180° headers
Burning Brakes
Joined: Mar 2002
Posts: 1,102
Likes: 0
From: Montreal QC
Hello! I've not been here for a while, so I have to find out that other thread too...
Anyway, there is 180 degree exhaust systems for rear exit also! I don't know if there is any systems you can buy straight from the "go fast" shops, but it is possible to make such an exhaust system by yourself.
Infact there is two different ways to do that. One is to run primary pipes over or below the car to get the correct ones matching. The other one is to calculate the lengths of the primaries to match the wanted rpm level so that the impulses will align.
I'm going to have a system that have primaries going below the engine in my car. Not an easy system, there is not too much space... But those headers have been in a vette before and I just need to modify them a bit to make room for power steering.
Here is a pic of the system...
Anyway, there is 180 degree exhaust systems for rear exit also! I don't know if there is any systems you can buy straight from the "go fast" shops, but it is possible to make such an exhaust system by yourself.
Infact there is two different ways to do that. One is to run primary pipes over or below the car to get the correct ones matching. The other one is to calculate the lengths of the primaries to match the wanted rpm level so that the impulses will align.
I'm going to have a system that have primaries going below the engine in my car. Not an easy system, there is not too much space... But those headers have been in a vette before and I just need to modify them a bit to make room for power steering.
Here is a pic of the system...
Burning Brakes
Joined: Mar 2002
Posts: 1,102
Likes: 0
From: Montreal QC
The system IS strange, but as far as I have studied there is no room anywhere else. Transmission is so low behind the engine that it's not possible to make the connection there. If made even far behind then the lengths of the primaries are not correct. Now the system is designed for 6000rpm.
It will fit under the stock small block hood! It has been in a '70 Corvette earlier!
Fitting the power steering is another thing. It's going to be interesting to fit that one in. But I will use rack and pinion system, so I should have a bit easier fit below the oil pan. I will be smarter after couple of weeks when the engine is back in it's place... 
It will fit under the stock small block hood! It has been in a '70 Corvette earlier!
Fitting the power steering is another thing. It's going to be interesting to fit that one in. But I will use rack and pinion system, so I should have a bit easier fit below the oil pan. I will be smarter after couple of weeks when the engine is back in it's place...
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
We normally use 4 into 1 on V-8s here. 180 header primary lengths are critical & the distance between the heads ia an issue w/ V8s, besides the complexity & only slightly more efficient.
Excellent conventional 4 into 1 are available from Dynomax & Hooker..
The Dynomax Corvette SB Cerama-Coat headers fit & flow great, much better than is commonly known. I have been rec. them & many have them now.
Excellent conventional 4 into 1 are available from Dynomax & Hooker..
The Dynomax Corvette SB Cerama-Coat headers fit & flow great, much better than is commonly known. I have been rec. them & many have them now.
Burning Brakes
Joined: Mar 2002
Posts: 1,102
Likes: 0
From: Montreal QC
4 into 1 is also commonly used here. 180 degree system is much more complicated. As far I know only one Corvette with 180 degree headers in Finland, mine is going to be the second (but with the headers from the first one...). I suppose that the power increase is only marginal (if any), but the sound is incredible! Some don't like it though because it doesn't sound like a conventional V8...
I remember seeing somewhere a pic of 180deg headers like mine. Does anyone of you remember seeing that pic?
I'd say that it would be a lot easier to use normal 4 into 1 headers, but somehow I'm insane and I want these headers badly...
I remember seeing somewhere a pic of 180deg headers like mine. Does anyone of you remember seeing that pic?
I'd say that it would be a lot easier to use normal 4 into 1 headers, but somehow I'm insane and I want these headers badly...
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
Marginally ? I would think that an exhaust stroke spacing of 90° pumping into the collector and pipes would cause some backpressure. That is why the 180° were made, to space the exhaust waves 180° apart. The effect on combustionchamber scavenging should be very noticable. But I guess that you would need a high revving engine to notice it, since scavenging only plays a very big role with long duration cams and thus higher rpm.
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Burning Brakes
Joined: Mar 2002
Posts: 1,102
Likes: 0
From: Montreal QC
Getting back to an old subject...
Too bad that I do not have any dyno results for those pipes. Unfortunately the engine dyno we are using is not able to handle those 180deg primaries. (Space limitation) The engine is relatively high RPM one (for V8), mine runs redline at 7200rpm. The pipes are calculated to work best at 6000rpm.
