Introducing Project Wasserboxer 2500E

[D Clymer]

Hello everyone,

This month I will be starting to assemble a very special wasserboxer and I thought some of you might find some of it interesting. Last year I stumbled upon a NOS set of original Oettinger 2500E pistons and cylinders. I had always dreamed of owning one of these engines, so I wasted no time in snapping up the set. The pistons turned out to be forged Kolbenschmidt brand units with a very shallow and flat combustion chamber - very much like the factory 2.1 10,3:1 DJ code pistons. These have a lower compression ratio of 9.7:1.

They measure a full 98mm, so they are too large for bored out stock cylinder liners. I knew this at the time I purchased the set, and knew that the old Oettinger literature mentioned "special cylinders," so I was very interested to see the cylinders. My prediction was that they would be 4mm larger in diameter than stock with stock wall thickness, and would require case machining. Here's what arrived.

These cylinders are indeed nearly 4mm larger in diameter at the base than the stock wbx barrels. Here is an interesting comparison of one of these 2500E barrels next to a slightly overbored (.5mm) 2.1 barrel. 2500E is on the left. 2.1 at right.

As you can see the wall thickness is retained with the 2500E barrel. At the top, however, I was surprised to see that they had machined the larger 2500E barrel to the diameter of a standard wbx barrel. There is a little bit of room the wbx heads for a larger diameter cylinder, but they obviously wanted to keep the heads as a standard replacement part. These cylinders were manufactured for Oettinger by J Wisemann Company and, due to their small production run, are actually machined from iron cylinder liner tube rather than originating from a specialized casting as is the case with the standard wbx cylinders. Making them fit the case was obviously the next step. Actually things didn't progress in this order at all, but for the sake of this write-up I think the case mods should be described next.

There is an excellent VW engine builder and machinest located in Walla Walla, Washington. He is someone all wbx engine builders should be aquainted with. His name is Rocky Jennings and he is known for his case mods to wbx cases to make them work with large air-cooled cylinders. After talking with Rocky on the phone, I was very impressed with his depth of knowledge and his willingness to talk with me about my project. I sent a 2.1 wbx case to him for modifications.

Rocky actually trial bored an old case he had first to be sure he had the bore size correct. Here is another shot of the finished bores.

I don't have a shot of the inside of the case, but the amount of aluminum structure surrounding the cylinder bases is about perfect. Between that and the amount of material between the bore and the head stud holes, it looks like Oettinger took this cylinder base diameter out as far as it safely could go. Here is a shot of the cylinders test fitted. The fit is perfect. You can start to get a feel for just how big these 98mm bores are in this photo.

Tomorrow evening I will write another post describing the solution I came up with for rods and a crankshaft. Hope this is interesting to some of you

David

[magician]

[wbx]

[klucz]

Cool!
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84 Westy 4spd sold

[allsierra123]

So I have a question for you. Can you get decent enough performance numbers out of a Built WBX. To make it a better choice than an engine transplant? I mean if it were feasable to make good reliable power out of the wbx it would seem to be the more economic way to go. But is it really that realiable. I figure those of you who build WBX engine would know better than the average vw driver.
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95 GMC Yukon 6.5 TD 2 Door Tow pig/ Daily driver.
91 Vanagon GL. 1.9TD Conversion Sold
81 Vw rabbit 1.6 Diesel. Sold

[Bern]

Hey David, nice looking project. I'll be very curious as to how this progresses. Are you planning some headwork as well? How balls to the wall are you going to go with this thing? And I'm curious as to if you have any plans for the factory injection? What did the oettinger kit put out power wise? Awesome stuff, keep it up.


allsierra: At this point there are so many options for motor transplants into vanagons that its getting down to personal preference. There are those out there that want to stick with a wbx and build it into something a bit better than factory, then there are others that want to option for a different engine alltogether... I am of the later thinking and broke away from a wbx'r as fast as possible, HOWEVER I give respect to those working with the original motors that came in these vans, and there are a few people on here with some awesome projects that get the wheels in my head turning about how fun it'd be to build up a wbx. Maybe someday
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VR6 Vanagon. Yup, it vrooms and stuff.

[Christopher Schimke]

NOICE!!! I'm excited! I love this kind of stuff.
_________________
"Sometimes you have to build a box to think outside of." - Bruce (not Springsteen)

*Custom wheel hardware for Audi/VW, Porsche and Mercedes wheels - Urethane Suspension Bushings*
T3Technique.com or contact me at [email protected]

[MarkWard]

Looking at the pictures, it looks like the stud inserts are right up to the edge after machining the case. That would be my only concern to reliability. There appears to be enough surrounding material to hold the inserts snug. Should be a nice project when completed.
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☮️

[tencentlife]

I want some! I want some now!!

<drool......drooly drooly drool....>

I figger at 98mm to get to 2500cc you need to have a 82.8mm stroke ( my calculator spit that out just before it died from drool saturation). DPR? What's that gonna cost? What did that P&L set cost? I wanna know! I wanna know everything!!! Waaah! I want them now!!!!!
_________________
Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/

Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[Alan Brase]

David:
Nice stuff. But about as practical as a Rolex watch. I bet the Oettinger parts new cost more than Porsche parts.
Now, if we could get the Chinese to make some 98mm P&L's and sell them for $199....
Al
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Al Brase
Projects: 67 sunroof bug, 67 Porsche 912 Targa, 70 Westy
Dec 1955 Single Cab pickup WANT 15" BUS RIMS dated 8/55, thru 12/55
To New owners: 1969 doublecab, 1971 Dormobile
Vanagons:
80 P27 Westy JUL 1979, 3rd oldest known US
83 1.6TD Vanagon, 87 Wolfie Westy daily driver, swap meet home

[D Clymer]

[tencentlife]

[D Clymer]

Part II: A Stout Bottom End.

When the pistons arrived the first thing I did was check the wrist pin location to see if Oettinger had used stock length rods or if maybe he had taken the opportunity to use 139mm rods. I was mildly disappointed to find that these pistons were definitely set up to run with stock 137mm rods. However, when I calculated the rod ratios for the two rod lengths I found that the stock rods yielded a 1.67 rod ratio, while a 139mm rod would have only bumped it to 1.70. A stock 2.1 has a rod ratio of 1.8 and a 1.9 wbx has a ratio of 1.99 - which is practically ideal. However, all of the VW/Audi inline four engines have rod ratios between 1.55 and 1.67 so there are definitely bullet proof bottom ends with rod ratios in the same range as this 2500E.

As most of you know, the 2.1 is notorious for being hard on rods. The rods are physically the same as the 1.9 wbx rods, but 2.1s usually have ovaled out big ends by the time they are torn down, while 1.9s typically do not. Some think the increased rod ratio of the 2.1 overstresses the VW forging. Others feel that over revving with a non-counterweighted crank and the increased rod ratio causes the wear. The most reasonable explanation is that the stretch bolts on the 2.1 stretch a little at higher rpms and allow a hammering force to occur, which eventually pounds out the rods. With the increased rod ratio of this engine, I wanted to make sure I had this potential weakness covered. There had been some discussion over on Shoptalk Forums about modifying Type 1 performance rods to work in a wbx, so I decided to go that route. I ordered a set of Unitech+ I beam rods. Here is a comparison between a Unitech+ and the standard wbx rod.

The Unitech+ rods come with ARP 3/8 - 24 rod bolts and are forged from 4140 chromoly steel. WBX rods resemble late style Type 1 rods, except their small end is larger and they are bushed for 24mm wrist pins rather than the 22mm T1 pins. The big end is however the same as Type 1. The Unitechs have enough material to allow overboring. It took a while to locate someone who was willing to convert these Unitechs to 24mm pins. Finally, I called Frank Stamos, who supplies the Van-Cafe rebuilt rods. He said he could do it, but would need to buy a new boring head for his mill. Frank is a great guy, and it speaks volumes about him that he was willing to buy tooling to do the job, when he could just as easily turned me away like Rimco and so many others had. Anyway, here's what he came up with.

The bushings he used are thicker walled than the 22mm ones originally installed in the Unitechs, so the surrounding material looks a little thinner than I had expected. However, that's only when comparing them to the stock wbx rod small ends. I'm satisfied that these will be strong rods in this application.

I was obviously in need of a crankshaft for this larger displacement motor. These pistons are designed to run with an 82mm stroke crank. A stock wbx crank is either 69mm for the 1.9, or 76mm for the 2.1 The original Oettinger (Okrasa) crankshaft used in these engines is an amazing piece of work - forged chromoly steel with integrated counterweights, specially nitride toughened. There was no way I was going to find one of those, so having the stock 76mm crank stroked out to 82mm and counterweighted was the next best option. DPR Machine Shop in Santa Ana does a lot of the VW welded stroker work these days, so I put in a call to them. Jose, the owner, was helpful and his price for a welded and counterweighted 82mm crank was $425. Not bad, considering all the labor involved. Here is what it looks like.

This crank has .010" undersized main bearings and standard sized rod bearings. You start to appreciate what a good value this crank was after you see how much hand work is involved in welding on the counterweights, rough grinding them, machining, hardening, finish grinding, balancing, and polishing the journals. It's nice that this service is available to wbx engine builders. Jose can also do a standard crank rebuild, provide a variety of stroke increases, and even counterweight and regrind a crank of stock stroke.

In my next post, I'll show you what I came up with for a camshaft and lifters.

David

David

[otiswesty]

Wow, amazing.

How are you planning on running the FI. I know you used Digifant for your DJ motor without apparent problems. Would you use a stock VW system for this motor too? Do we even know how the engine management was originally accomplished? Hmmmm.

I agree with some of TC's other posts about the perpetuation of the VW low end CR motor design by GW motor offerings, albeit in larger displacement. The real question is how higher CR affects engine longevity and whether the NOS sets like the one you have picked up would have better inherent design and engineering that has accommodated for the increased stresses on the motor.

This leads to the ultimate question. What is the maximum displacement and most ideal CR that can be accomplished within the VW WBX 4 cyl design? Perhaps this set is Oettinger's answer to that question.

jealous

[wbx]

Hey David,

Would you be willing to spend some time giving some more detailed information about those Oettinger pistons? Not just diameter, but CCs, and some of the important piston dimensions, so those thinking of custom pistons in the future could have a reference?

I'm really looking forward to this build.
_________________
'84 Westy (first owner).......but my daily driver has pedals
My "perspective" mantra:
A Volkswagen Vanagon is just a material thing,
As such, it is of the earth,
And if i need to, I can let my Van go.

[Christopher Schimke]

I think I just peed my pants!
_________________
"Sometimes you have to build a box to think outside of." - Bruce (not Springsteen)

*Custom wheel hardware for Audi/VW, Porsche and Mercedes wheels - Urethane Suspension Bushings*
T3Technique.com or contact me at [email protected]

[McVanagon]

[tencentlife]

Simply gorgeous.

I'm wondering about DPR, David. Is that price for the crank outright? I'm wondering if they can take 1.9 crank cores and stroke them. Otherwise these 1.9 cranks are worthless to me except for future turbo apps, and consequently I can't give my customers any core credit for them. I'd rather be able to pay people fairly for their 1.9 cranks even when they leave with a 2.1 crank. If I could have DPR turn them into stroked cranks then they would be worth something. Guess I'll have to give them a call, unless you know. Otherwise, my lazy dog does a pretty good job of keeping the shop door open, and I don't own a boat.

What I would really like are some large pistons with 22mm pins, so we could use the array of great aftermarket rods without the trouble of modifying them. I've even been considering bushing the pistons down to 22mm. The 24mm pin is total overkill, and using a smaller pin would be one more reduction in reciprocating weight. Already going to 4140 rods over stock cuts down recip weight a lot, several ounces per rod.

As to otiswestys musings about engine stresses, what I'm seeing is that you can safely put nearly twice the power thru these bottom ends without perceptible wear penalty provided you start tight and balanced and keep the oiling in top shape. Oil cooling is absolutely essential with higher rev use. Anecdotal support for my double-the-hp assertion comes from the numerous Euro tuners with turbocharged road motors and folks like Rocky Jennings who put upward of 200hp thru these things in drag motors. They're not complaining of bottom end deficiencies; they selected the wbx specifically because it's the toughest boxer platform VW ever built. I also don't see why using rod ratios down to 1.67 would cause any premature wear. That's a normal ratio for modern designs; many are much lower. I think David's right that the stretch bolts used in the 2.1 were a big contributor to the ovalling under high revs, and part of the equation is also the heaviness of the rods. The stock rods are very heavy. If you're gaining strength thru more mass it can bite you in the ass once things start moving really fast. That is why I aim to reduce those stresses in my motors by using modified rods that are much lighter and at the same time much stronger, with high-tensile fasteners. Other factory motors making big power run rod ratios far lower than 1.8 and have great longevity. The geometry of stresses is the same whether the pistons go up and down or side to side; what was different was those damn bolts, and the high mass of the rods didn't help.
_________________
Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/

Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[Alan Brase]

[jalopyjockey]

david- good score and good luck

dimer- i emailed dpr not long ago when they stopped mentioning cores on their site.....response i got was that price was outright and that they will still take cores....he did not mention what the core reimbursement was....last i remember it hovered around 140 er so which makes for a pretty good deal....as for 22mm pin pistons i dont know off the top of my head but on the type4rum they have a slugs database thread that might help ya out

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