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Author Topic: ALH bulletproof bottom end - BHW crank/rods vs ASZ pistons + rod upgrade, etc  (Read 848 times)

March 29, 2019, 05:56:45 pm

Chuck1978

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I'm looking in the long-term to build a bulletproof ALH bottom end to use with an ALH head and a Bosch VE mechanical pump from a Land Rover 2.5L 300TDI. I have one running 196k mile engine right now for the project, but want to build a very stout, fresh & upgraded version of it for long term use at some point before the final stages of the project.
This will be going into a 2400lb Suzuki Samurai 4x4 with the aerodynamics of a brick wall, pushing 31x10.5 tires, that may see somewhat regular use pulling a 4x8 trailer and 2-3 dirtbikes up steep mountain grades etc, & occasionally some 330-450lb street bikes, hauling firewood & misc etc.
Eventually the Samurai will be stretched to Canadian LWB (long-wheelbase) body specs with an Aqualu aftermarket marine grade corrosion-resistant 5/32" plate aluminum body tub, so it'll gain more cargo/towing capability - 55" cargo bed vs 32" stock US SWB version, 90" wheelbase vs stock, & will be thursty for more engine.
Aqualu body:


I am trying to keep this build plan as durable as I possibly can while still making plenty adequate power & lower end torque, and keeping the fuel economy very respectable. Honestly I am hoping this may be a semi-daily driver from now until they revoke my license in another 40 years due to old age! If it works out to suit my needs, I will be stockpiling another spare engine or two even.
Onto the engine bottom end...

I would say my maximum horsepower goals would be 130hp or 140hp minimum, but no more than 175hp in order to keep it durable, this is not a hot rod but I do want something that is fun to drive still. Torque output I am hoping is 225-275ft-lbs.
The Land Rover Defender 90 (who's injection pump I am using) weighs 1000lbs more, & has a 2.5L 300TDI 110hp/195ft-lbs Land Rover engine, gets 30-35mpg highway, & will pull the heavier Defender 90 up big hills just fine. I figured 1000lbs less and 130-140hp with more torque yet would without a doubt be A LOT more fun to drive still.
I currently have a brand new GT2052 turbo that came with this engine, & will swap on whatever injectors that I can in order to keep the smoke to a minimum or non-existent, and keep efficiency up, while still making great power, with emphasis on low-mid torque. This turbo is rated at 140hp to 220hp, and maybe a slight bit on the larger side than what I needed, but it is a brand new $800 turbo and is a highly efficient more modern design oh, so I will probably just run with it for now and see how it does on the low end and turbo lag. I originally planned to find an old Volkswagen KKK K14 turbo and rebuild it. That would definitely have more bottom-end but would be lacking in top-end and really is best to run at no more than 15 psi (I was hoping for just a touch more than that, perhaps 17 or 18psi).
Due to the emphasis on low-end torque, I was especially concerned about the durability of the bottom end, and especially the big end rod bearings, as when you are building more power at low RPM, the oil pump is not spinning faster, so you have less oil pressure. Sputter bearings at minimum will be necessary. I have also heard of people bending rods in engines that did not have substantially more high-end horsepower, but rather just boosted the low end torque more.
I would like to keep the piston size as close to stock as possible, only over boring to get a fresh cylinder bore surface if the cylinders are worn or damaged.
I was intrigued by converting a BHW 2.0 block to work with the ALH front main seal housing and timing belt idlers,  BSM delete/ALH oil pump, but not sure I want to go that drilling & tapping route for the missing idler.

Nor do I want to run significantly heavier 2.0L BHW pistons (slightly more vibes) until I need to bore the block that large of oversize in another 500,000+ miles, nor do I want to bore 1.5mm worth of meat out of the ALH cylinders to run the 2.0 pistons just for the extra 0.1L displacement.
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This leaves me with 2 main options & a few others:
1.) BHW/PD150 crank and rods (larger big end rod bearings than the rest, stronger cracked rods) & possibly BRM pistons or similar?
Sputter bearings on the big ends as well for longevity.
Disadvantage - BHW are a bit harder to find here in the USA.

