2056 Build Options

[SteveNMaine]

I am trying to work out compression ratio of my 2056 build. In calculating head volume my understanding from the forum is that stock 2.0 heads have 57mm and the valve pockets on the pistons I am going to use is 3mm. Do I add these together to use 60mm in my calculations for head volume?

[Geezer914]

Yes, anything that adds volume.

[technicalninja]

You should measure the valve depressions, head CCs and deck height yourself.

Don't EVER trust published data.

Now if the data came from Len Hoffman, LN engineering, or Raby I'd trust it...

Most published data shows the 2.0 head at 60cc and the 1.8 head at 55cc

I'd still check it.

What you need is a clear round piece of Lexan (Plexi-glass) approximately 105 mm in diameter (fits the cylinder register in the head) with two holes in it across the combustion chamber. One of the holes should be large enough to socket a 60cc veterinarian syringe in it and the other hole (completely across from the first but in the chamber depression) is an air bleed hole and can be very small.

A 60cc veterinarian syringe will work fine for anything below 10-1 but if you want to get "technical" a graduated burette is more accurate (and much bitcher to use)

You use a bit of grease/Vaseline to seal the edges of the plate to the flat surfaces in the head and then twist and turn until you can get all of the bubbles on of the air bleed hole. The placement of this hole is critical to reduce the bull shit you will encounter trying to remove the bubbles. I want the air bleed directly next to the edge of the chamber depression so I can tilt the head a little bit and have the critter bleed itself.

I'd LOVE to find a 70 or 80cc syringe but haven't been able too. 60s are super common. Burettes came in 100cc increments and work better with larger combustion chambers.

I'll sometimes use the 60cc syringe and then a 5 or 10cc syringe when I'm messing with things over 60 cc. Most combustion chambers are at 60 or below.

Use the plate directly on the piston to measure valve depression volume.
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[rfinegan]

IM doing this too..
This may help
https://www.youtube.com/watch?v=THjjnmbzDqk

amazon has the plastic circles already cut and the cheep syringes

http://www.914world.com/bbs2/index.php?sho...=371399&hl=

[technicalninja]

Another tip is to reduce the surface tension of the fluid (water) you are using to measure.

"Water wetter" or a bit of antifreeze does the trick.

This makes the bubbles "flow" together better and reduces tension in both the fluid and the technician doing the measuring.

[barefoot]

My understanding is that 2L heads are 60 cc and 1,7/1.8 heads are 48 cc.

[Jack Standz]

I am trying to work out compression ratio of my 2056 build. In calculating head volume my understanding from the forum is that stock 2.0 heads have 57mm and the valve pockets on the pistons I am going to use is 3mm. Do I add these together to use 60mm in my calculations for head volume?

Yes, you add the combustion chamber volume to the volume of the valve pockets on the top of the pistons. You figure out these two volumes by doing what the above posters said. You actually measure the volume.

Suggest you use one of those plastic circles with a hole drilled in it. Along with a burette with rubbing alcohol with a drop of food coloring in it. Best wishes for getting your compression ratio right.

[emerygt350]

I used my kids crayon clay and compared it to oil, came out the same for me but mileage may vary. You just drop the clay in a graduated cylinder with water and watch the displacement. It's clean and easy but I have access to stuff like graduated cylinders.

[930cabman]

I am trying to work out compression ratio of my 2056 build. In calculating head volume my understanding from the forum is that stock 2.0 heads have 57mm and the valve pockets on the pistons I am going to use is 3mm. Do I add these together to use 60mm in my calculations for head volume?

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I built a 2056 a couple years ago, worked out very well. Ended up at 8.8:1 CR Never pings, run on high test and pulls nice

[technicalninja]

I am trying to work out compression ratio of my 2056 build. In calculating head volume my understanding from the forum is that stock 2.0 heads have 57mm and the valve pockets on the pistons I am going to use is 3mm. Do I add these together to use 60mm in my calculations for head volume?

