inlet cleaning

[blahheed]

have looked down the inlet port and looks a bit furry.

can this be disolved with petrol or some sort of cleaner?

[Pete.]

Best to leave it alone - a rough surface in the inlet tract is preferable over a smooth one anyway.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Dalemac]

plus you dont want any of the crap going into you engine.

Dale
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YBR125 -> GPZ500S -> SL1000

[chillpill]

[The Artist]

turbulence = good. mixes better.

its why butterfly throttles work I think. They are designed to not be perfect otherwise fuel and air would not be mixed enough.

back up please..

[sickpup]

[rotax81]

its true. a rough port is better than a polished one.

ermmmm.... the best way i can describe it::

if you take a look at a river flowing, the middle of the river runs cleanly through and the edges are hardly moving. the edges have obstacles etc so vortexes create a nice smooth path for the middle.

a pickup creates more drag with the tailgate down (just another useless bit of info) lol
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ZX636C6F road. ZX636C1H track. ZX7R redundant. ZX0.5R minimoto as ornament.
Audi A4 Avant 1.9TDi and VW Transporter 2.5TDi 888 Special (no mot and tax lol)

[Pete.]

I don't know the mechanics of it but basically as Rotax said the molecules of air touching the surface it's flowing over (called the boundary-layer) are almost stationary. The smoother the surface, the better they stick to it, and the layer gets thicker as you move further down the surface. The rough surface of the port helps prevent this by stirring the molecules up.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[sickpup]

Just remembered. The rough edges that cause turbulence stop the fuel droplets falling out of suspension.

[Coxyzxr]

I got a very brittle, dry leaf stuck down one of my inlets once litrally fell out of the tree and into the inlet tract when I had the carbs off in the back garden. Tried getting it out with long nose and tweezers but it just fell apart into tiny pieces. I just bolted her back together and went for a spin.

That was the last I heard of old leafy...

Back on topic rough surface can also aid swirl. Don't listen to the old skool mustang crowd or gran turismo's tuning tips, port 'polishing' isn't a good idea for perfoamnce or fuel ecom.
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**WAS FITTED "WRONG WAY ROUND" !** CANT ACCOUNT FOR THE STUPID !

[chillpill]

cool , a good bit of info right there

[Mr Hammers]

[Coxyzxr]

[Mr Hammers]

I'd have thought that the speed of the airflow was pretty important, after all, whatever the given explosive potential of the mix, it being mixed well or not, if the engine can process more of it the power it could produce.....nicht war..?

Assuming for the sake of argument that that is true, i suppose it then becomes a balance (or compromise...depending on how you look at it) between enough turbulence generated by a rough intake to mix it all up and not lose droplets of fuel....and, a fast throughout of mixture made possible by a smooth intake.

Here's a hastily drawn graph to demonstrate;

https://www.planetash.net/bcf/mix-graph.jpg

As the smoothness increases, the ability to force more of the mix goes up, but the actual efficiency (or explosive potential) goes down.

As the roughness increases, the ability to force more of the mix goes down, but the efficiency goes up.

And then, where the two meet is the best combination of rough/smooth and less/more mix processed.

Does any of this make any sense.... or am i talking out of my graphs...?


Edit: Dang. Can't help feeling that that graph is just..wrong. Tried doing another (oo i love graphs, me...) but i'm not sure this one accurately reflects the point either, tbh.

https://www.planetash.net/bcf/mix-graph-2.jpg
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A Guide To Powerbands

[Pete.]

The whole point is that the rough surface allows a faster overall airflow, not the smooth one. Intake velocity IS important because with velocity comes momentum so more air-fuel mix gets into the cylinder past the closing inlet valve.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Mr Hammers]

[Vincent]

Yup, a rough surface is better. As above, a layer of fuel mixture sticks to the surface and the rest flows on top of this - faster and smoother.

[stevo as b4]

I'd suggest that port size and shape will have a far bigger effect on airflow for a given valve lift in (mm), than the effects between a highly polished port and a rough finished one.

Remember that as you port a cylinder head, you are slightly enlarging the ports by removing excess metal and removing rough edges and casting marks etc. The finish made by a rotary sanding drum will still be plenty rough enough to give turbulence, even when it looks fairly shiney IMO. Unless your polishing the port with a mop and polishing compound, then i don't think you need to worry about the ports being too smooth and allowing the fuel to drop out of the mixture etc.

[fra-zzr]

its the same principle you find in golf balls, although from a different perspective as its the air/fuel moving and the ball (inlet staying still) . The bumps cause drag initiailly but less chance of separation of fuel/air because of increased adhesion from the inlet face, so less wake

turbulent flow > laminar flow (polished face would give this)

Finally marine biology found a use
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04' Hyosung Comet Gt125
96' zzr600