AHU intake manifold options

[vwishndaetr]

Soon I will be beginning an AHU diesel build. I sourced a complete diesel swap and plan on building it up this winter to throw in my now gas powered ABA Jetta. So a build thread will be coming up soon.

Now more specifically, I am wondering about the intake manifold on the AHU. I have not been around the diesel stuff as much as gas, but I'm assuming intake and exhaust characteristics benefit from similar "mods" so to say. With that being said, has anyone accomplished manifolds such as:

This one is made by USRT, it's a "long runner" manifold for an ABA. The long runner as opposed to the short is supposed to provide more "low-end power. Since I've always wanted one of these fine gems, and not finally have a base that I don't mind spilling some money on, I thought I'd pull the trigger and try something like this out.

Personally it'd also work as a double wammy as I am think about doing a thorough write up to use it for my Senior Project for school as I will be graduating soon.

Any input on things of this nature, or links, or anything for more research and what not. Discuss.

 

[Pat Dolan]

You have obviously already figured out that the ALH manifold is a bottleneck. If you search the site, you will find threads describing some of the modified manifolds that use the stock ALH, sharp 90 degree flanges and put runners, plenums, etc. on that. IMHO, the flow would be so compromised, why bother? There are PD130 and 150 inlets that bolt up and seem to flow a fair bit better, but again, that short, sharp 90 at the port can not be good for the net flow numbers.

I have a Euro gasser manifold that uses the same port shape, and a "coiled up" runner surrounding the plenum (I think 1X is engine code). Got it from Ryan P (see vendors section) in the UK. It is the best I have seen since there is a straight shot from the runner into the inlet port. Another option is to build something using a TD manifold, but there is a lot of work to get the flat sided port shape from the round runner.

 

[vwishndaetr]

Just so we are on the same note, ALH is the Mark4 diesel, and AHU is the mk3 correct?

Does the ALH manifold bolt right up to the AHU head?

 

[Fix_Until_Broke]

I think this is the intake that Pat is talking about - from and SDI. This will fit with an OEM VNT turbo (15/17/17-22/18xx etc) with some minor modification. Not sure what turbo you're considering using. It does stick "back" quite a ways compared to most manifolds

There is also a Volvo D24 intake manifold that can be modified that looks decent.

Here's a recent thread... http://forums.tdiclub.com/showthread.php?t=276495

 

[vwishndaetr]

Interesting. I think I am definitely going to look into this in a bit more detail. Just have to put the block on the stand to begin tearing into things.

 

[TDIMeister]

My favourite manifolds for the TDI, if you feel the urge to replace yours (there are countless other areas I'd upgrade before I touch it) are the two OEM parts bin SDI manifolds, my first choice being the plastic runner one and second the figure-9 one pictured above. On an AHU, you cannot go wrong with an A4 11mm injection pump upgrade, later-model A4 ECU, good fresh injectors and going to a VNT turbo. When those things are done, then you have a worthy base to upgrade other parts that offer much less performance bang-for-the-buck like the intake manifold.

 

[vwishndaetr]

The manifold isn't the only thing I plan on "building up" throughout the build. I am upgrading many things, turbo, exhaust and all that other jazz included. The manifold is just something that caught my eye right off the top and was wondering what alternatives there are.

 

[Pat Dolan]

You wrote "AHU", I read "ALH"....happens when you get old.

Anyhow, same inlet manifold comments apply. And, yes, the manifold shown by FUB's post is indeed what I have for 200+ish ALH build.

 

[G60ING]

Be careful with that metal SDI manifold. There is no way I could have mounted my GT1749va with that manifold as the actuator would have hit the intake manifold. The cool part about my turbo upgrade is that it allows one to use all oem AFN oil lines, manifolds, downpipe and inlet pipe. The motor mount doesn't need to be clearanced either

I'm running a 130pd passat intake manifold:

 

[vwishndaetr]

Interesting. So it seems though all these intake manifolds posted are satisfactory upgrades from the caveman 90* manifold that is stock on the AHU.

 

[G60ING]

Anything is better. Hell a gasser 8v manifold with the mounting flange welded and ground to the correct intake port pattern will outflow a stock tdi intake manifold. Do some searching as there have been a number of threads like this over the past 2-3 years

 

[vwishndaetr]

Ya I plan on it. So much to know.