Fabbing the side exhaust with plenty of clearance (aka NASCAR Boom Tubes) - Exhaust - Third Generation F-Body Message Boards

askulte · 11-21-2006, 11:56 AM

Here's a few pics snapped while fabbing the side exhaust (the morning I was leaving for the NFME event at Indy Raceway Park last May). It took about 3 hours...

http://www.skulte.com/gallery/view_album.p...AR-Side-Exhaust

I started with a take-off NASCAR exhaust from Muscle Motorparts in Huntersville, NC.

Next I raised the exhaust to the floorboards with the motorcycle jack, and clamped it in place

There was a lot of cutting involved, but I wanted to save as many good pieces as possible. Measure twice, cut once!

Tack welding the cut sections together. I clamped it to a bar, to ensure the parts were aligned.

I'd tack on one section, test fit, and then cut the next section.

Completed exhaust. It's not too obnoxious without a muffler, since the turbos quiet things down very well, but is loud for the street (fiance covers her ears whenever I downshift, he he he). Over the winter, I'll remove the 3.5" y-pipe, and run the drivers side to the other outlet, and probably run a pair of 3" mufflers. It was easier to leave the second exit in place for now, to keep the alignment.

Underside view. The ovalized piping really helps the ground clearance.

Side 1

Side 2

Plenty of ground clearance with the ovalized pipe.

askulte · 11-21-2006, 11:57 AM

Two more pics (let me know if I should remove them, since it's 2 over the 10 limit. They're hosted on my site...)
Plenty of ground clearance.

Lime Rock Park had an 83 dBa sound rule, and I was concerned about passing it. Dave Zug and Mike Davis helped fab this baffle that was tack welded to the exhaust. It aimed the sound at the pavement, and it worked like a charm. Stuffing the exhaust with steel wool was our next temporary option, in case this didn't work.

AC · 11-21-2006, 03:09 PM

Andris, that's sick!! Nice job. Now that I'm back in CT I'll have to look you up to see if that's something that will work for my combo. Can I ask how you plan on tackling the good ol emissions test CT has?

92RS(real slow) · 11-22-2006, 10:52 AM

I like it but i think it'll look kinda wierd without exhaust on the other side that thing must be insanely loud

Tru2Chevy · 11-22-2006, 10:53 AM

That's a really nice job! I bet it sounds great

- Justin

Gumby · 11-23-2006, 04:13 AM

Tits n Balls cool!!!

unknown_host · 12-03-2006, 03:23 PM

Hey is your car lowered? If so, how much? How tall are your rear tires?

Thanks!

Demon355 · 12-03-2006, 04:56 PM

Sound clips!

I love it though, I've always wanted an exhaust like the race cars had. Anymore pics of that beast you call a car

askulte · 12-03-2006, 05:55 PM

I'm not sure on the ride height - it's got 175 lb springs in the back and 950's up front with Ground Control weight adjustable spring perches. I'd say it's similar to the Eibach Pro-kits, as far as ride height, and not as low as the Sportlines. Rear tires are 315 35 R 17's or 275 40 R 17's depending which set of wheels is on there (street or race tires). I'll get some video & sound clips when I get some more dyno testing finished throughout this winter. I'm sure I'll need a good aux mic, as the video camera's microphone will probably start clipping with something this loud. I've got more pics at www.skulte.com/gallery (Z28tt and Misc) as well as some at my new blog page (www.skulte.com/z28tt).

ws6gta89 · 03-08-2007, 01:36 AM

what ever happened to the sound clips?would love to hear it asap

askulte · 03-08-2007, 02:56 AM

I stripped the sound out of the dyno videos. Enjoy!

1.3 meg mp3, right click, save-as: http://www.skulte.com/video/bristoldyno_sound.mp3

Stephen · 03-08-2007, 03:19 AM

I'd love to hear it, but none of my players will play it, and the Muscle Motorparts page shows nothing at all, on it's NASCAR parts page.

Imagine your car WITHOUT the turbos, acting as "mufflers"! If its loud now....

askulte · 03-08-2007, 04:12 AM

Re-uploaded, sampled at 60k this time, so only 754 kb.

Stephen · 03-08-2007, 04:18 AM

Works great now. Thanks! Sounds great! You should do a drive-by video of it. For some reason, a video seems to have more "impact". Maybe it's just an audio/video thing.

I found the .drf dyno runs, but no idea what opens a .drf file, nor did a search reveal what could open a .drf file.

83 Crossfire TA · 03-08-2007, 04:58 AM

Andris, is that the new engine? Sounds really tame…

askulte · 03-08-2007, 05:23 AM

The dynojet viewer opens the .drf (dynojet run file). I'll edit the post to mention that.

