Finally Stage 2!
Joined: 12-30-07
Posts: 14,079
Likes: 197
From: NEPA
I'm very curious on those trq numbers if you ever get a chance and remember. That is interesting stuff. These things really do need more injector to begin with. I think I've only read one ported head only change on a dyno for a TVS car. I'm just curious what results would be on a m62 car both big and smaller pulley. We all know you'll gain HP for sure, how much just interests me.
That's a good comparison from yours and your buddies TVS set up. Makes me hopeful for the wife's Redline when we finally do the head.
Now that is a nice comparison. It all makes me wonder because lately on the forums and fb pages its all header and dp are a waste of time and no gain on a m62 car. You'll loose trq/flow blah blah. No real dyno of it.
I also thought bolt on's on a stock tune car were a waste because my completely stock Redline is just as fast if not faster then my buddies Cobalt with 3" intake, 3" dp, 2.25 cat back, dual pass, opt b car. Now I'm thinking he sucks at driving haha. I've driven his car and it feels like mine maybe faster. Hpt log times show similar results. Maybe now we'll video a slow as stock race haha.
Anyway I'm just curious guys. Thanks for sharing and info. I'm still leaning on ported head, injectors, tune/e85 as my first mods for my silver car. After a complete stock dyno read out first.
That's a good comparison from yours and your buddies TVS set up. Makes me hopeful for the wife's Redline when we finally do the head.
Now that is a nice comparison. It all makes me wonder because lately on the forums and fb pages its all header and dp are a waste of time and no gain on a m62 car. You'll loose trq/flow blah blah. No real dyno of it.
I also thought bolt on's on a stock tune car were a waste because my completely stock Redline is just as fast if not faster then my buddies Cobalt with 3" intake, 3" dp, 2.25 cat back, dual pass, opt b car. Now I'm thinking he sucks at driving haha. I've driven his car and it feels like mine maybe faster. Hpt log times show similar results. Maybe now we'll video a slow as stock race haha.
Anyway I'm just curious guys. Thanks for sharing and info. I'm still leaning on ported head, injectors, tune/e85 as my first mods for my silver car. After a complete stock dyno read out first.
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Joined: 10-02-11
Posts: 127
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From: Fargo, ND
I agree with you 100% with the FB pages. I was on the cobalt ss gang page but I left because I couldn't handle the stupidity.
Joined: 12-30-07
Posts: 14,079
Likes: 197
From: NEPA
I don't even go on any of the regular FB pages besides the IRL one once in a while, and usually only when someone tags me haha. One of my first races over 7 years ago when I was stock with a short ram intake was an LSJ SS with intake and full Hahn header-back exhaust. From a 30 roll we were close until about 50 and then he put 2 cars on me by 100. That's when I learned what exhaust did for these cars...then I bought his header and DP shortly after that when he sold his car 
Oh and after that race we raced from a dig in front of like 40 people and I got the launch and he couldn't catch me
lol
Oh and after that race we raced from a dig in front of like 40 people and I got the launch and he couldn't catch me
lol
I don't even go on any of the regular FB pages besides the IRL one once in a while, and usually only when someone tags me haha. One of my first races over 7 years ago when I was stock with a short ram intake was an LSJ SS with intake and full Hahn header-back exhaust. From a 30 roll we were close until about 50 and then he put 2 cars on me by 100. That's when I learned what exhaust did for these cars...then I bought his header and DP shortly after that when he sold his car
Oh and after that race we raced from a dig in front of like 40 people and I got the launch and he couldn't catch me lol
Oh and after that race we raced from a dig in front of like 40 people and I got the launch and he couldn't catch me
lol
Joined: 12-30-07
Posts: 14,079
Likes: 197
From: NEPA
Agreed. Got one person who dynoed on two different days and different dynos with unexpected results and now has the whole community thinking header/dp is a waste or time and money. SMH. I just know from personal experience doing those mods really made a difference, but again no one has and actual dyno proof.
Lol driver makes all the difference in these cars. See another exhaust test showing it helped. Just like staged said, gonna continue to have a lot of underpowered LSJ cars because people can't put their money in smart places.
Lol driver makes all the difference in these cars. See another exhaust test showing it helped. Just like staged said, gonna continue to have a lot of underpowered LSJ cars because people can't put their money in smart places.
From how he guided me with my build to the many other cars making good numbers with a free flowing exhaust, that's proof enough for me.
Last edited by Staged07SS; Jun 23, 2015 at 10:56 AM.
Joined: 12-30-07
Posts: 14,079
Likes: 197
From: NEPA
The stock SS/SC catback is 2.5" for the most part, minus a neck down portion over the rear axle and a tiny inlet to the resonator.
The gains from a catback are due to a straight through muffler, and larger inlet to the resonator.
Gains from a catback on the SS/SC are generally 5 hp or so. The real restriction lies in the exhaust ports in the head, and the downpipe.
Junior Member
Joined: 04-18-14
Posts: 424
Likes: 7
From: Mississauga, ON, Canada
3.0" is overkill on an M62 car unless u are spraying.
The stock SS/SC catback is 2.5" for the most part, minus a neck down portion over the rear axle and a tiny inlet to the resonator.
The gains from a catback are due to a straight through muffler, and larger inlet to the resonator.
Gains from a catback on the SS/SC are generally 5 hp or so. The real restriction lies in the exhaust ports in the head, and the downpipe.
