Options for '69 OE sidepipe mufflers
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
Options for '69 OE sidepipe mufflers
Has anyone built a custom pipe/muffler system to fit under the factory '69 sidepipe covers? I've got the Hedman side exhaust headers and it's pretty well documented how much the OE designed sidepipes kill both HP and torque. I'd like to come up with something a bit more quiet and a lot more efficient.
Racer
Joined: Nov 2007
Posts: 279
Likes: 0
From: Forrest City Ar
I am attempting to do that. I bought a 78 with factory side pipes. Now I am putting a 425hp engine in and need to change exhast. The problem lies in finding a good header. The hedmans I think have 1 5\8" primarys, my engine guy says thats too small for me & looking at your rwhp you too. There is a big science in header & secendary design, and If you are intersted in trying to turn your pipes PM and I will suppliy link to articals. Mcjacks makes a 1 3\4 primary into a 2 1\2 collector. If you use your current hedmans or other types for that matter have an muffler shop bend some pipes to fit your collector and run under your covers and buy a set of STS (sprial turbo baffles) to go into the ends tthen cap with turn downs. This is what I plan to do basicly. now if you have a pocket full of cash check out Stahl headers. headers, pipes, under car resonator. search archives for side pipes and performance for pic's ov that system. let me know if I can help futher I am doing a lot of research on the matter but have no practical experence inthe matter. Tom
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
Thanks for the thoughts. I sent you a PM. I don't have a pocket full of cash...that got sucked out a long time ago and I haven't figured how to shut off that switch yet!
I'd like something a bit more quiet than what I've heard out of the spiral turbo's. I'd almost like it to be sleeper quiet. I must be getting old because I'm even thinking about putting the stock exhaust back on my Harley.
I'd like something a bit more quiet than what I've heard out of the spiral turbo's. I'd almost like it to be sleeper quiet. I must be getting old because I'm even thinking about putting the stock exhaust back on my Harley.
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
Has anyone built a custom pipe/muffler system to fit under the factory '69 sidepipe covers? I've got the Hedman side exhaust headers and it's pretty well documented how much the OE designed sidepipes kill both HP and torque. I'd like to come up with something a bit more quiet and a lot more efficient.
Working on the same thing today, except that I'm using shorty headers (my new engine will use ported 2.5" exhaust manifolds).
Last edited by I'm Batman; Apr 3, 2008 at 12:11 AM.
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
http://forums.corvetteforum.com/show...517&forum_id=3
Working on the same thing today, except that I'm using shorty headers (my new engine will use port 2.5" exhaust manifolds).
Working on the same thing today, except that I'm using shorty headers (my new engine will use port 2.5" exhaust manifolds).
I'm thinking about a similar setup, but trying to find some sort of muffler that will fit the space under the OE covers. Since I haven't found anything off the shelf. Right now, I'm thinking of a 4" round dynomax ultraflows with a 2 1/2" center baffle squeezed down in a press to make it a ~3" X 5" oval. These mufflers don't have the flat ends, they are more of the bullet shape so I'm hoping they would flatten out without rupturing. The OE pipes have this oblong shape so I'm hoping it would work with this muffler.
I'd like to think I could do their 4" round with a 3" in/out, but I'm afraid putting a squeeze on this one might collapse the inside pipe diameter too....but if it only makes it oblong, this may still work. I may have to call Dynomax tech support next week and see if they think I stand a snowballs chance on this. I do like the thought of a full 3" setup though!
I guess the only way to get an outlet on the pipe to match the OE rectangle is many hours with a hammer and dolly.
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
I use 3.5" pipes under fiberglass covers. Tight but good enough.
Speedway sells an 'auger' muffler. I put 2 1/2 of them in the pipe and then reduced them to 3" for the exit and to mate to the headers ( I built my own)
go to Speedwaymotors.com and search for auger...
15$ a piece
Speedway sells an 'auger' muffler. I put 2 1/2 of them in the pipe and then reduced them to 3" for the exit and to mate to the headers ( I built my own)
go to Speedwaymotors.com and search for auger...
