[taff2]

No problem Tom. Yeah, it's hard to know which parts to hang onto and which parts to move on. Imagine a 900 hp 389 back in the '60's.

[RUDOLFSSON]

Originally Posted by taff2

Sorry Tom, it's not so much an article ,rather a snippet, but here it is anyway.

That's cool stuff right there !


PS... here's something I've always wanted to make... Billet manifolds out of few pieces and welded together..

https://steedspeed.com/shop/

https://steedspeed.com/video/


Kris.

[JLMounce]

Originally Posted by taff2

Sorry Tom, it's not so much an article ,rather a snippet, but here it is anyway.

Thanks for the info on this! This actually looks fairly straightforward to build with a flange and a weld up kit.

[n2ogpsj462]

What about starting with a center outlet manifold? i used one on my drivers side to run the pipe under the oil pan before merging the other side. Easy to make something out of that if twins were wanted

[Tom Vaught]

Originally Posted by n2ogpsj462

What about starting with a center outlet manifold? i used one on my drivers side to run the pipe under the oil pan before merging the other side. Easy to make something out of that if twins were wanted

If you could get Oil Pan clearance for two pipes you could do a bank cross-over deal where the center discharge manifold for 1,3,5,7 fed the Turbo mounted on the engine somewhere near the right head. Same deal for the 2,4,6,8 center discharge manifold feeding the Turbo mounted on the drivers bank.

To fit the pipes between the front of the pan sump and the frame front cross-member you would probably need a oil pan design like this one:
See Pic

Tom V.

[n2ogpsj462]

That's a good idea Tom. I used a 2 1/2 pipe from the drivers side that crosses between the front of the sump and frame. I tucked it close so my cradle is still the lowest point but could save room with a smaller pipe. How much power could 2" pipe support with twins before becoming a choke?

[Tom Vaught]

2" pipe can feed a lot of air to a turbo and the turbo does not need to be fed at really high engine rpm. 5000 engine rpm will feed a 2" pipe nicely to a single turbo.
That is a single pipe like a 389 Pontiac Catalina exhaust system would be. You are only feeding 4 cylinders worth of exhaust gas vs 8 cylinders to run to 5000 rpm.

Think Travis Quillen fed 500 hp two cylinders thru one 2" exhaust pipe. 4 pipes, 2000 HP on his 63 Tempest. So 1000+ HP with the system we are describing.

Tom V.

[JSPONT]

Like an idiot, I used a 3 inch crossover, since my header collector was 3 inches. Mt passenger side bolted right up (Jeff Palazos). My driver side was a full re-do. If I had to do it over, I would use a smaller pipe.
I like the idea of a log type manifold out of stainless.

[n2ogpsj462]

I failed to listen to experts and thought 'how is 6-700 hp worth of exhaust going to get out of my motor through small pipes' so I went with a 2 1/2 crossover. Because a big motor needs to get rid of the exhaust right? Might redo mine in 2 1/4 if time allows now that everything is apart anyway

[JSPONT]

I am not sure of the effects of the larger pipe. I have a 3 inch crossover, my car spools pretty fast. Wonder if the smaller pipe would spool it faster. I call my one header I made Frankenstein. Welded stainless for the 1st time on that header!!

[Tom Vaught]

What I have seen is everyone is thinking like the exhaust will get plugged up with too small of a pipe diameter.

The cylinders fire like marbles going down a pipe. If you had a 180 degree flat crank in the car then with the right exhaust you could get
four even 90 degree firings at one collector and four even 90 degree firings at the other collector.

But the Pontiac engine uses a 90 degree crank so now you have the 1,8,4,3,6,5,7,2 firing order and cylinders 5 and 7 fire right next to each other and the rest of the cylinders act line this:
1,space, space, 3, space, 5, 7 (driver's side)
and 2, space, 8, 4, space, 6 (passenger side)

So the pipes do NOT get plugged up and two cylinders on each bank fire one after the other
and there is always a space between the other cylinders on that bank.

2" pipe is plenty for one bank (from a center discharge manifold).

Tom V.

[7D9TA]

On my car I run 2.25" from the headers to the Merge at the T6. The merge is 3.5".

This is a pic from when I was figuring out how to get from the passengers side header to the Turbo. I went with a longer path and smoother bends over a short but really sharp turn. This helped me setup my wastegate angle also.