I was advised against headers & bigger pipes
Thread Starter
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
I was advised against headers & bigger pipes
I have a stock small block L46. My original plan as part of a bunch of upgrades was to spend some money on the exhaust. I was planning to go with ceramic coated long tubes, 2.5" pipes and either magnas or flows. I understand that the carb will need to be adjusted to balance out the larger exhaust.
Spoke with a few vette guys with many years of vette racing experience who told me not to waste my money unless I plan on racing the car (which I do not see myself taking it to the track). They said headers and 2.5" pipes are overkill for a stock 350 and the motor wont breath right. They said that yes, I may feel a little more HP but not worth the work/money. The advice was to upgrade exhaust to the next size up from stock OR leave it alone and just throw on new mufflers for better sound.
Are they completely off or should I trust their experience?
BTW....what is the stock exhaust size on a small block?
Spoke with a few vette guys with many years of vette racing experience who told me not to waste my money unless I plan on racing the car (which I do not see myself taking it to the track). They said headers and 2.5" pipes are overkill for a stock 350 and the motor wont breath right. They said that yes, I may feel a little more HP but not worth the work/money. The advice was to upgrade exhaust to the next size up from stock OR leave it alone and just throw on new mufflers for better sound.
Are they completely off or should I trust their experience?
BTW....what is the stock exhaust size on a small block?
Drifting
Joined: Aug 2005
Posts: 1,372
Likes: 4
From: Springfield VA
Factory exhaust manifolds were a compromise for cost, noise, and longevity. After market headers usually give up more noise but breath better.
If you are not making any major modifications to your motor I would do the exhaust headers and tie into what you have. Little cheaper but probably best bang for the buck for now. After that if you add any heavy engine mods then get larger pipes and mufflers later.
If you are not making any major modifications to your motor I would do the exhaust headers and tie into what you have. Little cheaper but probably best bang for the buck for now. After that if you add any heavy engine mods then get larger pipes and mufflers later.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
It's a free country. You're allowed to waste your $$$ any way you see fit. And it might help the economy unless you were planning on going the CHINESE OBX route.
Thread Starter
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
Thanks for the input. The money could be used elsewhere on the car. I would like to use the money wise so that I get the most improvement for what I spent.
Race Director
Joined: May 2006
Posts: 18,737
Likes: 2,583
You state the exhaust was part of a bunch of upgrades. For those upgrades to show their maximum potential benefit you need a better exhaust than stock so going for the headers and 2 1/2" exhaust is a good start.
Thread Starter
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
The other upgrades are mostly in the suspension/steering department...none on the motor... this is why I am considering putting off exhaust work until it can REALLY show some improvement.
Drifting
Joined: Jul 2007
Posts: 1,889
Likes: 23
From: Kansas
Yes Sir: Mr. rafale, I agree W/ Mr. Melwff, But by all means, Do the suspension/steering Frist! Both front & rear, Use all the H. D. up-grades, completely rebuild the trailing arms. Then do the brakes, all the way, No short cuts, stainless line replacement, never worry about rust again. Now it's ready for any motor. Have a ball, it's great fun. Gene
Racer
Joined: Mar 2009
Posts: 394
Likes: 1
From: Everywhere US
headers ..... you'll enjoy the sound and like the way it runs ..... bigger exhaust on its own with a stock motor ... not so much .... some loss in low end torque ...
the best part .... its your hot rod .... you get to choose what you do to it ....
ENJOY !!!!
the best part .... its your hot rod .... you get to choose what you do to it ....
ENJOY !!!!
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Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
it is my understanding that the L46, like it's cousin, the L82, is not a "stock" engine, in the same sense that an L48 is. It actually has a pretty good sized cam for a stock engine. I think that freeing up the exhaust on an engine like this would give noticeable results, especially when combined with a re-curved distributor. And if you are planning on engine mods in the future, the free-flowing exhaust will already be there for the new mods to take advantage of, so it won't really be money wasted. If it needs a new exhaust system, anyway, I would go ahead and do it, but if the present exhaust system is in good shape, I would leave it for later, and use the money for more immediate needs, such as brakes, suspension, and steering. If you are going to pull the engine and rebuild it, Install the new exhaust before you do so, it will make the chore of re-installing the engine easier. It's a big enough job without having to worry about a new exhaust, to boot. I hope this helps you make your decision, and good luck to you!
