Log Manifold vs Tubular Manifold

A common question, although many might not ask it, is "Which is better, a log manifold or a tubular manifold?" Look no further. I have compiled a list of the pros and cons of both log and tubular manifolds.

Log Manifolds
Pros:
- Cheap (in terms of price)
- Easy to make
- Very durable
- Require less work than tubular manifolds
- Allow for fast spooling due to short runners
Cons:
- Not very efficient
- Increased heat
- Yields more torque than tubular manifolds
- Limits size of turbos to smaller sized turbos due to common T25 flange, as well as the lack of clearance of the wastegate actuator to the motor (and in our case, the compressor side won't clear the firewall)
- Limits ~400whp
- More stressful on motor at high boost

Tubular Manifolds
Pros:
- Very efficient
- Doesn't restrict flow
- Achieves power goals quicker and easier than log manifolds
- Durable (stainless manifolds)
- Keeps torque low
- Able to achieve well over 400whp
Cons:
- Expensive
- More extensive/difficult to make
- Boost Creep if manifold is improperly made


If there is anything you would like to add, please post it up! Information is key :turbohug:

i found this when i had the same question..

Log manifolds do have their benefits though: they’re cheap, they’re easy to make, they’re durable (especially if cast and not welded), and they allow the turbo to spool very quickly due to its stubby primaries (an exhaust primary is the first tube through which exhaust gas from the cylinder flows; there is one for each cylinder) and overall smaller volume. If you go with a log manifold, make sure that the flange that bolts to the head is cut between each runner. The resulting spaces between the flanges of each runner will allow them to expand and contract independently as they’re heated up and cooled down, preventing the chance of cracking. Log manifolds are usually made of thick, mild steel--again, there's no point in using expensive and hard-to-work-with stainless steel if the main selling point of a log manifold is price.

Tubular manifolds are more expensive than log manifolds, but they do have their benefits. The design is far more efficient and high flowing, and while 350 whp can easily be produced using a log manifold, if you are looking to run a lot of boost and plan on making a lot of power (400+ whp), a tubular manifold will get you to your goal quicker. And while the longer tubes might increase the time it takes the turbo to spool up, a tubular manifold will never restrict flow (and therefore power) to the turbo in the upper RPM ranges. In fact, if you have the money, you can have the quick spool time of a log manifold with the high flowing characteristics of a tubular manifold:

Awesome, anyone else like to chime in? Hopefully we can get some great info and make this into a sticky.

I heard boost creep is a drawback when using a tubular manifold. Im nervous of my WG placement on my Peakboost mani. We shall see in a few weeks when tuning.

^ That's another good point. An improperly placed wastegate will cause creep, as well as poor manifold design.

I bought a Fabworx sidewinder manifold. The welds had pinholes, the tubes were almost too short, stay away from this brand. When I had my log mani, I took a grinder to it and ported it. Made 270 at the wheels on a mustang dyno, on a bone stock k20a3. The log manifolds are great for drivable (230-350) horsepower. I stay away from the stainless log manifolds. If you can find a cast iron you'd be in good shape.

Quote:

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Originally Posted by The Good DOHCtor

I bought a Fabworx sidewinder manifold. The welds had pinholes, the tubes were almost too short, stay away from this brand. When I had my log mani, I took a grinder to it and ported it. Made 270 at the wheels on a mustang dyno, on a bone stock k20a3. The log manifolds are great for drivable (230-350) horsepower. I stay away from the stainless log manifolds. If you can find a cast iron you'd be in good shape.

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Awesome info. I'll definitely add this to the final list, manufacturer reviews are extremely important as well.