Headers and sidepipes
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Joined: Jun 2006
Posts: 83
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From: Rockford MI
Headers and sidepipes
My rebuilt 327 isn't putting out the power that I expected (more of a "seat of the pants" thing than actual dyno results) and I'm wondering if my stock exhaust manifolds are a limiting factor.
Anyone have experience with buying off-the-shelf headers and using them on a car with sidepipes? Does the car get obnoxiously loud? And fitup issues?
Anyone have experience with buying off-the-shelf headers and using them on a car with sidepipes? Does the car get obnoxiously loud? And fitup issues?
Le Mans Master
Joined: Apr 2005
Posts: 6,359
Likes: 428
From: Seattle Area WA
Have you read any of the recent posts on Marks 327 with the LT1 cam or 632Cs 383 engine and their dyno results. Both use 2 1/2 stock rams horn exhaust manifolds and are performing extremely well.
What compression, and cam combination are you runnning. That may have more to do with it than the rams horn exhaust. Even a 2" rams horn exhaust performs very well.
What compression, and cam combination are you runnning. That may have more to do with it than the rams horn exhaust. Even a 2" rams horn exhaust performs very well.
Le Mans Master
Joined: Apr 2001
Posts: 9,556
Likes: 288
From: Granbury Texas
I can't speak for others, but I have run Hooker headers with sidemounts on my Corvettes for almost 40 years, and have nothing but good things to say about them. The mufflers are somewhat restrictive, but some of the new technology "spiral baffles" will remedy that. Also, any tubing header will be louder and more subject to reliability issues (mechanical failure due to heat stress) than a comparable cast iron header. I'd say "Go for it"!
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Joined: Jun 2006
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From: Rockford MI
Originally Posted by Scott Marzahl
Have you read any of the recent posts on Marks 327 with the LT1 cam or 632Cs 383 engine and their dyno results. Both use 2 1/2 stock rams horn exhaust manifolds and are performing extremely well.
What compression, and cam combination are you runnning. That may have more to do with it than the rams horn exhaust. Even a 2" rams horn exhaust performs very well.
What compression, and cam combination are you runnning. That may have more to do with it than the rams horn exhaust. Even a 2" rams horn exhaust performs very well.
Block 0.030" over
Keith Black hyper. pistons
1.94 "double hump" heads - modestly (non-professionally) ported
CR targeted at a touch north of 10:1
standard rocker setup
My cam is a Comp Cam - can't remember the details, but will track them down and re-post.
Burning Brakes
Joined: Jan 2006
Posts: 1,096
Likes: 0
From: Horsetown USA (Norco) Kaleeforkneeah
I just added Headman, sidepipe headers, and 2 1/2" side exhaust to my car. I sounds so much sweeter than the 2" under car I was runnig. My engine is such a dog though, that I couldn't feel any real difference in power, but I'm sure it will make a huge difference when I get a new engine, that breathes.
Pro
Joined: Aug 2003
Posts: 635
Likes: 1
From: cincinnati oh
i kinda did it
i added 2.5 inch pipes and chambered exhaust going out the back rather than side. i did not want exhaust on side and wanted noise coming out the back. first, love the exhaust, loud yes, but hey, you only live once. also, engine seems to breathe easier. gets on it much more. engine roars now. i had 2 inch pipes before with 3 chamber flowmasters. so, i think you will love the sound and probably get better performance. go for it. either out the side or out the back. it is loud.
Burning Brakes
Joined: Dec 2005
Posts: 998
Likes: 2
Everything I've read or heard seems to point that unless you are running OPEN headers, there is virtually no performance gains over the stock ram manifolds.
If you really want to see a performance difference, "roller" your motor. I did mine when I developed a slight oil seepage on a head gasket, mothballed all the L76 parts, and made the stock 326/365 seem like it was asleep in comparison.....
If you really want to see a performance difference, "roller" your motor. I did mine when I developed a slight oil seepage on a head gasket, mothballed all the L76 parts, and made the stock 326/365 seem like it was asleep in comparison.....
Racer
Joined: May 2006
Posts: 268
Likes: 0
From: Farmington Hills Michigan
Why not do both. Roller and headers.
Depending on the cam, carb., etc. the engine some pick up some power with headers. More with highly modified engines. I'm not familiar with the side pipe arrangement.
Also power will pick up quite a bit as the engine breaks in.
Depending on the cam, carb., etc. the engine some pick up some power with headers. More with highly modified engines. I'm not familiar with the side pipe arrangement.
Also power will pick up quite a bit as the engine breaks in.
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Thread Starter
Advanced
Joined: Jun 2006
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From: Rockford MI
Originally Posted by abedford
Here are some engine details:
Block 0.030" over
Keith Black hyper. pistons
1.94 "double hump" heads - modestly (non-professionally) ported
CR targeted at a touch north of 10:1
standard rocker setup
My cam is a Comp Cam - can't remember the details, but will track them down and re-post.
Block 0.030" over
Keith Black hyper. pistons
1.94 "double hump" heads - modestly (non-professionally) ported
CR targeted at a touch north of 10:1
standard rocker setup
My cam is a Comp Cam - can't remember the details, but will track them down and re-post.
The carb is a new Holley 600 single pumper vacuum secondary. The intake is an Edelbrock Performer.
The cam is a Comp Cams Xtreme Energy 12-242-2. Here are the specs:
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 1,600-5,800 RPM
Intake Duration at 050 inch Lift: 224
Exhaust Duration at 050 inch Lift: 230
Duration at 050 inch Lift: 224 int./230 exh.
