Hey guys,
I'm going to be building myself a front facing turbo manifold soon and I'm trying to do some research before I start trying fab this thing up. I've tried searching for ideal runner lengths, how to calculated the total length of each runner after having several bends and I have not found any clear answers on this stuff. I would really appreciate and input or advice on making a decent manifold.. Thanks in advance!!

 

for a turbo manifold, try to get to point A to point B trying to make the 4 runners as equal length as possible.

for n/a, its a different story with length

 

That's what I was thinking, I already have the location that I want the turbo to sit at so I guess I start by making the first runner and then I'll try to make the other 3 as close as possible to the first one.

 

The best runner length and diameter is going to depend on how much air the engine uses, and where you want the power band. This also changes when the motor is boosted. It isn't exactly cut and dry, the "best" changes from motor to motor.

 

I'm looking to put down 800hp+ with my setup when it's done but I want to leave room for more power. I'll proably just take the best guess that I can and build a manifold, it will be a good learning experience since it's going to be my first manifold..

 

equal length does not = equal flow. unless all the runners are identical. equal length is just a catch phrase used to sell manifolds by people who think they know what they're talking about.

 

Here's what I'm trying to with..

 

exactly.

op, pm me if you want any "tips"

 

Very true, I've always wondered about that because I have seen alot of manifolds that have unequal looking runners but they are still advertised as equal .. I will take you up on the PM offer lol.. Thanks

 

as long as you keep the runners uniform and equal length as possible you will be fine. if you wanna get down to the fine print, then yes equal length tubes wont have equal flow if one has more bends in it than the other....but who in their right mind would build a runner with about 180 deg of total bend and another runner with 400 deg of total bend?

for f/i, keep the runners as equal length as possible and try to use the same degree of bends for each runner as possible.

for n/a, we do the same as above but length plays a very important role...especially when you start making step headers.

 

just have a nice merge collector and good wastegate placement and you'll be fine. keep the wastegate branch as short as possible to avoid cracking issues.

 

I really appreciate all the advice guys!!!

 

I started welding my collector I thought I'd share some pics..

 

that material looks pretty thin. if not welded properly it will only be a matter of time before you start to see it fail.

 

also, thicken up your welds for better penetration...and shorten up your weld start and stops for better gas coverage.

here's a shot off one of our production collectors for reference.

 

I gave it 2 passes on each pipe. Should I go a bit hotter to get a wider bead?

 

that should be fine. try to get it down in one pass from now on though.

 

Here's what I have in my for turbo placement.

 

i would try to clock your collector a little more upward to make for easier transitions when you go to fabricate the runners. even if it means decking it at an angle prior to welding it to the flange.

 

As far as wastegate placement, what is the ideal location and why?

 

If you're still looking at figuring runner length I have some recommendations, but how good are you at math?

 

I started fitting up runner 1, here's what it looks like.

 

...the clearance for runner 4 coming off the flange is ok right?
nice usage of clamps

 

There is space on cyl 4 for a 90 pointing straight down.

 

i would tighten up the radius on the two bends coming off the collector to draw the runner away from the head.