Stroker 101: The beginners guide to stroked ACVW engines.

[Mal evolent]

No, I have not built a stroker. This is the research I am doing prior to building a stroker, pooled into one place so others don't need to do the same research.

This tutorial is about building an engine from scratch, using a fresh new case and all new parts.

Why: Picture a manual boat trailer winch. Put a window winder crank on it. Try to winch a boat on a trailer with that. Nothing happens. No leverage. Now put an 18" long crank on the winch and grind away. The boat comes along nicely. Longer stroke = more work gets done.

Engines produce torque. In the USA we measure torque in foot-pounds. The pounds comes from pressure on the piston caused by expanding gases. The foot part of foot-pounds comes from leverage, the length of the cranking handle. More length = more leverage. We stroke an engine to get more leverage from the down force derived from the expanding gases. This produces more torque.

When you need serious pulling power, you run a stroked engine. Type 2s, Type 3s and Baja bugs benefit from stroked engines.

What you get for what you do:

This chart does not show certain combinations. Fans of those combinations will scream and pout and kick the floor. Oh, well. My VW engine advisors - grizzly gray haired old goats who have been building VWs in the southwest USA for decades - will not do engines with 87s, 88s and 92s. They say those engines keep coming back for service. Not compatible with desert heat.

You can get thick walled 92s that fit into cases bored for 94s, but why would you do that when you are buying all new parts?

Cases bored for 94s are machined to the edge of the case savers. Therefore I do not show bores greater than 94.

Strokes greater than 84 are too wide for the stock engine compartment and require massaging the cooling tin. Outside the scope of Stroker 101.

This chart shows common combinations of currently available parts that can be used on the street. If you are building an engine with a bore greater than 94 and a stroke greater than 84 you do not need to read Stroker 101.

Parts:

Most of what follows is condensed from http://www.aircooled.net/vw-performance-engines/ and http://vwparts.aircooled.net/category-s/337.htm

Case: You can get a brand new case, bored for 90.5s & 92s, or 94 MM cylinders, clearanced for up to 84 MM stroke, with case savers and drilled and tapped for full flow, with #3 cylinder reinforced. No machining necessary, which is a major bonus for those of us who live so far out we have to truck in radio waves. No need to line bore and clearance an old case.

Gene Berg says don't line bore an old case. Gene Berg knows more than I do:

http://www.geneberg.com/cat.php?name=Technical%20Information&cPath=2984

Crankshafts: The crankshaft is the defining component of the stroker. Stroker cranks by any given manufacturer all cost the same. An 84 costs the same as a 74, or anything in between. If you're going to be a bear, be a grizzly

A word about cast cranks: No.

Different strokes for different folks:

74 MM, 76 MM & 78 MM: Why? Costs the same as an 84, gives you not much more performance. Only real benefit is you can run stock rods. If you're starting from scratch you don't have stock rods to run.

82 MM & 84 MM: You must run I-beams or H beams. H beams cost more but let you rev higher. If you are interested in longevity and you are not racing I beams are fine to ~6500 RPM.

86> MM: This is a higher level of effort. Different case, cooling aggravations, clearance headaches. Outside the scope of Stroker 101.

Connecting rods, Pistons & Cranks: A team effort.

The combination of connecting rods and pistons used is determined by the selected stroke.

Pistons come in 2 types, A & B. Stock VW pistons and aftermarket pistons for 69 and 74 MM strokes use A pistons. B piston have the wrist pin hole closer to the rings, so the piston stays in the cylinder with a longer stroke.

74 MM: A piston with 5.325" rods. You can also use stock 5.4 " ( 5.394" is factory stock ) rods with A pistons and .090 spacers, but your engine is now .180" wider. This is the last size that uses A pistons.

76 MM: 5.5 rods with B pistons.

78.8 MM: 5.5 rods with B pistons.

82 MM: 5.325 or 5.4 rods and B pistons. From this stroke up, I beam or H beam rods are required.

84 MM: 5.325 or 5.4 rods and B pistons

Links to essential information:

Deck height: Deck height keeps things from smacking into things, and you need the info to set your compression ratio.

http://www.aircooledtech.com/deck_height/

http://www.thesamba.com/vw/forum/viewtopic.php?t=609987

http://www.thesamba.com/vw/forum/viewtopic.php?t=587681

Compression Ratio: http://bobhooversblog.blogspot.com/2006/11/vw-compression-ratio.html

Cylinder spacing to achieve deck height: http://www.geneberg.com/cat.php?cPath=1_41&osCsid=eb9dcc56e6230384aa67b6378e979234

Heads: http://www.thesamba.com/vw/forum/viewtopic.php?t=573099

General Rebuild Knowledge:

http://www.aircooledtech.com/engine_build/

http://www.type2.com/rvanness/1600saga.htm

http://www.cwgsy.net/private/ramva/tech.htm

Gaskets: What goes where http://www.thesamba.com/vw/forum/viewtopic.php?t=527020
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Baja Bugs for Volkswagen Virgins: Index

[[email protected]]

Not to sound like an a$$ BUT you should probably build one before instructing or even having an opinion about a stroker build. Some of your information is just flat out wrong. I've been building engines for 25 years and have over 1000 under my belt. And as much as I know, the only absolute I know in engine building is.......I don't know everything.

