HP gain from header, down pipe and exh system.
03-30-2011, 12:07 AM
#1
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HP gain from header, down pipe and exh system.
I rarely post here, but I do read all the time. Please don't give me crap about doing a search, I have, and it just doesn't give what I'm looking for.
I have a Badmab header, although mine is older from Cobalt Addiction, it's been sitting in my spare room for a year now. I understand that these are one in the same. Nice piece and I see it's worth about 10hp and as much torque.
Been reading about the mandrelbentexhaust site and I see that they offer some nice stuff at a reasonable price.
So, how much HP (documented) is the 3" catted down pipe with a 2.5" mandrel exh and a good muff worth over the stock setup? Another 10hp? Less? More?
My car is all stock except for GM stage 2 and I like the way it runs. Not bad ass fast, but very pleasant compared to stone stock. Been running the stage 2 for 30K miles now, nary a problem. I even still have the stock air filter element.
I also wonder how long the aftermarket cats last, I haven't had good experiences with the Magnaflow or Dynomax cats, they seem to last about a year........
You can see from my .sig that I'm a rather serious hotrodder, and would like to tweak the Cobalt just a bit.......for now. I'ts been a great reliable fun car to date, I bought it new.
Ron
I have a Badmab header, although mine is older from Cobalt Addiction, it's been sitting in my spare room for a year now. I understand that these are one in the same. Nice piece and I see it's worth about 10hp and as much torque.
Been reading about the mandrelbentexhaust site and I see that they offer some nice stuff at a reasonable price.
So, how much HP (documented) is the 3" catted down pipe with a 2.5" mandrel exh and a good muff worth over the stock setup? Another 10hp? Less? More?
My car is all stock except for GM stage 2 and I like the way it runs. Not bad ass fast, but very pleasant compared to stone stock. Been running the stage 2 for 30K miles now, nary a problem. I even still have the stock air filter element.
I also wonder how long the aftermarket cats last, I haven't had good experiences with the Magnaflow or Dynomax cats, they seem to last about a year........
You can see from my .sig that I'm a rather serious hotrodder, and would like to tweak the Cobalt just a bit.......for now. I'ts been a great reliable fun car to date, I bought it new.
Ron
03-30-2011, 07:52 AM
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U should make about 15 more hp with a full exhaust. Depends on supporting mods tho like intake and tune. I've got a k&n intake and full exhaust on my 2.2 plus a tune and I could def feel a difference in mid to upper rpm rage.
03-31-2011, 03:03 AM
#8
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I'll just have to try this for myself. I'm not an idiot. I understand exh restriction.
When I changed my Nova from a dual 3" setup to a dual 3.5" setup it picked up 3mph and 2 tenths in the quarter mile. And that was from low tens to high nines. I built it all myself. This is on a 700 hp dyno tested engine.
I just want to know how much to expect from a header and good exh from the supercharged 2.0 with the stock blower, stage 2 and that's all. I don't have the M90 nor is it a 2.2NA motor.
Tune? There is no one here in Portland that I know of who knows the Balt SS/SC or knows of HP tuners. From what I've seen here, bad tunes result in grenaded pistons and dipsticks blowing out and sending oil all over the engine. If I were to get that serious, and I might, I'll buy HP tuners and learn it myself. I'm pretty good at this stuff, I have just been enjoying the Cobalt SS/SC as is and I like it.
Says a lot when I drive a low 9 second ride from time to time in the summer.
What can I say, I'm a die hard Chevy guy, and here in Portland OR, in 5 yaras, I have only seen about 5 of these on the road.
Ron
When I changed my Nova from a dual 3" setup to a dual 3.5" setup it picked up 3mph and 2 tenths in the quarter mile. And that was from low tens to high nines. I built it all myself. This is on a 700 hp dyno tested engine.
I just want to know how much to expect from a header and good exh from the supercharged 2.0 with the stock blower, stage 2 and that's all. I don't have the M90 nor is it a 2.2NA motor.
Tune? There is no one here in Portland that I know of who knows the Balt SS/SC or knows of HP tuners. From what I've seen here, bad tunes result in grenaded pistons and dipsticks blowing out and sending oil all over the engine. If I were to get that serious, and I might, I'll buy HP tuners and learn it myself. I'm pretty good at this stuff, I have just been enjoying the Cobalt SS/SC as is and I like it.
Says a lot when I drive a low 9 second ride from time to time in the summer.
What can I say, I'm a die hard Chevy guy, and here in Portland OR, in 5 yaras, I have only seen about 5 of these on the road.
Ron
03-31-2011, 03:22 AM
#9
going from a stock LSJ exhaust to a shorty, 2.5" dp of choice and 2.5" catback should net 10-15whp gain on a m62.
simply work out a deal w/ the dyno operator.
