Exhaust research - FYI

[hybrid]

Love that roush setup

[boofhead]

It makes sense that modern kit car parts suppliers would have the headers optimized
for the HO cam. So going back to it our sequence is right bank 1-7-6-4 and left bank 3-2-5-8. So on the left either 1 and 4 is the cross over pipes or 7 and 6 is and for the left bank either 3 and 2 is the cross over or 5 and 8 is. So looking at the photos - the Roush looks to me that 4 is staying so 7-6 must be coming from the other side hence 2 and 3 are crossing over.

I tried to find an original mk1 GT40 engine picture but it is hard to a close shot



and



Hard to tell.

[ozbilt]

Found a good pic of one of the original cars. Story here .....

http://www.sportscardigest.com/cars-for ... prototype/

Exhaust setup ......



Now to compare with the other pics to see if it is a HO type cam .......

[ozbilt]

After checking the 2 pics the above photo shows the early cam IMO

[ozbilt]

Love that roush setup

The whole car would be a dream build for me 2nd to a Daytona Coupe ........

[ozbilt]

The above pic looks like 3 & 7 were swapped

[nassi]

Damn, I should not have had beers before looking at your can of worms.

[Ausjacko]

I have drafted a spreadsheet off the back of some further reading that uses math magic to suggest the correct primary pipe diameter for a header based on peak torque rpm (ie max volumetric efficiency) and internal cross sectional area of the pipe.

If someone has access to a site that suggests the harmonic length of a motor I could build this into the sheet. This would provide the pipe dia and primary tube length for an exhaust.
Cheers Jacko

[boofhead]

It is hard to tell. So I will look at it again tomorrow.

Jacko - lots of different formula around so I am interested in which one or more you have selected. Here are two:

Lin. = (850 x (180 + EVO) ÷ rpm) – 3
Dia.in. = SQRT[(vol. x 16.38) ÷ ((L + 3) x 25)] x 2.1
Where:
L = primary pipe length
EVO = exhaust valve opening point from cam card or internet
vol. = volume of a single cylinder
Dia. = calculated primary tube diameter

I have many from simple to complex.

[boofhead]

So assuming it is expected that the original firing order - so we can so both 3 and 7 cross over. So if early then with 3 crossing over then 2 must also cross over and with 7 also 6 needs to cross over. I can accept 6 crossing over and 8 stays so indeed early firing order.

[ozbilt]

#4 at the 66 Le Mans was a 427 car, Driven by Mark Donohue (New jersey USA) & Paul Hawkins (Melbourne Aust) & preped by Holman & Moody.

[Astro]

Seeing as I'm about to have a system "built" for my notchback.

Would there be a benefit for a road car in these types of exhaust mods?

Is it worth letting Boof loose in the design stage 😳

Cheers

J

[Ausjacko]

in a word- Yes

[boofhead]

Seeing as I'm about to have a system "built" for my notchback.

Would there be a benefit for a road car in these types of exhaust mods?

Is it worth letting Boof loose in the design stage 😳

Cheers

J

Is SP taking down to the local exhaust guy and having it custom built?
I assume the JBA headers are still being used?

I am happy to do a few calcs for you and send the results onto you.

[Astro]

Yes and Yes.

Gav is away for the next week so will probably be going in a fortnight or so.

J