2a.)
Keep the ALH crank, run slightly stronger factory PD100 rods and Euro-spec ASV 19.0:1 c.r. pistons are the same compression and basically same height & layout as ALH pistons, but have the oil cooling passages underneath & a significantly thicker crown, as well as having the benefit of moving the compression rings lower than the ALH, BRM, BHW pistons in order to be able to tolerate a lot more heat under heavy loads.
*ARL pistons are the same but even thicker crown and 18.5:1 c.r., better for more boost/higher rpm power builds, but slightly more smoke on startup, and slightly less low-end torque.

2b.)
Same as above but run Rostens H-beam rods or Molnar etc H-Beam rods from Frank's TDI
EDIT - see later post on pistons:
2C.) BLT PISTONS & TRAPEZOIDAL RODS (OEM or H-Beam)
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3.) BEW crank & cracked rods, BRM(?) pistons?
4.) BRM crank, cracked rods, & pistons?
So from what I understand, the ASV pistons that have the lower compression ring position and oil cooling passages, were designed to use the squared parallel top rods?
BUT... you can still mate these pistons to the trapezoidal rods, but just not the other way around (obviously)?
Are there ANY other pistons in any international (non-USA) markets that are designed for the tapered small end aka trapezoidal rods? (EDIT - FOUND IT! BLT pistons, see later post) It seems that it would be best to match the trapezoidal rods to a trapezoidal piston, and not an older style piston made for the parallel topped rods, it seems that many people do to PD100 rod + ASV (or ARL) piston upgrade to ALH's.
Comments?
I recognize that the BHW/PD150 crank/rods are definitely going to be more stout on the big ends, but how crucial is this for my goals if I am running high quality sputter bearings especially. Should this be a must-do for my application goals?
If I cannot locate a BHW crank here, how difficult is it to import a PD150 crank?
Thanks,
Chuck in Ohio
« Last Edit: April 03, 2019, 03:09:10 pm by Chuck1978 »



Reply #1April 03, 2019, 02:58:49 pm

Chuck1978

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Here is a picture of the beast in it's current state other than the 33"×12"R16 tires have been traded off for more reasonable 31x10.4R16's.


I should also sway you VW purists back my in my favor by noting that we also have a 95 Eurovan Camper with the AAB NA diesel, and she has an 82 Rabbit 1.6D pickup, & I have an 82 Rabbit 1.6TD pickup truck (83 Quantum wagon CY code IDI 1.6L TD).


I'll also note that I am not concerned about swapping cranks due to the tone wheel/CPS or whatever you call them, because I am running a mechanical TDI pump from a Land Rover Defender 2.5L 300TDI engine, it is nearly identical to the ALH pump externally. I can get the same power out if tgis,but will only be missing out on a slight bit of fuel mpg.  There is no sense in trying to sway me to drive by wire, I'm very set in my target goals unless otherwise stated.

Reply #2April 03, 2019, 03:07:24 pm

Chuck1978

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Pistons and rods...
BEW/BRM (these are considered PD100, correct?) rods would suffice for my purposes, and the ASV pistons are really what I was shooting for with the significantly lower position for the compression ring and to keep it out of the highest heat zone for maximum durability on a modified engine that may see some harder heavier use, as well as the oil cooling passages under the crown, and the thicker crown in general. But... It'd be a shame not fully utilize the tapered top end trapezoidal rods by pairing them to the older piston design.
The ARL/ASZ pistons are very much like the ASV pistons, but designed for trapezoidal tapered small end cracked rods, BUT... they're a half point lower compression. This is good for those looking to run more boost to get big high rpm peak horsepower, but will give slightly smokier startups and less low end torque. I really would like to stay firmly at 19:1 compression. 19.5:1 would not be so bad either.
I figured there likely existed a newer model TDI piston that'd be near exactly what I was looking for. I then found a 2017-2019 Nüral Pistons catalog link in another thread...
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https://www.fmmotorparts.eu/content/dam/marketing/emea/fmmp/ecat/EMEA_CAT_NU_PISTON%20ASSEMBLIES_CATNU1601_2017-2019_EN_HQ.pdf

