OzVMX Forum
Clubroom => Tech Talk => Topic started by: pancho on April 14, 2012, 03:52:23 pm
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As I was pre-mixing some fuel for my RT1 this question occured to me--- What effect does adding oil to petrol have on the octane rating?
Maybe the tech. teacher told me 50 plus years ago but I forget!
Another who Knows question--- I know its possible to bronze weld and or braze with lpg But is it feasable to fusion weld, sheet steel for instance?
Cheers pancho.
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Not sure about effect on octane rating but there is some interesting reading in the 1978 Cycle magazine article (link below). Apparently the richer the mix the more HP up to a point.....
http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf
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That is an interesting article, thanks PC
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Would slightly increase octane ............maybe but oil has a higher calorific value than fuel
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you cant fusion weld steel with lpg but good for cutting with the correct tip of course and blazing/silver solder.i remember Lozza saying the more oil the more power but theres a limit on that as well before plugs over oil and foul,rejetting is needed as well.
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pancho you know how to fusion weld already.evertime the RT1 seizes ;)
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No doubt about it micks you're right on the ball!
Where were you anyhow, making another add?
[Hi Barry!]
Don't shave the beard off!
Pancho
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Another who Knows question--- I know its possible to bronze weld and or braze with lpg But is it feasable to fusion weld, sheet steel for instance?
Cheers pancho.
I pissed off the Acetylene bottle with its rent and high cost years ago.
LPG works great for cutting, brazing and heating.
I did hear that it wasn’t much chop for fusion welding but I scoffed at the rumours until I tried to do some fusion welding on a muffler to create those ‘old school’ look welds.
My results looked more like first time at school welds, just couldn’t get the flame right to get a decent ‘puddle’
I eventually gave up and just weaved with the TIG to get the look I wanted.
Setting the flame right with Acetylene is a piece of piece but LPG is a new trick this old dog can’t handle, and can’t be bothered learning for that once in a blue moon job.
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Not sure about effect on octane rating but there is some interesting reading in the 1978 Cycle magazine article (link below). Apparently the richer the mix the more HP up to a point.....
http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf
Interesting article.
Especially the bit about the 30/1 test providing the dirtiest piston then on another page they say that the 30/1 test gave the cleanest spark plug. ???
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15:1 gave the cleanest piston but the dirtiest plug, 15:1 gave the most HP and lower under plug temps 30:1 gave the least HP and the highest under plug temps. Inversely proportional
Interesting article.
Especially the bit about the 30/1 test providing the dirtiest piston then on another page they say that the 30/1 test gave the cleanest spark plug. ???
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Just as logic always insisted: It amazes me that I read from time to time scientific reports that proclaim what to the rest of us ,is just common sence.p
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What would have happened if they hadn't changed the jetting ?
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Would have run too rich or to lean. The fuel flow was calibrated to keep the same vicosity and AFR with the oil ratio changes
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Would have run too rich or to lean. The fuel flow was calibrated to keep the same vicosity and AFR with the oil ratio changes
So if they had NOT changed the jetting and had only changed the fuel oil ratio then they would have got different results ?
Would the 30/1 mix [30 parts fuel to 1 part oil ] have more fuel going through the engine than 25/1 and the 25/1 more than the 15/1 ?
If so wouldn't the 30/1 mix engine [which had come jetted for 25/1] be running cooler because it was running richer and the 15/1 run hotter because it was running leaner ?
The moment you change the parameters [ jetting/tuning ] then aren't the results false because the test bed [engine] is continually changing and you have no fixed reference point ?
They said that the spark plug got hot on the 30/1 test but if they changed the jetting why did they not put in a different heat range plug ???
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No the fuel flow and viscosity were calibrated. So the same amount of fuel flowed out the jet(whatever size it was) with the different oil ratios. If the same amount of fuel flows out the jets then the AFR remains constant. If you did not calibrate fuel flow for the different viscosity of the oil ratios then left the jetting unchanged you would be making the AFR richer and leaner.
. . . after a lot of fiddling with carburetor
jets. When you feed an engine 20:l premix,
only 95 per cent of the fluid passing
through the carburetor is fuel; five per
cent is oil, which does not burn. In switching
to a 30:l premix, we dropped the oil
content to 3.3 per cent and changed the
fluid's viscosity in the bargain, which
meant the engine's air/fuel ratio would be
changed unless corrective measures
were taken. We took those measures,
flowing premix through main-jets into the
dark of one night and almost to the
lunchbreak of the following day, until we
had achieved fuel-flow parity between the
20:l and 30:l gasoline/oil mixtures.
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We appear to be talking about two different ideas here Lozza.
Quote from page 1
"we were interested only in the two-level testing of a
broad concept: would more of a suitable
reference oil cause an engine to produce
more power or less, and would ring sticking
be reduced or made worse?"
I don't see any mention of different jet sizes in the above statement.
My argument is that if you [ I or we ] say to a young rider [ who is keen to learn but has no idea , and don't laugh because we have all been here]
" more oil is better " and forget to mention that you also have to change jet sizes then you [ I or we ] have mislead that young rider by omission and the results that young rider would get may be very different from the expected.
If he/she was for instance to mix up a 10/1 ratio and tip it in his/her tank on standard jetting then I would expect the bike to run hot and seize. [ seen it happen ]
The " more oil is better " statement is bullsh#t without the addition of " but you also have to do this ".
It annoys the sh#t out of me when I hear general statements that are short on facts.
" Seatbelts save lives , in an accident your organs continue to travel forward if you are not wearing a seatbelt , driving through just a couple of cm of water is dangerous , speeding kills , more oil is better ".
Cheers Mike
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The article clearly states "Simply making up sample batches of premix at various fuel/oil ratios and trying them in 5 min dyno runs did not seem to be a procedure to settle anything"
Coaching young blokes on jetting was not the scope of the article it was a scientific test to prove or disprove a theory, nothing more. To that it proved by using a repeatable method as with the SAE test that more oil equals more power.