Porting the intake manifold?

[ilovecoupes]

Thinking of porting the lower manifold. started doing cylinder #3.

I wanted to get some opinions

Is it pointless with out a flow-bench? Leave it to the Professionals? Little to no benefits?
Modified by ilovecoupes at 5:27 PM 9/28/2007

[frosti108]

ill give you benefits if you port my manifold

[ilovecoupes]

ill give you benefits if you port my manifold

uuuuhhhhhh.......

[float_6969]

As long as your just cleaning up the casting marks and port matching, you don't need a flow bench. It's when you start removing lots of material that you should leave it to the pro's.

[ilovecoupes]

what do you mean by alot? Cause, I removed a desent amount. Maybe a tea spoon full of cast aluminum, per port

[Masterdebater]

i would just smooth them out to a shine

[ilovecoupes]

ya im just going to finish it with like 80 grit. Mayyyybe 120 if I'm feeling frisky.

[float_6969]

You don't want to smooth the intake out too much. No smoother than the 80 grit on the intake. I got my porting info from THESE GUYS. I also got my kit from them as well.

[frosti108]

rougher surfaces make for better mixed air and fuel

[float_6969]

That's why you don't go finer than 80 grit on the intake ports. Now the exhaust should be finished to a mirror shine.

[ilovecoupes]

That's why you don't go finer than 80 grit on the intake ports. Now the exhaust should be finished to a mirror shine.

sweet, thanks for the link and the info.

Im pretty much doing it because im bored, and have no money for a new cylinder head.

Think it will make any noticeable power?

Im kinda close to being done, ill try to throw up some pics

[dnlx5]

i gasket matched the intake mani and intake ports (just made it fit the gasket beter by grinding aluminum) and my motor feels livelier (also did the 2ndary butterfly mod)

[ilovecoupes]

ya, I have to wait a few days for the gaskets to come in. And completely got rid of my butter fly valves.

what about gasket matching the exhaust gasket? seems like alot of material has to be removed

[iliketocrash]

i like how that DIY site promotes those stupid discs... i mean i'm sure they do great for certain things... but removing gasket material? seems like a pain. they make plastic discs with plastic finger type things which easy remove all gasket material and in no way harm the metal which is obviously a big concern when working with aluminum surfaces. just a little FYI as far as gasket removal is concerned =)

[ilovecoupes]

they make plastic discs with plastic finger type things which easy remove all gasket material and in no way harm the metal which is obviously a big concern when working with aluminum surfaces. just a little FYI as far as gasket removal is concerned =)

where do you get these jawn-skis or know the proper name for them ? I looked in a few auto part stores and couldn't find them, all i could find were scuff pads.

They also sell this gasket remover stuff, it comes in an aerosol can. Anyone tried it?

[tyrannix]

You don't want to smooth the intake out too much. No smoother than the 80 grit on the intake. I got my porting info from THESE GUYS. I also got my kit from them as well.

testing my engine theory here, but I would agree to a point. I would say that you want it smooth in the plenum, but not in the runner unit. follow me here

-> getting the air to the injector portion faster would be better, turbulence would slow it down. now *after* the fuel joins the air, thats where you want teh turbulence to both keep the fuel particulated and mixed in the air homogenously , but also keep fuel from pooling anywhere inside the runners (where a smooth air flow would go around it, if the venturi effect couldnt compensate) port-matching should eliviate that as well, but you still want turbulence for that mixing effect.

keeping in mind that reducing pipe diameter reduces pressure and increases velocity as well

refute me and tell me im full of crap with a reason why please

-CJ

[frosti108]

reducing pipe diameter reduces pressure??? im pretty sure it just increases velocity and reduces flow.

i see your thinking on keeping the intake smooth up until the injectors... but ofcourse if you want to nitpick like that, you could say the further back you rough it up, the more turbulant the air will be by the time it hits fuel.

but seriously, all of this **** is just silly nitpicking. just the kind of crap you worry about while there motors down and apart

[ilovecoupes]

tyrannix, think of it as a water hose. Reducing the diameter increases the velocity, and also increases pressure. Thus, making the stream smaller and go farther.

Quick question: how does a rougher surface ensure a better mixture? does it reduce flow. and increase pressure. then make more turbulence?

Turbulence is the variations in pressure. So turbulence is kind of like a stirring pot. you would want the different pressures closest to the injectors, making a better mixture. Right?

