ESE's works engine tuner

[wobbly]

FRRRIOLI - what pipe wall temps are you using, this will be the issue.

[lodgernz]

I need some advice please.

My normal practice when making a new head insert is to make the squish band straight, i.e. not to match the arc of the piston dome, for the required width based on the usual percentage of squish area to bore area.
I then cut the outer part of the piston dome to match the insert squish angle.
Actually I do it the other way around, but the point is that I cut the squish band on the piston at the chosen angle until the lathe tool hits fresh air.
This leaves some of the original dome in the middle of the piston.
As a result of this method, the straight cut squish band on the piston is wider than the squish band in the head insert.

My question is: Is this bad?

[Flettner]

Oil pump works, gears work, clutch works, throttle opens and more importantly shuts, belt clutch works. But one problem, water goes in, level goes down but no water external. Found it, in the gearbox, bugger it.

[Frits Overmars]

My normal practice when making a new head insert is to make the squish band straight, i.e. not to match the arc of the piston dome, for the required width based on the usual percentage of squish area to bore area. I then cut the outer part of the piston dome to match the insert squish angle.
Actually I do it the other way around, but the point is that I cut the squish band on the piston at the chosen angle until the lathe tool hits fresh air. This leaves some of the original dome in the middle of the piston. As a result of this method, the straight cut squish band on the piston is wider than the squish band in the head insert.
My question is: Is this bad?

No . . . . . .

[WilDun]

It looks that historically, externally (blower) charged engines using this layout did use the crank phasing idea and had it already worked out!
However, what effect does this crank phasing have on events at the other end of the stroke? ...... it seems to me that when the exhaust piston arrives at TDC then it must follow that the transfer piston arriving at TDC sees the exhaust piston already descending - right? - so, would this (in effect) mimic a dwell at TDC ? - Is that a good or bad thing? - ie does it help combustion or hinder it?

[yatasaki]

At some point theoretical TDC is prolonged by transfer piston hunting exhaust piston meaning combustion volume is moving with pistons. It works with diesel spining 2000-2200rews max. but with gasoline and 10-12k rew would say ignition should follow that volume-time.

[folke]

Post no longer wanted

[folke]

Post no longer wanted

[ceci]

Hi Ceci

Photos is from version 1.
On version 2 i have refitted the power valve so i can have a stable and accurate reference between std engine specs and experiments i am doing.I have also reversed the flow through the port to be more efficient and the bounce should be
stronger,in my head it says so! The cam gear have a fine spline so i can experiment with different closing positions of the valve.I could have some more pics soon if of interest.

Hi Folke
I thank you for having my mind active trying to find out how your prototype works and its architecture, because in these bad times it comes in handy.
There are many unknowns that I have as described by you of your prototype, if you were so kind as to publish more photos and thus help me solve them.
Thank you very much

[Frits Overmars]

Come to think of it i might contact Christian VKE.

I am impressed with Christians four-stroke products; it would be nice if you could interest him in two-strokes as well. He might surprise us.
Not everybody here may know Christian VKE, 'the man who never has to shave'. Here's some background info:
https://www.koenigsegg.com/innovations/
https://www.freevalve.com/freevalve-technology/

[ceci]

This begs for some form of supercharging Folke.
Come to think of it: if we use a mechanical compressor instead of a turbo, we no longer need crankcase pumping to start the engine.

Hi Fritz
.Your advice of supercharger might be a bit bald,i was actually thinking of an electric turbo.

Both solutions are typical of 4S, from my modest opinion I do not find them appropriate, 2S requires specific solutions for it, solutions that in 4S are not valid, because they are express for 2S

[wobbly]

Lodger - I tested all manner of combinations of angled piston edge and insert squish ratios fot the TM R1 engine.
Best by some margin was a 50% area,angle on the piston , with the " normal " 35% insert angled width.
The piston then has a flat top.
This result is coloured of course by the narrow insert squish width - mandatory with the idiotic straight line ignition we are forced to use.
But having equal widths on both made less power.

[lodgernz]

Thank you Frits and Wobbly.
I would love to have made the piston flat top with the squish areas equal on both piston and insert, but that would mean a very thin crown, so not an option.
From what you have both said, it seems that the arrangement I have is not going to be too negative, if at all.

[speedpro]

Wobbly said it made more power having it like you suggested, and less having the areas matched

[lodgernz]

Wobbly said it made more power having it like you suggested, and less having the areas matched

Yes, but that was in a kart engine with straight line ignition, so I'm not sure what I can draw from that, given that I have variable ignition.
I have 50% squish area in the insert, but lots more on the piston, whereas Wobbly's insert had only 32% in the head.