ESE's works engine tuner

[Pursang]

If we are talking OP uniflow, there are many possibilitys, including differential piston sizes / strokes and certainly piston phasing offsets.
Three main issues though
Exhaust piston thermal control
Combustion chamber shape
Transfer flow....

Exhaust piston is a challenge but Im hanging my hat on a steel aluminium composite. To do this I need make an electrode for spark eroding the piston crown underside .... but my CNC is out of action, for some time, so thats put a stop to that, for now.

Combustion chamber shape for spark ignition does hold both advantages and disadvantages, plenty to sort through to get an acceptable outcome.

Transfer, an issue because all the charge wants to do is rush straight for the exhaust. Swirl will slow this but leaves an unscavenged plume in the middle. So far with my OP engines Ive used a combination of some ports swirl and some aiming at the centre of the piston directly opposite each other to help clear the central plume. Now I have a completely different system .... involving transfer 'tumble'. Best idea Ive come up with so far to solve OP uniflow charge transfer issues.

But this will all have to wait ..... CNC electronics are expensive to fix, unfortunately.

In my OP 'vision' the exhaust porting is almost circumferential. Plenty of STA to allow for secondary transfers behind/below the exhaust ports.
This provides some cooling. Additional piston cooling could be achieved by feeding these transfers like old style boost ports, through the piston skirt.
In order to keep these transfers passages away from the exhaust heat their angle of entry is likely to be directed up the the cylinder axis toward the transfer piston crown.This could displace the stubborn centre plume.
My comment about blocking the main fresh charge from over scavenging was based on the idea of curtains of colder charge passing almost perpendicular to the exhaust ports, timing them late enough that the primary scavenging had been achieved. Pressure and volume of the secondary transfer might be controlled by finding the correct combination of piston diam, stepped piston and/or exhaust crankcase volume.

As far as a name goes...Opposed Piston Multi Flow works for me!

[Flettner]

In my OP 'vision' the exhaust porting is almost circumferential. Plenty of STA to allow for secondary transfers behind/below the exhaust ports.
This provides some cooling. Additional piston cooling could be achieved by feeding these transfers like old style boost ports, through the piston skirt.
In order to keep these transfers passages away from the exhaust heat their angle of entry is likely to be directed up the the cylinder axis toward the transfer piston crown.This could displace the stubborn centre plume.
My comment about blocking the main fresh charge from over scavenging was based on the idea of curtains of colder charge passing almost perpendicular to the exhaust ports, timing them late enough that the primary scavenging had been achieved. Pressure and volume of the secondary transfer might be controlled by finding the correct combination of piston diam, stepped piston and/or exhaust crankcase volume.

As far as a name goes...Opposed Piston Multi Flow works for me!

Lets get building then👍

[wobbly]

I always had to run 11 plugs in the Aircooleds on Meth , or got deto/ preignition burning up the middle of the piston or overheating the plug body.
10.5 in Watercooled running 18:1 , same issue.

[Pursang]

Lets get building then👍

Based on your previous work it shouldn't be too difficult to do some 'proof of concept' testing.
Should we take OP discussion to the 'Clean' thread?

[TZ350]

Ran 12's in air/oil cooled GSXR's on Meth/Toluene

I always had to run 11 plugs in the Aircooleds on Meth , or got deto/ preignition burning up the middle of the piston or overheating the plug body.
10.5 in Watercooled running 18:1 , same issue.

Interesting that the "C" port side of the piston and head is getting the hottest.

Methanol/Petrol. NGK B10EG plug. Plug certainly getting hot. Petrol pilot jet is responsible for the colour I guess.

Will have to see if I can source some NGK B12's or equivalents.

[TZ350]

.
Ok, NGK B12's, couldn't find anything affordable and/or without Iridium (Platinum) electrodes. "Fire and Flame" with Platinum and Methanol https://youtu.be/A2VpA_301rg?si=4JvV0KvNTtNQ8OMD

So purchased some equivalent heat range old school Champion N52R's and C53VC's. They will take two or three weeks to get here.

