true dual
Launching!
Joined: Nov 2004
Posts: 289
Likes: 0
From: Flower Mound, TX
if anyone here would time to read the FAQ that is stickied at the top of this section, they would see this. guess those things just arent for newbies after all... 
https://ls1tech.com/forums/showpost....11&postcount=6
https://ls1tech.com/forums/showpost....11&postcount=6
Originally Posted by BottleRocket
no it doesnt. velocity is the key at any RPM range. just like turbos, you can get one that spools early and makes good power down low, but its not going to do it's best at 7000rpm. same with headers, you can have some that are meant for all out racing and make great power up top, or you can get some smaller headers that are better for daily driving? all that does is make the ideal flow velocity for those headers come lower in the revvs. backpressure is the enemy.
Regardless of semantics, the point I'm trying to make is that when people move up to aftermarket exhaust setups, especially when they get to the level of headers and cats or lack thereof, they will sometimes lose that low end responsiveness that they originally had, and want it back. We are all making a compromise when we do these upgrades. I wish my car had the low end feel that it had when I had just manifolds, but it doesn't, even with Kooks LTs and a custom over the axle TD setup (no cats).
Originally Posted by BottleRocket
if anyone here would time to read the FAQ that is stickied at the top of this section, they would see this. guess those things just arent for newbies after all...
https://ls1tech.com/forums/showpost....11&postcount=6
https://ls1tech.com/forums/showpost....11&postcount=6
Thread Starter
On The Tree
Joined: Nov 2004
Posts: 130
Likes: 0
From: Houston, TX
oh and by the way guys... i bought duals so you dont have to convince me anymore...now i just get to see what they'll do, except i didnt get an x pipe i actually got a custom fabbed H pipe set up...anyone else seen those on a ls1? looks sick by the way kind of comes out as a center exaust look.
Launching!
Joined: Nov 2004
Posts: 289
Likes: 0
From: Flower Mound, TX
Originally Posted by MeentSS02
Since I'm sure your comment is directed at me, thank you.
just at everyone who needs backpressure. that writeup is very informative and it makes alot of sense. all that is required in an exhaust setup to scavenge is a few inches past the header collectors. sure, an X pipe would help pull the gasses out, but not as much as a properly tuned header.
Originally Posted by BottleRocket
just at everyone who needs backpressure. that writeup is very informative and it makes alot of sense. all that is required in an exhaust setup to scavenge is a few inches past the header collectors. sure, an X pipe would help pull the gasses out, but not as much as a properly tuned header.
I've seen on two occasions, two totally different set-ups. One, big heads/cam, one alot of spray. The heads/cam car had been tuned for open headers and picked up 30 rwhp and 30 rwtq in the mid-range with a 3" true dual system, Dr Gas X, and 18" Flo-Pro Twister mufflers - over tuned open headers(FLP's). Peak numbers were nearly identical.
The other car had duals out the back with two mufflers on each side. The system was 3" to the X and 2.5 right after with four Magnaflow bullet mufflers total. He decided to do two cutouts just past the collector and lost 15-25 rwtq in the mid-range. Peak power was basically the same.
Open headers sound very free flowing, but the engine is still just pushing exhaust gases out of the head - as opposed to them being pulled out by a good crossover...
Launching!
Joined: Nov 2004
Posts: 289
Likes: 0
From: Flower Mound, TX
Originally Posted by Lane
I disagree.
I've seen on two occasions, two totally different set-ups. One, big heads/cam, one alot of spray. The heads/cam car had been tuned for open headers and picked up 30 rwhp and 30 rwtq in the mid-range with a 3" true dual system, Dr Gas X, and 18" Flo-Pro Twister mufflers - over tuned open headers(FLP's). Peak numbers were nearly identical.
The other car had duals out the back with two mufflers on each side. The system was 3" to the X and 2.5 right after with four Magnaflow bullet mufflers total. He decided to do two cutouts just past the collector and lost 15-25 rwtq in the mid-range. Peak power was basically the same.
Open headers sound very free flowing, but the engine is still just pushing exhaust gases out of the head - as opposed to them being pulled out by a good crossover...
I've seen on two occasions, two totally different set-ups. One, big heads/cam, one alot of spray. The heads/cam car had been tuned for open headers and picked up 30 rwhp and 30 rwtq in the mid-range with a 3" true dual system, Dr Gas X, and 18" Flo-Pro Twister mufflers - over tuned open headers(FLP's). Peak numbers were nearly identical.