15$ a piece
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
I use 3.5" pipes under fiberglass covers. Tight but good enough.
Speedway sells an 'auger' muffler. I put 2 1/2 of them in the pipe and then reduced them to 3" for the exit and to mate to the headers ( I built my own)
go to Speedwaymotors.com and search for auger...
15$ a piece
Speedway sells an 'auger' muffler. I put 2 1/2 of them in the pipe and then reduced them to 3" for the exit and to mate to the headers ( I built my own)
go to Speedwaymotors.com and search for auger...
15$ a piece
I looked them up at Speedwaymotors.com and they are similar to but different than the spirals. the twists are segments instead of a constant spiral. Similar concept, different implementation.
Last edited by 68vertible; Mar 29, 2008 at 09:45 PM. Reason: update
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
Has anyone built a custom pipe/muffler system to fit under the factory '69 sidepipe covers? I've got the Hedman side exhaust headers and it's pretty well documented how much the OE designed sidepipes kill both HP and torque. I'd like to come up with something a bit more quiet and a lot more efficient.
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Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
I use 3.5" pipes under fiberglass covers. Tight but good enough.
Speedway sells an 'auger' muffler. I put 2 1/2 of them in the pipe and then reduced them to 3" for the exit and to mate to the headers ( I built my own)
go to Speedwaymotors.com and search for auger...
15$ a piece
Speedway sells an 'auger' muffler. I put 2 1/2 of them in the pipe and then reduced them to 3" for the exit and to mate to the headers ( I built my own)
go to Speedwaymotors.com and search for auger...
15$ a piece
There's a current thread discussing them. A quick search for "hedman" should turn it up.
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
Okay, I did the search, spent some time pouring thru the posts back into 2007 and for the most part, I see only fairly positive comments about the Hedman sidepipe compatible headers. They seem to be a good value for the dollar and most folks seemed happy.
The one I did find had a comment about them being too short and having unequal length tubes. While I agree that they will not net the same performance as a longer tube primary, they should certainly be more effective than the 'shorty' or rams horns on any engine which flows fairly well. David Visard has done some extensive research on the need for equal length in the primaries and essentially, he says it is not much of a consideration. Here's a link to one article David has done. He also goes into it quite extensively in a book he did on getting max horsepower out of a small block chevy.
http://www.superchevy.com/technical/...exh/index.html
The secondary size and length seems to be more of an issue, and it seems if you extend the collector to the proper length, you can 'tune' this header to be close to what is needed. I'm not building a racer here, just want to enjoy the fruits of my engine build as much as I can.
If, in my search, I missed the other post you folks are talking about, let me know.
The one I did find had a comment about them being too short and having unequal length tubes. While I agree that they will not net the same performance as a longer tube primary, they should certainly be more effective than the 'shorty' or rams horns on any engine which flows fairly well. David Visard has done some extensive research on the need for equal length in the primaries and essentially, he says it is not much of a consideration. Here's a link to one article David has done. He also goes into it quite extensively in a book he did on getting max horsepower out of a small block chevy.
http://www.superchevy.com/technical/...exh/index.html
The secondary size and length seems to be more of an issue, and it seems if you extend the collector to the proper length, you can 'tune' this header to be close to what is needed. I'm not building a racer here, just want to enjoy the fruits of my engine build as much as I can.
If, in my search, I missed the other post you folks are talking about, let me know.
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
How's the auger sound? Have to assume it flows pretty well...just visualizing an auger, I would think it's similar to the spiral, but that is just a guess. There's a lot of pipe length under the covers, so you just fill 'er up until it hits the right tone? Tell me more.
I looked them up at Speedwaymotors.com and they are similar to but different than the spirals. the twists are segments instead of a constant spiral. Similar concept, different implementation.
I looked them up at Speedwaymotors.com and they are similar to but different than the spirals. the twists are segments instead of a constant spiral. Similar concept, different implementation.
BTW, the spirals also are segmented...