Baseline your cobalt
install the header, redyno
install dp, redyno
install catback, final dyno
that will answer your question. The header and catback will be the most time consuming. If your dyno operator is cool, it should take you 5-10 minutes to bolt a aftermarket downpipe on.
simply work out a deal w/ the dyno operator.
Baseline your cobalt
install the header, redyno
install dp, redyno
install catback, final dyno
that will answer your question. The header and catback will be the most time consuming. If your dyno operator is cool, it should take you 5-10 minutes to bolt a aftermarket downpipe on.
03-31-2011, 10:47 AM
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I can say from experience that a full length header (like a cheapo pacesetter with a proper flange on it) with 2.5" downpipe and the rest of the exhaust stock I made 215whp/195ft.lbs. with nothing more than an intake. I do know the difference between my later revised 3" downpipe with 3" cutout on the dyno wasn't too noticable either. I had a Harrop with a 2.8 pulley and a slew of other mods. The 100% stock cat back was on the car though and the difference between it and the cutout open off the bottle...
8whp, -4ft.lbs.
Yes, I lost torque with the cut out open. Barely more hp than was worth it to run a 3" open exhaust on the street. This is why I used to get on people's **** when their first mod was a cat-back instead of the header.
8whp, -4ft.lbs.
Yes, I lost torque with the cut out open. Barely more hp than was worth it to run a 3" open exhaust on the street. This is why I used to get on people's **** when their first mod was a cat-back instead of the header.
04-02-2011, 02:54 PM
#12
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Thanks for the responses.
I have a plan, and it will be to keep the stock down pipe, but at least work it to match the 3" outlet of the header. At least make the transition less abrupt, if I can.
The stock cat is warrantied for 100K miles, and the aftermarket stuff just isn't that good in my experience.
For the ehx, I have the OTTP rear section of pipe, I just need to pick a good muff. Folks say to use the Dynomax turbo, well I have used those in the past on my Quad 4 car, and they do sound good, but last about a year before the fiberglass blows out. I'll try the longest Magnaflw that will fit. I have them on my Nova, and they are great and don't blow out. If it's a bit loud, there are tips that can help.
Ron
I have a plan, and it will be to keep the stock down pipe, but at least work it to match the 3" outlet of the header. At least make the transition less abrupt, if I can.
The stock cat is warrantied for 100K miles, and the aftermarket stuff just isn't that good in my experience.
For the ehx, I have the OTTP rear section of pipe, I just need to pick a good muff. Folks say to use the Dynomax turbo, well I have used those in the past on my Quad 4 car, and they do sound good, but last about a year before the fiberglass blows out. I'll try the longest Magnaflw that will fit. I have them on my Nova, and they are great and don't blow out. If it's a bit loud, there are tips that can help.
Ron
Last edited by RonSS; 04-06-2011 at 06:37 PM.
04-06-2011, 11:41 AM
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If you don't replace the DP along with the manifold it isn't worth doing the exhaust. Next to the manifold your DP is your next huge restriction. It bends down to a 2" pipe. With the amount of modifications you have you don't need to upgrade to more than a 2.5" and if you check out OTTP's website they have an over axle system which slips onto the stock cat-back replacing where ours narrows down to 2.25" with a 2.5" section. Replacing just the muffler on our cars can net you around 8whp.
04-06-2011, 07:07 PM
#14
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If you would have read the post you responded to, I have the OTTP over the axle pipe, I just need to pick a muffler and get it installed.
I have been under the car, and I don't recall that the stock DP get's that small. But, looking at the ZZP site, I see the reason. Can't be seen from the outside. The factory flex connector is what gets small. So I see your point here.
I have to pass emissions, and as I stated, I haven't seen an aftermarket cat last more than a year. There is a reason they cost $100 and the stockers cost $400.
Interesting that I have also heard that the inlet to the stock resonator is the most restrictive part....
Thanks for the response.
Ron
I have been under the car, and I don't recall that the stock DP get's that small. But, looking at the ZZP site, I see the reason. Can't be seen from the outside. The factory flex connector is what gets small. So I see your point here.
I have to pass emissions, and as I stated, I haven't seen an aftermarket cat last more than a year. There is a reason they cost $100 and the stockers cost $400.
Interesting that I have also heard that the inlet to the stock resonator is the most restrictive part....
Thanks for the response.
Ron
If you don't replace the DP along with the manifold it isn't worth doing the exhaust. Next to the manifold your DP is your next huge restriction. It bends down to a 2" pipe. With the amount of modifications you have you don't need to upgrade to more than a 2.5" and if you check out OTTP's website they have an over axle system which slips onto the stock cat-back replacing where ours narrows down to 2.25" with a 2.5" section. Replacing just the muffler on our cars can net you around 8whp.
