180 Degree headers

[Lambo]

Hi Guys, I have been doing some digging on info on 180 degree headers, from what i have read this is one way of making my V8 sound more like a V12, has anyone done this yet, do the rules of 4 into one apply or is it different for 180 deg ie: 2 into 1 x 4 have a read of this link,http://www.thorleyheaders.com/tech_basics_triy.html
the sbc and the ford example have the same firing order as we have on the 1uz, also have a look at the pdf file i found, do you think it's a possable to do. Just imagine a 1uz that sounds like a V12 yummy.



Best Regards
Lambo

 

[SCV8]

In a mid-engined car with some room behind the motor, yes, but not in most vehicles.
What if you were to have a common muffler chamber just before the collectors to dump everything into(right behind the motor)?
It'd be like a uni-collector.
The outlets could be on the bottom, to then go out the rear of the vehicle.
This is assuming a mid-engined car is the subject.

 

[JBrady]

Here is a set of 180 degree headers on a Porsche 928.

 

[Lambo]

Yes it will be mid engine so i do have a reasonable amount of space, did you have a look at the link above, they seem to cheat but still get 180 deg firing by connecting different cylinders that fire 180 deg apart on the same bank and then into a 2-1 x 2 for each bank
As per the web link:
Let’s go back to our “first four over second four” firing order stack and see how close we can get to pairing the cylinders 180 degrees apart without having to cross over or under the engine. Cylinders 1, 3, 5, and 7 are on the driver’s side of the engine. Cylinders 2, 4, 6, and 8 are on the passenger’s side of the engine. Let’s do the driver’s side first:
If we blend the gases from #1 with those from #5, and blend the gases from #3 with #7, we get the paired cylinders much closer to being 180 degrees opposite one another than if we just dumped all the exhaust gases together and let them fight their way out of the collector as a four-tube header does.--- This method would save crossing the block from the other side, if i use 180 deg as per the 928 example the pipes would be very long, and equal tuned length would go out the window is this correct , if i use the above method does a 2 into 1 formula apply x 2 per bank any thoughts.
Regards
Lambo

 

[Lambo]

Yes it will be mid engine so i do have a reasonable amount of space, did you have a look at the link above, they seem to cheat but still get 180 deg firing by connecting different cylinders that fire 180 deg apart on the same bank and then into a 2-1 x 2 for each bank
As per the web link:
Let’s go back to our “first four over second four” firing order stack and see how close we can get to pairing the cylinders 180 degrees apart without having to cross over or under the engine. Cylinders 1, 3, 5, and 7 are on the driver’s side of the engine. Cylinders 2, 4, 6, and 8 are on the passenger’s side of the engine. Let’s do the driver’s side first:
If we blend the gases from #1 with those from #5, and blend the gases from #3 with #7, we get the paired cylinders much closer to being 180 degrees opposite one another than if we just dumped all the exhaust gases together and let them fight their way out of the collector as a four-tube header does.--- This method would save crossing the block from the other side, if i use 180 deg as per the 928 example the pipes would be very long, and equal tuned length would go out the window is this correct , if i use the above method does a 2 into 1 formula apply x 2 per bank any thoughts.
Regards
Lambo

Any thoughts guys on the above plan

Regards Lambo

 

[svpmx83]

I suppose it depends on how much effort you want to put into doing it and how "right" they need to be

pairing

2/4 6/8 & 1/5 3/7 is about ideal without full 180deg

rush headers are

2/4 6/8 & 1/3 5/7 and are still an improvement over factory (but then anything is an improvement )

here are two shots of 180deg for a GT40 replica

 

[Lambo]

Thanks Steve that makes it much clearer, i think it may be worth a try to get the sound i want, do you happen to know of a site that covers calculating a 2 into 1 header length.

Best Regards
Lambo

 

[1youZee]

http://popularhotrodding.com/enginemasters/articles/hardcore/0505em_exh/

its not about 180º headers but has very good info on primary pipe length, collector size and stuff. very informative.
-chris

 

[Lambo]

Thanks for that Chris very usefull info
Regards
Lambo