Hot Rod Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
379 Posts
Discussion Starter · #1 ·
Just as the title says I am looking for a set of tri-y headers that have been arranged for the 4-7 swap on an sbc. Shoenphield says their headers do work with the 4-7.

Preferably they would be hugger shorty tri-y equal length primary tubed arranged for the 4-7 swap.

Otherwise any good custom header builders in MN usa?
 

·
Registered
Joined
·
12,338 Posts
curious as to why you want both shorty and tri-Y,both of which are not usually connected to high horse power engines,where as the 4/7 swap is more common in very high horse power engines?
 

·
Registered
Joined
·
379 Posts
Discussion Starter · #6 ·
For higher rpm power it requires the total length prior to the collector to be rather short. the longer primaries are for lower rpm power.

my motor hits 8k
 

·
WFO
Joined
·
5,030 Posts
Maybe I'm missing something here (not the 1st time), but "tri-Y/shorty/block hugger" and 8K rpm are usually not in the same sentence. Tri-Y headers are traditionally for low/midrange power. Shorty and hugger headers are just bad for making power (especially power at 8K rpm), at least those that I've seen.

Shorter primaries and collectors (and larger ID) do tend to support higher RPM power ranges. But a high RPM-tuned long tube header is still longer in most cases than what's seen in a block hugger or shorty type header. Plus has a much better design that includes a proper collector.

There are LS-type headers by Doug Thorley that have what I think you want. Thing is they're not huggers.:
 

·
Registered
Joined
·
12,338 Posts
tri y block huggers will not be the best for high RPM or big horse power.
primary length and diameter and collector length and diameter are all important.I already posted 1 of the best headers guys in north America,and if you are building a 327 like in your other post I doubt you will need anything bigger than 1 3/4 primary tubes and 3 inch collector.
If you do make big power then step headers are likely enough
 

·
Registered
Joined
·
157 Posts
Just as the title says I am looking for a set of tri-y headers that have been arranged for the 4-7 swap on an sbc. Shoenphield says their headers do work with the 4-7.

Preferably they would be hugger shorty tri-y equal length primary tubed arranged for the 4-7 swap.

Otherwise any good custom header builders in MN usa?
If you study the standard Tri-Y header for a SBC, they are designed to only work with the standard firing order.

Take a look at this photo. The right side header pairs 2 with 4, & 6 with 8.



Now the left header is different. It pairs 1 with 5, & 3 with 7.

This matches the firing order somewhat 1-8-4-3-6-5-7-2

2 is Y'd with 4, they fire 180 degrees apart
6 is Y'd with 8, they fire 180 degrees apart
1 is Y'd with 5, they fire 180 degrees apart
3 is Y'd with 7, they fire 180 degrees apart.

Now if you do a 4/7 swap, this is what happens: 1-8-7-3-6-5-4-2

2 is Y'd with 4, but now they are 90 degrees apart
3 is Y'd with 7, but now they are 90 degrees apart
(the other cylinders are still 180 deg apart)

My guess is that you will get some big time reversion (back flow) in the #2 cylinder & #3 cylinder.

You will need custom Tri-Y headers to work with the 4/7 swap. If anyone tells you anything different, they don't know what they are talking about.

.
 

·
Registered
Joined
·
379 Posts
Discussion Starter · #10 ·
I know how they work, I am attempting to avoid making them entirely. Shorty for rpm, hugger because of the constraints of space I have, and tri-y (waaaay to long to explain either way cobalt you know how long this project has been going on so you know how much research I have done so...).

This is the last step of my motor. I would like to run a 4-7 swap for the stress on the crank shaft goes down quite a bit. I thought of doing the 2-3 as well and following the ls fireing order entirely but for the $$$ I am not sure if its worth it. If it was I would just buy aftermarket z06 headers, they are tri-y from the factory... so are maserati gran turismo headers (ferrari motor with a cross plane crank), as well as the bmw s65 motor. I would run 180* headers if 1 they weren't so damned long, and two they would fit in my chassis. the doug thorely won't work because the ls has a 4-7 swap and a 2-3 swap factory.
 

·
Registered
Joined
·
157 Posts
I know how they work, I am attempting to avoid making them entirely. Shorty for rpm, hugger because of the constraints of space I have, and tri-y (waaaay to long to explain either way cobalt you know how long this project has been going on so you know how much research I have done so...).

This is the last step of my motor. I would like to run a 4-7 swap for the stress on the crank shaft goes down quite a bit. I thought of doing the 2-3 as well and following the ls fireing order entirely but for the $$$ I am not sure if its worth it. If it was I would just buy aftermarket z06 headers, they are tri-y from the factory... so are maserati gran turismo headers (ferrari motor with a cross plane crank), as well as the bmw s65 motor. I would run 180* headers if 1 they weren't so damned long, and two they would fit in my chassis. the doug thorely won't work because the ls has a 4-7 swap and a 2-3 swap factory.
Are you building a LS motor?
 
1 - 13 of 13 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top