Turbo Log Manifold?

[brianpgriset]

I want to build a turbo manifold for my BMW. I really would prefer to make a simple split pulse log style manifold over an equal length style manifold for lower cost and complexity.

What should I use, tube or pipe for the runs? Will 16ga tube be enough? Will be using carbon steel, don't want stainless.

Any other tips?

 

[JJThrasher]

We used to do .065 tubing iirc. It has been a while since I did exhaust though.

What is the purpose of this BMW?

 

[shocwav3]

I want to build a turbo manifold for my BMW. I really would prefer to make a simple split pulse log style manifold over an equal length style manifold for lower cost and complexity.

What should I use, tube or pipe for the runs? Will 16ga tube be enough? Will be using carbon steel, don't want stainless.

Any other tips?

Many will weigh in here, with many good ideas, but I typically use Schedule 10 s/s pipe when building my turbo mani's. Back purge the welds to prevent sugaring. Its time consuming but worth the effort if done correctly.

 

[justanengineer]

My suggestion would be to build it good and heavy. Ive seen quite a few homemade manifolds crack between the heat and vibration. Keep the runners and log as short as possible, heat into a turbo is a good thing.

 

[brianpgriset]

Many will weigh in here, with many good ideas, but I typically use Schedule 10 s/s pipe when building my turbo mani's. Back purge the welds to prevent sugaring. Its time consuming but worth the effort if done correctly.

I wanted to use carbon steel as my flanges are CS and I would prefer to avoid the dissimilar weld joint. Looks like use of 1-1/4" schd 40 CS will be my best choice. Only about .030" thicker than SS 10s and still larger than the exhaust ports.

Sound reasonable?

 

[RKSpeed]

Lot of cheap horsepower in an equal length manifold.

 

[kellymc]

Look up "weld-els" and use them for you piping in a log manifold. What motor? There are a number of turbo manifolds available for most BMW motors, it may seem cheaper to build but trust me, it's cheaper to buy

 

[FastKat]

There's a book that covers this - Maximum Boost by Corky Bell:

http://www.amazon.com/Maximum-Boost-Turbocharger-Engineering-Performance/dp/0837601606

I read this book about 4 times several years ago when I was contemplating a turbo setup for my hotrod. I wound up going with a supercharger due to engine bay & packaging constraints. He does a really good treatment of building a turbo manifold. It's pretty much required reading if you're doing a turbo setup. It'll be the best $27 you spend.

EDIT: The name may sound a little corny, but it's a good book. The guy's a helicopter engineer, and goes through math & equations, which leads to sound practical advice.

I think he also mentions using the Weld-Els.

 

[amt]

I am currently using 1-1/4" sched 40 304L, but I bet CS would be fine. I did not do a log manifold and opted for a merge collector, which I bought on ebay (search for "Turbo manifold merge collector 304 stainless sch 40 diy"). The collectors were very high quality. I am not done yet, but I hope to be soon.

 

[rockchucker]

There's a book that covers this - Maximum Boost by Corky Bell:

http://www.amazon.com/Maximum-Boost-Turbocharger-Engineering-Performance/dp/0837601606

I read this book about 4 times several years ago when I was contemplating a turbo setup for my hotrod. I wound up going with a supercharger due to engine bay & packaging constraints. He does a really good treatment of building a turbo manifold. It's pretty much required reading if you're doing a turbo setup. It'll be the best $27 you spend.

EDIT: The name may sound a little corny, but it's a good book. The guy's a helicopter engineer, and goes through math & equations, which leads to sound practical advice.

I think he also mentions using the Weld-Els.

Do you mean, "May sound a little Corky..."? =)


One of the best books out there on Turbos bar none. Weld-els are a VERY good way to start. Most of the time though the Manifold that you need is already out there and you could buy it for cheaper than you could build it.

 

[brianpgriset]

Motor in question is an m20 in an e30 BMW. I've already researched existing options and they are cheap ****, don't put the turbo close to where I want it, or cost too much.

I'm really not worried about equal length as I'm not looking to make crazy HP.

I've spent $80 for the two flanges and can get 8 els and a section of pipe for under $100 bucks so this won't be costing me too much.

 

[alan_3301]

You may want to look at a y adapter pipe that fits on the stock manifolds.
do a google search for "m20 turbo manifold adapter" and you will see.
Some of them are seemingly overpriced, but it may be worth looking in to.

 

[SpiderGearsMan]

Trunk Turbo

 

[brianpgriset]

You may want to look at a y adapter pipe that fits on the stock manifolds.
do a google search for "m20 turbo manifold adapter" and you will see.
Some of them are seemingly overpriced, but it may be worth looking in to.

You said it, just too pricey. And they are ugly too. And they require oil filter mods on the m20. The log will clean up the bay and let me put the turbo exactly where I want it.

 

[FastKat]

I am guess you already say this one? It's $300, and you're already spending $180 on parts so far. It's also a log style.

http://turbochargingdynamics.com/?wpsc-product=m20-turbo-manifold-top-mount

Gotta be honest - I am partial to cast iron in this application. If you're going with mild steel, make it nice and thick!

And no joke - buy that book.

 

[cordes]

Maximum Boost is good, but a lot of the info is a little outdated or misguided IMO. For example, his take on alky injection is way off base. Guys use it successfully to run crazy amounts of boost.

In my experience a lot of his guidelines for pipe sizing are also not the best. I've seen gains from going much larger than what he suggests as ideal.

That being said, it's still a great book for beginners. Frankly, there must be enough turbo BMWs out there to allow for their forums to give a how-to. I would seek that out.