Oddball engines and prototypes

[lohring]

Good luck with sealing. There's a reason round pistons in round bores are used in all successful steam and IC engines. It's easy to get a good seal even when the parts are made by early, low precision machines. Fancy engines, even with modern machines and materials, have always stumbled on the sealing issue.

Lohring Miller

[ken seeber]

Good luck with sealing. There's a reason round pistons in round bores are used in all successful steam and IC engines. It's easy to get a good seal even when the parts are made by early, low precision machines. Fancy engines, even with modern machines and materials, have always stumbled on the sealing issue.

Lohring Miller

Have to agree with Lohring. I worked on the Sarich Orbital engine in the mid 70s. It became clear after some time that there were fundamental issues with this engine, ultimately leading to the two fluid (air and fuel) fuel injector and its application to various engine applications. The 4 main key faults of the engine, which can be seen on the many new IC engine concepts are:

1. The total seal grid length of anything other than a round piston can me many times longer friction
2. Any square corners are very, very difficult to seal = leakage
3. Any combustion shape that has large squish areas will suffer from "quenching" of the combustion flame = inefficiency & unburnt HCs.
4. Any combustion shape that departs from being spherical means a high surface area to volume ratio = heat loss = inefficiency.

For me, it is 2 strokes and after that it is electricity. Interesting that many companies are now dropping the "green hydrogen" concepts, particularly combustion, and going electric & batteries. Here's my perspective as to why:



Sorry, bit of a rave...

[lohring]

We're getting way off topic. It's very hard to beat the modern two stroke for compact IC engine power. Two strokes dominate the small and large engine areas. They suffer from breathing issues so more complex four strokes have taken over in the middle sizes. Honda especially has perfected the small four stroke and gas turbines have taken over all but the very largest IC engine sizes.

However, even gas turbine mechanical simplicity can't beat an electric power plant. Mobile electric power has been limited by battery technology from the beginning. Stationary electric motors dominate everywhere there is an easy electricity connection. Electric motors have very long lives, even in inexpensive versions. We are in an era of exploding (not literally with proper design and care) battery technology. This is starting to make electric power popular in the small to medium size mobile power areas.

In my sphere of radio control racing, 26 to 36 cc two strokes still dominate, but electric power has replaced IC in many non racing model airplanes and boats. It's slowly expanding into race boats. I have loved small two strokes since before I built one in high school shop. I still love them as high power racing engines. We'll see how long they last.

Lohring Miller

[Pursang]

...
We don't need no 'Stinking Chambers'......the Bloohie pipe lives

https://www.youtube.com/shorts/fIGne6fW8mE

[katinas]

Not sure, but try to list in short way, just the main changes through the years, without obscured test models.

1981 - 1983 NS 500 V3 112 deg. symetrical 1-3-2 firing every 120 deg. - with long jackshaft, crank turning backward.

1984 NSR 500 V4 90 deg. symetrical 1-4-3-2 firing every 90 deg. - with long jackshaft, crank turning backward.

1985 - 1986 V 90 deg. symetrical 1-2-3-4 firing every 90 deg. - without jackshaft, crank turning forward.

1987-1989 V 112 deg. symetrical 1-4-3-2 firing every 90 deg. - with long jackshaft, crank turning backward.

1989/1990-1991 V 112 deg. symetrical paired 1.2-3.4 firing every 180 deg. - with long jackshaft, crank turning backward.

1992-1995 V 112 deg. big bang paired 1.3-2.4 firing 68 deg. one piece crankshaft connected to short jackshaft from center, crank turning backward.

1996 V 112 deg. big bang paired 1.3-2.4 firing 68 deg. two cranks connected to short jackshaft from center, crank turning backward.

1997-2002 V 112 deg symetrical paired 1.3-2.4 firing every 180 deg two cranks connected to short jackshaft from center, crank turning backward.

The last two "Racers" issues are dedicated to GP two-strokes, YZR 250 vol.74 and NSR 500 vol.75.
I must correct my previous post about the NSR 500 crankshaft from 1992 to 1995. It was a one-piece crankshaft, with a central gear and a short jackshaft. Two pieces crank was used from 1996. Looks like central gears made like one piece with center pin.
In general, a lot of interesting material. The NSR 500 crankshaft absolutely piece of art.

Third picture, reed valves from early versions of 112 deg. NSR 500

[husaberg]

This does raise and interesting (well to me anyway) question For Mr Thiel if he's about. Plus Mr Overmars
Given the rules of he period for the GP500 class hat layout and engine configuration would he have chosen
l always admired focused output ideal with the single crank and liked the room for intakes and transfers with the single crank and balance shaft set up.
Especially;;y Compared to the Twin crank set ups.
But would they have gone twin crank and Disc valve "V four" twin, 3 ? stepped Square?

[katinas]

The balancer weights are very interestingly arranged on the intermediate shaft. I marked them with three arrows.
Looks like this is 1993 model with additional fuel pump for the EFI system.

Some Interesting disclosure from Honda engineers.
From 1994 to 1999 there were 5 different crankshaft pins phase tested. In addition to the two main ones ( 68 degree and 180 degree), three more were tested
A. 90-degree equal interval explosion (like 88 89)each crank pins phased 0-22-180-202 deg. tested in 1998.
B. 90-degree Big Bang crank pins pairs set at 22 deg.
C. 112-degree explosion, all crank pins set in line

[F5 Dave]

This does raise and interesting (well to me anyway) question For Mr Thiel if he's about. Plus Mr Overmars
Given the rules of he period for the GP500 class hat layout and engine configuration would he have chosen
l always admired focused output ideal with the single crank and liked the room for intakes and transfers with the single crank and balance shaft set up.
Especially;;y Compared to the Twin crank set ups.
But would they have gone twin crank and Disc valve "V four" twin, 3 ? stepped Square?

My gues is; only if the tracks were longer with less of those pesky corners. Maybe 2025 tyres could have altered the formula. . .