The stock SS/SC catback is 2.5" for the most part, minus a neck down portion over the rear axle and a tiny inlet to the resonator.
The gains from a catback are due to a straight through muffler, and larger inlet to the resonator.
Gains from a catback on the SS/SC are generally 5 hp or so. The real restriction lies in the exhaust ports in the head, and the downpipe.
That's exactly what I needed to know, thanks!
Joined: 12-30-07
Posts: 14,079
Likes: 197
From: NEPA
I knew about the size reduction to 2.25" before the rear axle, but not the tiny inlet into the resonator..... so there might be a few horses to be had by replacing the resonator inlet and resonator to something that's 2.5" in/out, but probably not worth it.
That's exactly what I needed to know, thanks!
That's exactly what I needed to know, thanks!
Junior Member
Joined: 04-18-14
Posts: 424
Likes: 7
From: Mississauga, ON, Canada
People are so stuck on pipe size being the determining factor for performance that's really half the battle probably even less then that. What you should be more concerned about is cfm flow. Even 2.25 is enough for the m62, its getting rid of the restrictive parts of the exhaust, the factory cat, the resonator and muffler.
Good components like Borla, Corsa, Dynomax are good places to start. People don't realize that in most Magnaflow components the like of the inner diameter of the mufflers or resonator shrink. 2.5 mufflers or resonators usually have 2.25 cores. They also use baffled resonators or louvered ones which hurt flow.
People think they are gaining going to a 3" exhaust, but what's they really get from that is not the piping size, but the mufflers size increase adding more flow. Eventually 2.5 will restrict a high flowing set up, gotta dyno to find out when.
Good components like Borla, Corsa, Dynomax are good places to start. People don't realize that in most Magnaflow components the like of the inner diameter of the mufflers or resonator shrink. 2.5 mufflers or resonators usually have 2.25 cores. They also use baffled resonators or louvered ones which hurt flow.
People think they are gaining going to a 3" exhaust, but what's they really get from that is not the piping size, but the mufflers size increase adding more flow. Eventually 2.5 will restrict a high flowing set up, gotta dyno to find out when.
Joined: 12-30-07
Posts: 14,079
Likes: 197
From: NEPA
People are so stuck on pipe size being the determining factor for performance that's really half the battle probably even less then that. What you should be more concerned about is cfm flow. Even 2.25 is enough for the m62, its getting rid of the restrictive parts of the exhaust, the factory cat, the resonator and muffler.
Good components like Borla, Corsa, Dynomax are good places to start. People don't realize that in most Magnaflow components the like of the inner diameter of the mufflers or resonator shrink. 2.5 mufflers or resonators usually have 2.25 cores. They also use baffled resonators or louvered ones which hurt flow.
People think they are gaining going to a 3" exhaust, but what's they really get from that is not the piping size, but the mufflers size increase adding more flow. Eventually 2.5 will restrict a high flowing set up, gotta dyno to find out when.
Good components like Borla, Corsa, Dynomax are good places to start. People don't realize that in most Magnaflow components the like of the inner diameter of the mufflers or resonator shrink. 2.5 mufflers or resonators usually have 2.25 cores. They also use baffled resonators or louvered ones which hurt flow.
People think they are gaining going to a 3" exhaust, but what's they really get from that is not the piping size, but the mufflers size increase adding more flow. Eventually 2.5 will restrict a high flowing set up, gotta dyno to find out when.
Junior Member
Joined: 04-18-14
Posts: 424
Likes: 7
From: Mississauga, ON, Canada
People are so stuck on pipe size being the determining factor for performance that's really half the battle probably even less then that. What you should be more concerned about is cfm flow. Even 2.25 is enough for the m62, its getting rid of the restrictive parts of the exhaust, the factory cat, the resonator and muffler.
Good components like Borla, Corsa, Dynomax are good places to start. People don't realize that in most Magnaflow components the like of the inner diameter of the mufflers or resonator shrink. 2.5 mufflers or resonators usually have 2.25 cores. They also use baffled resonators or louvered ones which hurt flow.
People think they are gaining going to a 3" exhaust, but what's they really get from that is not the piping size, but the mufflers size increase adding more flow. Eventually 2.5 will restrict a high flowing set up, gotta dyno to find out when.
Good components like Borla, Corsa, Dynomax are good places to start. People don't realize that in most Magnaflow components the like of the inner diameter of the mufflers or resonator shrink. 2.5 mufflers or resonators usually have 2.25 cores. They also use baffled resonators or louvered ones which hurt flow.
People think they are gaining going to a 3" exhaust, but what's they really get from that is not the piping size, but the mufflers size increase adding more flow. Eventually 2.5 will restrict a high flowing set up, gotta dyno to find out when.
Per David Vizar (Auto Exhaust Science - View All Page), 1sqin of pipe flows about 115cfm, and you need about 2.2cfm of exhaust gas flow per HP. Now, assuming we're talking about a mild bolt-on LSJ M62 engine, we're in the range of 240whp, which is about 264 crank HP (10% driveline loss). That's about 580cfm of airflow, or 5sqin of pipe area requirement or 2.52" diameter.
Obviously things like a cat will increase exhaust flow reqs after it, and mufflers/resonators will decrease flow reqs, and some engines just seem to prefer different sizes for whatever reason.
In any case, everybodies experience pretty much aligns with the math - 2.5" is good for an M62... and the challenge is fixing the choke points in the factory system
Also interesting that all of the long tube headers have 3" collectors, where the math says that 2.5" would be a better match...
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