ESE's works engine tuner

[oxracer]

Some pictures from seel cylinder.

Any idea why studs place is so high? Does it not look to have high porosity?
Attachment 337350Attachment 337351Attachment 337352Attachment 337353Attachment 337354Attachment 337355

Hi Romeu, that cylinder has been re-plated by Racing Cylinder Services in the UK, as denoted by the RCS serial number. The other serial number starting with A denotes APTEC who are also in the UK. I've been told by my local kart tuner that RCS use a very aggressive solution for stripping the old plating off that eats certain elements out of the aluminium which leaves those tiny holes everywhere. He won't use them for that reason though I don't know if it's such a bad thing!?
Mark

[RomeuPT]

Hi Romeu, that cylinder has been re-plated by Racing Cylinder Services in the UK, as denoted by the RCS serial number. The other serial number starting with A denotes APTEC who are also in the UK. I've been told by my local kart tuner that RCS use a very aggressive solution for stripping the old plating off that eats certain elements out of the aluminium which leaves those tiny holes everywhere. He won't use them for that reason though I don't know if it's such a bad thing!?
Mark

On the transfer passages etc might be :/

This is not Langcourt you are mentioning!?

[Frits Overmars]

Some pictures from seel cylinder. Any idea why studs place is so high?

That's an oldie. Later Seel cylinders had slightly lower ears with some ribbing, a power valve and auxiliary exhaust ports instead of the central bridge.
The ears on your picture were so high to prevent them from bending or breaking off, like used to happen on various Kawasaki, KTM and Honda cylinders when fitted onto too may paper gaskets by ham-fisted mechanics.

I didn't realize how bad those kart motors are down low, 7ish hp at 8k? They must really hit hard coming on the pipe

Any 125 cc engine making 50ish hp without the benefit of a power valve, power jet and variable ignition, is just waking up at 8 o'clock. It's the nature of the beast.
Sure, it will hit hard coming onto the pipe, but this will only be a bother if you'll allow it to drop out of the power band. That's about the first lesson you learn when operating one of those power houses: staying in the power band is safer than dropping below it and opening the throttle.

Recently we made new version of 2-cylinder boxer using Yamaha RD-350 reed valves. Using carburetor without filter we saw fuel spraying out in atmosphere...
Then we make simplest experiment: install inside short tube, see red colored and problem completely disappear.
Anyone had similar experience? If no could be useful for community. In any case we are publishing articles in academic press and applied for invention.

With that short red tube you effectively created a Tesla diode.
The fuel spray you were seeing, may have been bounce-back rather than blow-back. Here is a text I wrote some time ago about the subject.
=================================================
In all inlet systems the inlet flow accelerates as long as the pressure upstream of the inlet tract is higher than the downstream pressure.
When both pressures are equal the flow has reached its maximum velocity and because mixture keeps entering the crankcase, the case pressure rises above the upstream pressure and this rising pressure gently slows the flow down to a standstill (or suddenly instead of gently if the inlet port closes too soon, which can happen in both piston port and rotary induction systems).
In any case, the pressure at the crankcase side of the inlet tract will then be higher than the pressure at the bellmouth, and mixture will start flowing back towards the free world. The extend of this backflow may be so small that it is not noticeable at the bellmouth, but it is happening nevertheless. Reed valves do it just as much as other inlet control systems.

I call this phenomenon bounce-back and it should not be confused with the blow-back that occurs when an inlet port closes too late.
Bounce-back mixture never really made it into the crankcase; it returned at the closed door.
Blown-back mixture initially entered the crankcase but then reversed its flow direction because of the rising case pressure before the case was closed.
This rising case pressure resulting in flow reversal has rather little to do with the piston moving down after TDC. It can even happen before TDC if the Helmholtz frequency of the inlet system is too high for the engine revs (low revs, big carb diameter, short inlet tract, small case volume).

By the way, bounce-back may be hardly noticeable, but on the other hand it can be even more vicious than blow-back.
As an experiment I once put a 200 mm elongation tube between the carb and the rotary inlet cover of a 125 cc Rotax.
It lowered the Helmholtz frequency of the inlet system so much that inlet flow velocity was still near its maximum when the inlet disc closed. Bounce-back was so severe that within seconds the dyno room was completely fogged up with mixture. It frightened me to death; a spark would have been enough to blow the roof off.
=================================================

[jbiplane]

Maybe similar.....
And another successful experiment was putting a divider in the inlet so one half could be closed off effectively changing the inertia and resonance to get rid of a pesky resonance hole.

Thanks, interesting input

[jbiplane]

With that short red tube you effectively created a Tesla diode.
The fuel spray you were seeing, may have been bounce-back rather than blow-back. Here is a text I wrote some time ago about the subject.

Hi Frits thanks fo so detailed description !!! Agreed. Will play out with intake geometry.

[peewee]

hey guys i was wondering if someone knows the reason nitro engines explode ? i figured the ign system fails to fire and a buildup of raw fuel hydraulically explodes

anyways i found a good way to richen lectron needles. just determine what spot you need more fuel . measure current thickness with calipers. mark it with red or some colored pen. grind with small diamond bit. remeasure thickness . mark with color pen again and grind as needed. works a treat. i did that procedure and now have the needle working well for 20% nitro mix with plenty of adjustment remaining so i think it can take the mix up near 40%. tomorow im testing it to see

[husaberg]

hey guys i was wondering if someone knows the reason nitro engines explode ? i figured the ign system fails to fire and a buildup of raw fuel hydraulically explodes

anyways i found a good way to richen lectron needles. just determine what spot you need more fuel . measure current thickness with calipers. mark it with red or some colored pen. grind with small diamond bit. remeasure thickness . mark with color pen again and grind as needed. works a treat. i did that procedure and now have the needle working well for 20% nitro mix with plenty of adjustment remaining so i think it can take the mix up near 40%. tomorow im testing it to see

AFAIK A lot of nitro 4t explode as the nitro contaminates the oiling system, I understand that's why a lot of drag racers run total loss oiling.