Keep the shiny side up!
Scott
Keep the shiny side up!
Scott
Burning Brakes
Joined: Dec 2010
Posts: 945
Likes: 10
From: Winston Salem NC
My philosophy for my car has been to make the car enjoyable first, then to work on performance. I redid my interior in 2011. I added insulation and replaced some broken worn out console stuff. Also rebuilt the AC system. I did alot to keep hot air out of the cabin.
This year I rebuilt the tranny, replaced the clutch, redid the rear main and put in a new exhaust.
My L-48 engine is stock and my long tube headers and dual exhaust have helped performance. I did not tweak the carb. Also, I needed a new exhaust system. The old one was rusty and leaking. I did not want to go halfway or have to touch it again so I went with stainless headers and ceramic coated them. I also got the Magnaflow 16842 system which is 2.5" with an x-pipe. I love it.
I heard the same comments about free flowing exhaust hurting performance or not being able to tell a difference. My experience is the complete opposite.
This year I rebuilt the tranny, replaced the clutch, redid the rear main and put in a new exhaust.
My L-48 engine is stock and my long tube headers and dual exhaust have helped performance. I did not tweak the carb. Also, I needed a new exhaust system. The old one was rusty and leaking. I did not want to go halfway or have to touch it again so I went with stainless headers and ceramic coated them. I also got the Magnaflow 16842 system which is 2.5" with an x-pipe. I love it.
I heard the same comments about free flowing exhaust hurting performance or not being able to tell a difference. My experience is the complete opposite.
Last edited by jcloving; Aug 1, 2012 at 04:07 PM. Reason: added more comments!
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
it is my understanding that the L46, like it's cousin, the L82, is not a "stock" engine, in the same sense that an L48 is. It actually has a pretty good sized cam for a stock engine. I think that freeing up the exhaust on an engine like this would give noticeable results, especially when combined with a re-curved distributor. And if you are planning on engine mods in the future, the free-flowing exhaust will already be there for the new mods to take advantage of, so it won't really be money wasted. If it needs a new exhaust system, anyway, I would go ahead and do it, but if the present exhaust system is in good shape, I would leave it for later, and use the money for more immediate needs, such as brakes, suspension, and steering. If you are going to pull the engine and rebuild it, Install the new exhaust before you do so, it will make the chore of re-installing the engine easier. It's a big enough job without having to worry about a new exhaust, to boot. I hope this helps you make your decision, and good luck to you!
Keep the shiny side up!
Scott
Keep the shiny side up!
Scott
78 L-82 4 Speed totally stock internals (cam, heads, intake, pistons etc), 65,000 miles (time of dyno last year) with the only changes from the OEM factory components:
1. Holley 650 CFM spreadbore Qjet replacement-lightest vacuum secondary spring Holley sells versus the one that came in the carb.
2.Comp Cams Roller tipped 1.5 rockers (same ratio as stock, not true rollers).
3. McJacks Shorty headers, not block hugger headers.
4. 2.5 inch true duals with Monza Turbo mufflers-no cats.
78 L-82 rated from the factory at 220 Net HP
4 Dyno pulls in Oct 2011 with Forum member, Karol, witnessing as well.
Best pull was 233 RWHP which is about 290 Net HP using a 20% correction factor for drivetrain loss or about 330 Gross HP (pretty even with the 330 Gross HP LT-1.
You decide if it is worth doing the exhaust?
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
Really depends on the state of tune you're engine is currently in, but always find a freer flowing exhaust to be a good thing. Another thing to consider, while the coated long tubes aren't exactly cheap, can actually make rest of the exhaust system cheaper, and maybe save you some bodywork paint scratches. Installer can do everything from underneath, without even raising the hood.
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
Go for it - your L46 will LOVE the new exhaust - mine does! I suggest putting in an "X" also - I feel it helped the flow and sound a lot!! I have Flowmaster 50's - they have been good and I like them because they are not obnoxiously loud - but I have heard one with Magnas and that would be my choice if I were to ever decide to change them.
Scott (scottyp99) has some excellent advise - take heed!!
Scott (scottyp99) has some excellent advise - take heed!!
