4 Cylinder Header Design
4 Cylinder Header Design
(OP)
Currently this engine uses a 4-2-1 Setup with a crossover a few inches away from the exhaust port(on the header primaries), only on cylinders 2 and 3(which is well before the first collector)
This Engines Firing Order is 1-2-4-3
The Crossover linking Cylinders 2 and 3 confuses me since they are not paired. Since Cyl 2 Fires then next to fire is Cyl 4, so there isn't any scavenging from these two (Cyl 2 and Cyl 3). I believe this is done to alter the sound of the exhaust, is my assumption correct?
I have an idea to create a dual exhaust system which
(Cyl 1 and Cyl 2)
and
(Cyl 4 and Cyl 3)
Are paired
So the exhaust is a Dual 2-1 system. But, now two cylinders will not receive scavenging (Cyl 1 and Cyl 4)
To Remedy this I propose to put crossover pipes on the header primaries between
(Cyl 4 and Cyl 2)
and
(Cyl 1 and Cyl 3)
So now all cylinders can receive scavenging.
What are your opinions on the system? Is there any literature on crossover pipes in headers?
This Engines Firing Order is 1-2-4-3
The Crossover linking Cylinders 2 and 3 confuses me since they are not paired. Since Cyl 2 Fires then next to fire is Cyl 4, so there isn't any scavenging from these two (Cyl 2 and Cyl 3). I believe this is done to alter the sound of the exhaust, is my assumption correct?
I have an idea to create a dual exhaust system which
(Cyl 1 and Cyl 2)
and
(Cyl 4 and Cyl 3)
Are paired
So the exhaust is a Dual 2-1 system. But, now two cylinders will not receive scavenging (Cyl 1 and Cyl 4)
To Remedy this I propose to put crossover pipes on the header primaries between
(Cyl 4 and Cyl 2)
and
(Cyl 1 and Cyl 3)
So now all cylinders can receive scavenging.
What are your opinions on the system? Is there any literature on crossover pipes in headers?





RE: 4 Cylinder Header Design
"Schiefgehen will, was schiefgehen kann" - das Murphygesetz
RE: 4 Cylinder Header Design
The Problem- Instead of running a traditional 4 to 1 setup, I propose to run a dual 2 to 1 system that can produce similar performance when compared to a 4 to 1 setup. So the ultimate question is how do crossovers by the headers function, and if there is a book that talks about them I can read so I can optimize them. The two Engine books I have do not speak about them. Also I would like to hear some opinions about this.
RE: 4 Cylinder Header Design
Regards
Pat
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RE: 4 Cylinder Header Design
RE: 4 Cylinder Header Design
The reason is that the exhaust gas pulse then has equal separation, ie 360 deg between each cylinder. Closer is better, but then you get uneven with a bit to close then a lot to far apart ie 180 then 540 then 180.
In my experience 3 into 1 works really good, but 4 into 1 also works fine.
Pipe layout is but one aspect of this.
Regards
Pat
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RE: 4 Cylinder Header Design
So could you give your opinion and Help me better understand the Stock Engine's 4-2-1?
It pairs 1 and 2, and 3 and 4 with a crossover on 2 and 3 so these two receives 360 deg Scavenging, the other two receive 540 scavenging from its primaries and then all cylinders receive a weaker scavenging effect from the final collector. . . But The same engine just greater displacement gets rid of the crossover, otherwise it's the same setup. I cannot see why they would give the greater displacement engine less scavenging?