ESE's works engine tuner

[teriks]

run more oil = more power, every time.

My stuff must make ridiculous amounts of power then, running on 20% castor, remainder methanol :-P

Joking aside, really interesting to hear of your experiences confirming theory Wob!

I can confirm Berts statement about getting away with murder in the methanol fueled, castor lubricated model engines.
I have on too many occasions molten the Platinum/Rhodium glow plug wire, holed a few pistons and even had the edge of the squish band rounded by melting on one occasion. I never had the piston seize though.

[Ocean1]

Now about the fuel

90% nitromethane / 10% methanol works quite well at about 65psi...

[cookie1965]

I was there as well till they banned me for exposing him lol Iluvtwostroke was my name
He doesnt do them anymore anyway he found it to hard and decided that it as no good. after telling every one how good it was and if you disagreed you were just misinformed. He mainly sticks to the aprillia forum now where is a moderator and he simply bans you if you disagree
I am banned

Oh yeah I remember you from over there LOL. So he's quit altogether trying to sell his PFI set up? For everything? I looked at his site just now and don't see any reference to it.

[wobbly]

This is only conjecture on my part as I have never done a back to back with two optimised setups.
But,I fail to see how lowering the octane rating of AvGas by diluting it with pump gas, would somehow be offset by a figment of manys imagination that flame speed has suddenly increased.
Yes I know, AvGas has a pile of shit added to prevent icing at altitude, but it jets, and reacts to detonation exactly the same as 105 octane VP leaded race gas as used by SKUSA.
I tested a 1US Gallon tin of it that cost over 200nzd to fly here on a special dangerous goods flight.
When the squish is optimised, as is the com, and the ignition,Avgas makes a heap more power than unleaded.
Flame speed doesnt appear to be an issue - it works.
Unleaded hates compression, needs alot more advance ( why would it if the flame speed was faster? ) and has to be run rich to make best power.
The two fuels need wildly different conditions to work best - a nightmare to try and sort out - not worth the brain damage in my opinion.

Re the oils - in the KT100 air cooled the best power on bean oil is had at 16:1.
Running 909 as most Yamaha karters do now, going below 20:1 gave a minimal advantage - on the dyno at least.
Some say that 16 "works better" but thats, again, probably a figment.
Bottom line is that if you are tuned hard out in your air cooled bucket, then 20:1 will be about as good as it gets.
As always though there is a down side - 909 wont stay mixed with AvGas for long.
You have to add a small amount of Acetone to ensure mixing, its fine in pump gas to leave for weeks, but you wouldnt do that would you.

[wax]

Oh yeah I remember you from over there LOL. So he's quit altogether trying to sell his PFI set up? For everything? I looked at his site just now and don't see any reference to it.

If you go the aprillia forum he says he can get just as much power out of a ditech engine as he can a pfi and in the end it was not worth it. the ditech is one of the slowest things around. If you see him smartmouthing again just ask him how much power his turbo scooter made I think it was 8hp.

[F5 Dave]

As the big shpeal about castor was basically saying - pure synthetic "oils " are shit at lubricating anything when the combustion temps are thru the roof ie 650*C in the header.
This is the perfectly normal situation on pump gas with the air cooled KT100, and perfectly normal when running AvGas in a properly tuned race engine of any sort.
. . ..

Thanks ok that is interesting to say the least.

When we are talking Bean oil are you only saying castor like R30? or using A747?

I had intended to use R30 for a couple of meets & swap back to 800, but its sounding like I should wait until I watercool the barrel/head, but I was waiting till I got the sealing problem sorted before progressing. &or swap to Elf.

But to use Av & R30 I'd have to use Acetone & the rules don't seem to mention it anymore.

[wobbly]

Today I would include all the semi synthetic and castor based oils in the term - bean oil.
Now we have these trick mixes available, running straight R30 is no advantage in power and for sure film strength, havnt seen it for ages, is it cheap??
The good new ones like 909,Kart, Maxima etc sure arent.

[F5 Dave]

yeah I found it in super cheap for $29.95 a l.

Wiped over my pipe nice.

So if I mix it with Av I'm asking for trouble? I have some 95 pump gas I was going to use.

[Yow Ling]

So if I mix it with Av I'm asking for trouble? .

You that good?

[breezy]

this may still be relevent and worth a lookat http://www.klemmvintage.com/oils.htm

[TZ350]

this may still be relevent and worth a lookat http://www.klemmvintage.com/oils.htm

Thanks Breezy, that is a very good read.

