordering the TR 224 cam <Again> by the end of the month.

When are you planning on getting your cam/heads?

See ya at the track!!!!!!!!! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Bad02WS6, thanks! I'll be out at PR tonight!!!

 

Cool. I'll be there too. <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />