Extrude honing a Carrera 3.2 intake

[Tippy]

I know very few have done this, but when they hone the intake, do they maintain the 41.5mm outlet size of the runner?

It seems impossible considering how the process works, but maybe I'm wrong.

I want to do mine but I would hate if the outlets got larger.

TIA

[Fly911]

I think that the general consensus is that only extrude hone the intake runners do very little, other than a more equal air flow to the cylinders, especially #6.

However, in combination with bigger displacement, bigger cams, bored out TB, modified heads, headers, MAF rather than the restrictive AFM, then a standard intake might become a restrictive factor.

[Tippy]

Originally Posted by Fly911

I think that the general consensus is that only extrude hone the intake runners do very little, other than a more equal air flow to the cylinders, especially #6.

However, in combination with bigger displacement, bigger cams, bored out TB, modified heads, headers, MAF rather than the restrictive AFM, then a standard intake might become a restrictive factor.

Yeah, I am 993SS cams and boosted. Although it's not much of a restriction, every bit helps.

My MAIN goal is uniform as possible flow between ports. Running a cylinder or two lean due to the average AFR's is not a good thing, especially when boosted!

[Peter M]

Cory,

Why don't you test the manifold on a flow bench first to check if there is an imbalance between the runners in the first place?

From my reading on this topic, some manifolds are fine and some, due to production variation, are not. I also can't imagine Porsche deliberately designing imbalance in although I acknowledge runner 6 has a kink to fit around the AC compressor.

You may find that the imbalance, if it exists, could be corrected with some simple die grinder work.

Alternatively you could cut the manifold in half, clean the flow up with a die grinder and then weld it back together like what was done in the good old days.

I also get the impression that some of the extrude hone flow numbers posted by the providers isn't "reliable" so I think if you want to do this properly, doing your own flow numbers before and after are a crucial check.

However, is this really a problem that needs solving and are the potential benefits worth the cost?
How much richer are the lower flow cylinders having to run to make up for the high flow cylinders? You may not be losing as much Hp as you think.

How about upgrading your ECU, adding an extra o2 sensor and maybe two knock sensors so you can individually tune each cylinder? This may be a better first step as this search for "perfection" seems to be a goal of yours and will have to be done anyway.

[stownsen914]

I've heard that extrude honing is more about improving surface finish than porting. But just googled and found their FAQ which states that up to 1 mm can be removed in the process.

https://www.extrudehoneafm.com/faqs/faq-automotive/

[Tippy]

Originally Posted by Peter M

Cory,

Why don't you test the manifold on a flow bench first to check if there is an imbalance between the runners in the first place?

From my reading on this topic, some manifolds are fine and some, due to production variation, are not. I also can't imagine Porsche deliberately designing imbalance in although I acknowledge runner 6 has a kink to fit around the AC compressor.

You may find that the imbalance, if it exists, could be corrected with some simple die grinder work.

Alternatively you could cut the manifold in half, clean the flow up with a die grinder and then weld it back together like what was done in the good old days.

I also get the impression that some of the extrude hone flow numbers posted by the providers isn't "reliable" so I think if you want to do this properly, doing your own flow numbers before and after are a crucial check.

However, is this really a problem that needs solving and are the potential benefits worth the cost?
How much richer are the lower flow cylinders having to run to make up for the high flow cylinders? You may not be losing as much Hp as you think.

How about upgrading your ECU, adding an extra o2 sensor and maybe two knock sensors so you can individually tune each cylinder? This may be a better first step as this search for "perfection" seems to be a goal of yours and will have to be done anyway.

Peter, it's not about hp gains, it's about equal flow for me. I had huge swings in AFR's which I believe was due to the intake port flow variance.

I had signs of detonation and absolutely killed some Nikasil cylinders and rings. Now, I did not have enough gap for the boost I was running, so that was one factor too.

To your point, yes, I want to check flow before spending the money. If it's within 5%, I'll leave it be and run as is.

But the after numbers do look promising!

[Tippy]

Originally Posted by stownsen914

I've heard that extrude honing is more about improving surface finish than porting. But just googled and found their FAQ which states that up to 1 mm can be removed in the process.

https://www.extrudehoneafm.com/faqs/faq-automotive/

I've seen some decent removal of material, especially around sharp bends. That's where it seems to shine. On broad surface areas, removal seems minimal.

[Mixed76]

Originally Posted by Tippy

I know very few have done this, but when they hone the intake, do they maintain the 41.5mm outlet size of the runner?



It seems impossible considering how the process works, but maybe I'm wrong.



I want to do mine but I would hate if the outlets got larger.



TIA

From the website:

"The tooling is a holding fixture that directs media flow to the target area of the part, while protecting areas where abrasion is not desired."

"I want my parts to be flow matched. Can my parts be bolted together while they are Extrude Honed?
Fixturing assembled parts is physically impossible; but mating part can still be easily matched for flow. What we do, is we the match parts to the gasket. This way they will have the same dimensions post process."

Seems they can protect the ID at the mating surface; that said, maybe call them or send an email telling them what you want to do and ask if they can do it?

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