ESE's works engine tuner

[F5 Dave]

I bought a small electric weed eater for the wife. Only works on small stuff.

The Grass cutterer guy has progressed to doing our lawn with a weed eater as he's transferring from heavy lawn mowers as he's well past 80. He'll probably stop all together soon. Can't rely on the in-laws forever.

So where can I get a tuned weed eater? Sounds like it could make the mundane fun.
As long as it siezes occasionally and throws me to the turf. Roughly.

[Jan Van Hamme]

Also, if you are absolutely insistent on accelerated engine wear, and loosing Hp, carry on using Motul 800 @ 30:1, I wouldn't use that cats pee if it was free even @ 20:1 where you should be.

Yes, damn it, I've made the “right” choice again.
A few years ago, I bought a pack of 12 x 1 litre cans of Motul 800 road race oil because I thought it was very good oil.
It is unopened and waiting to be used when my motorbike is assembled.
Now, after reading that message, I won't be able to get rid of that “cat's piss” anymore. Does it really cause so much wear and tear that I'd better not use it?


Translated with DeepL.com (free version)

[F5 Dave]

Works great in my trials bike.

[Jan Van Hamme]

In case you wish to compare it to the original text and at the same time brush up your German a bit:

Hi Frits,
I had already saved and printed your text on ignition curves for later use.
Now, in order to find and compile an optimal ignition curve, with your text in mind, I ran a simulation (in turbulent mode) in Engmod2T for every half degree of advanced ignition across the entire rev range.
So 8° fully from 3000 rpm to 9700 rpm.
8.5° fully from 3000 rpm to 9700 rpm....
up to and including 28° fully from 3000 rpm to 9700 rpm.

When I combine all the highest horsepower values per half degree in a curve, I get a strange ignition curve.
Namely, a flat curve of 15.5° over a large part of the rev range.
Could that be useful in practice?

Regards,
Jan

[Wos]

LODGER - I see a few things that have set you off on a dead end tangent.
You say you used an EGT of 470* - this is completely erroneous.
Any engine with that number in the header is about as well tuned as a weed eater.

All of the pipe compute programs are using the BULK AVERAGE PIPE TEMP, including the cooler duct, and this is in the range of 550* to around 625* dependent upon the fuel quality.
This gives an average speed of sound of 560 to 610m/s, thus a pipe average wall temp of around 425*C to 450*C at peak, and the EGT as measured in the header well into the 600*'s.
Quit working in the dark, even after a ton of carrots, IMHO it is absolutely impossible to do any meaningful engine design work, let alone accurate track/dyno tuning without using a data logged or at the very least a max recall EGT gauge.

Also, if you are absolutely insistent on accelerated engine wear, and loosing Hp, carry on using Motul 800 @ 30:1, I wouldn't use that cats pee if it was free even @ 20:1 where you should be.

The Wobbly Duct info sheet also states a recommended cooled duct length @ 1.5 bore for a square engine, with the header entry @ 2X bore - you stated a cooled duct out to 2X bore, this is NFG
as the A/F out at 2X bore is never going to make it back into the cylinder due to the return wave, as the port is closing.

EDIT - again, taking a suggestion the 192* " is a bit conservative ". What the hell does that mean, what is the actual Blowdown STA, and what are the transfers doing. JanBros has a free , really good port calculator.
Quit working in the dark - free technology is at your fingertips.

Dear Wobb,

For sure i am not experienced in diffrent 2 T Oils like you.
We run motul 800 in 8 h race liedolsheim where the best 50cc bikes have about 20 hp13000 and reving over 15000. Mix is 1:25

Which negative experience do you have with the french cats pee

Which oil would you adive for pump gas 98 mixture ?


Thanks a lot

every little step forward is a part of the puzzle ��

Grüße! Wolfgang

[Frits Overmars]

I ran a simulation (in turbulent mode) in Engmod2T for every half degree of advanced ignition across the entire rev range. So 8° fully from 3000 rpm to 9700 rpm. 8.5° fully from 3000 rpm to 9700 rpm.... up to and including 28° fully from 3000 rpm to 9700 rpm.
When I combine all the highest horsepower values per half degree in a curve, I get a strange ignition curve. Namely, a flat curve of 15.5° over a large part of the rev range.
Could that be useful in practice?

