1961 "Crossover Pipe"
05-11-2008, 10:31 PM
#22
Team Owner
Thread Starter
[QUOTE=1snake;1565414864]I have the solid lifter 270HP dual carb motor with NO cross over pipe - I'm guessing somewhere along the line the incorrect exhaust was installed.
05-12-2008, 12:59 AM
#24
Live Free or Die
Whether or not there was a performance gain or not, sound was the impetus behind the crossover.
Last edited by Plastic Pig; 05-12-2008 at 01:01 AM.
05-12-2008, 06:52 AM
#27
Team Owner
Thread Starter
This is from the article that MICK3 provided:
"On a full exhaust system, after the header tubes dump into the collectors, the two close firing cylinders are fighting each other for space in the collector and exhaust pipe. The result is reflected pressure waves traveling back up the exhaust system, backpressure, lost power and poor economy.
At the same time two cylinders exhaust in one bank, there is no activity in the opposite bank. The traditional H-pipe equalizer allows some of the excess pressure to bleed over to the 'quiet side' of the exhaust system, resulting in some low and mid-range torque improvements. At high RPMs, however, in traditional exhaust systems, the gases cannot bleed across the H-pipe fast enough to help power significantly. Performance systems with the H pipe design, attempt to over come this by using a shorter cross over pipe which is also slightly larger in diameter as the main exhaust, then would be used in a standard exhaust."
Thanks for the pics K2 - that is what I'll show my muffler shop to get this done.
"On a full exhaust system, after the header tubes dump into the collectors, the two close firing cylinders are fighting each other for space in the collector and exhaust pipe. The result is reflected pressure waves traveling back up the exhaust system, backpressure, lost power and poor economy.
At the same time two cylinders exhaust in one bank, there is no activity in the opposite bank. The traditional H-pipe equalizer allows some of the excess pressure to bleed over to the 'quiet side' of the exhaust system, resulting in some low and mid-range torque improvements. At high RPMs, however, in traditional exhaust systems, the gases cannot bleed across the H-pipe fast enough to help power significantly. Performance systems with the H pipe design, attempt to over come this by using a shorter cross over pipe which is also slightly larger in diameter as the main exhaust, then would be used in a standard exhaust."
Thanks for the pics K2 - that is what I'll show my muffler shop to get this done.
05-12-2008, 09:33 AM
#28
the mid years had room for oval shaped bypass type mufflers that took away the "harsh" exhaust sound.
05-12-2008, 10:26 AM
#30
there is a "cross over" pipe used in C-5s and in the pipe was a "washer" with a hole sized to control the loudness of the exhaust system. different year C-5s had different size "hole" and the exhaust sound was different in different years. i case anyone is interested i have owned all new the following corvettes, 1959,62,63,64,65,66,97,99,2002,05 and 08 so i have a lot of experience with these cars. i also help crewed the GULF reasearch race corvettes back in the 50s and 60s
05-12-2008, 12:23 PM
#31
Race Director
Member Since: Jun 2006
Location: Inverness FL
Posts: 17,891
Received 727 Likes
on
621 Posts
St. Jude Donor '07
there is a "cross over" pipe used in C-5s and in the pipe was a "washer" with a hole sized to control the loudness of the exhaust system. different year C-5s had different size "hole" and the exhaust sound was different in different years. i case anyone is interested i have owned all new the following corvettes, 1959,62,63,64,65,66,97,99,2002,05 and 08 so i have a lot of experience with these cars. i also help crewed the GULF reasearch race corvettes back in the 50s and 60s
1) the C1s had oval mufflers too, only the off roads were round
2) and i have read many articles on exactly what Frank quoted above about the use of "H" pipes, which the C1 crossover pipe is a version of
all that said, the thing we do agree on is that the use of a crossover pipe (H-pipe) has a beneficial effect on the exhaust sound.
Bill
05-12-2008, 12:44 PM
#32
Race Director
Member Since: Nov 2000
Location: Beverly Hills (Pine Ridge) Florida
Posts: 10,152
Received 525 Likes
on
374 Posts
Anybody who has added a crossover pipe (be it the factory C1 Vette style, H, or X pipe) will flat out tell you it helps the low and mid range, as well as mellow the sound. The immediate difference is readily apparent.