Please don't be discouraged by what I said. I think you have a great idea but once you build one, you'll already understand 1000% more than you do right now.
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Cylinder Head Reference Sheet

[mark tucker]

[jfats808]

Just a small input, I or h beams arent a requirement for XX stroke. Stroker clearanced 311s can be used just fine in more than a few apps and have been for years prior to the intro of aftermarket rods. You list only one rod length per a stroke size. But many of us here know that there is more than one way to skin a cat in regards to working combinations.

Without getting into a berg info war, let me say this. Lots of bergs ideas about limitations, piston size, cr and case lineboring have been surpassed and accomplished successfully.

I can appreciate your attempt to do a write up, but its going to be difficult to cover all the little tricks and prep work.
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[bugguy1967]

There are varying opinions on whether or not increasing stroke adds benefit over increasing bore. Some have data to suggest that any increase in engine capacity, whether it be by increasing stroke or bore will give equal results. I've read and heard plenty about how certain combos feel snappier than others, but have never seen side-by-side dyno results of two similar cc'd engines with the same components.

[theDrew]

Build an engine or two and then get back to us....

I started building a stroker engine a year ago and I've changed directions a few times, pulled the engine 2x to swap parts, etc.
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[56vwoval]

Coming from a guy who has built a few engines for himself, I want to say thanks! It takes a lot of time and research to plan an engine build be it a VW or any other type of engine! This kind of stuff can only help people find answers and that is all most are looking for! It takes a lot of time and effort to put something like this together! I also read a lot of the comments from the samba mainstays and then make my own opinion. Lots of good advice from engine builders on here as well and even they agree to disagree! Good luck and thanks!
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[modok]

78 stroke needs 5.5 rods?? not true.

most B pistons are 35mm pin height, perfect for 78 stroke
All AA brand B pistons are 35mm pin height

But some are 34.5 (mahle 92b) or 34mm ( mahle 90.5b), which are a bit shorter. SO....still doable with 78 stroke, if you check pin height and deck case accordingly.

94mm cylinders and some 92 thickwalls are 1.5mm longer than stock, this makes people confused. The idea is you deck the case .060 for these big cylinders so the seating surface is nice and wide and flat. If this is not done then it throws off the deck height and more likely to leak too. Same can happen building a 1915.

[raul arrese]

Poor guy got slammed !!! there are too many combinations that will work and most builders have there own techniques and combos ...
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[Brian]

Great compilation, thanks Mal.

Also this made me laugh

[VWCOOL]

Because Internet...

[58Dub]

I think its a great reference for the majority of people.... maybe not all the pros.
Thanks for the info. I look at it as a collection of data, not a set by step idiots guide to assembly.
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[Type 5 Joe]

I remember way back in the old days... Oh about three decades ago.

All you had to work with was your Hot VW's magazines and your imagination.

Minimum wage was just raised to gasp... $3.35 an hour.

Quality VW parts were mostly American Made, by Americans and were quite expensive $$$$.

Putting together a SCAT drag flange bottom end with H-Beam rods was not easy for a teenager.

Here in Oregon there were few knowledgeable people to turn to for advice to build a nice VW engine.

We made or own advice through hard work, late nights in the shop... A ton of mistakes were made, but it built character.

82mm strokes were a thing to drool over... And somehow they worked with stock, clearanced rods.

Those engines saw some extremely High RPM use... To the sky when you missed a shift.

What people need is to return to the old way of doing things... And use the Internet as a tool, not the foundation for the Hobby.

[[email protected]]

[mark tucker]

[Dan Ruddock]

One thing I don't like is the lack of Porsche journal cranks on the market today "I guess they are no good" is the conclusion some will take from this.

Dan

[mark tucker]

I dont see why it's needed. just saying it has a porsche journal does nothing.I think there should be honda sized instead of chevy/buick/olds sized.

[raul arrese]

two good point here from both of you , just another example of so many different ways of building a motor . there is no perfect list to a stroker.
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[Dan Ruddock]

[dsrtfox]

I'd like to know more about this Dan. Are the rods Porsche length and the size of your engine, bore stroke...

Thanks Curt.