69' side exhaust performance
Thread Starter
Instructor
Joined: Jun 2003
Posts: 101
Likes: 16
From: Calverton N.Y.
69' side exhaust performance
I am going to be putting on 69' style side exhaust on my 69' BB427 and have read they are pretty restrictive. My question is which system is the best performance wise to put under the 69' covers? It seems allen, and sweet thunder are 2 options. I don't want it ridiculously loud, but want the BB to breath as best as possible. Anybody have any recommendations?
Team Owner
Joined: Feb 1999
Posts: 34,454
Likes: 665
From: Republic of Texas
I am going to be putting on 69' style side exhaust on my 69' BB427 and have read they are pretty restrictive. My question is which system is the best performance wise to put under the 69' covers? It seems allen, and sweet thunder are 2 options. I don't want it ridiculously loud, but want the BB to breath as best as possible. Anybody have any recommendations?
Team Owner
Joined: Sep 2006
Posts: 31,274
Likes: 4,366
From: Westminster Maryland
Hi blk,
For years I've read that the 69 side exhaust system was quite restrictive, even more restrictive than the stock under car exhaust.
As far as sound is concerned I think part of the problem, (or pleasure), is that the outlet is about 2' from your left ear!
But, boy do they look good!
Regards,
Alan
These are 69 covers painted black.
For years I've read that the 69 side exhaust system was quite restrictive, even more restrictive than the stock under car exhaust.
As far as sound is concerned I think part of the problem, (or pleasure), is that the outlet is about 2' from your left ear!
But, boy do they look good!
Regards,
Alan
These are 69 covers painted black.
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
I have the Allen's oversized 2-1/2" and just like the orange warning sticker on their shipping carton stated "THESE PIPES ARE LOUD." Unfortunately, less restriction equates to more noise. The original or repro factory side exhaust are really just 2 parallel tubes with holes between them...an inlet on the end of the top one and an outlet on the other end of the bottom one. Very little muffling is going on. With the T-Tops on, the drone inside the car could be bothersome on a long trip. Around town, it sure is a lot of fun to annoy other drivers while idling at traffic lights. The neighbor two houses down tells me his windows rattle when I start the car. 
The only thing I don't like about them is the exhaust pipes are not mandrel bent, which undoubtedly causes some unecessary restriction. If you go with them, make sure to have them shipped in pieces and do the fitment and tack welding on your car, with the covers in place. I really don't think stainless is necessary. The aluminized steel will last a long time and doesn't look quite as non-original. They can provide you with new GM repro covers for a discount...which I believe all come from Paragon.
Here is a link to 4 YouTube videos I made using a cheap still camera, so the sound is not real good..but you can get the idea.
http://www.youtube.com/watch?v=mqNXJ9FBNZM
The only thing I don't like about them is the exhaust pipes are not mandrel bent, which undoubtedly causes some unecessary restriction. If you go with them, make sure to have them shipped in pieces and do the fitment and tack welding on your car, with the covers in place. I really don't think stainless is necessary. The aluminized steel will last a long time and doesn't look quite as non-original. They can provide you with new GM repro covers for a discount...which I believe all come from Paragon.
Here is a link to 4 YouTube videos I made using a cheap still camera, so the sound is not real good..but you can get the idea.
http://www.youtube.com/watch?v=mqNXJ9FBNZM
Last edited by Faster Rat; Sep 9, 2011 at 08:44 PM. Reason: Added video link
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
I have the BB 454 Sweet Thunder oversize tubes, I found them to be quite comapared to other similar exhaust systems,
I was slightly dissappointed they were not louder.
I was slightly dissappointed they were not louder.
Thread Starter
Instructor
Joined: Jun 2003
Posts: 101
Likes: 16
From: Calverton N.Y.
Alan, beautiful 71' you have there.
FasterRat, sweet car you have there as well. That info and those videos are a big help, thanks.
I'm going to try to listen to the sweet thunders and try to figure out which one is louder. I imagine they are pretty similiar.
FasterRat, sweet car you have there as well. That info and those videos are a big help, thanks.
I'm going to try to listen to the sweet thunders and try to figure out which one is louder. I imagine they are pretty similiar.
Melting Slicks
Joined: Jan 2003
Posts: 2,877
Likes: 13
From: Doha
St. Jude Donor '08
my car came with Allen's side exhaust (the 2.5 in.) and it was loud to my taste, but worst of all, I was really shocked when I saw that much better performance when I switched to a normal undercar exhaust, that thing is so restrictive, maybe I gained 40 HP or so just by going to the under car exhaust, my car was a '71 big block stock.
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Drifting
Joined: May 2011
Posts: 1,536
Likes: 1
From: Boca Raton FL
I have a '69 SB 350/350 with factory side pipes. Not sure how restrictive they are because never ran w/o them but they sound nice - not too loud but loud enough.
Click on the images below - they are videos:
Click on the images below - they are videos:
Team Owner
Joined: Sep 2006
Posts: 31,274
Likes: 4,366
From: Westminster Maryland
Hi Ganey,
PLEASE don't take any offence!!!!
I believe you know that "off road'" and "sidepipes" don't go together.
'Off road' refers to the optional undercar exhaust with less baffles in the muffler so may have been less restrictive than the standard undercar exhaust.