Mopar (as well as others) did it during the 60's specifically to help performance. Anytime a high cammed engine was used, low and mid range suffer. Adding a crossover was elementary to bring back some of that low and mid range power. That is why you see it on the higher cammed SBC C1 Vettes.
As to why the 63 and up don't have them is probably due to a bean counter at work, besides the fact that the engine and frame packaging made it much harder. Mid years came with either Power Steering rams or steering dampers in the area formerly used by the crossover pipe making it more difficult to add.
Plasticman
Mopar (as well as others) did it during the 60's specifically to help performance. Anytime a high cammed engine was used, low and mid range suffer. Adding a crossover was elementary to bring back some of that low and mid range power. That is why you see it on the higher cammed SBC C1 Vettes.
As to why the 63 and up don't have them is probably due to a bean counter at work, besides the fact that the engine and frame packaging made it much harder. Mid years came with either Power Steering rams or steering dampers in the area formerly used by the crossover pipe making it more difficult to add.
Plasticman
Last edited by Plasticman; 05-12-2008 at 03:41 PM.
05-12-2008, 01:09 PM
#33
Melting Slicks
This is a thread I started last October when I installed a crossover pipe. For me it made a big difference and for others there was minimal change. There are also videos showing the difference in sound. Check out this write-up "Crossover Pipes Explained". I don't know how accurate it is, but it is interesting reading.
Roy
Roy
05-12-2008, 03:50 PM
#34
Team Owner
Thread Starter
Well I had the crossover installed - the tech talked me into putting a flange in the middle instead of the slide fitting with sealant; just easier to get apart and less prone to leaking...as you can see this guy does lots of classics so I was in good company and trusted his advice. Car sounds much better and does pull out stronger on the bottom end but it was rush hour and I didn't get a chance to 'stress test' it...
Last edited by Frankie the Fink; 05-12-2008 at 04:01 PM.
05-12-2008, 05:33 PM
#36
a little write up on "H" pipe type crossovers
For any performance exhaust system, some type of crossover connecting the two sides of a dual exhaust system is important because it acts to balance the two banks of the engine. The common H-style crossover is good at balancing sound pulses between the two halves, but does little to promote scavenging because the exhaust gases tend to follow the path of least resistance, which is straight through each pipe rather than taking the 90-degree turn through the H-pipe into the other half of the system. this is why the "X" pipe works and the "H" type like on the corvette does nothing for power.
05-12-2008, 08:25 PM
#37
Race Director
Member Since: Jun 2006
Location: Inverness FL
Posts: 17,891
Received 727 Likes
on
621 Posts
St. Jude Donor '07
For any performance exhaust system, some type of crossover connecting the two sides of a dual exhaust system is important because it acts to balance the two banks of the engine. The common H-style crossover is good at balancing sound pulses between the two halves, but does little to promote scavenging because the exhaust gases tend to follow the path of least resistance, which is straight through each pipe rather than taking the 90-degree turn through the H-pipe into the other half of the system. this is why the "X" pipe works and the "H" type like on the corvette does nothing for power.
Bill
05-12-2008, 08:49 PM
#38
Race Director
Where did you get the Tri-Clamp style collector and crossover flanges and clamps?
Thanks,
Doug
05-12-2008, 09:38 PM
#39
Race Director
Member Since: Nov 2000
Location: Beverly Hills (Pine Ridge) Florida
Posts: 10,152
Received 525 Likes
on
374 Posts
This is where David got his clamps and flanges:
They are V band clamps. I got them from Verocious Motorsports. Pricey little buggers. They have the flanges too.
http://www.verociousmotorsports.com/.../V-Band-Clamps
Plasticman
05-13-2008, 05:20 AM
#40
Racer
Actually, there is a lot more to the cross over pipe then we could discuss here if you look at it from the exhaust gas pulsing effect and the phase relationship to where the connection is made as to where the RPM effect takes place...