ESE's works engine tuner

[tjbw]

I had a pleasant exchange of thoughts with CITS-inventor Basil van Rooyen (picture) last year. I think I did comment on the CITS engine before, didn't I?
Attachment 323062

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I just discovered https://www.hondarandd.jp
...

CITS links have been posted here, and on pit lane, quite a few times, without any response. Though I do remember one comment about it infringing some patent.

Thanks Frits for the Honda R & D link

[TZ350]

Page 1550 .......

SP125 has a guide for running the front facing airbox on the RS125. Most of us run them and many of us have seen a noticeable effect on making sure they are properly sealed. I was reading the guide and don't quite understand the full effects of one of the recommendations. Can someone please elaborate on the effects of this slid hole:


4: CARBURETTOR VALVE SLIDE
Drill a small hole (Ø 1.0mm ~ 1.5mm) in the outside face of the carburetor slide, centrally, at distance of 16.5mm from the top of the slide.


http://www.sp125racing.com/rs125-hon...tructions.html

When running a sealed airbox you have residual pressure inside this volume after backing off into a corner. With higher pressure on the intake side of the slide, and virtually no flow into the engine you will get an excess of fuel being picked up by the idle circuit.


And when getting back on the gas the engine is then suddenly partially flooded with overun fuel. The hole in the slide equalizes the pressure on both sides and prevents the airbox pressure from all running under the cutaway and into the idle circuit.


Helps quite a bit in stopping those highsides that hurt like hell.

The stock cage may be fine for flow, depends upon the power.
But in general a VeeForce will make better power simply due to having way less tip lift for an equal curtain area.

I have recently purchased a used HE-JA barrel and head , just searching for info on what piston they used with it . It's a flat top piston with the ring peg in the centre . Cheers

I've tested a flat top/chamfer piston against dome. All else being equal, the flat/chamfer was a full 1hp better mid on up on a 125

Has anyone tested a flat top vs domed?

I know RSA is domed piston, but for the mere mortal engines the hybrid seems best. Primarily because of excellent flow stability at EX opening. What gives the pure flat top an advantage? Is it more even "push" on piston during expansion?

I would not worry at all about the distance between the ground strap and the piston dome.
Ive run it as close as 1.5 mm and seen no issues at all.

The idea with a flat top is to get the spark gap in the middle of the chamber by using a toroid.

With a dome,the best is a flat roof bathtub, so that the highest turbulent zone from the squish action points at the gap.

But I have found that the toroid also works best with a dome, in many situations like aircooled heads or for use with pump gas ie low bmep. It allows alot more advance and a leaner mixture before deto, making the head way less fussy to tune closer to the limit.

In all cases a sharp edge from the squish into the chamber is the go.

Re port chamfers - you must put chamfers on the Ex before plating or you will grind thru to alloy before getting it correct. The transfers dont need any chamfer before or after plating.

All genuine A kits ran flat tops with central peg, the flat tops for customer Honda RS125 had an offset peg as the cylinder had a wide gap on one side of the boost port - dumb.

There are dozens of good 54mm single ring with center pin. Best I have tested would be a Meteor thin ring lightweight for a TM125 - KZ10 ,has a 4* conic dome.

I have tested flat tops Vs domed and the critical element isnt the piston at all, its the chamber shape.

A flat top with a proper toroid will make more power than a dome with a bathtub, and that is way better than a hemi.
Its all to do with spark gap positioning.

Jan tested the difference in the Aprilia but I havnt seen any comment from him anywhere about the chamber configs that were compared, along with the dome shape.

Many people ( including Yamaha ) have found that the flat top with a chamfer ( and VHM with a radius on the timing edge ) is also superior to the dome - but again it comes back to the chamber shape, and Yamaha for sure has a well developed toroid.

I have also done the hard yards and found the " best " combination when working on the BSL500 piston.
This ended up with the piston edge chamfer matching the squish band width ( at 50% area ) then going flat, this gave the best flow regime from the transfers around BDC and had a good chamber shape as well.

If you combine that with ceramic coating on the chamber/piston, but not anywhere in the squish area, then get clever and find a trick way of cooling the squishband you suddenly have the best elements combined in a synergistic fashion.