Jan, I dropped my crystal ball, so I don't know anything about your engine. I assume it's a two-stroke, but I'm not even sure about that. That's not much to base an opinion on...

[Jan Van Hamme]

Jan, I dropped my crystal ball, so I don't know anything about your engine. I assume it's a two-stroke, but I'm not even sure about that. That's not much to base an opinion on...

Sorry Frits,
I didn't phrase my question clearly enough.
The ignition curves for 2-stroke engines that I see here and there always start low in degrees, then rise steeply to +/-30 degrees and then drop back down at the start of the power band. Around max hp and rpm to 15° and from there further down.

What I mean is, an almost flat curve of 15.5° is very different from the usual curve shape I describe above. Would that still be useful in practice?
My engine... See attached screenshots.

[wobbly]

Wos, I made a post a few pages back about oils and the results I got in a quite extensive dyno test session.
The customer wanted to choose a replacement for R30, they had been running for years at 16:1.

The short story was that at high EGT numbers ( 650*C+) the oils I tested at 30:1, 25:1, 20:1 and 16:1 all made more power going down to 20:1 but no more at 16:1
Two oils made more power than the R30, these were HTX 909 and Maxima 927.
I tested several fully synthetic oils and none got close to the two oils above, and Motul 800 was the worst.
During the testing I decided to check what was occurring with the Motul and did some extended running - and discovered that the piston skirt wear was dramatically worse than the semi synthetic castor mix oils.
It was easy to measure as the wear was double, the clearance as new was exactly 0.002" ( the customer wanted Imperial numbers, as that is what he was honing to ) after1 Hr of hard running the Motul was 0.003"
where as the Maxima was 0.0025".

This result confirmed what I had read in the well known DynoTech publication ( Snowmobile guys with a real good Superflow dyno setup ).
They did alot of oil tests as well, and the technical issue is that when run at very high temps the Synthetic breaks down into its component chemicals, none of which are actual lubricants.
The Castor based oils when overheated, they break down at a lower oil film strength, but the component parts still lubricate very well.
Many 4T experts rubbish the Timken/Falex oil test rig, saying its not realistically representing what happens in a running engine.
But the rig results mirror exactly what happens in a 2T - Synthetics can have 10X the film strength of a Castor based oil, but the instant the film is broken the surfaces get physically torn up badly.
The Castor film fails much earlyer, but the wear pattern on the test drum is dead smooth.

Thus since that result I have been using Vrooam on track, and Maxima 927 on the dyno in the KZ engines , both semi synthetics, where we see 685*C EGT when running 110 octane.
The Vrooam is very clean, and hardly gives piston maps at all, but that is irrelevant when using EGT to get within one jet size of deto every run session.


HTX 909 will separate out of AvGas in about 1/2 Hr, but it and the others have no issues in 98 pump gas.

F5 - of course Motul 800 is just fine in a trials bike, not much more high temp loading then a weed eater.

EDIT, the other pointer I have is that I rebuild many KZ cranks, all after the same logged run time. The cranks run on full synthetic oils, have much of the silver coating worn off the cage and washer wear surfaces.
The Vrooam cranks still look like brand new.

[lodgernz]

LODGER - I see a few things that have set you off on a dead end tangent.
You say you used an EGT of 470* - this is completely erroneous.
Any engine with that number in the header is about as well tuned as a weed eater.

All of the pipe compute programs are using the BULK AVERAGE PIPE TEMP, including the cooler duct, and this is in the range of 550* to around 625* dependent upon the fuel quality.
This gives an average speed of sound of 560 to 610m/s, thus a pipe average wall temp of around 425*C to 450*C at peak, and the EGT as measured in the header well into the 600*'s.
Quit working in the dark, even after a ton of carrots, IMHO it is absolutely impossible to do any meaningful engine design work, let alone accurate track/dyno tuning without using a data logged or at the very least a max recall EGT gauge.

Also, if you are absolutely insistent on accelerated engine wear, and loosing Hp, carry on using Motul 800 @ 30:1, I wouldn't use that cats pee if it was free even @ 20:1 where you should be.

