Porting ALH head

One downside to the reliability of TDIs is that I don't have cause to look inside. Now that we are FINALLY getting around to building a fairly warm 1.9, I pulled the head to de-coke (yucckk!) and do a little cleaning up. The intake ports are the strangest thing I have ever seen. Looks like VW was trying to get the intake air to swirl at the valve?

Anyone had any time to put one of these things on a flow bench and see what can be gained? Sorry to be posting this late at night for our Eastern members. It is tempting to hog the corner off of the directional "dam", but intuitively, I think there must be some pretty good reason to bias the flow so hard to one side.

(on edit) Another question: what revs are those valve springs good for? I have that much on Honda roto-tiller engines!@!

Pat

Pat,
Agreeded, I had lots of goo in the head. Number 3 runner was nearly clogged. here's a couple of shots of what I did.









I'm still in the rebuild process on the engine, but did run the head for a week. Major reduction in smoke even with a bad 11mm inj pump. You can see that the runners have been smoothed, polished and straightened. It'll be awhile before I have any dyno numbers but on a flow bench the air is moving much better.

Here's a shot down the valves:


Steve

Pat Dolan said:

One downside to the reliability of TDIs is that I don't have cause to look inside. Now that we are FINALLY getting around to building a fairly warm 1.9, I pulled the head to de-coke (yucckk!) and do a little cleaning up. The intake ports are the strangest thing I have ever seen. Looks like VW was trying to get the intake air to swirl at the valve?

Anyone had any time to put one of these things on a flow bench and see what can be gained? Sorry to be posting this late at night for our Eastern members. It is tempting to hog the corner off of the directional "dam", but intuitively, I think there must be some pretty good reason to bias the flow so hard to one side.

(on edit) Another question: what revs are those valve springs good for? I have that much on Honda roto-tiller engines!@!

Pat

Click to expand...

Pat, yes this what is reffered to as a swirl port. There are definate gains to be had from porting, the intake side more than the exhaust side. There is some good flow you can recieve higher up in flow, but down low the port is simply too large. If you arent familiar with porting swirl ports I wouldn't reccomend more than just your basic smoothing and matching.

Dave do you port heads also. How much?

Passenger Performance said:

Pat, yes this what is reffered to as a swirl port. There are definate gains to be had from porting, the intake side more than the exhaust side. There is some good flow you can recieve higher up in flow, but down low the port is simply too large. If you arent familiar with porting swirl ports I wouldn't reccomend more than just your basic smoothing and matching.

Click to expand...

What is the philosophy applied to porting this configuration? To completely maintain the directional bias or to reduce it?

Pat Dolan said:

What is the philosophy applied to porting this configuration? To completely maintain the directional bias or to reduce it?

Click to expand...

Completely removing and completely maintaining the swirl are both undesireable for high performance engine operation . You will gain much more flow by completely removing the swirl on the flow bench but you will kill the engines low end effeciency and your engine will run like complete garbage. However there is a certain amount (i'll just say its small) that can be removed from the swirl port and maintain your lower rpm operation but have increased flow for higher rpm and boost.

Krout, please PM me.

Dave,
The guy that did mine must have figured that out. For the week I drove it with a bad Inj pump it was so strong in RC 3 mode that I never even went to 4. can't wait to try it with the other mods I'm doing at present.

The thing about porting in general is that it's a lot easier to lose power than it is to gain it ...

Best bet for the uninitiated is to use a Dremel to carefully smooth out the casting edges and surface roughness, but don't change the overall shape of the ports. It's better to err on the side of removing less material.

Sootman said:

Dave,
The guy that did mine must have figured that out. For the week I drove it with a bad Inj pump it was so strong in RC 3 mode that I never even went to 4. can't wait to try it with the other mods I'm doing at present.

Click to expand...

Good on him Its pretty tricky. The more effeciently you can get the air in and out of the motor the more effecient it is. I have seen some botched swirl ports form even very experienced head porters, if you arent familiar with the swirl port than stick to what gofaster said.

It'll be interesting to see some dyno numbers. Maybe in a month or so.

This is my PD head :



after:


before:


after:


before:

These pics are awesome. I wish I could have seen them before I cleaned the gook out of my intake ports last week (when you haven't seen the shape it's pretty confusing if you haven't pulled the head.)

Gulu,
Great pictures. I wished I'd had a better camera when I did muine. It's seems like there is plent of casting material to be shaped.

veget8,
Mine were so clogged it still amazes me that I could dyno at 185 HP. I ran a variety of Biodiesel products over the years and assumed it wouldn't "coke-up" on me but something certainly caused the runners to be so clogged.

Thanks everyone for the good (and consistant) advice and great pics.

I pretty much just cleaned up the casting flash and surfaces of the ports, except I did the usual VW thing and carefully blended the bowl into the throat of the valve seat. That sharp casting edge down there (the transition from the throat to the bowl) kills an awful lot of flow. The insides of the swirly bits I pretty much just cleaned up and kept the rate of change in cross section progressive.

Where I spend most of my time is on the valve and seat areas that have mega-high velocity at small lift. I did the inlet valves to full radius (same seat size and location) - which was easy with valves that are this surprisingly well prepared as stock. I did not radius the seats, just stuck with the stock angle cuts (after all, this is not a race engine and that takes DAYS to do right). What I did do, though, was blend the recess where the inlet valve seat sits below the head surface (that's a NASTY bit of bad detail).

The exhausts just get a light touch-up with a careful radius on the inside of the bowl-to-port intersection.