Last edited by RonSS; 04-06-2011 at 08:00 PM.
04-06-2011, 08:31 PM
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I apologize, I didn't see that. I have a Magnaflow muffler like they use on the over axle kit or you could get a Borla. I didn't even know our resonator was that restrictive, thank you for mentioning that. If you get a SPUN cat they are apparently really good. From what I read our cars have potential to pass cat-less but I wouldn't recommend that.
04-07-2011, 12:59 PM
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Here in Oregon, they look to see if the cat is in place......
I suppose as long as I don't throw away the stock parts, I could re-install them at test time if need be.
How did the install of the OTTP over the axle pipe go? Looks like you have to guess at where to cut....and be conservative.....too short is not good. And what did you use for hangers on the muff?
I've built lots of exh systems for older cars, but these new cars have really nifty hangers and I haven't found any place to buy the parts to make them.
The stock muffler cracks me up, it looks like a gas tank! I wonder how bad they really flow? It would be fun to cut one open and look inside.
Thanks again for the response.
Ron
I suppose as long as I don't throw away the stock parts, I could re-install them at test time if need be.
How did the install of the OTTP over the axle pipe go? Looks like you have to guess at where to cut....and be conservative.....too short is not good. And what did you use for hangers on the muff?
I've built lots of exh systems for older cars, but these new cars have really nifty hangers and I haven't found any place to buy the parts to make them.
The stock muffler cracks me up, it looks like a gas tank! I wonder how bad they really flow? It would be fun to cut one open and look inside.
Thanks again for the response.
Ron
10-18-2012, 07:02 PM
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I hav a 07" 2.0 ss colbalt with gm stage2 and its tuned with 2.5" magmaflow full pipe. My question is i replaces stock flex pipe with a flex pipe of 2.25" (stock 2.5"). Now i am going to bounce to up to 3" down pipe with a 4 - 1 header 3" exit.whT gain will i get withe whitch.
10-18-2012, 08:44 PM
#19
This is not true. Our cars love to breath trust me. I have a dyno sheet to prove it too. With a badmab header, zzp 3in dp with the factory cat added in n 3in mandrel bent tubing into a flowmaster. I made with NO TUNE 234hp 200tq @ 12psi with stock pulley n no aftermarket air filter either
10-19-2012, 07:21 AM
#20
This is not true. Our cars love to breath trust me. I have a dyno sheet to prove it too. With a badmab header, zzp 3in dp with the factory cat added in n 3in mandrel bent tubing into a flowmaster. I made with NO TUNE 234hp 200tq @ 12psi with stock pulley n no aftermarket air filter either
Not to mention, dyno numbers don't mean much unless you have a before & after dyno graph on the same dyno, on the same day. If you do, than cudos to you. Post em up.
Biggest gain from the exhaust will be see after porting the exhaust side of the head. That's where the main restriction is once you start modding.
10-19-2012, 07:58 AM
#21
U know that the stock SS/SC dynos around 210-215whp right? So your gains are on par with the quote you are disagreeing with.... If that is indeed what you are disagreeing with.
Not to mention, dyno numbers don't mean much unless you have a before & after dyno graph on the same dyno, on the same day. If you do, than cudos to you. Post em up.
Biggest gain from the exhaust will be see after porting the exhaust side of the head. That's where the main restriction is once you start modding.
Not to mention, dyno numbers don't mean much unless you have a before & after dyno graph on the same dyno, on the same day. If you do, than cudos to you. Post em up.
Biggest gain from the exhaust will be see after porting the exhaust side of the head. That's where the main restriction is once you start modding.
10-19-2012, 08:05 AM
#22
You wouldn't want exhaust ports on the head larger than the ports on the header. This can lead to turbulence. Most cases you will be fine with leaving the header alone.
I plan on doing a gasket matched port to the exhaust ports on my head if I cant source out a GMR head.
10-19-2012, 08:21 AM
#23
Depends on how big you go with the ports....
You wouldn't want exhaust ports on the head larger than the ports on the header. This can lead to turbulence. Most cases you will be fine with leaving the header alone.
I plan on doing a gasket matched port to the exhaust ports on my head if I cant source out a GMR head.
You wouldn't want exhaust ports on the head larger than the ports on the header. This can lead to turbulence. Most cases you will be fine with leaving the header alone.
I plan on doing a gasket matched port to the exhaust ports on my head if I cant source out a GMR head.
from there a full exhaust wont do ya much, maybe just get rid of the kink
10-19-2012, 08:39 AM
#25
Are you talking about how it turns into 2.25" piping over the axle?
Also, the inlet of the stock resonator is only 2 1/16". That is one of the main restrictions not many people know about.