[Grumph]

I've got D12's left but no B's. Asked around down here but no-one's got any tucked away sorry.

The Champions are really doing it old style.

[TZ350]

I've got D12's left but no B's. Asked around down here but no-one's got any tucked away sorry. The Champions are really doing it old style.

Thanks for asking around for me. Yes, the Champion plugs are old style but they wont have any Platinum in their electrodes. As best as I can make out, Iridium plugs have Platinum/Iridium alloy electrode's or a Platinum earth electrode button. I already have the special tools for adjusting the N-52R retracted gap plugs (NGK 11's). The others are cold surface gap's (NGK 10.5's). So these Champions are still not as cold as NGK 12's. I will keep looking.

[wobbly]

Gota be R plugs for Ignitech remember.
Back in the middle of last century R didnt mean Resistor.
And a Big Block McLaren didnt need an ECU.

[TZ350]

Back in the middle of last century R didnt mean Resistor.

Champion N52R Yes, the "R" did not mean resistor or even racing. It meant retracted gap. the earth strap is retracted back inside the plug body. Extra clearance for high dome pistons I guess.

Gota be R plugs for Ignitech remember.

I am hoping to get away with a higher resistance plug cap. Something like 25k. Currently it is 10k Ohm's. Any suggestions here would be helpful.

[wobbly]

A " normal " setup would be 5K in the plug and 5K in the cap , having extra secondary series resistance probably has more down side effect on turning ignition energy into heat , than it does
forming a more effective RC filter for EMI suppression.
I have used high quality spiral wound ( read expensive ) suppressor wire in one project using the twin fire CDI setup , as the expensive resistor caps for the also expensive shorty plugs were unreliable as they kept going
open circuit .
This seemed to be just as good at noise suppression , as the Ignitech gave no problems.

[TZ350]

.
Have had another thought on this running on problem. Maybe the Blow Down Time Area is insufficient at 10k RPM, leaving a lot of hot nasty stuff in the cylinder. The factory ran these engines to 8,500, with a similar size exhaust port (72%) and blow down I guess. I will have another look at this with EngMod2T.

[husaberg]

I've got D12's left but no B's. Asked around down here but no-one's got any tucked away sorry.

The Champions are really doing it old style.

I will see if i can dig up a few Lodges or a KLG
11.5 but 70$ nz
https://www.nzperformance.co.nz/ngk-...g-spark-plug-2

if you feeling rich you could pay over 2x the rate at Repco $157Nz
https://www.repco.co.nz/parts-servic...115/p/A1054497

[Grumph]

In the late 80's running the GSXR mentioned before, we were offered by the then NGK agent a set of the plugs made for use in the IOM.
No idea of the heat range - but they were made for use from sea level to quite high altitude and widely varying temperatures.

$NZ65.00 each in the late 80's. Relatively speaking the rare competition plugs haven't gone up much at all.

No, we didn't buy them.

[TZ350]

.Have had another thought on this running on problem. Maybe the Blow Down Time Area is insufficient at 10k RPM, leaving a lot of hot nasty stuff in the cylinder. The factory ran these engines to 8,500, with a similar size exhaust port (80atdc & 72%) and blow down I guess. I will have another look at this with EngMod2T.

Ok. EngineMod has the inlet, transfers and blow down peaking about 8,500 rpm and the exhaust port at 7,800 rpm. I had asked EngMod to design a pipe for peak HP at 9,500 rpm. Indeed the engine makes peak power at 9,500 rpm and will touch 10,000 but runs on. I wonder if the rpm mismatch with the exhaust is my problem? Residual hot exhaust gases making it run on. It may be I have to reconsider the expansion chamber and more closely match it's design to the ports potential.

Any thoughts on interpreting RPM figures in the right hand column of the EngMod screen shot would be greatly appreciated.