LS Turbo Headers
For a LS1 5.7 budget build single turbo in a boat 3000-6000 rpm 700-800 FHP
I bought some Chinese up and forward turbo headers,But they are just too thin I think for any serious use.So I am looking at making some
So tring to decide on log or tuned length, plenty of room in a boat but will make them tight to hopefully be able to swap to the front for our Commodores down under/ your pontiac gto.
Looking at what the big boys are using Matt and others make plenty of power with a log type
Nelson with the Tuned equal length
BUT surely equal length on a twin system V8 is wrong with cylinders on each bank firing with odd spacings .I can see the point of equal primaries on a
8 into 1 system.
So with a standard LS firing order 18726543 crank angle between firing would be?
Left bank 1-7 180 deg 7-5 270 deg 5-3 180 deg 3-1 90 deg
Right bank 8-2 180 deg 2-6 90 deg 6-4 180 deg 4-8 270 deg
So shouldn't there be 2 pipes of equal length 1 short and 1 long for a twin system?
For ease of math lets say 90 deg rotation = 12" primary tube length
Cyl 1 =24" cyl 3=32" cyl 5=12" cyl 7=24"
cyl 2 =24" cyl 4=24" cyl 6=32" cyl 8=12"
Working on the 90 deg being the long pipe to make the time longer to reach the collector
What do you guys/gals think? Has anyone done it like this

 

The thin wall, cheep, up and forward headers have shown to be holding up well. There's a few guys using them on a boating forum I participate in. I'm using them on my boat build, twins though. Not a running deal yet, so can't speak to it firsthand.

They say... no cracks or unusual warping. But, to wrap them in exhaust wrap, as the heat on their backs is nearly unbearable.

I could see myself getting geeked out on exhaust design. That said, I think it would have to be a project of passion. I'm not convinced there's enough gain there to warrant the effort. For me to take on the project primarily in search of a few bits of power, I'd have to be in competitive racing and at the end of other solutions within the class rules.

It is fascinating science though.

 

My thoughts are, unless your sneaking every last bit of hp out of a system, the turbine is still the biggest restriction with sound pulsing almost non existent. All motor stuff, tuned header, turbo stuff is more like hvac, plumb it and be done. A proper turbo cam won't have much overlap anyways to take advantage of the tuned length and we're just getting the exhaust to the turbine

On that note, my project deemed something better than stock manifolds simply from an appearance platform. I used 1-3/4 16ga tubing and had them coated. The original china headers I had were 1-7/8 18ga and are holding up just fine in another project car

 

Don't most of the boat guys plumb a water jet into the manifolds to help cool them down anyway? I'd think a cast manifold for toughness and crack resistance with a decent sized water jet pumping through them pre and post turbo would keep everything plenty cool and easily hit your goals. No need to over complicate it.

 

The world over, yes, most boats inject water into the exhaust stream at some point. Most have a water jacketed manifold and introduce water after the primaries merge. It keeps everything cool in the typical enclosed engine compartment of a boat. So much so, that exhaust is, in many cases, routed into fiberglass exhaust tubing.

A few down sides to doing it that way for a performance build. It creates some exhaust flow restriction and water will kill an O2 sensor on a closed loop EFI deal. The O2 sensor problem can be dealt with by extending the water jacketed portion of the exhaust and introducing it into the exhaust stream further away from the O2 sensor location.

I suspect what you might have been referring to is direct port injected headers, which is a way to keep a performance tubular exhaust header cool. Both, for safety, and it helps keep chrome from discoloring or burning and flaking off. In this method, a small amount of water is injected into each primary, right at the exhaust port. And it's only injected above idle rpms. Just enough water that a steamy fog is visible out of the collector. The exhaust pipes will still be hot enough to burn you, but they wont instantly vaporize entire limbs from existence.

There are a couple problems with this method, especially for turbo charged applications. The water vapor wont hurt the exhaust turbine, but the water would have to be further pressurized to overcome exhaust back pressure to be able to push it into the exhaust stream. And there's the O2 sensor issue again.

My original plan was to use the stock style water jacketed manifolds, water jacket the entire exhaust, and dump the water overboard, completely eliminating it from the exhaust stream altogether.

That's a ton of fab work, to weld a tube within a tube. Wouldn't be all that bad if it were just a straight shot, but it would have to continue through bends. Currently I have zero welding skill, no appropriate fabrication tools, and the cost to have it done is waaaaay beyond the scope of the project.

Cheep headers and wrap it is.

 

Be aware wrapping thin wall headers will greatly accelerate corrosion and risk of cracking. Being a BOAT I imagine you already considered this. May want to consider ceramic coating and wrap over the CURED ceramic coat. Local shop quoted a couple hundred bucks to high heat coat my longtubes AND cure them in their oven.

 

For the price of the ebay headers if you had to buy a new pair every other year it wouldn't be a huge deal. I agree thick wall SCH.40 SS stuff is the way to go if you want them to last, but it's hard to argue with the cost of the china junk manifolds. They are pretty much disposable at that price and I think they would last awhile.

Same with a factory manifold. You could pick up some SS C6 manifolds pretty cheap. Built much better than the ebay stuff I'd bet.



Or even the 98 Fbody manifolds were stainless.

 

5th Gen Camaro ZL1 (LSA engine) manifolds are stainless.

Andrew

 

You will find that most longtube designs are a compromise between what fits and what's optimal for performance.

 

I've thought about this for a long time.
A pair of factory Truck or LS3 manifolds flipped upside down will allow a T4 Flange welded directly to the manifold with little to no length in extra piping. You can set your turbo's up top (Not too high) and get cold air and the exhaust will shoot straight out the back of the boat. You can even drill/tap in the manifold for your wastegates. This would be so damn easy to do in a single weekend.

EDIT: I just realized you were talking about a single turbo. If twins are an option, then you can do exactly what I was talking about. You can get some damn good turbo's for cheap that will make a Ton of power. And, 2 is always better