Mechanically the two shapes have no advantage over each other - apart from the flat top that wont lock the ring in the groove if deto collapses the top face. If you collapse a domed piston , even a little, it automatically crushes the ring groove,leading quickly to a seizure and a DNF.

a few matters regards to Engmod.

1) when reading the mach index traces on the exhaust, I'm a bit confused at what the numbers actually represent? I am no engineer, but if I see a peak value of .8, does that mean that I am seeing 80% of the speed of sound?

2) I've been trying to replicate the leaning out and retarding Ign on over-rev, to get some more usable power past peak, but when I try to simulate it, it doesn't work. If I keep it on the rich side and adv. the timing, I gain more over-rev??? What am I doing wrong? Thanks in advance!

Re the EngMod questions - Mach 0.8 is as you say 0.8 X Sonic.

If you change the A/F ratio from say 12:1 at say 12,000 to 13:1 at 12500 the Ex temp will rise in the pipe, but just as in reality the lower fuel energy available my not in fact be sufficient to make more power. This is way more likely to be affected by the Delivery Ratio dropping greater than the pipes positive effect from temp has on Hp.

Pulling out advance also affects the pipe temp, but again in many cases the engine efficiency drops way more rapidly than the rise in power seen from the pipe effect. Thus if the bmep drops, then cylinder pressure drops, and more advance will often make better power - just as in reality, again.

What average pipe temps are you using, as this input shows a much greater effect on the Hp curve.

Remember that a solenoid powerjet is not " leaning out " the mixture, it is simply opposing the carbs natural tendency to go rich over the top of the powerband . ie the A/F ratio is forced to remain alot closer to a constant number, not rise to make the engine hotter.

Thanks for the response Wobbly.

I am starting the exhaust wall temp at 325* and have peak power at 425*, I got those numbers from earlier in this thread. Are these numbers close to reality in a MX application?

As you stated above ^^^ I am seeing more over-rev with advancing the timing and keeping A/F constant. So this is due to the delivery ratio dropping off? So does that mean that if I increased the time-area of intake and exhaust the delivery ratio shouldn't drop off as much, allowing the heated pipe to suck more?

Was not aware of the powerjets keeping the a/f more constant on over-rev. Makes sense now that I think about it.

Thanks again!

PS. Wobbly, what combustion efficiency number would you use for a MX 250 with a bore of 66.4mm, and stroke of 72mm?

So if you are running a solenoid powerjet you can simulate its action more accurately by setting the pipe temp at 450 at say 500 rpm past peak.

It will take some fiddling to find the element that is affecting the power the most past peak.
I have found time and again that all it needs is to pull down the Ex exit area to 75% and add a tapered nozzle out to the 100% header area.

The increased pipe temp doesn't make it " suck " more it increases the wave speed,that in turn reduces the effective tuned length.

You can try adjusting the intake length to get it into resonance in the overev, depending upon the harmonic being used and the room available.

A 250 well tuned will sim accurately at around 85 to 88% C.E (combustion efficiency)

heres a list of the prox lower rod bearings with part# which are made by ntn and probly a few other manufacturers.