It's the same 399 cubed AFR210 headed 236/230 on 113 cammed smallblock. Much of the sound clip was during the steady state tuning of the fuel map (you can hear the dyno load the engine near the end of the clip), so it's not the usual 4 second blasts on the dyno. I built it to have some street manners (some Dynomax Ultraflows will be added as well), so the cam/heads aren't too wild (AFR 210's & 236/230 cam). Power peaks around 5700 rpm, and on 4 psi, has over 400 ft-lbs from when the dyno run started at 2500 to 6000 rpm (drops to 300 ft-lbs at 6500). More boost will fix that.

askulte · 03-08-2007, 12:22 PM

Spent 4 hours cutting down 20 minutes of footage to 4 minutes last night.

Here's the end result:

http://video.google.com/videoplay?do...46413965&hl=en

This is just the first run and some steady state tuning off the street... I'll get the other runs done tonight, but it'll give a better idea of what the car sounds like.

Andris

irocman88 · 03-08-2007, 12:33 PM

wow. thats one nasty ride.

92camaroz28ss · 03-08-2007, 12:36 PM

how would i go about finding exhaust like that? i mean just the tips that you started with not the whole system

Stephen · 03-08-2007, 12:50 PM

Quote:

Originally Posted by 92camaroz28ss

how would i go about finding exhaust like that? i mean just the tips that you started with not the whole system

Since the page he got his from, seems to be blank on the the NASCAR parts page...

Here's one place... Dr. Gas Pretty cool tips, round to oval transitions, etc.

83 Crossfire TA · 03-10-2007, 05:42 AM

Yea Andris, that’s exactly my point… very tame sounding for that much cam, and nothing much to quiet it down. I would expect more of a lope to the idle.

Interesting. Do you think that the fairly short power band is the result of the low boost and the engine will wind up higher with more boost or do you think something else is going on? I’ve been noticing that some turbocharged engines tend to make power at a lower rpm then you would otherwise expect, and I haven’t quite figured out a pattern to why some do and some don’t.

askulte · 03-10-2007, 01:15 PM

Quote:

Originally Posted by 83 Crossfire TA

Yea Andris, that’s exactly my point… very tame sounding for that much cam, and nothing much to quiet it down. I would expect more of a lope to the idle.

Interesting. Do you think that the fairly short power band is the result of the low boost and the engine will wind up higher with more boost or do you think something else is going on? I’ve been noticing that some turbocharged engines tend to make power at a lower rpm then you would otherwise expect, and I haven’t quite figured out a pattern to why some do and some don’t.

I'm thinking the high rpm turbo engines either have big turbos that don't see full boost until higher rpms (masking volE with higher boost), or just have very free exhaust/turbos that let you run more of an NA grind cam. Do any of the runs you see have boost logged? Does the boost climb with rpm, or is it constant? I'd think dividing the power by pressure ratio at the rpm would show true VolE, to compare apples to apples.

I think in my case, the power starts dropping off significantly by 6000 rpms, but the torque is within 50 ft-lbs from 3500-5500 rpms, which to me is a pretty broad powerband (but just doesn't have the top end of an NA racing engine), and much easier to drive for autox/road racing. I think a bigger cam, solid lifters, bigger heads, tubular turbo manifolds, and bigger turbo would extend the usable power from a 6200 rpm shift point to another 1000 more rpms. The reason I didn't go that way is that the stress on the rotating assembly from a 6500 to 7500 redline is a huge increase, and I didn't want to go to lightweight pistons/rods/wristpins, which might not like the huge cylinder pressures from big boost. I thought a 6200 rpm big boost engine would be more reliable than a 7500 low boost engine that needs a valvetrain refresh every year, to make the same power (although, the appeal of a heads/cam LS1 & 200 lb weight savings on the nose is tough to resist!). If you have Engine Analyzer, try modeling a 500 hp NA engine, and then sticking a restrictive exhaust on it to see how the power curve changes - I bet most of the change will be at over 5000 rpm...

acescarrsRS · 03-30-2007, 01:18 AM

Man, that's bad a%%! Finally, someone used boom tubes & posted pics & vids! Awesome job man. Quick question, off topic though....what's the name of the song at the end of the vid on google? Thanks!

askulte · 03-30-2007, 08:12 AM

Thanks - The song is Pedal to the Metal, by Kazzer.

AC · 03-30-2007, 08:30 AM

Sick...absolutely sick. Did I notice NY plates on the car? Curios on the street legalness (if that's a word) in CT? I'm going to have to stop by to check that car out.

Rob Wade · 03-30-2007, 06:46 PM

Quote:

Originally Posted by 92camaroz28ss

how would i go about finding exhaust like that? i mean just the tips that you started with not the whole system

Dr gas or spintech

Stephen · 03-30-2007, 06:51 PM

Dr. Gas for those boom tubes. They even have boom tubes as mufflers built-in. Hope your wallet is deep though, for those!