Kinda wish i was still in Physics

[r34 gtr]

The rough surface would cause more turbulence in the air going into the cylinders. This would provide for a better mixture with the fuel. If you put oil and water in a glass and stir smoothly and slowly, the two dont mix, however if you shake it up really good the two mix. Sort of the same concept. I would think of a better explanation but I am already several beers in the hole. Yay college!

I ported the crap out of my lower manifold and saw a good increase on the flowbench. You can make one yourself, its really quite easy. Google how to make one, you just need an old vacuum cleaner and some stuffs.

[tyrannix]

The Venturi effect is an example of Bernoulli's principle, in the case of incompressible fluid flow through a tube or pipe with a constriction in it. The fluid velocity must increase through the constriction to satisfy the equation of continuity, while its pressure must decrease due to conservation of energy: the gain in kinetic energy is supplied by a drop in pressure or a pressure gradient force. The effect is named after Giovanni Battista Venturi, (1746–1822), an Italian physicist.

thats from wiki.

basically, with the incresed velocity from reduced pipe size, the pressure must drop to balance the equation.

You can think of it like a water hose too, but think about what you do with your 3" intercooler pipe couplers, vs the little vaccuum tubes for sensors, which one requires clamps?

(not being malicious, just want everyone to work with correct facts )

back to original topic, if youre eeking out every last little bit of power, youll need things to measure and/or have a lot of trial and error to determine which has the best effeect (rough vs smooth)

Actually, rethinking it, the best DIY would probably be just to port match and make sure the surfaces inside each runner match (rough vs smooth) so you are even across all cylinders.

-CJ

[ilovecoupes]

okay I get it now, the intake manifold kind of acts like a venturi tube.

Venturi Tubes A venturi can also be used to mix a fluid with air. If a pump forces the fluid through a tube connected to a system consisting of a venturi to increase the water speed (the diameter decreases), a short piece of tube with a small hole in it, and last a venturi that decreases speed (so the pipe gets wider again), air will be sucked in through the small hole because of changes in pressure. At the end of the system, a mixture of fluid and air will appear. -wikipedia

makes sense, didn't realize that the intake air, tried to sustain equilibrium by changing velocity and pressure.

You can make one yourself, its really quite easy. Google how to make one, you just need an old vacuum cleaner and some stuffs.

Can you expalin this a little more? searched google, the ones i saw had crazy gauges and manometers. what is the other stuff?

[float_6969]

Wow, I should have kept up on this post, sorry guys!

Ok, this is how it works from how I understand it. First and foremost, this is the most important formula you will need in understanding the basics of how a gas (air) acts under different circumstances; pV=nRTWhere:p is the ABSOLUTE pressureV is the volume of the container holding the gasn is how much gas, which is measured in molesR is the gas constant, which is a number I don't remember off the top of my head right nowT is the temperature of the gas measure in Kelvin IIRC.

OK, I just wiki'd it. Less typing this way...

http://en.wikipedia.org/wiki/Ideal_gas_law

As for the Venturi effect, it sort of applies, here, but not really. Yes, we are effecting the pressure of the gas flow by varying the diameter of the runners, but we aren't really using the venturi effect to introduce any sort of fluid or gas into the air stream. If the system was carburated, it would be a very different story as a carburator wouldn't function without the venturi effect.

As for the plenum and intake runners, I THINK you could port them smooth as they don't need to keep fuel in suspension, but something tells me that they need to be rough because the temperature of the gas is VASTLY different than that from the exhaust. From what I understand, the slightly rough surface creates a small area of turbulence at the surface of the runner, that actually lets the larger column of air travel faster than it would if the port were completely smooth. The exhaust is different because the increased temperatures causes the air to become more viscous and so the port needs to be as smooth as possible.

Also remember that all of these principles were based on steady state flow. A piston engine IS NOT a steady state air flow device. And those pluses and waves have a BIG impact on how the air flows into and out of the combustion chamber.

At least that is the way that I understand it. I don't exactly have a degree in thermodynamics.

[ilovecoupes]

pV=nRT

ya, that was the equation i first thought of, but it doesn't take into account velocity.

P1*V1*A1=P2*V2*A2 where P equals pressure and V equals volume and A equals acceleration got it from here... its a PDF file page.466

ParisHiltonsextape.com

but the problem with this equation is that, it doesn't take into account the difference in volumes of the runners and manifold

Wow, I should have kept up on this post

haha I know, I love how this thread went from a dumb question, to a full blown deliberation about physics and fluid dynamics.

gaskets are taking forever to arrive