The other car had duals out the back with two mufflers on each side. The system was 3" to the X and 2.5 right after with four Magnaflow bullet mufflers total. He decided to do two cutouts just past the collector and lost 15-25 rwtq in the mid-range. Peak power was basically the same.
Open headers sound very free flowing, but the engine is still just pushing exhaust gases out of the head - as opposed to them being pulled out by a good crossover...
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'
Brett Foote
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
yes, someone that knows the difference between backpressure and velocity.
backpressure is a build up due to a restriction. in the case of exhaust, it's when the diameter of the pipe can no longer expell the amount of gases introduced into the system. the higher the rpm, the more volume of gases that need to be gotten rid of. so you increase the diameter if the pipe to do this. but theres a cost. you start to trade low speed velocity for high speed velocity. also power output and cid comes into play as well. it's the whole squeeze the water hose trick.
same goes with the diameter of headers.
you don't need backpressure. you need correct diameter of all the pipes to keep the velocity of the exhaust pulse up. the faster the pulse travels, the more you can get out. and with the speed of the pulse, it creates a vacuum behind it. this in turn helps to extract the next pulse behind it.
we could also get into how keeping heat in the pipes helps the velocity as well if you want.
backpressure is a build up due to a restriction. in the case of exhaust, it's when the diameter of the pipe can no longer expell the amount of gases introduced into the system. the higher the rpm, the more volume of gases that need to be gotten rid of. so you increase the diameter if the pipe to do this. but theres a cost. you start to trade low speed velocity for high speed velocity. also power output and cid comes into play as well. it's the whole squeeze the water hose trick.
same goes with the diameter of headers.
you don't need backpressure. you need correct diameter of all the pipes to keep the velocity of the exhaust pulse up. the faster the pulse travels, the more you can get out. and with the speed of the pulse, it creates a vacuum behind it. this in turn helps to extract the next pulse behind it.
we could also get into how keeping heat in the pipes helps the velocity as well if you want.
Originally Posted by BottleRocket
then the headers were too big for the car. if you put the correct size headers on it, you would get a similar effect if the collector was designed right. yeah, the X-pipe can help scavenge, but adding any sort of mufflers SHOULDNT add HP. if it does, your setup isnt the right size
Originally Posted by Lane
I didn't say 'adding mufflers added HP'. I said adding the X added HP and torque - in those two applications. And yes, a properly designed header/collector can scavenge very well, but these were off the shelf FLP's and Hookers. Which apparently need some help... I doubt most people on this board have custom made headers/collectors for their applications - agree?
Originally Posted by MeentSS02
That's the point I was trying to make...off the shelf products aren't necessarily the best, but they work pretty well.
Launching!
Joined: Nov 2004
Posts: 289
Likes: 0
From: Flower Mound, TX
Originally Posted by Lane
I didn't say 'adding mufflers added HP'. I said adding the X added HP and torque - in those two applications. And yes, a properly designed header/collector can scavenge very well, but these were off the shelf FLP's and Hookers. Which apparently need some help... I doubt most people on this board have custom made headers/collectors for their applications - agree?
I absoloutely agree. my point was just that all a properly tuned pair of headers needs is a little extension past the collector. but that wasnt what i was focusing on, it was the whole backpressure thing.
Originally Posted by Lane
Yes they do - even the un-sexy Macs make great power - complimented by a good exhaust system. Heck - the factory GTO manifolds are putting down long tube numbers. The LS1 is just an excellent base.
TECH Fanatic
Joined: Oct 2003
Posts: 1,655
Likes: 0
From: Northern Va
(Torque x Engine speed) / 5,252 = Horsepower
hp is merely a function of torque. all its good for is car advertisements and bench racers.
for you huggerorange you made a good choice, with a cam you should see an improvement over a ory set up.
for the people who are stock internally you wont see much of an improvement if any over a good ory set up. Unless its weight savings and sound you are looking for, then td's would be a perfect choice.
hp is merely a function of torque. all its good for is car advertisements and bench racers.
for you huggerorange you made a good choice, with a cam you should see an improvement over a ory set up.
for the people who are stock internally you wont see much of an improvement if any over a good ory set up. Unless its weight savings and sound you are looking for, then td's would be a perfect choice.
Originally Posted by slik98z
(Torque x Engine speed)....for the people who are stock internally you wont see much of an improvement if any over a good ory set up..
<---Picked up 24 rwhp at 5000-5500 over a custom 3" open Y, and almost as much torque - stock internal.
Took the weight savings as gravy...