[wobbly]

Ha Ha Dave, you want to vomit - well join the club.
After the euphoria of the new cylinder duct geometry, today had to be a fail day.
The factory have made special manifolds in the past where the bottom matches the oval floor, but the roof has a big 1/2 moon step.
I took the CNC part I made that matched the entire cylinder exit face and ground out the top , into a step.FAIL
This gained a little mid, but killed the overev.

Then I put in the IAME piston with the radius recut to 1.5mm - FAIL.
Lost all the mid power and equaled the original top end.

All perfectly normal way to waste a day on the dyno , and have no idea what the hell is going on - yet.

[SwePatrick]

I think I'm going to vomit. The amount of dyno runs I've done trying shit that didn't work and was supposed to.

And most funny is, things that don´t work with 'this' setup might work if altering setup with a second mod or third mod........ and so on.

[JanBros]

Is there any correlation between effective transfer area and effective blowdown area ?
(effective as is flow area)

And when you do know the blowdown area, it is better to have the blowdown area at 1.5*bore distance in the exhaust duct instead of 75/90% of total exh area ?

[katinas]

Then I put in the IAME piston with the radius recut to 1.5mm - FAIL.
Lost all the mid power and equaled the original top end.

Similar results was on KTM sx 85, with bigger radius ( from 0.8mm to around 1.3mm). Remember, we decide not overcome 1mm. rad, but very likely, that with sharp edge on piston at C, all changes.

But really, yesterday was strange day. On NS tested piston with sharp edge at C and first time with matched head. I think it was bests results from my 3 months intensive tests. Engine pulls very hard from 10000 to 12000rpm, top left the same to 13000. But then suddenly engine lost power in third gear and stop.
First time in six years I lost one of Denso IA01 spark plug. Half of ceramic falls in to engine, but I cant say why - piston touch the head or deto or spark plug tired.

[oldjohnno]

hey guys i was wondering if someone knows the reason nitro engines explode ? i figured the ign system fails to fire and a buildup of raw fuel hydraulically explodes

The most common failure mode seems to be burnt pistons. If you watch top fuel cars go down the strip you'll notice they sometimes blow greyish smoke over the last 50m or so before they cross the line. This is vapourised aluminium from the pistons. If the piston burns right through and they're lucky they might just lose a cylinder or two but often the blower pressurises the entire crankcase with fuel/air and this ignites, possibly also igniting the fuel diluted oil in the sump. This all results in a spectacular unintended disassembly and fire.

Another common failure results from ignition of the pressurised mixture in the manifold and blower, because of a backfire or stuck or damaged intake valve or spring. When this happens the blower is usually popped right off in a brief fireball but thankfully blower restraining straps are mandatory. In the early days there were spectator deaths as a result of blowers etc. being launched into orbit and coming down in the crowd.

Hydraulic damage can occur but the big fuelers run two plugs per cylinder and two magnetos rated at 44amps each, so they can damn near light tap water.

[F5 Dave]

Ha Ha Dave, you want to vomit - well join the club.
After the euphoria of the new cylinder duct geometry, today had to be a fail day.
The factory have made special manifolds in the past where the bottom matches the oval floor, but the roof has a big 1/2 moon step.
I took the CNC part I made that matched the entire cylinder exit face and ground out the top , into a step.FAIL
This gained a little mid, but killed the overev.

Then I put in the IAME piston with the radius recut to 1.5mm - FAIL.
Lost all the mid power and equaled the original top end.

All perfectly normal way to waste a day on the dyno , and have no idea what the hell is going on - yet.

Ok I feel a bit better.
My most notable fail was going from a bent inlet to a straight with a lot of dicking around to get the throttle to work past obstacles. It had to be better! But. .
Maybe I needed more time to try other stuff in conjunction.

[RomeuPT]

Ha Ha Dave, you want to vomit - well join the club.
After the euphoria of the new cylinder duct geometry, today had to be a fail day.
The factory have made special manifolds in the past where the bottom matches the oval floor, but the roof has a big 1/2 moon step.
I took the CNC part I made that matched the entire cylinder exit face and ground out the top , into a step.FAIL
This gained a little mid, but killed the overev.

Then I put in the IAME piston with the radius recut to 1.5mm - FAIL.
Lost all the mid power and equaled the original top end.

All perfectly normal way to waste a day on the dyno , and have no idea what the hell is going on - yet.

I am not sure yet what you mean or did on the piston, radius recut, is just putting a small radius on the edge and push the cylinder down to keep port timings!?

[nine-thirtysix]

Hi there.

I'm thinking right now about to change my power valve control from a mechanical govenor system to a direkt servo.
There it would be better for me out of package reasons and weight to fit a servo motor directly to the engine. May be with rubber bushing or something like that and also not with gears but with a pushrod system like RC-cars have for servos.

I haven't read or seen about anyone using anything else than a cable driven system.
Is it because these cable servos are really cheap or because a servo boltet to the engine gets ratteld apart?

And a question I came over with Ignitech is what happens with a engine without battery? Does the servo pulls out the power from the system while kicking or is the start up check time delayed?

Thanks for your answers!