I've always been intrigued with side exhaust and like the truth to be known about them. Even the down side to them.
Regards,
Alan
PLEASE don't take any offence!!!!
I believe you know that "off road'" and "sidepipes" don't go together.
'Off road' refers to the optional undercar exhaust with less baffles in the muffler so may have been less restrictive than the standard undercar exhaust.
I've always been intrigued with side exhaust and like the truth to be known about them. Even the down side to them.
Regards,
Alan
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
Any exhaust silencing system creates backpressure, causing a drop in performance. I guess if one is into street racing it would be important. If going to the strip is your thing, slap on some open headers. When I give somebody a ride that has never experienced the sound and feel of a BB muscle car, I ususally take the opportunity mash the pedal to the floor at least once. Then I have all that I can do to hang on to the wheel and keep it going straight down the road, hoping that some 42 year old item doesn't let go. I am amazed that I haven't even gotten a ticket in 7 years. Performance? I don't need no more stinkin' performance.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Hi Ganey,
PLEASE don't take any offence!!!!
I believe you know that "off road'" and "sidepipes" don't go together.
'Off road' refers to the optional undercar exhaust with less baffles in the muffler so may have been less restrictive than the standard undercar exhaust.
I've always been intrigued with side exhaust and like the truth to be known about them. Even the down side to them.
Regards,
Alan
PLEASE don't take any offence!!!!
I believe you know that "off road'" and "sidepipes" don't go together.
'Off road' refers to the optional undercar exhaust with less baffles in the muffler so may have been less restrictive than the standard undercar exhaust.
I've always been intrigued with side exhaust and like the truth to be known about them. Even the down side to them.
Regards,
Alan
There was a pic. & it was factory side pipes, so maybe they should not have called them "off road".
I suppose you know side pipes came from lakes pipes which were run open.
I found out about restrictive exhaust on my first car when it blew the straight through glass packs off & exploded w/ power!
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
...and she purrs like a kitten til the lake pipes roar.
- Little Deuce Coupe by The Beach Boys
I remember when my greaser buddy across the street put fake ones on his '56 Ford convertible back in the early '60s...just as a decoration, along with the pair of foam dice hanging from the rear view mirror.
- Little Deuce Coupe by The Beach Boys
I remember when my greaser buddy across the street put fake ones on his '56 Ford convertible back in the early '60s...just as a decoration, along with the pair of foam dice hanging from the rear view mirror.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
We would start lining up & I would blow them off. Too late now.
Thread Starter
Instructor
Joined: Jun 2003
Posts: 101
Likes: 16
From: Calverton N.Y.
Ok, so I guess it's either Allen or Sweet Thunder. I am leaning towards sweet thunder because of their performance 2 1/4" inner baffle tube diameter. http://www.sweet-thunder.com/corvett...pes_68_74.html Both are 2 1/2 pipe. And their prices are almost identical.
Melting Slicks
Joined: Feb 2001
Posts: 3,330
Likes: 13
From: Europe , Luxembourg
Hi
But even the 2 1/4 " sweet thunder pipes have 2 in parallel running muffler tubes that seem to be interconnected by longitudinal holes somehow.
Doesn't anybody build just a straight through glasspack muffler single tube like the HOOKER high flow glass pack muffler ?
That would be the least restrictive.
Rgds. Günther
But even the 2 1/4 " sweet thunder pipes have 2 in parallel running muffler tubes that seem to be interconnected by longitudinal holes somehow.
Doesn't anybody build just a straight through glasspack muffler single tube like the HOOKER high flow glass pack muffler ?
That would be the least restrictive.
Rgds. Günther
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
Hi
But even the 2 1/4 " sweet thunder pipes have 2 in parallel running muffler tubes that seem to be interconnected by longitudinal holes somehow.
Doesn't anybody build just a straight through glasspack muffler single tube like the HOOKER high flow glass pack muffler ?
That would be the least restrictive.
Rgds. Günther
But even the 2 1/4 " sweet thunder pipes have 2 in parallel running muffler tubes that seem to be interconnected by longitudinal holes somehow.
Doesn't anybody build just a straight through glasspack muffler single tube like the HOOKER high flow glass pack muffler ?
That would be the least restrictive.
Rgds. Günther
Thread Starter
Instructor
Joined: Jun 2003
Posts: 101
Likes: 16
From: Calverton N.Y.
OK, here's the update. I bought the sweet thunder 2.5" baffle system. I installed it the other day. Sounds great, not too loud and definetly not too quiet when you step on it. No annoying drone on the highway. Performance wise I don't feel a difference, which I am happy with. I just didn't want to lose performance.
On a side note, to anybody that wanted 69' side exhaust, DO NOT let leg burns or heat sway your decision. I have read that, and was a little nervous about one of my kids touching the exhaust after a drive. The ceramic insulators inside the covers work perfectly. I can immediately touch the side covers after a long hard drive, no problem. Just warm. I'll try to post a pic of the system tomorrow. Loving it!
On a side note, to anybody that wanted 69' side exhaust, DO NOT let leg burns or heat sway your decision. I have read that, and was a little nervous about one of my kids touching the exhaust after a drive. The ceramic insulators inside the covers work perfectly. I can immediately touch the side covers after a long hard drive, no problem. Just warm. I'll try to post a pic of the system tomorrow. Loving it!