[RMS eng]

yeah I found it in super cheap for $29.95 a l.

Wiped over my pipe nice.

So if I mix it with Av I'm asking for trouble? I have some 95 pump gas I was going to use.

this topic has been on here before,but just to put my 2 cents in i run R30 in my air cooled vintage MX 125 bikes on Av and pump with 5% acetone,and it is fine,AV gas is the safe way to go.Dave i can sell you R30 for $66.00 for 3 bottles 1LT or $122.00 for a box of 6.

chris RMS engineering 09 817 9500

[rgvbaz]

Click image for larger version. Name: BigCrankBluevisSmallCrankRed.jpg Views: 25 Size: 207.2 KB ID: 277890

"The Red line is the smaller crank with 2mm clearance. I am not sure why the improvement is all at the bottom end and drops of earlier at the top.
Helmholtz frequency, my dear Watson. The smaller crank will give the pipe more crankcase volume to breathe from. This larger volume will also lower the resonance frequency of the inlet system, hence the drop at high rpm. It can be compensated with a shorter inlet tract, a bigger carb diameter and a later inlet closure. To put it real simple: if you have more volume, you need more time to fill it. But more time, i.e. later closure, has adverse effects at low revs. So my preference is a shorter tract (unless you go the 24/7-way and employ a reed for the low revs, and swing it out of the way at high revs)."

This is a Quote from Frits on page 710

I was playing with a reed spacer on an AM6 engine. In the graph below run 44 and 45 are with just the reed. Runs 48 and 49 are with a 46*40*8mm spacer between the crankcase and the reed which changes the crank case volume by about 15cc. But the peak rpm goes the other way? Am I missing something obvious?



Dave

[husaberg]

mr overmars Here's some more Helmholtz-encouragement:

Regarding induction systems: build a short induction tract and visit a test bench.
You can forget about calculations. The formulas you find in various books are all based on the Helmholtz resonator. It made me write a simple story, called:

Helmholtz blues
"A Helmholtz resonator consists of a volume connected to a duct". That is what Wikipedia tries to tell you.
But that is a Helmholtz resonator in its simplest form; one that you won't find anywhere in an engine.
What you do find in an engine is an intake tract with a variable cross-sectional area. This tract is from time to time connected to a variable volume (the crankcase) through a very variable window (the intake port / reed valve / rotary inlet).
The crankcase is connected to a number of transfer ducts with variable cross-sectional areas, which are from time to time connected to a very variable volume (the cylinder) through a number of very variable windows (the transfer ports).
The cylinder is from time to time, through a very variable window (the exhaust port), connected to an exhaust pipe with a very variable cross-sectional area who at the same time doubles as a volume. This pipe volume is constantly connected to a big volume (the outside world) through a tailpipe with a constant cross-sectional area and constant entry and exit windows (thank God, finally someting that's not variable).
We call this a compound Helmholtz resonator .
The various papers also tell us how to calculate the resonator's frequency:
" frequency = speed of sound / (2*pi)* Sqr ( cross-sectional area of the neck / ( volume of the resonator * effective neck length ) ) ".
O yes, the speed of sound... It is dependent on temperature, which is not really constant in the intake tract and the crankcase, rather variable in the transfer ducts and very variable in the cylinder and the exhaust pipe.
Now the above frequency formula is not exact; it is an approximation that is usable as long as the volume of 'the' tract is very small compared to the resonator's volume.
So when engines are concerned, that formula goes very far out the window.
Who said gas dynamics is simple dull?
PS:
It's a similar story with acoustics. That is a sub-branch of gas dynamics, simplified with a lot of assumptions that are acceptable as long as the sound pressure does not exceed a certain limit. The wave pressures in a two-stoke exhaust exceed that limit by a factor of thousand. Bye bye, acoustics...

Wouldn't also your spacer also as well as increasing the volume make the track longer also......................
In fact it throws up a huge amount of variables shape of tract shrouding of reeds etc. Aren't two strokes a cruel mistress

[Frits Overmars]

I was playing with a reed spacer on an AM6 engine. In the graph below run 44 and 45 are with just the reed. Runs 48 and 49 are with a 46*40*8mm spacer between the crankcase and the reed which changes the crank case volume by about 15cc. But the peak rpm goes the other way? Am I missing something obvious?

Increasing the crankcase volume has several consequences. One of those is that the flow through the carb will be more even, less violent, which usually results in a leaner mixture. Looking at your curves that would seem to be the most probable explanation. Did you fiddle with the jetting as well as with the spacer?