Getting more air/fuel into a 3.2 motor

[89911]

I've recently had my motor out to the shop for a 3.4/twin plugging upgrade and had time to polish the intake ports and extrudehode the intakes. I also will be using a bored throttlebody and a MAF. The heads came back from Ollie where they were machined and drilled for the other plug. They came back looking brand new and they did a nice job. The bottom pic is the inside of an extruded intake. Took some pictures that I think give some interesting perspectives:

[CarreraCab]

89911, very nice work. Ollies does a great job. Is there any particular reason you went to a 3.4 instead of the 3.5 (100mm) ? Also, what are you planning to do for your ignition ? I have done a 3.5 in the past, but with Webers, and am toying with the idea of doing a 3.5 again, but staying with the Motronic similar to what you are doing. Looks great, please keep the info coming. Doug

[Wil Ferch]

Sorry for interfering...but wouldn't 3.4's be plug-n-play and 3.5's require case machining ???
---Wil Ferch

[89911]

Mahle big bore 3.4 is a common upgrade for this system. You can go bigger, but it usually involves a crank change and wilder induction system. Nothing wrong with this, but you have to draw the $$$line$$$ somewhere. I'm using a dual 964 distibuter and having a custom chip from SteveW for the advancement change.

[Wavey]

Wow, great post 89911! Inspiring...

[ChrisBennet]

I was under the impression that polishing the intake ports was a no no.
-Chris

[Noel]

Mike,

Looks GREAT! You're giving that Dremel a workout.

My car is pretty much done except I'm getting the wind screen replaced today. It is amazing how pitted 24 year old glass becomes.

Let me know when you need a hand to put her back in the car. It sounds like you are getting close.

Noel

[89911]

Originally posted by ChrisBennet
I was under the impression that polishing the intake ports was a no no.
-Chris

It was suggested by my mechanic. As far as any measurable benefit, it can't hurt. I've had everything above it altered, honed, or polished. It didn't seem to make sense to have it feed into a port that was full of rough castings and seems. Done alone without any other changes, it would be pointless. Don't forget, your talking to someone that actually enjoyed polishing his fuchs!

[ChrisBennet]

What I've read is that polishing after the injectors will allow the air to "stick" to the walls (laminar flow) moving at a slower rate near the walls. When that happens the fuel suspended in the air will condense out on the walls. For that reason, intakes ports are left rough or even dimpled. For a real world example of laminar flow think of rain drops moving up the windsheild. They are moving much slower than the air going over the car because they are in the slow moving layer of air right next to the car's surface. So yes, polishing the intake port can hurt at leeast in theory.

Found it, here's a link explaining this topic:

Why Not Polish The Ports ??

-Chris

[89911]

Chris, I've heard that arguement with the intakes. But I've heard of good gains in flow with these (Steve@Rennsport). I've also heard arguements that "Porsche designed it that way and they know what they are doing". True I guess, but they have to mantain cost effectiveness also. Its too bad I don't have a before shot. There was a pretty ugly casting seems on both sides along with numerous casting blebs and imperfections. Can't see how those were meant to be there. I also slightly enlarged them prior to polishing. Who is this Motoman? I thought he only dealt with engine break in !

[ChrisBennet]

Originally posted by 89911
Chris, I've heard that arguement with the intakes. But I've heard of good gains in flow with these (Steve@Rennsport). I've also heard arguements that "Porsche designed it that way and they know what they are doing". True I guess, but they have to mantain cost effectiveness also. Its too bad I don't have a before shot. There was a pretty ugly casting seems on both sides along with numerous casting blebs and imperfections. Can't see how those were meant to be there. I also slightly enlarged them prior to polishing. Who is this Motoman? I thought he only dealt with engine break in !

I'm talking about polishing after the injector i.e. the head not the intake.

Here's another link: Cylinder Heads by ENDYN

While most believe that highly polished surfaces work best, just the opposite is true in the real world. Exhaust ports may be polished, but once the engine has some (miles) on it, the flow will never see that slick surface again, as combustion byproducts will finally win out. Once even minimal carbon has attached, the only thing the flow will be interested in is the shape of the port itself.

Intake ports should never be polished, especially past the point of fuel injection. Slick port walls will cause fuel attachment, resulting in poor cylinder mixture delivery and cyclic dispersion from power stroke to stroke. Proper intake port texturing will help eliminate these tendencies.

-Chris

[911ctS]

Originally posted by ChrisBennet
What I've read is that polishing after the injectors will allow the air to "stick" to the walls (laminar flow) moving at a slower rate near the walls. When that happens the fuel suspended in the air will condense out on the walls. For that reason, intakes ports are left rough or even dimpled. For a real world example of laminar flow think of rain drops moving up the windsheild. They are moving much slower than the air going over the car because they are in the slow moving layer of air right next to the car's surface.

I've always thought the same. Another example would be a sharks skin, course like a 300 grit sandpaper. This allows them to swim faster through the water. Although from the pictures it does not look as though you polished it to a mirror finish (like a totally polished fuch would be). Had you done that, I would think that the fuel would certainly puddle at low RPM's.
For the exhaust however, polish the crap out of them. Less carbon build up means more velocity through the port.

[TimT]

coarse like a 300 grit sandpaper

In one direction sharks skin is smooth as glass... the other is like 80 grit paper

I remember something about micro vortices... or something like that... the americas cup sailboats were doing something that wouldnt let the water "attach" to the hull


Ive heard the intake side should be left kinda rough, not micro poilished

[Wavey]

Those ports aren't really polished - they still have a fine grinder finish. "Polished" is a mirror-like reflective finish, and that's what you DON'T want. Some engine builders grind to a finish like this then hit it with glassbead, which just smooths things out a little more and leaves a non-polished surface.

[KTL]

Mike,

Sorry if this question has been answered in a previous topic.

What did you choose for your camshafts? 20/21? 964?

Thanks.

[89911]

Kevin 20/21 grind from WebCam. I've got a laundry list of components that have been added if you have any other questions. I also regeared 3-5 on my G50 to lower ratios to match the torque curves of the rebuild. Should be interesting.

[1987C1]

What gains in HP can be expected with the extrudehode intakes?
What is the cost for this process?

Looks nice!

[dean]

89 911.
Nice interesting pics.

[89911]

Originally posted by 1987C1
What gains in HP can be expected with the extrudehode intakes?
What is the cost for this process?

Looks nice!

Extrudehone by itself is not going to change much. With a larger displacement and more need for air/fuel, the 3.2 intakes can be limiting. The honing cost me $425.

[KTL]

Thanks for the cam answer Mike.

I'm sure i'll bug you in the future when the 3.4 idea comes knocking on somebody's door around here. Hopefully not my door...............