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
it is my understanding that the L46, like it's cousin, the L82, is not a "stock" engine, in the same sense that an L48 is. It actually has a pretty good sized cam for a stock engine. I think that freeing up the exhaust on an engine like this would give noticeable results, especially when combined with a re-curved distributor. And if you are planning on engine mods in the future, the free-flowing exhaust will already be there for the new mods to take advantage of, so it won't really be money wasted. If it needs a new exhaust system, anyway, I would go ahead and do it, but if the present exhaust system is in good shape, I would leave it for later, and use the money for more immediate needs, such as brakes, suspension, and steering. If you are going to pull the engine and rebuild it, Install the new exhaust before you do so, it will make the chore of re-installing the engine easier. It's a big enough job without having to worry about a new exhaust, to boot. I hope this helps you make your decision, and good luck to you!
Keep the shiny side up!
Scott
Keep the shiny side up!
Scott
L46 is 11 to 1 comp, big hydraulic cam, 2.02 valves, screw in studs, Forged crank, pink rods, 1 HP per CI with a low rise intake and stock manifolds. This is not a typical "stock" engine but a hydraulic cam version of an LT1. Headers and a low restriction 2 1/2" exhaust is the best bang for your buck improvement you can make on this engine. A good flowing intake is right up there. Performance distributior recurve is a must. You should see close to 400 actual FWHP with these two upgrades.
Last edited by 63mako; Aug 1, 2012 at 09:40 PM.
Tech Contributor
Joined: Jun 2004
Posts: 20,910
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Can you cite any law of physics to support that claim?
Drifting
Joined: Dec 2004
Posts: 1,714
Likes: 42
From: Austin Texas
I just went through this decision myself. I found this site to help me determine pipe sizing cfm http://www.exhaustvideos.com/faq/how...pipe-diameter/
This is a long read but Super Chevy thinks you can lose a bit of torque if the pipes are too big. http://www.superchevy.com/technical/...h/viewall.html perhaps bs.
I spoke with a Magnaflow tech and he said that they crush bend their mufflers to reduce sound. That is why I am going to try the ones in this video. http://www.youtube.com/watch?v=wxPIt-eoT3w
My car rear wheel dyno'd with 270 hp through a TH400. I have long tube headers and plan on a 2.5 in crush bent system with the Jones mufflers.
This is a long read but Super Chevy thinks you can lose a bit of torque if the pipes are too big. http://www.superchevy.com/technical/...h/viewall.html perhaps bs.
I spoke with a Magnaflow tech and he said that they crush bend their mufflers to reduce sound. That is why I am going to try the ones in this video. http://www.youtube.com/watch?v=wxPIt-eoT3w
My car rear wheel dyno'd with 270 hp through a TH400. I have long tube headers and plan on a 2.5 in crush bent system with the Jones mufflers.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
The engine should make more power everywhere, but, if I understand how long tube headers work, it will gain more top end power than it does low end power. That might be what hal1phx is trying to express. On the other hand, maybe not.
Keep the shiny side up!
Scott
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Read the sizing info. Measuring straight pipe (no bends) 2 1/4 will handle 371 HP max. 2 1/2 will handle 463 HP max. Add in bends and muffler restriction 2 1/2 is correct sizing. Good info. Primary sizing on headers with stock heads it shows 1 1/2 primaries. I would go 1 5/8.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Anyone who tells you that headers aren't worth the $$ on these cars is full of it... period.
My stock L48 was night and day improved when I went from exhaust manifolds to headers. It was power you could feel and it proved it.
0-60 times (against an accelerometer) went from 7.1 seconds down to ~6.5. In other words, with headers my stock automatic 78 L-48 was hitting 60 faster than a 4-speed L-82.
These effects will be even greater on a high performance motor, as mentioned above.
$300 for about 30 hp? It doesn't get better than that. The next big bump for me cost close to $3000.
My stock L48 was night and day improved when I went from exhaust manifolds to headers. It was power you could feel and it proved it.
0-60 times (against an accelerometer) went from 7.1 seconds down to ~6.5. In other words, with headers my stock automatic 78 L-48 was hitting 60 faster than a 4-speed L-82.
These effects will be even greater on a high performance motor, as mentioned above.
$300 for about 30 hp? It doesn't get better than that. The next big bump for me cost close to $3000.