66mm Vs 71mm and larger

[JDub]

I am looking to build a Type 4 for my 63 bug and I have been hitting the searching button a lot and I am learning a lot but not quite the answers I am looking for. I thought I would post this question and maybe get the answers I am looking for and maybe help some one else.

So here goes, What are the pros and cons of using a 66mm crank vs a 71mm crank or larger? I am still confused on what engine to look for to start with, Do I look for a 1.7,1.8, or a 2.0L or does it even matter? Should I even look at a 66mm or 71mm crank or just jump in with both feet and go 78mm? I am sold on the idea of a upright type 4 but am needing a little help to be pointed in the right direction. I have read this forum till my head hurts and the more I read the more confused I get. Hopefully that will change with time.

My apologies if these questions seem redundant or have been covered many times before. Though I have been around VW's for many years I am a newbie to the type 4 and am wanting to learn.

Thank You!

[H2OSB]

I understand your confusion, believe me. You'll have substantially more questions than stoke before long, but know this...there are very knowledgeable folks on here regarding T4s(I'm not particularly one of them).

The 66mm crank is a nice factory part. It's substantial enough to not have the flexing issues of the factory 69mm T1 crank and usually doesn't need balancing to run. They can comfortably handle up to 96mm bore making a 1911cc which is good for about 100hp. The rod journals are 55mm like the T1

The 71mm crank is, essentially, a factory offset rewelded crank, thus the rod journals were resized to 50mm. It is also a very nice part that can be run without balancing. Also can be used with 96mm bore making a 2056 and good for about 125-130hp depending upon other factors like cam and exhaust. Larger bore size can be used, but it gets more complicated quickly when you go beyond 96mm.

To be sure, the 66 crank is far easier to find and less expensive than a 71 but is worthwhile to find(assuming you're looking for a used factory part). The 66mm crank came in the 1.7 and 1.8 while the 71mm came in the 2.0. The 1.8 and 2.0 share the same size register at the head end of the cylinder, and the 96mm cylinders on the market and made to that same head opening. You can go to larger bore, but machine work is required to open the heads up.

Hope that helps a bit
H2OSB

[JDub]

H20SB

Thank You, for your reply. That answers some of my questions. So, I think I will be on the look out for a 2.0 long block to build from. If I can't find one locally is it generally worth the price of having one shipped? I know that is a question that come with the answer of : Depends on the situation, but I have never paid to have an engine shipped so therefore I have no idea of what that might cost. Is shipping something like that expensive?

back on topic, will a 71mm crank last as long and be reliable as a 66mm crank? One thing I do know is that whatever I build I will opt for the 96mm P/C's.

I like the idea of a 2270 which seems to be quite popular but it looks to me to be more expensive to build compared to a 1911 or 2056 or am I wrong?

I sure there are more questions I need to ask but this is a start.

Thanks!

[wreck]

a 71mm crank is just an offset ground 66mm crank , so even if you had a 1700/1800 you could just get the crank ground 71mm specs or just use it as a core . new rods are limited for the 66mm crank where as the 71mm is catered for .
A stock 71mm crank can be reved at lot harder than a stock T1 69mm crank without any issues as long as it's well balance .
Going stroker and using a crank with type 1 big end journels has the advantage of being able to use cheaper type 1 after market rods .
It all depends on your engine building experience . I wouldn't recommend going with a stroker if it is your first engine build . If you've built type 1 strokers than it's not really that different .

[JDub]

Good Info wreck, I think your are right. start will something simple and close to stock to learn on and then branch out into a stroker as knowledge and experience grows. 1.7 or 2.0? We shall see what I can find. So now time for some fun and do a little shopping and see what I can come up with. As I gather the goodies I am sure I will have tons of questions. If anyone has any comments, tips, info, or anything in between please drop in here and post. I am all eyeballs here, ready to read and eager to learn.

Thank You

[Clatter]

Lots of times the 2.0 vs. 1.8 or 1.7 question will be answered by what you end up finding.
At least with a basic/budget build..

Pick your exhaust first, and your cam last.

Things get expensive quickly with a stroker.

[cal 67]

a 71mm crank is just an offset ground 66mm crank , so even if you had a 1700/1800 you could just get the crank ground 71mm specs or just use it as a core . new rods are limited for the 66mm crank where as the 71mm is catered for .
A stock 71mm crank can be reved at lot harder than a stock T1 69mm crank without any issues as long as it's well balance .
Going stroker and using a crank with type 1 big end journels has the advantage of being able to use cheaper type 1 after market rods .
It all depends on your engine building experience . I wouldn't recommend going with a stroker if it is your first engine build . If you've built type 1 strokers than it's not really that different .

I don't think you can offset grind a 66 to a 71 without welding. If you did, it'd be more likely to fail than a factory 71 stroke because of stress risers. A 71 stroke's journal is approximately 2" and a 66's is 2.165". .165" is 4.16mm, so with a standard journal, you could possibly offset grind to 70mm. From the factory, those crank forgings had plenty of meat on the crank to grind s longer stroke, and even increase the main diameters, if they so pleased. After it gets turned into a 66, that's no longer possible without welding.

If you're in the U.S. 2.0s are cheap if you're patient. Obviously the 71 will be weaker than the 66 for two reasons: less journal overlap and smaller rod journals. It's still terribly adequate for any vehicle that's not a Bus. Also, the lighter your reciprocating assembly is, the less stress on the crankpins. So if you use an H-beam and any lighter than factory piston, you will alleviate stress.

[wreck]

An 1800 big end is 55mm , a 2lt is 50mm ,there is your 5mm stroke difference as long as the crank is standard. I know of 2 cranks first hand that are in 103 x 71 engines that are an 1800 crank offset ground . My was done almost 20 years ago and still going strong . I started with and 1800 core .

[cal 67]

Oh, I gotcha. So a 71 would probably be .010" under after stroking then. Idk where my math got screwed up, but that's dead-on.

[JDub]

Okay Guys, Since my last post I have picked up a GE Case 2.0L long block for a real reasonable price. it turns over by hand, intake ports look clean, and inside the valve covers is really clean, no build up of gunk and I was told it has Hydraulic lifters. But i won't know any more until i get the opportunity to tear it down. I will need to find a flywheel though, It did not come with one. What flywheel should I look look for? Also, If it does have hydraulic lifters, would it be a good idea to ditch them for solid lifters and cam? That all I have for now. I am sure there will be more questions to come. I will try to get some pics of the motor to post sometime soon.

Thanks!