Here's my car with them. Remember it's a high compression small block 434, so you car may sound a bit different!
http://gallery.corvettengineering.co...VetteIdle1.wma
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
I like them better than the spirals, the center tube is smaller so I think they would flow better.
BTW, the spirals also are segmented...
Here's my car with them. Remember it's a high compression small block 434, so you car may sound a bit different!
http://gallery.corvettengineering.co...VetteIdle1.wma
BTW, the spirals also are segmented...
Here's my car with them. Remember it's a high compression small block 434, so you car may sound a bit different!
http://gallery.corvettengineering.co...VetteIdle1.wma
From what I can tell, it leaves a lot of the mids and highs in the lope so you can really hear it hit. The one little bump you gave it didn't seem to get terribly loud. How is it on the road?Right now, my OE style stainless pipes are louder than my Harley with screaming eagles on it.
Advanced
Joined: May 2007
Posts: 83
Likes: 4
From: Leander Texas
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
Now that just sounds freakin' schweet! From what I can tell, it leaves a lot of the mids and highs in the lope so you can really hear it hit. The one little bump you gave it didn't seem to get terribly loud. How is it on the road?
Right now, my OE style stainless pipes are louder than my Harley with screaming eagles on it.
From what I can tell, it leaves a lot of the mids and highs in the lope so you can really hear it hit. The one little bump you gave it didn't seem to get terribly loud. How is it on the road?Right now, my OE style stainless pipes are louder than my Harley with screaming eagles on it.
On the highway the wind noise is louder, but the exhaust rumbles more.
standing beside the car at idle you have to raise your voice to talk, but not yell.
It is loud, but not open pipe Harley loud.
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
Finally fired up the car today...the 3" side exhaust with 4" stainless-body high-flow cats and 2 12" Speedway augers (with a washer welded on the end of the forward auger for a partial cap) sounds great. Not obnoxiously loud, but it has a good throaty rumble at idle.
Melting Slicks
Joined: Jun 2003
Posts: 2,802
Likes: 241
From: Niles, MI
They do fit, but they use their stipid 'O ring' flanges and the primary lengths are hugely different. I would recommend block huggers way before Headman side pipe headers.
They epitomise every possibly thing you can do wrong with a header.
*The o-ring seals work very poorly.
*The primary length is too short to be of value.
*The difference in Primary length is almost as much as the shortest tube. This makes the engine very hard to tune as some clyinders are lean while the others are rich.
It's all about tuning, not performance.
the headmans are something to be concerned about...
I've had them. The engine was untuneable. when some clyinders were rich others were lean. It was impossible to get close."
427V8 in Fiberglass side pipe covers?
Last edited by Kid Vette; Mar 31, 2008 at 01:12 PM.
Team Owner
Joined: Jul 2004
Posts: 40,412
Likes: 792
From: Redondo Beach, California
Sweet Thunder (forum sponsor) makes duplicates of the factory sidepipe mufflers in SS. One thing they offer is larger tube dimensions than the factory mufflers. Maybe Sweet Thunders sidepipes, with the larger tubing, is not as restrictive as the factory's.
Stahl makes sidepipe headers with matched tube lengths. Somewhere in the archieves, there's a photo of them.
Stahl makes sidepipe headers with matched tube lengths. Somewhere in the archieves, there's a photo of them.
Team Owner
Joined: Feb 2003
Posts: 30,183
Likes: 313
From: Lake Norman NC
a 4" round muffler will not fit under the stock side exhaust covers...they touch the insulators on the inside. I know this, because I tried it. I am running 3.5" glasspacks turned backwards (for better flow) with 2.5" pipe running off the hedman side exhaust headers. I agree, the hedman headers suck ***. I am actually in the process of redoing this whole exhaust setup...first off, getting rid of the headers, and go from there.
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
I don't see why people keep putting the hedmans down. I havent finished installing them on my car yet, but seriously what makes them so bad? Unless you are reving the **** out of your engine or have big block cubic inches out of a small block, they ought to be perfect. I'd bet money they flow better than huggers and they definitely outflow the ramhorn manifolds.