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X-Pipes and H-Pipes for V8s


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#1 Wuzak

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Posted 10 June 2020 - 01:46

I was watching a video about Ryan Tuerck's Ferrari powered  Toyota."GT4586" where he talks about being disappointed with the exhaust note and that he is considering changing to an 8-into-1 exhaust collector.

 

 

As they discussed the exhaust set-up they showed how the exhausts from each bank joined in the middle to make an X-pipe before exiting either side of the nose.

 

http://www.speedhunt...entation-301957

http://www.speedhunt...entation-301944

 

http://www.speedhunt...ed-toyota-gt86/

 

 

I know that X-Pipes and H-pipes are common on cross plane V8s, and the reason for them is to do with exhaust pulses.

 

 

But is an X-pipe necessary for a flat plane crank V8, such as the Ferrari 458 engine?

 

In the original Ford GT40s the exhaust pipes from two cylinders from each bank would crossover to join two pipes from the opposite bank

 

https://www.alamy.co...um=1&flip=0&pl=

 

By doing this Ford, as I understand it, avoided the need for an X-pipe or H-pipe. 

 

Are X-pipes needed for other configurations, like V6, V10 and V12? 

 

In the video Tuerck references a couple of cars that have 8-into-1 exhaust systems. These have Chevy LS engines with, presumably, cross plane cranks. Would changing to an 8-into-1 make as much difference to the Ferrari engine as it does for the LS?



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#2 gruntguru

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Posted 10 June 2020 - 08:23

V8s with cross-plane cranks only have an exhaust "beat" because pulse from different cylinders get different treatment on the way from the exhaust valve to your ears.

 

If there was no X or H pipe it would sound crap. Each outlet would sound like a separate odd-fire 4 cylinder. The X or H pipe means each outlet emits sounds from all 8 cylinders - more or less evenly spaced but slightly different amplitudes depending on which bank they came from and slightly jumbled due to the time they spent between the collector and the X/H pipe. 

 

The LS engine with cross-plane crank and 8-1 headers allows every pulse to get identical treatment between valve and ears. Same as flat-plane with single outlet - even if it is a 4-2-1 system.

 

The car in the video (sounds f'n awesome BTW!!!!) has that same pure sound coming out of each outlet - problem is there are two outlets and your ear gets a jumbled version of the two pure sounds from the two outlets.

 

8-1 will create the single pure note he is looking for.

 

IMO he could have the same pure note with simple modification of the existing system to 8-2-1 and save a fortune. Oh well.


Edited by gruntguru, 10 June 2020 - 22:02.


#3 Greg Locock

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Posted 10 June 2020 - 09:21

"If there was no X or H pipe it would sound crap." The exhaust boys tried that. Ouch. We actually had a  V8 exhaust where we 'lost' the throb. Time to abandon the computers and get busy with the welder.



#4 Wuzak

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Posted 10 June 2020 - 13:02

V8s with cross-plane cranks only have an exhaust "beat" because pulse from different cylinders get different treatment on the way from the exhaust valve to your ears.

 

If there was no X or H pipe it would sound crap. Each outlet would sound like a separate odd-fire 4 cylinder. The X or H pipe means each outlet emits sounds from all 8 cylinders - more or less evenly spaced but slightly different amplitudes depending on which bank they came from and slightly jumbled due to the time they spent between the collector and the X/H pipe. 

 

The LS engine with cross-plane crank and 8-1 headers allows every pulse to get identical treatment between valve an ears. Same as flat-plane and single outlet - even if it is a 4-2-1 system.

 

The car in the video (sounds f'n awesome BTW!!!!) has that same pure sound coming out of each outlet - problem is there are two outlets and your ear gets a jumbled version of the two pure sounds from the two outlets.

 

8-1 will create the single pure note he is looking for.

 

IMO he could have the same pure note with simple modification of the existing system to 8-2-1 and save a fortune. Oh well.

 

So he doesn't really need that X-pipe on the Ferrari flat plane crank V8 - just join the two banks into one outlet?

 

Would it better if the exhausts exited parallel, rather than in opposite directions?



#5 Bob Riebe

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Posted 10 June 2020 - 18:32

Way back in the 70s , 180 degree headers became the latest greatest idea for race car horsepower.

They made the cars sound like a tenor with a very sore throat.

It went away.

Greenwood who was the bastion of big V-8 power into the end of the decade, found very short collectors, on standard headers,  to be the best producer of power, which the Chevys were never short of.

Ford on its 302 Trans-Am engines used a 8 into 4 system which worked well but always gave them a tinny sound.

I have never found the V-8s that sound like a horde of mosquitoes to be pleasant, the same way I find screeching sopranos in opera to be annoying. :smoking:

Now four into four GP bikes do fascinate me.



#6 gruntguru

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Posted 10 June 2020 - 22:17

So he doesn't really need that X-pipe on the Ferrari flat plane crank V8 - just join the two banks into one outlet?

 

Would it better if the exhausts exited parallel, rather than in opposite directions?

 

With an outlet either side he needs the X pipe. With a single outlet it won't make much difference whether its 8-2-1 or 8-1.

 

If the two outlets were together it would probably sound like the 8-2-1 or 8-1.



#7 Wuzak

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Posted 11 June 2020 - 04:40

With an outlet either side he needs the X pipe. 

 

Why?

 

Surely each half of the engine would operate happily on its own?



#8 gruntguru

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Posted 11 June 2020 - 21:55

Only for acoustics.

 

(same for all comments in my last post)



#9 Fat Boy

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Posted 12 June 2020 - 18:45

Some of the best headers I've ran sounded crappy.



#10 blueprint2002

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Posted 19 June 2020 - 00:59

Way back in the 70s , 180 degree headers became the latest greatest idea for race car horsepower.

……….

Now four into four GP bikes do fascinate me.

Sorry, didn't understand that. Could you please explain "180 degree headers"? Thanks.

4 into 4: My guess is you are referring to Gileras, MVs and Hondas of the 50s and 60s?



#11 Bob Riebe

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Posted 19 June 2020 - 02:49

Sorry, didn't understand that. Could you please explain "180 degree headers"? Thanks.

4 into 4: My guess is you are referring to Gileras, MVs and Hondas of the 50s and 60s?

They are aligned  to imitate the exhaust pulses of a flat crank

They are far from gone but not the latest greatest they were back then.

A big block Chevy running these has a coarse sound.

Routing the headers was a annoying item also.

https://www.hotrod.c...idrange-torque/

 

Part 2 is  really aimed at drag racing but applies to road racing, especially back when the exhaust was not permitted to pass through or over any part of the body.

https://www.onallcyl...-header-tuning/

https://www.onallcyl...um-performance/

https://www.onallcyl...hich-to-choose/

 

4 into 4, straight pipes  with megaphones.   (I ran this on my MV with end caps inserted but nothing inside the megaphones. Before they arrived I ran 4 straight short pipes. No tickets, but very loud.)

Now a 2 stroke boat motor with straight pipes and megaphones can only be outdone by straight pipe Wankels..


Edited by Bob Riebe, 19 June 2020 - 02:53.