Advertised Intake Duration: 268
Advertised Exhaust Duration: 280
Advertised Duration: 268 int./280 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.477 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.480 in.
Valve Lift with Factory Rocker Arm Ratio: 0.477 int./0.480 exh. lift
Lobe Separation (degrees): 110
Any comments about this setup and the potential improvement (if any) by adding headers?
Don't get me wrong - the car is fast, but not the kind of FAST I guess I was expecting. Could be my expectations just aren't realistic.
Last edited by abedford; Jul 25, 2006 at 08:37 PM.
Race Director
Joined: Jul 2002
Posts: 11,593
Likes: 173
From: Clayton NC
Originally Posted by Formula Outlaw
Everything I've read or heard seems to point that unless you are running OPEN headers, there is virtually no performance gains over the stock ram manifolds.
If you really want to see a performance difference, "roller" your motor. I did mine when I developed a slight oil seepage on a head gasket, mothballed all the L76 parts, and made the stock 326/365 seem like it was asleep in comparison.....
If you really want to see a performance difference, "roller" your motor. I did mine when I developed a slight oil seepage on a head gasket, mothballed all the L76 parts, and made the stock 326/365 seem like it was asleep in comparison.....
As for the roller cams I haven't entirely bought into it all yet. I have a roller cam but it hasn't really impressed me yet due to the what I believe are the restrictions of the stock intake manifold. Dave
Thread Starter
Advanced
Joined: Jun 2006
Posts: 83
Likes: 0
From: Rockford MI
Originally Posted by Formula Outlaw
Everything I've read or heard seems to point that unless you are running OPEN headers, there is virtually no performance gains over the stock ram manifolds.
If you really want to see a performance difference, "roller" your motor. I did mine when I developed a slight oil seepage on a head gasket, mothballed all the L76 parts, and made the stock 326/365 seem like it was asleep in comparison.....
If you really want to see a performance difference, "roller" your motor. I did mine when I developed a slight oil seepage on a head gasket, mothballed all the L76 parts, and made the stock 326/365 seem like it was asleep in comparison.....
Can you give me an idea what your total cost was to go with the full roller setup?
Race Director
Joined: Jul 2002
Posts: 11,593
Likes: 173
From: Clayton NC
Originally Posted by abedford
I've also read that only OPEN headers will make a significant improvement. I just keep thinking about my setup and wondering if the stock manifolds are preventing the engine from breathing like it really can.
Can you give me an idea what your total cost was to go with the full roller setup?
Can you give me an idea what your total cost was to go with the full roller setup?
Le Mans Master
Joined: Apr 2005
Posts: 6,359
Likes: 428
From: Seattle Area WA
The cam durations and lift look just a tad larger than the GM 151 cam, but what is killing your low end is the lobe seperation angle of 110 degrees. It has way too much overlap, even with headers it is too much. I would try to exchange it for a custom ground cam with 114 centers or just switch to a 151 cam and I think you will notice a big difference.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Originally Posted by Scott Marzahl
The cam durations and lift look just a tad larger than the GM 151 cam, but what is killing your low end is the lobe seperation angle of 110 degrees. It has way too much overlap, even with headers it is too much. I would try to exchange it for a custom ground cam with 114 centers or just switch to a 151 cam and I think you will notice a big difference.
As with almost all aftermarket cams, it has too much overlap that kills the low end. I'd put the "151" (L-79) hydraulic cam in it, and swap the intake for a factory SHP intake. If it's recently rebuilt you probably don't want to pull the heads, but if you do, I'd treat them to some pocket-porting and a 3-angle valve job. That will give you a nice street engine that's reliable and has more low-end torque than you have now. Forget the headers - they cause more problems than they solve, and they don't help any with a conventional exhaust system.
Safety Car
Joined: Mar 2002
Posts: 3,780
Likes: 442
From: Southwest MI
Originally Posted by abedford
My rebuilt 327 isn't putting out the power that I expected (more of a "seat of the pants" thing than actual dyno results) and I'm wondering if my stock exhaust manifolds are a limiting factor.
Anyone have experience with buying off-the-shelf headers and using them on a car with sidepipes? Does the car get obnoxiously loud? And fitup issues?
Anyone have experience with buying off-the-shelf headers and using them on a car with sidepipes? Does the car get obnoxiously loud? And fitup issues?
Headers
- Hedman makes a decent, low cost, sidepipe car header,
- Stahl make a very nice, expensive, sidepipe car header.
Side pipes
- Original design with the 2.5" pipes and the 1 7/8" core pipe; more restrictive than typical under-car system, but more sound.
- Aftermarket design with 2.5" core pipe; flow significant better than above, more sound yet
- what currently seems to be the best option for serious perf applications; spiral baffled side pipes (3" or 3.5" pipes, with polished SS tips, positioned under the covers with spiral baffles in the pipes).
example => http://www.spiralturbobaffles.com/
if i were you... with a mild street 327? (but understand, i don't mind a little sound)
2.5" manifolds, gutted/opened up heat riser valve!, a little mild porting work on the manifolds with a die grinder, a set 2.5" CORE side pipes.
Note: open a heat riser valve sometime and look thru it.... then imagine 4 cylinders trying to flow thru that little opening at high RPM? plug the shaft holes, & open it up with a die grinder!
or, for a few less $$, just get the Hedmans and fit some 2.5" core pipes to the collectors. (it all depends if you want the "stock look", and if don't mind header maintenance.)
Last edited by 66427-450; Jul 26, 2006 at 10:10 PM.