SS RRR

iTrader: (2)

You are saying a true dual exhaust won't sound as good as one with a crossover pipe?

smitty2919

I'm saying all the systems offered for these cars as "true dual" have a crossover. So I ASSUMED it was for a reason whether it be sound or "performance". Otherwise, why would companies go through the hassle of adding one?

I'll admit, I have never heard an ACTUAL true duel system running the length of the car with a rear mounted muffler except on a 80's camaro with a HCI 6.0L running glasspacks off the headers and dumped. It sounded like ***. It had VERY definitive firing order sound that did not appeal to me one bit.

I suppose the muffler out back will act as a "crossover" though.

Gumby83

very nice and tidy work man, impressive. yeah, there are some hard lessons learned yesterday. don't eat mystery chicken wings from the fridge and the pieces i have tack'd in have to be cut apart now, because i tried pulling them out to complete the welds and.... they are not cooperating because my slip fits at the front require 3 1/8" of travel to come out..... lol! However, i too have thought about doing a small H-pipe right off the headers (by small i mean like 3/4" of tubing...) but i don't understand what the difference in sound would be. do you have an example video of a car with a distinctive firing order? maybe its a sound i would like?

also, just watched Motor Trends Engine Masters (Straight pipe vs H Pipe vs X pipe) and they saw a 4-5hp gain on the H pipe below 4600rpm, after that its pretty much like straight duals.

X pipe and H pipe are VERY similar, only benefit to the X pipe is over 5k rpm it will add 2-4hp because the exhaust speeds at higher RPM pretty much ignores the crossover of the H pipe and blows straight past it.

The tests we're done on a LM7 5.3 with a small cam and 2.5" tubing diameter.

(edit: dont worry about the example of straight duals, i am putting in a little H pipe now... because i am doing it anyway for free horsepowah.

smitty2919

Exhaust work takes some thought for sure. You need to think about joint placement and account for removing the exhaust via slip fit joints....which you found out lol. But again, your muffler will blend the sound before exiting. Maybe leave it alone and run muffler lone to see how it sounds. Then go back and add a crossover if you want.

Maybe this video I found? Very distinct exhaust pulses. I know I know it's a truck...

Gumby83

thanks for the video, i agree that sounds sound bad. I have to remove the pipe before the slipfits (from the headers back) so i can easily mark, measure and cut out a little crossover and weld it in. for the power benefits its worth the tiny bit of trouble. it will also give me a chance to fix the rear of the exhaust without having to cut my tacks.

SS RRR

iTrader: (2)

The muffler has a huge impact on exhaust resonance and tone.
Dual exhaust on a stock application always sounds horrible. If that truck had a cam there would be a night and day difference.

smitty2919

Yes a muffler obviously has a large impact on resonance and tone.

The video was simply showing what an actual dual/separate exhaust pipes sounds like with a cam or no cam. It simply showed how you can hear the exhaust pulses. A cam will only amplify that sound...and IMO not for the better.

Again, aftermarket companies marketing "true duals" for fbody's still implement some sort of crossover AFAIK.

SS RRR

iTrader: (2)

If that is the case, are you sure that isn't to help with exhaust evacuation/reversion moreso than exhaust note?

smitty2919

It's been proven time and time again that a crossover and merge design plays a decent roll in exhaust note. The power difference is negligible IMO on a basically stock car. H pipe has been known as "mellow old school muscle" sound and x pipe is known as "screamer/higher pitched" sound. Switching from the Pacesetter Y merge to the merge I made was a HUGE difference in smoothness of note, you have been around here long enough to know that.

If I had the time/money to try it, I would make an actual true dual setup and run completely independent pipes with 2 mufflers out back (sound similar to the truck video I suspect though). Then add a cross over and see how the exhaust note changes. BUT I have neither the time nor the money to experiment lol. I've come to really like messing with exhaust systems on my cars.

I suppose you would have to ask Kooks/Bassani/TSP/Hooker design engineers exactly why they integrated a crossover in their "true dual" kits for the Fbody. Sound sells kits.

SS RRR

iTrader: (2)

I dunno. All the straight pipe true dual setups I've heard that were dumped before the axle with Edelbrock mufflers sounded the best, of course on heavily modified engines. Loud as ****, but sounded great.

Gumby83

Well, i measured, marked and pulled the exhaust off. cut a piece of tubing to 2" and then proceeded to break 2 pilot drill bits on my 2 1/8 holesaw.

but, i got my crossover, its tiny but maybe it will flow better?

I got the rest of the exhaust all welded up, muffler mounted and all tubing connected. however i have 1 bad weld (i let my buddy weld one joint right off the headers, he missed a tiny bit, water is leaking through it, easy fix. dont even have to take em off to spot weld.) two of the band claps i picked up don't cinch down hard enough on the slip fit to seal it, so i got some joint/exhaust leak sealer. I had a chance to start the car, sounds 1000% better, even like the exhaust note more than my previous setup.

I never took any pics after completing the crossover, it was head down *** up time

smitty2919

I would suggest getting some spray paint on that system before it rusts too badly. Give it couple months and your welds will be fully rusted.

Nicely done, post up a video! Now you can add "exhaust making" to your knowledge bank.

Gumby83

thanks guys, i dropped the car off the jackstand's about an hour ago, full exhaust without a single leak, isn't retard loud and has lots of ground clearance!

I completely forgot to take a picture of the underside before i dropped it. but i used 2.5" flex tubing from after the axle to the muffler (i did not want the possibility of that muffler putting load on the headers, especially with that much leverage) I have to say its satisfying having everything done. Now, i got EGR plates to put on then i get my handbrake tuned up and i am off to get it dyno tuned/EGR delete

Gumby83

EGR blocking plates are exceptionally easy.... took it out for some Victory donuts/burnouts. Happy as hell right now, unfortunately clipped a speedbump with the header flange..... gonna have to be mindful that the car is lower than stock regardless of the rest of the exhaust system.

Gumby83

Heres a stealth burnout with my new exhaust setup. its surprising how much more fun a very quiet exhaust is... i can really let it rip without drawing attention to myself. however i am getting surging from the engine, i believe its a mixture of full exhaust and air intake probably throwing the AFR's off or something. anywho, thanks for the help guys!

smitty2919

Everyone likes to be loud, but doesn't mean the car is fast lol. I still swap to a glasspack every once in a while when I feel the need, but that need is becoming less and less. I'll keep the full size muffler for DD, but swap to a smaller Vibrant muffler that should be louder, but not "glasspack loud".

There is definitely a place for a quiet nice sounding exhaust. Makes highway trips more enjoyable, no headaches from drone.

AnotherWs6

iTrader: (17)

There is nothng Stealthy about a burnout, lol.

Crossover helps with raspyness. Had true duals with no crossaover and 40 series flowmasters on my 396 truck. Should sound good, right? F no. Loud as **** and sounded like ***.

smitty2919

Gumby83

^^ yup.

smitty2919

So where is a "normal person" exhaust video...idle, some revs maybe a calm drive-by? lol

These donut videos are useless!