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Thoughts on mTDI AHU head porting
by
jhax
on 31 Jan, 2024 12:12
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Hello,
I have an AHU with a LR300 injection pump that will be installed in my T3 high top. I would like to be able to get more usable power out of the motor for this application without risking messing up the trans (already re-geared for TDI and DMF will be installed), I would like to be able to get more air into the chambers via porting the head. I have a KKK14 turbo which as I understand is the best WG turbo for the particular application. I have been doing some reading on porting methods and I would like to know thoughts on how much material to remove from the various parts of the intake and exhaust ports and chambers in order to achieve my goal.
Thank you,
Justin
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#1
by
RabbitJockey
on 05 Feb, 2024 14:48
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check out the david vizard article stickied in the idi section, thats a great start. frank06 has explained some of what he does over at tdiclub if you search.
you can also check out some of vizards videos on youtube, try to search for some that just cover basics because he is very technical and gets into the nitty gritty.
richard holdner has a few good videos on the basics, and he is not a head porter so he literally just covers the basics.
I did my ahu head, the intakes are pretty easy, just clean up the casting in the ports and smooth out the transition to the valve seats, they're not too bad stock you dont want to do too much with out a flowbench, less is more.
the exhaust can use a lot of clean up, i'd recommend following the vizard guide for them as theyre basically the same. remember less is more, and hoggin them out kills air speed which will kill power everywhere except for high rpms
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#2
by
RabbitJockey
on 05 Feb, 2024 16:59
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There is also a bump in the intake bowl that you don't not want to remove, reduce and smooth it sure but don't remove it. It's extra material around the injector boss to help prevent it from cracking. Unfortunately I removed most of that material because I didn't realize what it was at the time.
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#3
by
fatmobile
on 05 Feb, 2024 19:56
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I think that bump helps with swirl/flow too.
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#4
by
RabbitJockey
on 06 Feb, 2024 11:57
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that could be, either way it's not worth removing it completely the risk are worse than the tiny amount of flow you might gain.
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#5
by
RabbitJockey
on 06 Feb, 2024 14:54
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in this video holdener gets a 10% increase in flow from just doing the basics.
https://www.youtube.com/watch?v=6o3SaUtfai8I also did a 3 angle valve job and back cut all 8 valves on my head. It doesn't run yet so i can't tell you how well that stuff works. plus its not like i had a before and after flow test. But these are cheap mods the machine shop can do to improve flow.
also now that i've thought about it more, if you're going to be modifying the head you really want to a bigger turbo. the k14 is great for low end power but it can only flow maybe 125hp and the stock head can easily move that much air at low boost. You really want to choose a power goal and build to that.
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#6
by
jhax
on 13 Feb, 2024 15:44
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Thank you for the replies. As far as HP and torque goals are concerned. I am looking at maybe 110HP out of this. Remember it is going into a vehicle with the aerodynamics of a brick and heavy. I kept the K14 because of it's early spooling throughout the rev range and I plan on not allowing it to go above 18PSI. I understand that I can get much more HP and torque with the LR IP but, once again, heavy brick. I am aware of the swirl bump in the intake ports, which assists with atomization of the fuel and air. My plan is to smooth it a bit, but from my understanding, the more it's reduced, the more the fuel just get dumped into the chamber and less efficient atomizaton, more heat, more black smoke. I also understand that the exhaust ports should remain smaller and it seems like that step from the head to the exhaust manifold allows the hot air to move quicker to the exducer, creating quicker spooling response. So with that information, port matching the exhaust ports may not be the ideal scenario. And smoothing out the intake chambers (opening up the bowls), grinding down the valve stems, and opening up the D ports, plus using some grinding paste on the valve seats and valves seems like the best option. What do we think?
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#7
by
RabbitJockey
on 13 Feb, 2024 18:52
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there is the swirl bump but there is also another one closer to the valve seat that is there to help prevent cracking from the location of the injector.
If I were you I wouldn't port the head because it's time consuming and the benefits aren't really worth it for 110hp.
if i were going to do it in your scenario I'd focus on just smoothing everything out and not enlarging or changing the shape of anything. only use sand paper cartridges, no burrs. this would hopefully help to gain efficiency with out losing any low speed power. Also definitely get a PD style intake, with the pd intake and very very mild porting it should run cooler and smoother.
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#8
by
jhax
on 14 Feb, 2024 08:52
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I was afraid of that, I already bought the burrs, oh well. I ended up getting the BRM intake, which, according to TDIClub research, is the one that provides the best air flow. Thanks for the information though!
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#9
by
RabbitJockey
on 14 Feb, 2024 09:10
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you're welcome, and good luck, hopefully you have an intercooler too.
The thing with your setup is if you increase the head flow too much it will out flow the turbo even at only 18psi which will make the turbo overspeed and this will obviously affect reliability.
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#10
by
jhax
on 15 Feb, 2024 07:42
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I do have an intercooler
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#11
by
RabbitJockey
on 16 Feb, 2024 14:48
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hell yeah, please keep us updated on your project
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#12
by
jhax
on 25 Mar, 2024 12:09
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Exhaust port on head gasket side before:
Exhaust port on head gasket side after:
Overall first porting on headgasket side:
Exhaust ports before and after on manifold side:
Other two:
One left:
Final product:
I ended up smoothing out the exhaust ports to keep airflow as laminar as I could. While keeping the intake ports dimpled in order to promote turbulence for more efficient AF mixture sooner.
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#13
by
RabbitJockey
on 27 Mar, 2024 13:04
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looks good, did you do anything in the intake bowls/seat area? it looks like you opened up your exhaust more than me. i wish i had done it more like yours, but i was trying to keep it simple.
how much time did you get into it?
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#14
by
jhax
on 08 May, 2024 10:38
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I opened the intake bowls a little bit, I was more focused on the exhaust though, although Im not sure if it will help due to the fact that smaller ports would allow for exhaust gasses to get to the turbo quicker, fluid dynamics and all. But we will see what happens.