The Wobbly Duct info sheet also states a recommended cooled duct length @ 1.5 bore for a square engine, with the header entry @ 2X bore - you stated a cooled duct out to 2X bore, this is NFG
as the A/F out at 2X bore is never going to make it back into the cylinder due to the return wave, as the port is closing.

EDIT - again, taking a suggestion the 192* " is a bit conservative ". What the hell does that mean, what is the actual Blowdown STA, and what are the transfers doing. JanBros has a free , really good port calculator.
Quit working in the dark - free technology is at your fingertips.

Thank you again Wobbly. Let me address your points please:

1. I used the term EGT erroneously, I really meant the bulk average pipe temp

2. I take your point re the Motul 800. I used to run 25:1 but changed to 30:1 recently. I'll go to 20:1, or change to a better oil. I remember you said the Motul Kart oil is better?

3. I missed the advice to cool the port only to 1.5 x bore, so will fix that. The engine is close to square at 39.5 x 41.4

4. EO is 192°, blowdown angle-area is 2932⁰-mm2. This is 45% of the optimal angle-area recommended by Frits for 50cc and 13500RPM, based on the Aprilia RS125.

5. Transfers are as close as I can get to all of yours and Frits's axial and radial specifications, with angle-area of 28241⁰-mm2. A transfers duration 126°

6. I'll think about getting an EGT probe from Exhaust Gas Technologies. Which of their probes is best for bikes?

[wobbly]

Lodger - glad you get the point about the pipe temps.
The Motul Kart GP is a full synthetic, and suffers the same big end cage/washers wear as the others.
Depending upon who will give you a good price , any of the castor based oils I mentioned work just fine.
HTX 909 was used by Aprilia, we use Vrooam in KZ as its CIK approved and is very clean as I said.
But I use Maxima 927 on the dyno as it is one of the few oils that does not suffer from chrome bore streaking when running in.

I would still get JanBros port calculator as it works really well if you dont want the expense and drama of learning EngMod 2T.

The Stinger exposed tip probes are the best, and have a 2 year guarantee - I've sold and used literally a hundred of the things, never had a failure.

Gauge wise the best bet is to talk to the Kart shop guys, there are plenty of Mychron 4 - 2T( two temp inputs ) around as everyone has gone for the 5 version, that does the same logging but uses GPS
and Bluetooth, not " better " just easier.

[diesel pig]

Very interesting about the 2T oil's.
So just to make sure I understood what you are saying.
Use either
Maxima 927
HTX 909
Vrooam Caster based
Use whichever one is easier for one to get a hold of?

I would just like to back what was said about Exhaust Gas Technologies exposed tip probes. My one has ever given no problems since I have had it.

[lodgernz]

Lodger - glad you get the point about the pipe temps.
The Motul Kart GP is a full synthetic, and suffers the same big end cage/washers wear as the others.
Depending upon who will give you a good price , any of the castor based oils I mentioned work just fine.
HTX 909 was used by Aprilia, we use Vrooam in KZ as its CIK approved and is very clean as I said.
But I use Maxima 927 on the dyno as it is one of the few oils that does not suffer from chrome bore streaking when running in.

Thanks again Wobbly. I seem to be saying that a lot lately.

From your oil related post above, I gather that Vrooam Factory Racing 2T Kart oil is fine with 98, with no separation or carb deposits.
Would you still recommend 20:1 for this oil in a Bucket??

[reefmuncher]

Not sure if my comment was missed, was wondering if anyone had experience with the effect of axial and radial of the additional "boost" ports have around the C port on many smaller capacity Spanish and Italian race cylinders? The axial angles can be quite different between brands as seen in the image with DEA, Bidalot and Voca.

Appreciate any thoughts on the subject.

[diesel pig]

That picture of the water cooled DEA cylinder fed reed. Got me all excited hoping it might be for a bored and stroked 50cc that would perfect to revitalize the Honda H100 engines I have in the rafters of my shed. But no they are for a 150cc vespa.

[wobbly]

So just to reiterate, yea all of the castor based oils work fine in pump gas, and yea they all make more power at 20:1.
Buckets , whatever, are no different.