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Scrolling down to pdf file page #'s 1200 and low 1300's, you will find the VW sections.
VW piston design #18 is the ASV piston, which supersedes all of the 1Z / AHU / ALH pistons and many other European models that we did not get here in the US.
VW piston design #21 seems to have a typographical error that omitted any of the build criteria codes (TR = Trapezoidal Rod, but no 2 letter codes are shown for this one), so I cannot see if this has the trapezoidal rod construction or not, but it is an 8v four-cylinder 1.9 TDI piston.
Starting with VW piston #22 through #27, THESE are the pistons of interest to this discussion...
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#22 looks to be THE PISTON TO HAVE if you are going bigger valve lift camshafts and bigger boost, it has 0.2mm deeper valve pockets than the rest, & 18:1 compression. This isnt for my goals, but others may find this to be their best fit. This fit engine codes AJM, ATJ, AUY, & BVK in 115PS (113.5 hp) engines in the Bora, Golf IV, Passat, & Sharan, as well as 4motion versions of those models.
87-114900-05 (cyl 1-2) & 87-114900-15 (cyl 3-4) (std. bore, 07 vs 00 is 0.5mm OS & shorter crown height for decking block)
85-114900-55 (cyl 1-2) & 87-114900-56 (cyl 3-4) is another variation for use with different injectors. The first -05 & -15 are for angled injectors. The 07 vs 00 is still the same for 0.5mm overbore and shorter crown for head gasket surface milling/decking on rebuild/overbore job.
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#24 I think may be the BRM piston but I'm not sure, several US engine code designations are not even listed, but BSW, BSJ, BLS, BMT, etc are listed. This is a higher compression piston at closer to 19.5:1 judging from the shallowest of bowl depths. 90hp engines. Good stock trapezoidal rod replacement.
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#25 is the piston for ARL/ASZ/AVF/AWX 130PS & 150PS (128 & 148hp) engines, 18.5:1 piston for Trapezoidal Rods.
Standard valve relief cut, lower compression ring for longevity to keep rings away from the high heat zone, and 18.5:1 compression ratio. A GREAT choice for a moderate but fairly significant amount of boost for a street engine.
18-114900-25 (cyls 1-2) 18-124900-35 (cyls 3-4) Std. bore
18-114907-25 (cyls 1-2) 18-124907-35 (cyls 3-4) 0.5mm overbore, (& as typical for Nüral, these 0.5mm OS pistons are 0.25mm shorter crown height to allow for block decking)
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AND FINALLY... The crown jewel of pistons for my goals,
Nüral VW piston #27[/B]...
This was spec for the high output 2004-2009 1.9TDI Polo 130PS (128hp) BLT code engine, as well as the Multivan and Transporter V 2006-2009 84PS(82hp) BRR & 102PS(100hp) BRS code engines.
This has a slightly shallower bowl chamber than the ARL piston, for 19.0: 1 compression ratio vs the ARL @ 18.5:1, the desirable lowered compression ring land positions for keeping them further out of the high heat zone, also designed for tapered small end "Trapezoidal Rods," with oil cooling passages underneath the crown, and again has a thicker overall crown for better heat dissipation & strength.
these would have to be ordered from across the ocean of course since RockAuto no longer carries Nüral Pistons, but as it stands, THIS is the piston for my low end torque + moderate boost & maximum durability goals...
18-114900-45 (cyls 1-2) 18-124900-46 (cyls 3-4) Std. bore
18-114907-45 (cyls 1-2) 18-124907-46 (cyls 3-4) 0.5mm overbore, (& as typical for Nüral, these 0.5mm OS pistons are 0.25mm shorter crown height to allow for block decking)
https://m.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2322090.m4084.l1313.TR12.TRC2.A0.H0.Xthe.TRS0&_nkw=8711490046
https://www.ebay.co.uk/itm/NURAL-ENGINE-CYLINDER-PISTON-WITH-RINGS-8711490046/283059089211

https://m.motointegrator.de/artikel/14558-kolben-nural-87-114900-45

 

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