Nothing radical, no trade secrets used or hidden. Just thinking like an air molecule (and trying to guess what a VW engineer was trying to accomplish).

The swirl port design is used in diesel engines to promote better combustion. If you look at the combustion in a direct injection diesel there is only a narrow band of the fuel cloud from each injector hole that has the proper air/fuel ratio. The inner portion is burning rich. The swirl helps to spread out the flame front creating more area burning at the proper air/fuel ratio - better power, lower emissions.

As was stated above, this can also be overdone. The flame front from one injector hole can run into the one next to it. The area with the ideal ratio is no longer increasing, but the air flow restriction is getting higher.

IMO you should be able to get a health increase in flow without killing your bottom end power, but of course that depends on your mods (combustion chamber shape, piston shape, injectors, etc.) And of course the shape in your head is a compromise of casting process capabilities, machining capabilities, cost, production variation, etc. so improvements can definetly be made.

One some small diesels with high injection pressures the fuel can actually hit the cylinder wall before it all atomizes or burns, eroding the cylinder wall in the process, so swirl is also used to keep that from happening.

As a side note, this design was used on many gas engines in the 80-90's (probably to get better emissions with the slow computers), but many went way overboard and caused too much restriction. Many current engines use some swirl, but nothing like your heads Sometimes you will hear the term "tumble" used.

Great information. It's good to see people trying different things to improve these engines. How much do you gain by doing these mods? Is it applicable only to highly modified TDI's?

I was under the impression that a boosted engine isn't particular about induction porting.

By porting the heads you can decrease the pressure drop through the heads. Less pressure drop = more efficient turbo = more Hp.

Without changing anything except porting the heads you may actually see the boost pressure in the intake go down. You are moving as much or more air, but the head is creating less restriction. Remember that boost pressure is created by trying to push a lot of air through a restriction. More boost does not necessarily mean more air!

(The same applies to opening up the exhaust side. Less pressure drop gives the turbo more to work with.)

I have done a few 1.9TDi heads but have functionality data only from one because other are still on customers shelfs.
This is measured with Gtech RR / 3rd gear acceleration.
Car was earlier "calibrated" to show same numbers as dynamometer, actually it shows a little less because of drag from wind resistance, but gains are clearly shown in RWHP change:
http://www.sunpoint.net/~pirkonen/TDIporttaus/Portattu_Hattu_Gtech.jpg
This engine never made to dyno as car was selled and head was removed before selling.
This test was made with stock head and after head change, NOTHING else was changed between tests.
Before new head injection was limited because of EGT and i truly believe that this result could have been doubled with proper tuning.
even that this engine had totally too small turbo. (VNT15/20 if i remember correctly).

MarkoP
Sorry but I am not able to interpert the findings of your data. Are you saying there was a reduction of torque/power after porting? As the post is a picture, I can't wscroll through the data.

there is "comp run2" which is the one with stock head and "main run" is done with ported head.

So there was 10kw / 30nm increase with ported head at the wheels compared to stock head and the increase was ~10kw all the way from 2300rpm to 4300rpm.

I just ported a head to golf III 1.9TDi that is goin 14.4sec 1/4-mile with stock head.. i am really curious to see the impact of ported head because cylinder head is really restricting this engine.

13 HP and 22 ft-lb respectivly at the wheels...even more at the crank.

Not too bad if you ask me... that'll take a 90 HP VE to the same power as the 100 HP PD withouting monkying with boost or fuel. 90 HP -> 103 HP and 155 ft-lb -> 177 ft-lb

How much does a ported ALH head cost? Or how much does it cost to port a head?

I doubt you'd see the same gains on a non modded car.

I'd rephrase that to say "there's no way you'll see that kind of gain unless it is OVERfueled to begin with". If you're making smoke, this will help turn it into power. If it's stock (underfueled) it ain't gonna do ANYthing.

Even stock won't the MAF see more air coming in and tell the injectors to inject more fuel if it is requested?

No!!!

Bob_Fout said:

...How much does a ported ALH head cost? Or how much does it cost to port a head?

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Probably far less than having RC reprogram your ECU, or picking up injectors from Kerma. I'd put this down as the "I've run out of parts to replace but I still have money left" mod.

Id put it down as the 200+hp mods. And will be getting one sooner or later

Yes, this car was smoking with stock head from 3000rpm and up, but from about 2000 to 3000rpm there was not too much smoke, so i belive that these gains come mostly from reduced pumping losses and some of it came from more air.

Porting will allow more fresh air to be stucked in, better turbo spool and more fuel to be added.
Someone could as well say that you should not get a bigger turbo (its doing the same thing basically) but with ported heads stock turbos will go away from best efficiency area and turbo will spin like hell trying to keep that pressure that ecu is asking.. I believe that engine in above graph would have gained some more power with less boost pressure or bigger turbo as there was allready near 4bar exchaust pressure with stock head.

Port job for stock motor aint going to give much power as stock head is equate for stock power levels but you would get better fuel consumption.. at least if there is not boost requested much when driving at the high way.

So i could really recommend head porting only for modified engines.
There have been lots of discussion that there aint no gains by porting diesel head but i think this will end that discussion.
Just to clarify, I am from Finland so speaking bullocks at the US forum would not help my business anyhow so i really just wanted to share my experiences.

Bob_Fout said:

How much does a ported ALH head cost? Or how much does it cost to port a head?

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Ran me $780.00 for the porting job. Gaskets and disassembly and reassembly extra

I got a price of 850 from a guy. That included porting and 3 angle valve job.

I just didn't think the return would be worth the money.