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Exhaust pipe diameter

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Angelking
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Exhaust pipe diameter

Post #1 by Angelking » Wed Jun 24, 2020 6:42 pm

Working out the exhaust on the hotrod. Ford 300, bored 030 over, comp cam 248 with kit, offenshauser intake, Holly 600 4-barrel. It has the exhaust manifolds shown in the pic. Will be using Thrush glasspacks. What would be the recommended exhaust pipe diameter? I am running the exhaust as shown in the rough drawing in the pic. The glasspack inlet/outlet size choices are 1 3/4" 2" 2 1/4" 2 1/2" 3"

Image

Thanks

AK

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THE FRENCHTOWN FLYER
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Re: Exhaust pipe diameter

Post #2 by THE FRENCHTOWN FLYER » Wed Jun 24, 2020 8:13 pm

(2) x 2.25 is plenty.

(2) x 2.5 would look better in my eye.

A crossover pipe would be time and money well spent, but spoil the classic look of the system.

Think about some shiny heat shields where passenger elbows might touch.

Nice T-bucket. Get ready to hold on to your shorts.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

Angelking
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Re: Exhaust pipe diameter

Post #3 by Angelking » Wed Jun 24, 2020 8:25 pm

THE FRENCHTOWN FLYER wrote:(2) x 2.25 is plenty.

(2) x 2.5 would look better in my eye.

A crossover pipe would be time and money well spent, but spoil the classic look of the system.

Think about some shiny heat shields where passenger elbows might touch.

Nice T-bucket. Get ready to hold on to your shorts.


I also think 2.5 would look best.. Thank you, have been working on it for about 2 years now. Trying to give it a '40's dirt track look.

AK

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old28racer
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Re: Exhaust pipe diameter

Post #4 by old28racer » Thu Jun 25, 2020 12:20 am

I'm with the others, 2 1/2" exhaust.
Have you thought about narrow front rims & tires for more of the 40's dirt roadster look? JMO
Bad Day Racing Is Better Than A Day In The Stands :mrgreen:

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jgregg13
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Re: Exhaust pipe diameter

Post #5 by jgregg13 » Thu Jun 25, 2020 12:20 am

I vote for 2-1/2" as well. Mainly for the looks. If you're using EFI exhaust manifolds, I would use two front manifolds so the pipes come out at the same angle, again for good looks. It's easy to modify a front manifold to fit in the rear.

I am using a front exhaust manifold on the rear three cylinders instead of the normal rear manifold. This is to facilitate mounting the twin turbos. The mounting of the manifold is the same at cylinders 5 & 6 as 2 & 3 but cylinder 4 mounting is quite different from cylinder 1. So I cut off the front mount ear for cylinder 1 and milled a couple of flat spots to allow clamping at the top of #4. Also made two clamping bushings to clamp at the new flat spots. Then at the bottom of #4 I drilled and tapped a new hole in the head for an extra stud that is locked and sealed (water jacket) with high temp red Loc-tite. The lower two holes are so close together that I have to use a socket head capscrew in one for wrench clearance.
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Angelking
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Re: Exhaust pipe diameter

Post #6 by Angelking » Thu Jun 25, 2020 5:52 am

old28racer wrote:I'm with the others, 2 1/2" exhaust.
Have you thought about narrow front rims & tires for more of the 40's dirt roadster look? JMO


The tires on the car now will be changed. These are just on there to roll it around. The rims are '40's era wide 5 rims that were used on many race cars back in those days including my fathers.

Thanks

AK

Angelking
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Re: Exhaust pipe diameter

Post #7 by Angelking » Thu Jun 25, 2020 5:55 am

jgregg13 wrote:I vote for 2-1/2" as well. Mainly for the looks. If you're using EFI exhaust manifolds, I would use two front manifolds so the pipes come out at the same angle, again for good looks. It's easy to modify a front manifold to fit in the rear.

I am using a front exhaust manifold on the rear three cylinders instead of the normal rear manifold. This is to facilitate mounting the twin turbos. The mounting of the manifold is the same at cylinders 5 & 6 as 2 & 3 but cylinder 4 mounting is quite different from cylinder 1. So I cut off the front mount ear for cylinder 1 and milled a couple of flat spots to allow clamping at the top of #4. Also made two clamping bushings to clamp at the new flat spots. Then at the bottom of #4 I drilled and tapped a new hole in the head for an extra stud that is locked and sealed (water jacket) with high temp red Loc-tite. The lower two holes are so close together that I have to use a socket head capscrew in one for wrench clearance.


I actually was looking into this about a year ago and couldn't remember why It wouldn't work. Now I remember...... The engine is set back a bit. Putting front manifold on the rear would require almost a 90 degree bend to clear the firewall then another 90 degree bend to run it along the body. By keeping the rear manifold stock it just takes a mild circular bend to align with the other pipe. Just one of the limitations of a T-Bucket. But it is an excellent idea and thanks for the pics!



AK

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old28racer
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Re: Exhaust pipe diameter

Post #8 by old28racer » Fri Jun 26, 2020 1:12 pm

Ya 40's wide 5 rims are period correct & will look great all around. Have fun building.
Bad Day Racing Is Better Than A Day In The Stands :mrgreen:

Angelking
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Re: Exhaust pipe diameter

Post #9 by Angelking » Fri Jun 26, 2020 6:09 pm

old28racer wrote:Ya 40's wide 5 rims are period correct & will look great all around. Have fun building.


Thanks!

AK

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