Exhaust Header/Manifold development

Competition engines and ancillaries - general discussion
DeltaDave
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Exhaust Header/Manifold development

Post by DeltaDave » Sun Jan 10, 2010 1:15 pm

Over the next few months I am going to post in here the full development cycle of my Exhaust Header/Manifold for my Lancia Delta Integrale. It has been noticed recently by GC that many of the aftermarket Headers availiable are pretty in design but very poor in function as they have very poor flow characteristics. Here I am going to attempt to build a "No loss" exhaust header using a "Golden Rule" that GC has told me. This rule does not just apply to a Turbo setup, it also applies to normally aspirated.

My apologies to all about the length of time this may take to complete but it will give us all time to discuss the theory and pitfalls, and also flow bench results at the end.

Guy may also wish to add to this by post with his technical knowledge (hopefully correct me if i'm wrong) and information regarding previously tested headers that have failed test to show you all what NOT to do.

The GOLDEN RULE as far as we are concerned

For any bend in a header primary pipe there should be no bend tighter than a 2:1 ratio, this ratio is "Chord Radius of the bend : Pipe Internal Diameter".

see picture below:-
2_1Rule.jpg
Chord Radius to Pipe Diameter
2_1Rule.jpg (69.37 KiB) Viewed 6875 times
All calculations will be shown for my header, this does not mean that it will be exactly the same for your own, but you will be able to use the methods for your own calculations.

PRIMARY PIPE DIAMETER

To calculate the primary pipe diameter you need to think about the theory of what you are attemping to do. Too smaller pipe and you will have good low end torque but the engine will be strangled at higher RPM and not produce its full power potential. Too larger pipe and torque at higher RPM will be good but not at lower RPM's. The Ideal situation is to keep the exhaust gas speed the same from when it leaves the cylinder to when it hits the turbine or in the case of a non turbo engine the 1st collector.

Now we may all know that if you increase a pipes diameter the gas speed will slow down, and if you decrease a pipe diameter the gas speed speeds up so where do we start? Where do we find our pipe size? The answer lies in the head at the exhaust valve throat. The exhaust valve throat is most likely to have the smallest CSA (Cross Sectional Area) between the cylinder and the turbine or collector. So we measure the exhaust valve throat and calculate its CSA. As in my case a 16V engine we add the 2 throat CSA's.

Area of a circle = Pi x rad x rad
Throat diameter = Td
Throat radius = Tr
Throat Area = Ta

Td = 24.5mm therefore Tr = Td/2 = 12.25mm

Ta = Pi x 12.25 x 12.25 = 471.45 mm sq

Total throat Area for 16V Engine = 2 x Ta = 942.9 mm sq

So now we need to find the nearest availiable pipe size that has a CSA of approximately 942.9 mm sq so work backwards.

Pd = Primary Diameter
Pr = Primary Radius

Pr = Square root of (942.9 / Pi) = 17.32mm
Pd = 2 x Pr = 17.32 x 2 = 34.64mm

1.500" OD pipe has a 1.6mm wall thickness so 2 x 1.6 = 3.2
add the calculated bore size (Pd)
Pd + 3.2 = 37.84 mm

If you want to convert to inches 37.84 / 25.4 = 1.489 inches

It is acceptable to go to the next pipe diameter up from your calculation, so I will be using 1.500" OD pipework purely because the bends are easily available and the kit to model the primaries which you will see at a later date is going to be available shortly.
GC_28

Guy Croft
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Re: Exhaust Header/Manifold development

Post by Guy Croft » Thu Jan 21, 2010 10:04 am

Some photos of headers on test at GCRE to illustrate the point.

G
Attachments
DH with aftermarket Integrale header on test.jpg
thumbs down on one Integrale type from Dave Harper on a visit to GCRE
DH with aftermarket Integrale header on test.jpg (68.47 KiB) Viewed 6694 times
AG header on test at GCRE (4).jpg
thumbs definitely down on this one from a Fiat Coupe 16v
AG header on test at GCRE (4).jpg (117.83 KiB) Viewed 6694 times
NHRA 4-1_02.jpg
and thumbs up from this one, as used on the GC NHRA unit on the cover of my old book, zero loss and you'd expect it given that the engine developed 199.5bhp
NHRA 4-1_02.jpg (116.25 KiB) Viewed 6694 times

ASF72
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Location: Sheffield

Re: Exhaust Header/Manifold development

Post by ASF72 » Fri Jul 09, 2010 12:42 am

Hi,

Has any of the development work on a new manifold/header been put into production at all on this thread ?

This is my new manifold for my 8v Integrale.
001.JPG
001.JPG (57.89 KiB) Viewed 5725 times
002.JPG
002.JPG (49.1 KiB) Viewed 5725 times
003.JPG
003.JPG (59.33 KiB) Viewed 5725 times
Regards

Nino

Guy Croft
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Re: Exhaust Header/Manifold development

Post by Guy Croft » Fri Jul 09, 2010 8:30 am

Dev?

Only by you by the look of it Nino!!


G

ASF72
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Joined: Mon Apr 07, 2008 9:57 pm
Location: Sheffield

Re: Exhaust Header/Manifold development

Post by ASF72 » Fri Jul 09, 2010 11:47 am

Oh right,

I will post up my results once all put back together then, I'm in need of a new radiator now so i have ordered an aluminium one.

