How To Calculate Engine Compression Part 1

Рет қаралды 4,061

Күн бұрын

How to Measure Engine Compression Part 1 of 2
Any time that you make a change to an engine by machining the crankcase or machining the cylinder heads, you change the compression relationships. Today with the limited availability of original pistons and cylinders it means aftermarket pistons are becoming more normal. Combine machine work and the use of aftermarket pistons and it cements the need for accurate compression measurements.
In this video lesson, we show you how to gather the needed measurements from the engine. After showing you how to get the measurements we start an Excel program to work with the numbers.
I would highly recommend working through this lesson so that you are ready for lesson two, where we bring all the numbers into play and you end up with an adaptable engine compression program.
Visit our site for the full write up on this video with the formulas written out.
While you are there check out lots more air-cooled engine goodness.
www.klassikats.com
Tools you will need
Barrette tube and holder amzn.to/3jms5hx
1.25 Piston Deck Height
15.37 Piston Dome Volume
26.36 Chamber Volume
If you would like to support us on Patreon that would be great
/ klassikats

Пікірлер: 14

@tycotoys Жыл бұрын

This is the guy I want to rebuild my 2.7, he knows his stuff.

@klassikats Жыл бұрын

Thanks, Kurt

@no-speedlimit 2 жыл бұрын

Hi, very interesting ... I have a couple of clarifications to ask: 1. Min 19:22: why did you chose 20 mm as down fill distance, is it empirical value based on experience? 2. Min 28:35: the plastic cover is also placed into the head recess? Thank you a lot.

@klassikats 2 жыл бұрын

I use 20 mm to be sure that the compression lump on the piston will be well below the top of the barrel. You can use any down fill dimension that you want. Yes on the 2.0L heads the barrel is recessed into the cylinder head. So when you take a chamber reading you need to have your cover at the same height that the barrel top will sit to get an accurate number. On the 2.2L and up engines the barrel and head design changed. The barrel on those heads sits flush against the sealing surface. Thanks for watching Kurt

@no-speedlimit 2 жыл бұрын

@@klassikats thanks a lot for your answer and for posting your video, we are rebuilding the 2.7 911/83 of our 1974 Euro Carrera, we would like to do things right :) ...

@robhurley5258 2 жыл бұрын

Wow! I’ve read about this but never seen it done before. I’m rebuilding a 911 2-liter racing engine (with a 1-mm overbore) and would like to try this. I think I need to invest in a height gauge, I’m not sure the measurements can be done accurately with hand tools. Also, the plastic disc with the recess, I’m not sure how to make that. Will need to think about that. Very cool video!

@klassikats 2 жыл бұрын

Rob, yes you do need good quality tools to take accurate measurements. When it comes to the plastic discs we use, we make those in house. let us know if you cannot find someone to make one for you and we could cut one for you. Thanks For watching Kurt

@robhurley5258 2 жыл бұрын

@@klassikats thanks Kurt. What model height gauge are you using?

@klassikats 2 жыл бұрын

@@robhurley5258 I had trouble finding a 300mm scale I liked too. This one on amazon looks ok too. amzn.to/3dUcQfx What you are looking for is one that is big enough, not 6" 150mm, and the digital helps. A heavy base is good too. I also got a flat stone to help with accuracy. amzn.to/3oYCh6c

@robhurley5258 2 жыл бұрын

@@klassikats thanks Kurt

@user-yo1wo6yg2r Ай бұрын

Now calculate dynamic compression😅

@klassikats Ай бұрын

Sure we can do that in another video Kurt

@sdrtech 11 ай бұрын

Deck height .99mm? Ive always measured from center crank to the top of block

@klassikats 11 ай бұрын

Deck height is the relationship between the piston top and the cylinder head sealing surface of the barrel. This can be either a positive or negative number. Kurt