16 x 22 x 13 13 pcs Copper / M-Cage 22.162213
18 x 24 x 14 13 pcs Silver / M-Cage 22.182414
18 x 24 x 15 15 pcs Silver / Flat Cage 22.182415F
20 x 26 x 14 16 pcs Silver / Flat Cage 22.202614F
20 x 26 x 15 14 pcs Silver / M-Cage 22.202615
20 x 26 x 15 16 pcs Silver / Flat Cage 22.202615F
20 x 27 x 14 12 pcs Silver / M-Cage 22.202714
20 x 27 x 14 14 pcs Silver / Flat Cage 22.202714F
22 x 28 x 16 14 pcs Silver / M-Cage 22.222816
22 x 28 x 16 18 pcs Silver / Flat Cage 22.222816F
22 x 29 x 14 16 pcs Silver / Flat Cage 22.222914F
22 x 29 x 16 14 pcs Silver / M-Cage 22.222916
22 x 29 x 16 15 pcs Silver / Flat Cage 22.222916F
22 x 29 x 17 14 pcs Silver / M-Cage 22.222917
22 x 29 x 17 16 pcs Silver / Flat Cage 22.222917F
24 x 30 x 17 17 pcs Silver / M-Cage 22.243017
24 x 30 x 17 19 pcs Silver / Flat Cage 22.243017F
24 x 30 x 20 19 pcs Silver / Flat Cage 22.243020F
24 x 31 x 16 - Silver / Flat Cage 22.243116F
24 x 31 x 17 15 pcs Silver / M-Cage 22.243117
24 x 31 x 17 16 pcs Silver / Flat Cage 22.243117F
24 x 32 x 20 12 pcs Silver / M-Cage 22.243220
24 x 32 x 20 16 pcs Silver / Flat Cage 22.243220F
25 x 31 x 20 15 pcs Silver / M-Cage 22.253120
25 x 32 x 16 17 pcs Silver / M-Cage 22.253216
25 x 32 x 16 17 pcs Silver / Flat Cage 22.253216F
25 x 32 x 16.5 17 pcs Silver / Flat Cage 22.253216.5F
25 x 32 x 20 16 pcs Silver / M-Cage 22.253220
26 x 33 x 18 16 pcs Silver / M-Cage 22.263318
26 x 34 x 20 14 pcs Silver / M-Cage 22.263420
26 x 35 x 20 14 pcs Silver / Flat Cage 22.263520F
27 x 34 x 21 16 pcs Silver / M-Cage 22.273421
28 x 35 x 18 17 pcs Silver / M-Cage 22.283518
28 x 36 x 20 15 pcs Silver / M-Cage 22.283620
30 x 38 x 16 17 pcs Silver / M-Cage 22.303816
30 x 38 x 18 17 pcs Copper / M-Cage 22.303818C
30 x 38 x 18 19 pcs Silver / Flat 22.303818F
30 x 38 x 18 19 pcs Silver / Flat 22.303818F-1
30 x 38 x 18 17 pcs Silver / M-Cage 22.303818S
30 x 38 x 19 20 pcs Silver / Flat 22.303819F
32 x 40 x 18 20 pcs Silver / Flat 22.324018F
32 x 40 x 20 18 pcs Silver / M-Cage 22.324020
32 x 40 x 20 20 pcs Silver / Flat Cage 22.324020F
33 x 41 x 20 20 pcs Silver / Flat Cage 22.334120F
34 x 42 x 20 21 pcs Silver / Flat Cage 22.344220F
34 x 42 x 21 21 pcs Silver / Flat Cage 22.344221F
34 x 43 x 20 16 pcs Silver / M-Cage 22.344320
35 x 42 x 20 21 pcs Silver / Flat Cage 22.354220F
35 x 43 x 22 19 pcs Silver / Flat-Cage 22.354322F
36 x 45 x 23 20 pcs Silver / Flat-Cage 22.364523F
37 x 45 x 22 22 pcs Copper / Flat-Cage 22.374522F
38 x 50 x 23 17 pcs Silver / Flat Cage 22.385023F
40 x 50 x 23 19 pcs Silver / Flat Cage 22.405023F

[breezy]

CITS links have been posted here, and on pit lane, quite a few times, without any response. Though I do remember one comment about it infringing some patent.

Thanks Frits for the Honda R & D link

nautilusengineering.com/ (more hcci)

[Frits Overmars]

THE NAUTILUS CYCLE (HCI/HCCI)
Our unique patent pending design solves the inherent challenges of pre-ignition, poor cold starting, unbalanced combustion, uneven temperatures, limited RPMs...

Limited rpms with HCCI. Now that adds a lot to this site's credibility, doesn't it Flettner?

[Flettner]

Limited rpms with HCCI. Now that adds a lot to this site's credibility, doesn't it Flettner?

They are sooo last month on this Although they probably hold a patent on this system. I'm looking at a better idea (and way simpler) (ish)

[Lightbulb]

With all the people they employ, if only 4 of them had 1/4 of Flettner's ability and enthusiasm, they would have a whole range of working demonstrate-able engines for the world to see.
Sad, all that cad and no real engine to see..
Neil L

[tjbw]

With all the people they employ, if only 4 of them had 1/4 of Flettner's ability and enthusiasm, they would have a whole range of working demonstrate-able engines for the world to see.
Sad, all that cad and no real engine to see..
Neil L

My thoughts too. I was clicking everywhere, hoping to find video of the engine.

