Driver's side header is done, 1 7/8" stepped to 2" primaries, 3.5" v-band collector. Waiting for the correct flange from TTi so he can do the other side (they sent a 1 3/4 flange), then on to the 3.5" duals. Thanks again bro, can't wait to hear this thing breathing through the big tubes

 

Very nice. That had to take a while! Props to Marshall

 

I know where I'm going next to get any fab work done! Looks great.

 

He definitely does great work, I'm a very happy camper

 

I'll be the first to admit that I don't completely understand why things work the way that they do, but why are the tubes smallest at the head, and then get bigger? Does that increase the velocity or something?

Nice looking welds, by the way...

 

I believe it's similar to the idea that most turbo outlets are significantly smaller than the end diameter out the rear. The o2 housing then get progressively larger and then the actual downpipe usually goes 3".

 

Yup, a stepped header allows you to keep torque while not hindering your topend power. A compromise if you will, for a street/strip setup. If I was going full race, I'd probably go 2" straight through (maybe bigger depending on the setup, I'd probably run a bigger cam if it was a race car), if it was strictly a street cruiser, than maybe straight 1 7/8", or even a 1 3/4" stepped to 1 7/8", to maximize torque. But with the 4200 converter I don't need to squeeze out every bit of lowend torque, I can afford to sacrifice a lil on the bottom to have more power up top. Especially when I'm spraying, with an extra 300hp being added, the big tubes will really shine.

 

I never have understood a lot of things when it comes to headers and crazy manifolds... My mentality is that it makes less sense to have a pretzel shaped twist and turn manifold or header than it would to have as few bends and turns as possible.. but fortunately for everyone else in the world I'm not the one designing them.

I guess I need to do some research and learn about them. That's always been something that's interested me.

Looks good though Marshall! Looks like your work is getting better and better!

 

Looks good... how's the labor ratE?

 

Keep in mind that in turbocharged applications, the exhaust manifold is pressurized just like the intake side is. An exhaust leak anywhere pre turbine wheel is considered a boost leak as well. That's why turbo cars can run a wastegate on runner number 1 for example and release pressure throughout the entire manifold and control psi. With larger turbo applications this wouldn't be optimal as the total pressure within the system is to large for the number 1 runner to release it. This is why boost "should" be regulated at the collector versus at the #1 runner. Mine was always off #1 and I never had any problems but some experience boost creep issues.

The bends are "crazy" in design due to fitment issues within the engine bay, and depending on the manufacturer, some are trying to achieve equal lengths in the runners causing the runners to be longer. A log manifold gets the job done but it's far from as efficient in flow as say a full-race manny, or shearer fabrications. If you notice how drag cars generally have longer length turbo manifolds because their application allows it. They can mount the turbo in the front of the bumper which allows the runners to be equally sized and very straight when entering the turbine. Once the exhaust exits the turbine housing and cools then gradual angled bends and large diameter piping help out alot.

Of course then you have some crazy assholes going mid 11's on a 14b and 2.5" exhaust / stock intercooler and IC piping. Problem is not everyone is able to do this, for one reason or another.