Question about making turbo headers (twins)
 

So I have been doing some research and I am still in the planning stages of making my own turbo exhaust manifolds. I know logs have been getting it done for years and truck manifolds work just fine but I want to do the work I can for my own car that I am capable of doing. That being said, the question that I want to know is there a optimal position for the cylinder tube going into the collector? Or does it matter?

Let me clarify, think of the passenger side of the engine. It has the even cylinders (2,4,6,8) so would it be best to have it go in firing order from the top right 8, top left 2, bottom left 6 and bottom right 4? The same with the driver side top left 1, top right 7, bottom right 5, and bottom left 3.

I know V8's don't work the same as 4 bangers with being able to match cylinders to prevent any interference with each other while the suck squeeze bang blow happens. I just want to keep it from possibly being a restriction to making the power I would like to achieve.

Many factors come in with the entire system but this part I want to make sure I have some good info on before I get started. This isn't happening this week or next month as I want to make sure I know as much about the small details as possible just for peace of mind. Thanks for looking and possible help ahead of time.

Are you making manifolds or headers? Sounds like headers.

sorry late night typing, yes I am making headers. I am doing a pvc mock up and tig welding away from the car.

A lot is really going to depend on how much room you have.

I guess if you have the room, make them all equal length, other than that I really wouldnt worry.

Keep tube diameters a sensible size...ie not huge, use a quality merge collector as opposed to some of the cheaper plain sized stuff
The merge to a smaller diameter then open up slightly seems to help evacuate the other tubes better which can only be a good thing too.
There should still be this effect even with pressure inside the system.

And not forgetting a more important part...plug access and general access to work around them.
In that respect truck manifolds are just great, but then they should be being a factory part.

I wouldn't worry about where you put the tubes in the collector as far as firing order goes.

There were a few things I tried to do when I built mine. I wanted thick material for heat retention, I wanted the turbos close the heads to keep runners short, and I went with a twin scroll set up. I also wanted reasonable access to plugs and over all easy to work on.

I did all of this to try to get decent size turbos to spool as early as possible. And it was fun project. Lots of pics in my build thread.

Twin scroll unless the tubes/wastegates are properly divided to make use of proper twin scroll type pulsing from correct cylinders is a waste of time.

these are good point to bring up. I have already went through and got that taken care of. I am just wondering if at the collector there is a optimum position of the cylinders on each bank.

You have done some great work with your car. That build is amazing and I can't wait to see the finished product. I have read up on the twin scroll and I don't see how it can work with a V8 with the pair cylinder being on the other side. It is interesting you are doing it and has me curious to what the results will be.

I would agree. Making a twin scroll would be hard to get right on a V8 and would take a lot of tubing to get the pulses to stay strong over that length.

I am really looking for something that takes the concept of twin scroll I guess. Not with pairing cylinders but to keep the pulses from causing problems with the valve train to keep back pressure down. Also any ideas or concepts people are thinking about are welcome. Like I don't know maybe a uneven collector or something.

Just chose sensible size turbine and housing and backpressure will not be an issue, likewise with cam/valvetrain.

There will only be problems if you create problems.

But from what you're trying to achieve, again just a proper merge collector with pointy bit inside etc, and place turbine inlet directly after the merge and that will keep each exhaust valve as isolated from each other as is practical.

But choosing a cam with little overlap and perhaps shorter valve events will help isolate them too. But again with a well implemented setup EGBP should not be a concern, so none of those things should really be much of a concern either.

Even with two DIY modified truck manifolds and small 2" ID Sch10 elbow into the T4 flange on mine, up to around 17psi I'm almost 1:1 with boost.
Sensor took a shit a few weeks back and only replaced it a few days ago, so havent tried with more boost yet.

IMO if you're seeing 2:1 or higher, something else really needs looked at unless it's a super fast spooling setup

Exhaust Pulse Tuning. Try googling it. Here are a few discussions on it.

http://www.turbobuick.com/forums/threads/928-hp-on-the-chasis-dyno-today-thanks-otto.362375/page-4

https://ls1tech.com/forums/advanced-engineering-tech/973299-exhaust-pulse-tuning.html

http://forums.nasioc.com/forums/showthread.php?t=1390611

thanks for the insight. I will see what I can see about the cam specs that I want. As for the where the turbo will be I would say it would possibly be a foot to 2 away from the collector.

Thanks for the help, giving me a direction to look and something to read. I will read and get back to this thread.

good entry level logs (ie not 90 deg entrys) are hard to beat because on a turbo motor cam overlap is not a much a factor on total performance. It is more important to keep the drive pressure/boost pressure a difference as big as possible