[ken seeber]

In some respects, the idea of the Nautilus piston entrant pre-chamber might be good for the HCCI process.
However, I do what wonder what clearance might be necessary between the piston projection and the hole in the head. This is a practical type question as there are so many design factors that would have to be considered in establishing this clearance: piston rocking, the thermal expansion of the projection, the max running temp of the piston projection and possible thermal deformation, the positional tolerance (ie its true concentricity wrt piston skirt) of the projection on the piston and the positional tolerance of the hole in the head (ie its true concentricity to the bore axis).
Frits, you’re good on this sort of stuff, what sort of clearance do you think necessary? Given it must achieve a claimed 2 to 3:1 pressure ratio above the major compression ratio. I know it is an open question as the rpm, engine capacity and probably the major compression ratio should be known.

[sispeed]

Frits have you been on the Luxembourg Race event last weekend?
There was a 50ccm machine racing class.
While I was changing my jets there was a man greeting me, but I was concentrated on my work.
After finishing the Job I thought was it Frits? But could not find the person to clarify.
Regards Siggi

[Tim Ey]

Has anyone experiences overhauling the Aprilia RS250 / Suzuki RGV crank? Mine needs a rebuild because of too much play at the right conrod.
I want to fit 110mm long TZ250 rods instead of the 105mm series.
1. Is it a good idea to convert the Crank to Washers at the low end? Is it even possible without milling of the crank web on the inside?
2. does anyone have a .dxf file of the base gasket?

[Frits Overmars]

Frits have you been on the Luxembourg Race event last weekend? There was a 50ccm machine racing class.
While I was changing my jets there was a man greeting me, but I was concentrated on my work. After finishing the Job I thought was it Frits? But could not find the person to clarify. Regards Siggi

Wasn't me, Siggi.

[Frits Overmars]

In some respects, the idea of the Nautilus piston entrant pre-chamber might be good for the HCCI process.
However, I do what wonder what clearance might be necessary between the piston projection and the hole in the head. This is a practical type question as there are so many design factors that would have to be considered in establishing this clearance: piston rocking, the thermal expansion of the projection, the max running temp of the piston projection and possible thermal deformation, the positional tolerance (ie its true concentricity wrt piston skirt) of the projection on the piston and the positional tolerance of the hole in the head (ie its true concentricity to the bore axis).
Frits, you’re good on this sort of stuff, what sort of clearance do you think necessary? Given it must achieve a claimed 2 to 3:1 pressure ratio above the major compression ratio. I know it is an open question as the rpm, engine capacity and probably the major compression ratio should be known.

Thanks for the flowers Ken, but I'm not that good. My instinctive reaction: the piston rocking won't allow the necessary clearance. Calculating the piston projection dimensions and volumes is easy enough, assuming there is no leakage. But there will be leakage and I haven't got a clue about its magnitude.

[jonny quest]

Anyone have piston dimensions for a nsr250r mc21?

Looking for wrist pin to timing edge of piston crown please. Thanks!

[breezy]

They are sooo last month on this Although they probably hold a patent on this system. I'm looking at a better idea (and way simpler) (ish)

come on then Flettner, lets have it. spill the beans,,,,

[Lightbulb]

In some respects, the idea of the Nautilus piston entrant pre-chamber might be good for the HCCI process.
However, I do what wonder what clearance might be necessary between the piston projection and the hole in the head. This is a practical type question as there are so many design factors that would have to be considered in establishing this clearance: piston rocking, the thermal expansion of the projection, the max running temp of the piston projection and possible thermal deformation, the positional tolerance (ie its true concentricity wrt piston skirt) of the projection on the piston and the positional tolerance of the hole in the head (ie its true concentricity to the bore axis).
Frits, you’re good on this sort of stuff, what sort of clearance do you think necessary? Given it must achieve a claimed 2 to 3:1 pressure ratio above the major compression ratio. I know it is an open question as the rpm, engine capacity and probably the major compression ratio should be known.

From model glow plug engine experience, a clearance of 0.02mm prevents them from running. They will run with 0.01mm clearance but lack any power.This is for ringless engines. Unless they are looking at the leaking gases from the small area getting super heated then starts combustion. But due to not seeing a working engine , after the Ryger affair, I'm now sceptical.
Neil