Depth of dish in NR .21DD piston?????

[eekern]

What is your measurement? Want to cross reference for accurate squish band measurement. Thanks

 

[eekern]

While were at it, anybody measure the volume of the dish yet?

 

[steve wood]

I made a "dummy sleeve" with a shoulder in it, that I put the piston in,then put the head in and held it down against the piston,then filled it with alcohol to the top of the bowl,as close as I could(turbo plug head). I got .18 cc

 

[Marty Davis]

The next thing that is needed from the 21DD is a VERY ACCURATE area of the exhaust ports. I have a pipe design program that will allow me to design a specific pipe for this engine (or any other) and if someone will take on the accurate measurement of the ports, I will be able to design such a pipe.

 

[Marty Davis]

There are 2 thoughts on the area of a port. One is like you say, rolling it out. The other is viewing the port as a window looking straight at it as a flat opening. Talking with Brian Callahan, neither has been accepted at the norm. Personally, judgement makes me think that the port is really just a flat window rather than a curved window.

The best way to measure the port seems to be either the way you are doing it or, putting a piece of paper inside the liner, putting a flat piece of shim stock or something as a backing and then using a sharp pencil to draw the port. Then measure across the port to get the exact measurement to determine the amount the pencil missed by and then draw a line outside the pencil tracing that distance.

Maybe a cross check would be good. The final thing is to draw it in AutoCad and use the Mass Properties to calculate the area of all the ports combined.

Maybe we can get someone to make a mandrel and cast some Carbon pipes from that after the pipe has been designed.

 

[Marty Davis]

I have been Inking my liners and rolling them out on a sheet of paper to measure the exhaust areas

then I draw them in CAD. Is there any better ways to work out your areas ?

If you can get this done and send me a Cad drawing (earlier version .dwg) [email protected] I will see what I can do. I will be gone for a week and will check back here when I get back in a week.

 

[dwilfong]

I have always thought about this. what is port area.

What you are looking at is the window in the sleeve.

But that is not really a good representation of what the PORT is.

the port dose not end at the plane where it intersects the cylinder?

So what is port area and what will you accomplish with this number?

I have had some conversations lately about ports and what thy do in there different configurations in contexts to are boats.

All those little knife ports work good in a car eng as when the revs go way up 400000+ thy actually slow down the flow. making the ports seam smaller.

Good in a rolling chaise with little drag. But in a boat it dose nothing.

Seams that would hurt performance. But as the eng unloads at high RPM. Less flow is needed as the inertia is over and you are just running on the RPM not the toque.

In are boats we never see those RPM because we are loaded all the time.

What I have found in are boats is the pipe will over load the cylinder and the temps will drop stalling the eng.

I am fighting this now with my new pipe design. no program will compensate for this.

The front side of the pipe controls how the cylinder is cleared and the pipe is loaded.

Numbers do not tell the whole story.

 

[eekern]

Seems taking the measurement of port area using both measurement methods. Building a pipe based off each measurement as well as the average of the two might shed some light on the topic......who has a lot of extra time and money?

 

[dwilfong]

Yes that is the problem time and money.

custom pipes just don't pop out of midair to test.