dimpled intake/header (what's your thoughts/experience?)

[humfrz]

Originally Posted by Escobar89

So the the winter is comming in Sweden and the Subaru is about to be put in the garage soon, and by that it also means its time for some minor projects! ..or as well just your thoughts!

Well, Escobar89, my thoughts are that if you just want a project, dimple away. However, if you're looking for any significant gains in power, I'd suggest you find a different project.

I assume your garage is heated -


humfrz

[86MLR]

With my very limited knowledge of fluid dynamics (2/5 of F all) I can understand the concept.

But, I know no-one that has done this, has any of the million dollar high hp exotics have utilised this?

I have quite a few freinds with more money than sense and when they build a motor it is all out, computer designed stuff, trying to gain every edge.

I would love to see some computer based designed flow differences.

The R&D of it alone would be a interesting read, results of different dimple size, depth and such.

It would be all boundry layer and laminar flow stuff.

Science is cool, especially when it's about optimizing power, and stuff.

Some engineer geek should get their nerd on and post up some fluid dynamic magic for our reading pleasure.

Me, I struggle to type a post and use basic Excel

[churchx]

Without extensive knowledge about how it all is designed & works as a whole, blindly doing by hunch mod to one of component has chances to actually do something (but why noone in these 6 years hasn't done it yet?), be wasted money for no (or too minimal gains) that better could have been spent on something actually netting gains, or even have losses due other components not designed to work with such changed one of component of intake-engine-exhaust-tune.

Hence you should go for proven solutions of fuel atomizing magnets

[86MLR]

Originally Posted by churchx

Without extensive knowledge about how it all is designed & works as a whole, blindly doing by hunch mod to one of component has chances to actually do something (but why noone in these 6 years hasn't done it yet?), be wasted money for no (or too minimal gains) that better could have been spent on something actually netting gains, or even have losses due other components not designed to work with such changed one of component of intake-engine-exhaust-tune.

Hence you should go for proven solutions of fuel atomizing magnets

Crystals and magnets are where it's at, or was....

https://www.google.com.au/amp/s/jalo...1822559023/amp

[Lantanafrs2]

That Saab head looks like it has a full radius valve job and some deshrouding work in combustion chamber. Probably much more of a factor than the dimples.

[bcj]

Originally Posted by gtengr

IMO the most likely flow improvements from surface treatment is knowing how to implement a gentle spiral shape in the intake port.

Rifling looks to be the way forward

[gtengr]

Originally Posted by Escobar89

The saab engine is from a old standard that goes back in the earlier 80's actually, but is it really so, that Subaru actually has manufactured this engine so good that there is only minor or even none benefits by improving the engine parts?

I can't say for certain that strategic dimpling won't improve anything. There are definitely other parts that can be improved (CNC porting, multi-angle valve job, blending, port matching, etc.). I just think dimpling specifically is probably not going to help. Generally speaking, I think any naturally aspirated engine producing ~ 100hp/L will have a well-designed intake port. I have read that the FA20 heads are much more responsive to exhaust port work than intake port work, and that's similar to another car I'm familiar with that has output in the 100hp/L range.

Originally Posted by Escobar89

The reason you could find a lot of power by just modify or improve existing engine parts, is that the manufacturer isn't able to put the effort it needs to polish or porting everything. This was very badly described by me, but I hope you get my point though?

I understand and agree on your point. Your results on the Saab without the turbo are impressive. I just think an attempt to dimple a modern head is more likely to be neutral or detrimental because it will likely interfere with the port shape or other engineering schemes the manufacturer is already using to achieve the same end result.

Originally Posted by bcj

Rifling looks to be the way forward

Yes! That's the word I was looking for. I had the good fortune of working for an NHRA pro stock racer as a teenager. They had won several NHRA championships, and their shop had everything: engine and chassis dyno, flow bench, CNC machines, etc. I just cleaned up metal shavings and did other odd jobs, but the boss would sometimes show me some of the stuff they were trying out and rifling in the intake port is what they were working on when I left.

[Lantanafrs2]

I've only heard of or used one technique that's been applicable to everything I've worked with and that is the 85 percent rule. The i.d. of The valve seat should be 85 percent of the valve diameter. Every bike head I worked on from the last 20 years or so had that characteristic.

[Lantanafrs2]

Rifling would probably be done to promote swirl which is desirable when the fuel and air are introduced to each other way before the valve seat. Of course valve guides/bosses and stems become an issue.

[Escobar89]

"

Originally Posted by gtengr

I can't say for certain that strategic dimpling won't improve anything. There are definitely other parts that can be improved (CNC porting, multi-angle valve job, blending, port matching, etc.). I just think dimpling specifically is probably not going to help. Generally speaking, I think any naturally aspirated engine producing ~ 100hp/L will have a well-designed intake port. I have read that the FA20 heads are much more responsive to exhaust port work than intake port work, and that's similar to another car I'm familiar with that has output in the 100hp/L range."

"

I get you here, but there would still be parts, like intake chambers were you could find ways to improve it and it is also possible that dimpling may even reduce the power instead, there are tons of factors that by them self or together would affect other variables.



"

Originally Posted by gtengr

"I understand and agree on your point. Your results on the Saab without the turbo are impressive. I just think an attempt to dimple a modern head is more likely to be neutral or detrimental because it will likely interfere with the port shape or other engineering schemes the manufacturer is already using to achieve the same end result."

"

Thank you. Well yes, but I have copied almost everything from other tuners and i would say that this engine is pretty badass original as well. The engine at it self is good for about 600hp without even opening it.
On topic: I am actually tempted to dimple the head, just for an experiment now. If you never test things in practice it would never be anything than just theories



"

Originally Posted by gtengr

"Yes! That's the word I was looking for. I had the good fortune of working for an NHRA pro stock racer as a teenager. They had won several NHRA championships, and their shop had everything: engine and chassis dyno, flow bench, CNC machines, etc. I just cleaned up metal shavings and did other odd jobs, but the boss would sometimes show me some of the stuff they were trying out and rifling in the intake port is what they were working on when I left.

"

The "rifle type" is also interesting. But I have no idea how it works, only that it makes a bullet to stay in line when it is spinning. I need to Google this!

[Escobar89]

Originally Posted by Lantanafrs2

Rifling would probably be done to promote swirl which is desirable when the fuel and air are introduced to each other way before the valve seat. Of course valve guides/bosses and stems become an issue.

This is also interesting. Can't say that I know anything about the technique though.

[Escobar89]

I am in discussion about this subject on Facebook with other persons, and yeah, I don't want to push it to far, but I printed some of the discussions and there is also a interesting dyno result which I hope you as well thinks. The engine is maybe not be representative for a boxer, but it is still pointing at facts and the engine is also quite new and are (as for what I know) a well developed engine.

[Lantanafrs2]

On a daily driver, deposits may find a home in the dimples. Imo if there was any significant gain in output it would mean that there was poor atomization in stock form.