I'm not an expert in these things, but my opinion is that you could get almost the same result with "long tube" headers. So that the pressure waves will not harm each others in normal 4-1 headers. Of course these normal headers will not have the same effect with pressure waves to "help each others", but somehow I think that with these engines the difference is not so huge. Anyway, we are still speaking less than 100hp / liter. I suppose that they will play bigger role with engines that have bigger output versus engine size. For example bike engines with about 150hp/litre or even more...
Too bad that I do not have any dyno results for those pipes. Unfortunately the engine dyno we are using is not able to handle those 180deg primaries. (Space limitation) The engine is relatively high RPM one (for V8), mine runs redline at 7200rpm. The pipes are calculated to work best at 6000rpm.
I'm not an expert in these things, but my opinion is that you could get almost the same result with "long tube" headers. So that the pressure waves will not harm each others in normal 4-1 headers. Of course these normal headers will not have the same effect with pressure waves to "help each others", but somehow I think that with these engines the difference is not so huge. Anyway, we are still speaking less than 100hp / liter. I suppose that they will play bigger role with engines that have bigger output versus engine size. For example bike engines with about 150hp/litre or even more...
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Pure waste of effort in a street car with limited space under the hood. around here you only see 180 degree headers are race cars with the passenger side door exhaust, the pipes pass over the bell housing and often through where a passengers feet might be.
Read up on header science - 180 degree headers, stepped primary headers, merged primary with megaphone collectors. Very little gains in all these years in pipes that are practical to produce.
You are better off spending your money else where.
Read up on header science - 180 degree headers, stepped primary headers, merged primary with megaphone collectors. Very little gains in all these years in pipes that are practical to produce.
You are better off spending your money else where.
Racer
Joined: May 2003
Posts: 375
Likes: 0
From: LaSalle ON
Concerning X-pipe location, you can see mine here. It's waaay back in the system though.
http://forums.corvetteforum.com/show....php?t=1708900
http://forums.corvetteforum.com/show....php?t=1708900
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Those are not 180 degree. That is probably a poor mans headers on a Pantera.
180 headers are combining cylinders in an equal firing pulse order.
I'm not 100% sure this is how the 4 primary pipes in each collector would be. but this is an educated guess.
Here is a typcal Chevy small block firing order
1-8-4-3-6-5-7-2
so you would make one 4 into 1 collector with cylinders 1-4-6-7 the other 4-1 would be 8-3-5-2
This is how your would be able to tune the other pipes to see a negative pressure wave hitting behind the next cylinders ehaust valve just as it starts to open creating better cylinder scavaging.
180 headers are combining cylinders in an equal firing pulse order.
I'm not 100% sure this is how the 4 primary pipes in each collector would be. but this is an educated guess.
Here is a typcal Chevy small block firing order
1-8-4-3-6-5-7-2
so you would make one 4 into 1 collector with cylinders 1-4-6-7 the other 4-1 would be 8-3-5-2
This is how your would be able to tune the other pipes to see a negative pressure wave hitting behind the next cylinders ehaust valve just as it starts to open creating better cylinder scavaging.
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
If they go the the header on the same bank, the pulses come 90° after each other, while the other pulses are spaced 180°. This 90° pulse loads up the collector and pipes, but also creates the typical V8 exhaust note.
If you go to a 180° style, the pulses are spaced 180° and thus the capacity of your exhaust system is enlarged as well as creating a sucktion effect.
But... in a Corvette it will be difficult to do. They only way to do in my opinion is to route the center primaries under the engine to the other side. However, due to thesteering system space is limited under the engine.
Yves
Last edited by Belgian1979vette; May 30, 2007 at 05:55 PM.
Melting Slicks
Joined: Aug 2004
Posts: 2,165
Likes: 950
From: Keizer Oregon
Burning Brakes
Joined: Mar 2002
Posts: 1,102
Likes: 0
From: Montreal QC
Originally Posted by Belgian1979vette
But... in a Corvette it will be difficult to do. They only way to do in my opinion is to route the center primaries under the engine to the other side. However, due to thesteering system space is limited under the engine.
It is difficult and there is not too much space to live with. In my first pic you can see the primaries travelling beneath the oil pan. Next pic shows the engine back in it's place with one side header in it's place. The other side header can not be placed with the air conditioning box. I have to modify the aircon box, fortunately i wasn't planning to use the A/C anyway... The steering is the next problem to solve.
