making a 2 liter, Cylinder Question Options

[malcolm2]

I plan to buy new 94mm dished pistons for my bus project. AA has the set for $250.

They also have just the pistons for $140. Should I consider having the 1.8 cylinders done to accept the 2.0 pistons?

Not sure about the cost yet. The shop I planned to go to has been closed for the Holidays. So his charges might answer my question.

But what does the group think? Especially the Bus people. They have recommended going with the 2 liter vs the 2056. So here I am with more questions... (IMG:style_emoticons/default/piratenanner.gif)

Would the stock, honed 1.8 cylinders (unknown mileage) be better than new from AA?

[Miguel K R]

With 94mm diameter pistons and cylinders, if you use the 2L crank (and the corresponding rods) with the 71mm stroke you will have a displacement of 1971cc (the displacement of the standard 2L).

You mention that you are considering a set of pistons from AA and in that case you will get a reasonable compression ratio. When these were not available the choice was between the cylinders and pistons of the 2L VW Bus, which have a low compression ratio (and lead to a low power) or the considerably more expensive cylinders and pistons of the 2L 914. Another alternative was to buy a set of 94mm pistons and cylinders for a VW Type 1, re-bush the Type IV 2L rods from 24 to 22mm, and use these pistons with used honed 2L 94mm cylinders from a Type 4 engine. This way you were able to get a high compression 2L without the extra cost of a set of 914 cylinders and pistons.

If you stick to the 1.8L crank and rods, you have a stroke of 66mm and a piston diameter of 93mm (displacement of 1793cc). If you change to 94mm pistons you increase the displacement to 1832cc . This is reasonable using the 1.8L cylinders (when you enlarge from 93 to 94mm diameter, you are removing just 0.5mm per side).
On the other hand 96mm pistons lead to a displacement of 1910cc but I would not recommend at all enlarging the 1.8L cylinders from 93 to 96mm as the walls would be too thin.
In this case you would have to buy pistons plus cylinders from AA for 381.95USD : https://aapistons.com/collections/vw-piston...der-kit-914-bus

NOTE : 96mm pistons and cylinders, with a 71mm stroke 2L crank and rods, correspond to a displacement of 2056cc

Of course, it is tempting to obtain a larger displacement, but you have to invest in a 2L crank and Rods, and have the crankcase and heads enlarged to match the larger cylinders.

Miguel

[HAM Inc]

Yes. If the O.E. German jugs are in good condition and you have a competent shop to bore and hone.

Since you already have bus heads, whatever pistons you use (94mm or 96mm) will have to have the ~ 15cc dish that the bus pistons have to keep your compression ratio from being stratospheric.

[TargaToy]

NOTE : 96mm pistons and cylinders, with a 71mm stroke 2L crank and rods, correspond to a displacement of 2056cc

Of course, it is tempting to obtain a larger displacement, but you have to invest in a 2L crank and Rods, and have the crankcase and heads enlarged to match the larger cylinders.

Miguel

Are you positive about this last statement? Any Type IV case as well as the 1.8L heads should accept 96mm jugs with no machine work.

[HAM Inc]

NOTE : 96mm pistons and cylinders, with a 71mm stroke 2L crank and rods, correspond to a displacement of 2056cc

Of course, it is tempting to obtain a larger displacement, but you have to invest in a 2L crank and Rods, and have the crankcase and heads enlarged to match the larger cylinders.

Miguel

Are you positive about this last statement? Any Type IV case as well as the 1.8L heads should accept 96mm jugs with no machine work.

This is correct. All T4 cases have the same size spigots and will accept 1.7-2.0 jugs.

1.7 head registers are 100mm. 1.8 & 2.0 are 105mm and will accept all typical 96mm jugs.

[Bills914-4]

Here's some 96mm done right on samba classifieds ,

https://www.thesamba.com/vw/classifieds/det....php?id=2248064

[malcolm2]

My original thought was 96 mm, after a few posts hearing from long time bus folks, i decided to go stock 2.0. And yes, using the dished pistons to keep the CR to stock as well. IIRC stock bus compression ratio was 7.3:1.

Still have work to be done, I hope my machine shop is enjoying his long holiday. It is killing me.

[Miguel K R]

Sorry for the wrong information about the need to machine the crankcase and heads for the 96mm cylinders.
Several years ago I started with a 1.8L and as I was told that the 96mm cylinders were thin, I decided to buy 2L rods and a crank, and used 103mm cylinders with JE pistons to get a displacement of 2336cc. That engine was recently removed from my 914, which is going to get a 3.6L engine, so the Type iV will go to my VW Notchback.

I do have a VW bus with a 2L engine, without dished pistons, running on two 40 dual Dellortos.
Probably the gas you have in the US has a lower Octane level than in Europe ...
When VW designed the engine for the Bus they used dished pistons to reduce the compression ratio and thus avoid overheating in a heavy Bus. I guess that the lower compression ratio also had to do with emission controls in the US (VW engines, and Porsche 4 and 6 cylinder engines in the 1970's were sold with less horsepower in the US than in Europe).
I do not know how strict the emission controls are in the US for a BUS which is now some 45 years old ...
When the 2L Type IV engine was developed for the 914, dished pistons were not used, to increase the compression ratio. The heads were redesigned with the sparkplug repositioned (most people say this was for a more efficient burning and increased power... now I wonder if this was also to avoid detonation), and injection was used, instead of carburetors.

If you will be driving the bus in hot summers, on mountains, and loaded, you should use the dished pistons.
If the Bus will have a lighter use, you may consider using pistons without the dished area, to give you more torque and power.

Miguel

[HAM Inc]

The 2.0 914/4 got Porsche designed heads with the unique to T4 plug angle.
The combustion chambers stock are around 59cc's and they weaken the heads with their large size.

The Original T4 design, the 1.7 had heads with chambers around 49cc's and they were much stronger and rarely cracked. Unlike the 2.0 914/4 heads.

VW did a smart thing when they designed the bus 2.0 to have large piston dishes and small combustion chambers (around 50cc's). The piston is lighter, and the head is stronger. They still crack with heat down in the exhaust ports, but chamber cracks are rare, unlike the 2.0 914/4 heads.