Regards

Nino

DeltaDave
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Re: Exhaust Header/Manifold development

Post by DeltaDave » Thu Jul 28, 2011 9:03 pm

Yes work is in progress I will continue further when I have time soon.

Heres a little preview
manifoldsm.JPG
manifoldsm.JPG (55.76 KiB) Viewed 4628 times
Dave

tricky
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Re: Exhaust Header/Manifold development

Post by tricky » Fri Jul 29, 2011 12:58 am

Continue further ? Looks like your almost there, will you run the water radiator as a rear mount ? The double slip collector is a nice thing to have, thats what I plan to use too. What grade of stainless did you use ?

Thats two decent looking exhaust manifolds I've seen this week on delta builds, must be catching on. Good job, I look forward to more photos.
Twice as many valves

Guy Croft
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Re: Exhaust Header/Manifold development

Post by Guy Croft » Tue Aug 02, 2011 9:48 am

It's good to see all of these taking shape (literally).

These projects by all you enlightened folk have played an important part in raising awareness of the importance of this subject, to which for so many years 'lip-service' has been paid.

G

rmouthaan
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Joined: Fri Oct 29, 2010 7:51 am

Re: Exhaust Header/Manifold development

Post by rmouthaan » Sat Jan 14, 2012 8:32 pm

Nice manifold delta dave, i have made something simulair for an australian guy, he wanted an turbo setup for his scorpion and asked me to make him an manifold. The only downside (again) was room, and not willing to make place for it.

This will sometimes turn into somewhat difficult to make manifolds, but i keep trying.
S7300031.JPG
S7300031.JPG (276.87 KiB) Viewed 4458 times

Brit01
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Re: Exhaust Header/Manifold development

Post by Brit01 » Mon Jan 16, 2012 1:53 am

Interesting read Dave.

In the coming months I will need a new manifold for my 8v Alfa boxer.
I have read many discussions on straight types or crossovers for the boxer.

Hope I'm not hijacking. Not sure about your experience/knowledge with manifolds.

What about this for a 1.7 boxer? The firing sequence is 1-3-4-2 for the Alfa boxer.

front right side: 1-3
front left side: 4-2


45mm primaries - 65cm long (1.75" / 25.5")
Y connector on each side
50mm secondaries - 25cm long (2" / 9.75")
Y connector
57mm to end the manifold. (2.25")

Regards

Chris

rmouthaan
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Joined: Fri Oct 29, 2010 7:51 am

Re: Exhaust Header/Manifold development

Post by rmouthaan » Thu Mar 29, 2012 8:36 am

Just some pictures,

16v manifold equal length tryout, turbo had to move for an nicer route of the 4th cil.
38mm 1,5mm wallthickness, although tuners seem to prefer the 42mm/38mm id manifolds.
Attachments
S7300061.JPG
Equal length tryout
S7300061.JPG (244.59 KiB) Viewed 3947 times
S7300059.JPG
Equal length tryout 2
S7300059.JPG (277.85 KiB) Viewed 3947 times

tricky
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Joined: Tue Jul 06, 2010 5:41 pm

Re: Exhaust Header/Manifold development

Post by tricky » Thu Mar 29, 2012 5:40 pm

Hey Remco, how goes it ?

The turbo needs to move for sure to stop that nasty cheating off the head flange, nice effort.

How close to equal did you get and how acuratley / what method did you use to measure ?

Mine is nearly finished, been talking about it for a while I know :-)
Twice as many valves

rmouthaan
Posts: 7
Joined: Fri Oct 29, 2010 7:51 am

Re: Exhaust Header/Manifold development

Post by rmouthaan » Thu Mar 29, 2012 7:10 pm

Hi Tricky, i am fine thanks ;), hope you are doing well also ofcourse!

For measuring i just used the centerline of the pipe, the lengths should be equal but i have to check it again as this one was made a long time ago and just
came back to me. Dont look at the finish or anything, it was just an sample for an manufacturer to see what the idea should be like.

Moved the turbo (again) towards the gearbox and a bit towards the front of the car, if everything worked out ok, even the flowresults should be the same for every runner.

I cannot believe that yours is almost done now, must be an real artwork by now and i would love to see some pictures if you are willing to share them.

Thanks for your reply and hope to hear from you soon again with some nice header suprise ;).

Regards and all the best,

Remco

tricky
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Joined: Tue Jul 06, 2010 5:41 pm

Re: Exhaust Header/Manifold development

Post by tricky » Thu Mar 29, 2012 9:32 pm

The reason I ask is there can be a lot of error by "thumbing" a tape measure around the centre of the bends, I found it can vary by several mm in either direction for each bend, so quite a bit per runer. An acurate way is to lay the tape along the inside and then the outside of the bend, add the two together then half the outcome a perfect result each time. Maybe that is what you meant I don't know.

To fit in a decent header, and indeed a decent sized turbo you might find yourself moving things around so much it becomes barely recognisable to how the manufactuer intended, but completely nesacery of course .

Sure, I'l send you some photos when it's done.
Twice as many valves

tricky
Posts: 101
Joined: Tue Jul 06, 2010 5:41 pm

Re: Exhaust Header/Manifold development

Post by tricky » Thu Mar 29, 2012 9:36 pm

Appologies to Dave, for hijacking the thread slightly.

We'd all love to see some more photos of your manifold I am sure, perhaps some taken from above or side would be cool. How does it fit with the front 'slam' panel ????
Twice as many valves

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