ESE's works engine tuner

[trevor amos]

Nice images Frits, point taken, my education continues.

But the weather here is also windy,cold and wet, but I`ve just gained a little more knowledge so that makes me happy and content, at least until the next irksome question! Thanks.

Trevor

[Grumph]

Thank you Frits - much better angle to see how deep the notches are. I suppose the question is - did they work ? If they weren't used on the later engines, the assumption is, it wasn't worth doing.

Ha, weather...two big race meetings here on successive weekends. One VERY wet, one quite warm. Not our usual early summer at all.
Big job in the workshop today - and i'm going to have to light my fire to get warm enough. Enough to make me a grumpy old man...

[F5 Dave]

Gee Greg I would have never thought of you as grumpy. More jolly. Actually what with that white beard. . . hey wait a minute.

Are there any elves in this workshop of yours?

My son says he`d like some hot wheels cars and my daughter blithered something about a pony, but I`m not sure we could fit one in the oven.

[wobbly]

The fact that a long rod dwells at bdc LESS was the only reason I could think of that Honda persisted with the short rod 105/54 approach for so many years.
Less dwell = less effective transfer STA and maybe they figured this effect overcame any perceived advantage gained from a long rods less angularity thus
bore friction, plus better combustion from dwelling more at TDC.
The other factor to consider with a reed valved engine is that they dont respond favourably to big case volumes like a RV does, with around 1.3 being
the effective bottom limit on case size.
Mentioning the 400 Chev, this had a huge issue with bore friction due to the insanely short rods,but the short rods also give an advantage in
engines that have not very efficient intake ports .
This being due to the faster acceleration away from TDC getting the intake charge moving faster/earlier as the peak piston acceleration is earlier as well..
As usual though in the many tests done by magazines they didnt optimise the cams to take advantage of the differing rods characteristics.
Always more to it than meets the eye.

[Grumph]

Gee Greg I would have never thought of you as grumpy. More jolly. Actually what with that white beard. . . hey wait a minute.

Are there any elves in this workshop of yours?

My son says he`d like some hot wheels cars and my daughter blithered something about a pony, but I`m not sure we could fit one in the oven.

Oh, very good try - but guys who use as much devcon as you, are on the naughty list...
Kev left a pass for me at Levels gate, saying Santa in a silver van would pick it up...One of the girls on the gate squealed and screamed, "it's him !" The other looked closer and asked for ID...Kev has paid for that one.

[Frits Overmars]

Thank you Frits - much better angle to see how deep the notches are. I suppose the question is - did they work ? If they weren't used on the later engines, the assumption is, it wasn't worth doing.

That picture was from a 2013 DEA cylinder because it showed the notches best. But the 2014 cylinder has them too, so they can't be all bad.
Andrea degli Esposti (DEA) is a free thinker who does more than just copy Aprilia stuff. Here he is with his home-built pulsating flow bench.

[F5 Dave]

Anyhoo, back to whether a case reed like mine shrouds the C port entry. . .

[senso]

That an interesting machine, if not asking much, could you(Frits) explain a bit what it does and how it does its work?
There is a stepper attached to the crank probably to rotate the engine, the hose in the intake might be a positive air pressure, and then there is a sort of x-y table on where the head would go, is it used to scan the bore in steps while measuring pressure(like a pitot comb, but instead of a use array of sensors/pitot tubes it scans the entire bore), or I'm totally wrong about my assumptions?

Regarding the con-rod angles, I have a simple excell file to calculate/graph the con-rod angle and the piston position, its very basic, you can only enter the stroke and two con-rod lengths and thats it, its clean of virus and trojans(at least I think my laptop is clean).

[wobbly]

Dont understand the need for the question about the C port duct entry, you can clearly see the reed stops are miles away
and there is nothing impeding the flow into the bottom of the cylinder in that area.
If you wanted you could put a radius on the bottom of the case, below the gasket surface that helps flow turn the corner.

DEAs anemometric flow tester uses a single tube with 10 i think individual pitots inside.
This detects flow vector as well as velocity passing the tubes end.
The pitot is CNC controlled to develop an array of measurements all around the cylinder and this is then displayed on a screen with coloured areas of differing velocity
showing how the scavenging streams interact.

His pulsating bench simply allows controlled " puffs " of flow to be sent thru the transfers/Ex - this was first developed at Queens by Flec etal and much closer simulates
what actually occurs in a running engine - ie its not constant flow like you get from a Superflow etc developed for 4T use.

[peewee]

The piston travels the same distance in any engine with the same stroke, irrespective of the rod length. The amount the piston travels per degree of crankshaft rotation will differ at various crank positions, sometimes more and sometimes less with different length rods. It's all down to geometry.
.

nobody said the total amount of stroke would change with different rod lengths. we all know the full stroke remains the same regarless of 100mm rod or 10000mm rod. i merely said the amount of piston travel per degree of crank revolution will vary with different lod lengths. i 'briefly' looked at a calculator last night, between 0-180* it appeared the piston always traveled a lesser distance per degree with the long rod, except near tdc/bdc where both rods appeared to be the same. maybe i need to look again at the calculator ?

[senso]

The xls that I attached does just that, calculates all the values for a full rotation( 360º), and plots them in two separated graphs, made it just to prove someone that different rod lengths do indeed change the rate that the piston moves with each crank degree.

[peewee]

never mind guys. i think i was misinterpreting the calculator wrong. around 90* is that where the longer rod travels further per degree than a short rod ?

[F5 Dave]

Dont understand the need for the question about the C port duct entry, you can clearly see the reed stops are miles away
and there is nothing impeding the flow into the bottom of the cylinder in that area.
If you wanted you could put a radius on the bottom of the case, below the gasket surface that helps flow turn the corner. . .

.

thanks
it was more if the skirt would shroud any reverse flow back up the C but if reed will feed it fully then I'm ok.

[wobbly]

Peewee, read the bloody posts in here.
A long rod dwells LONGER around TDC and SHORTER around BDC, the opposite for a shorter rod.
That is why I wondered about Honda using short rods - they dwell at BDC longer thus effectively increasing the STA of the transfers.

[peewee]

Peewee, read the bloody posts in here.
A long rod dwells LONGER around TDC and SHORTER around BDC, the opposite for a shorter rod.
That is why I wondered about Honda using short rods - they dwell at BDC longer thus effectively increasing the STA of the transfers.

youll have to forgive me. fixing train railroad tracks is my normal job. working on engines is just a hobby. alot of things ive yet to learn