Yes, you add the combustion chamber volume to the volume of the valve pockets on the top of the pistons. You figure out these two volumes by doing what the above posters said. You actually measure the volume.

Suggest you use one of those plastic circles with a hole drilled in it. Along with a burette with rubbing alcohol with a drop of food coloring in it. Best wishes for getting your compression ratio right.

I used my kids crayon clay and compared it to oil, came out the same for me but mileage may vary. You just drop the clay in a graduated cylinder with water and watch the displacement. It's clean and easy but I have access to stuff like graduated cylinders.

The use of clay and a burette is a good idea.
Not sure about the alcohol, might work fine, evaporates so fast that it MIGHT cause inaccuracies. Normally I just use antifreeze.

I use a bunch of alcohol in my Automotive AC business, probably 100 gallons a year.
One thing to ALWAYS be aware of is the fact that alcohol burns with a flame that you CANNOT see unless the room is dark.
You can be ON FIRE and not know it!


The actual clearance volume measurement is a bit more complicated.
+Head CC
+ valve pocket CC
+ deck height CC
+ clearance around top of piston to first ring land (usually around 1cc)

In the case of a stock 2056 flat top at optimal quench (.040") with two 1.5cc valve depressions would go like this.

Head= 60 measured
Valve pockets 3 measured
deck height at .040 7 calculated
upper ring clearance 1 calculated

total "clearance volume" of 71cc

Swept volume of 514 (calculated)

(Swept + clearance) / clearance = compression ratio
or
Swept / clearance +1 = compression ratio

514+71 / 71 = 8.24

No valve reliefs and 55 cc heads
clearance = 63
63+514 / 63= 9.16

One of the reasons I decided to not walk the T4 route is the difficulty in hitting 10/1 ratios without stroker cranks/ pistons larger than 96mm or other "fully bespoke engine" type mods.

That second example, which is just over 9/1 will require verifying valve to piston clearances and it will most likely limit valve travel.

And it gets more critical as valve diameters go up.

And all this measuring and calculation means NOTHING AT ALL if you haven't properly selected the cam you will be using.

The engine actually runs on what is called "dynamic" compression ratio.
You cannot verify this by measuring. It takes a dynamic compression ratio calculator program. Dynamic compression ratio is often 2 full points LOWER that static comp ratio (10/1 engine is really an 8/1 engine!).
Higher static compression ratio DEMANDS larger duration camshafts...

Compression ratio, available fuel octane, intended use, expected RPM range, transmission gearing, induction and exhaust all factor into your camshaft choice.

Raby is RIGHT!

It's the total combination of everything that makes it work!
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[porschetub]

Did all that when I did my last build for a customer,was using NOS raised dome high compression pistons and barrels from a 411 FI ,had some research to do and a respected builder on the Samba helped there and tested for volume over and over and got 8.8 to 1 which was suitable for this motor ,had to play with base shims to achieve this however .
On my engine stand this turned out to be a strong motor and buyer happy,its a lot of time but differance between a strong motor and average one.

[emerygt350]

Well spent time. And on a type 4 it's some pretty easy time compared to water buffaloes or fancier air cooled.

[technicalninja]

@porschetub The .028 on the top of the piston is negative deck height, correct?

Did you use a fire ring?

If so, how thick?

If not, .028 is 4 thousands CLOSER than anything I've ever run across or built.
I have built a tight bore, cast piston water pumper at .033-.034.
It worked fine but I was nervous about lack of clearance.

.028 sets a new "low" for me...

@emerygt350 OMG are you right! You take off too much on a water pumper there are only two ways to save it.
Thicker head gasket (if someone makes it!!!)
Replace block (and do ALL of the block machine work again!!!).

I do my WP builds WITHOUT decking the block.
Get everything perfect before pulling it back down for the decking.

I also let the machine shop know that if they take more than I ask for they will get to purchase and machine another block for me!

I'll also pay DOUBLE for the extra precision!