TDIMeister
Phd of TDIClub Enthusiast, Moderator at Large
What changes when you have a positive pressure gradient in a forced-induction engine as opposed to vacuum?
i'd of thought you would have known.doesn't the ph.d degree your getting give you privy access to air flow software or something like that.What changes when you have a positive pressure gradient in a forced-induction engine as opposed to vacuum?
What changes when you have a positive pressure gradient in a forced-induction engine as opposed to vacuum?
Flow at low valve lift heights has to do with the valve head shape, the valve job and chamber (in gas engines) and not actually the port shape. Since the TDI cam barley lifts into what would be considered "mid lift" the valve job and valve shape are critical to a performance cylinder head, almost more important than porting on the intake side. These are all of the valves I've tested so far, all of them have a flat face.i just port to known port designs and shapes(w/i reason,every head i see from vw is different in construction,close)) that flow well.and use seat cutters w/ excellant flow characteristics under boost.works pretty well so far for me and btw,i took my port design from pd's about 4yrs ago and moved on and up from there.
well i wish you the best of luck and just maybe you can dethrone me on hp/tq in the alh head.i hope you complete a ported head sometime soon.love to see some results.Flow at low valve lift heights has to do with the valve head shape, the valve job and chamber (in gas engines) and not actually the port shape. Since the TDI cam barley lifts into what would be considered "mid lift" the valve job and valve shape are critical to a performance cylinder head, almost more important than porting on the intake side. These are all of the valves I've tested so far, all of them have a flat face.
Those are all intake valves, and I have a few more shapes that I want to test.
~Alex
w/ the right air grinders,theres no place in an alh or pd head that can be ported.the extrude hone process is great for getting each port to flow w/i small percentages of each other.remember you have to start w/ hardened adapters so the entrance is protected.I always wanted to try pumping an abrasive putty like diamond or silica based compound in direction of flow through the head to port it.That way one could ensure even portwork on swirlports where your dremel port tool doesnt even reach.Tdi meister what would you say?i know nascars get there heads done there too.Im in the process of building one with industrial hydraulic rams.extrude honing
I always wanted to try pumping an abrasive putty like diamond or silica based compound in direction of flow through the head to port it.That way one could ensure even portwork on swirlports where your dremel port tool doesnt even reach.Tdi meister what would you say?i know nascars get there heads done there too.Im in the process of building one with industrial hydraulic rams.extrude honing
all i'll say is,,don't deter and keep on your path.have you tried it?Do you know of anyone that tried it?Ill use the cnc to open the valves up and then pump it with abrasive.The swirl port will be uniformly enlarged.The shape remains the same just bigger.If someone that actually had there tdi head extrude honed chimed in that would be great.
No, rate of material removal is proportional to the local flow velocity and so therefore will be selective on parts of the ports that are relatively restrictive first. The only time the ports are enlarged uniformly larger is when the flow velocity is also uniform throughout. That's why you do the abrasive extrusion in stages, alternating with the measurements in a flow bench. At some point you reach diminishing returns.The problem is that it would uniformaly make the port larger. Thats not the way to go. Its already too large in some parts.
Exactly just picture a straw with a restricted end , when pumping abrasive through, the end of the straw thats restricted will open up first before the rest gets bigger.Im sure it will take some practice to get things right and there will be a certain point until it actually wont help anymore.The unit im thinking of will have a pressure regulation on it so we can dial in the pressures.Again needs to be played with
Updates: The fresh engine now has about 5K on it and an RC3+ tune (Thanks Jeff!) and the clutch is starting to slip a bit in 4th and 5th gear but my brother has made a phone call about that and we are waiting to hear back. Looks like we should have gone with a SB endurance or stronger. The car is also going to be getting a set of Porsche calipers as well. I should be getting back to this project in a few weeks.Update? Pics?
D
Correct me if I'm wrong, I have zero knowledge of porting heads just tossing this out. With a "media blasting" your talking about on the swirt ports, I'm thinking the flow of media through the swirl ports would be similar to that of a water through a menandering lazy river. It'd be thorwn against the walls whenever there is a change of direction, wouldn't this eat away at the "outer bank" exagerating the swirl, the "meandering" is that the desired goal? Or are you guys talking about using this technique on non swirl ported heads?