Page 3 of 10 FirstFirst 12345678910 LastLast
Results 21 to 30 of 96

Thread: What 2 stroke oil yall runnin?

  1. #21
    Team Member
    Join Date
    Jun 2012
    Posts
    49
    Post Thanks / Like

    Default

    well since yesterday i have changed from amsoil saber out board to now " redline Race synthetic oil "
    looking forward to trying this new oil out sunday!!

  2. #22
    Team Member
    Join Date
    Jul 2009
    Location
    Indianapolis
    Posts
    136
    Post Thanks / Like

    Default

    Quote Originally Posted by Tim Kurcz View Post
    This thread offers great reading, and I'm certrain there are terabytes more data available, but a few tech questions should be addressed to make oil purchase and mix ration decisions:

    1) For all the various oils claimed performance presented; at what mix ratio(s) and operating conditions was the data derived?
    2) What is the relationship between mix ratio and lubricity? With what type of fuel? 100LL Avgas which is loaded with lead, 93 Automotive unleaded? Methanol?
    3) Why do factories test at 16:1 or 18:1 (as reported on BRF elsewhere), when most outboard oils are rated at 50:1?
    4) What effect does higher or lower base oil viscosity have on power output and/or durability?
    5) What affect does mix ratio have on power output? (also reported elsewhere on BRF)

    Now a few functional questions:

    6) How many of you have actually worn out a piston, cylinder wall, or bearing directly attributable to lubrication failure?
    7) How many have actually fouled a spark plug or stuck rings directly attributable to oil selection?
    8) If you're burning 10:1 mix ratio, does the quality of oil really make a difference?
    9) Is it possible to prove the differences in oil performance lakeside?
    10) If you only run your race motor 10 hours/year (generous), how many years racing does it take to stick a ring or clog a port attributable to oil selection?

    For the record, my engines run 10:1 (for racing) or 16:1 (laking) name brand TC-W3 oils in 100LL Avgas at speeds up to 8500 RPM with no apparent problems. How can this be?

    Tim
    I think all of these are great questions and putting data points together is great. As you said, you have to put the ratio together with the oil. Some oils don't provide as much lubricity, but you can increase the mix ratio and make up for it in large part. If you use more oil you are reducing the octane of your fuel and are more susceptible to detonation. If you run higher octane fuel you can get back sufficient octane to prevent detonation. But we also know that running lots of oil can foul plugs, so then do we put in a higher heat range plug, and then are you courting detonation with the hotter plug??? It's a thermodynamic rubix cube, if you twist it one way it can work, or if you twist it another way you can get to the same place. Adding more data is the way to figure out what works or doesn't, and the more data is shared, the more we all learn.

    I didn't know that the factories tested at 16:1 or 18:1. That's news to me, but that tells you a lot about where the engines run best. I'd guess, and it's only a guess, that more oil provides better ring sealing and more power, up to a point, and that may be somewhere in the 16:1 to 18:1 range, but they are also running pump gas, and they don't want to be constantly changing plugs, so there could be some compromise in what they use for testing.

    Base oil viscosity makes a big difference in bearing and ring wear as well as sealing, but can be offset somewhat with higher oil ratios. Since we are diluting the heck out of the oil with fuel the amount of oil can make a big difference if the ratio is drastically increased.

    I think that most racers tend to flood the engine with oil because oil is cheap and parts are expensive, and in this game engine teardowns are frequent, so ratios like 10:1 are common. That doesn't mean that it's the best way to do it, but these engines have been around for a long time and there's a lot of experience that was put into them and folks found out the hard way what works and what didn't.

    Typical racers are doing teardown so frequently that I don't think rings are going to load up with deposits, or ports are going to be clogged like you see in a engine used on a pontoon boat. I just got a Merc 500 powerhead off of a pontoon boat and the exhaust pipe in the the bottom pan was more than half clogged with carbon, and when I take the exhaust cover off I expect it to be full of crap too. The previous owner probably mixed extra oil in the engine "to keep it from wearing out" and I'm guessing that he wasn't doing the engine any good by not running it hard to burn that crap out of the engine.

    I think that running a mix like 10:1 is pretty much flooding the engine with oil, and you can get away with it if you run higher octane fuel, so yes it can easily work for you and the way you run your engines. If you aren't fouling plugs, don't have detonation, and aren't clogging up the engine in the teardown interval you are using, then it can and is working for you. In my airplane I used to have some dental pics that I used to pick the tiny balls of lead out of the spark plugs that formed from 100LL. You need a pretty hot plug to run lots of oil and that also helps keep the plugs from "lead fouling" or shorting out from the lead coating the electrodes, but again that takes you closer to detonation and limits the compression ratio you can run.

    I'm just thinking that oils have changed significantly since there was just "two stroke oil" in the 50's and 60's when these engines were initially developed and the latest oils aren't don't have the lubricity of the old oils that we used to have due to the environmental requirements. That being the case, it makes sense to me to look at what's out there and maybe go beyond the garden variety of outboard oils since there are oils out there that have different and better properties.

  3. #23
    Sam Cullis Mark75H's Avatar
    Join Date
    Nov 2004
    Location
    Annapolis, MD USA
    Posts
    3,975
    Post Thanks / Like

    Question

    I would like to see documented proof that lubricating oil is less than 85 or 90 octane.

    Maybe its not.

    Also, the dilution rate is not significant in most cases to have an observable effect. Do the math and compare.

    I also suspect there are some synthetics with rather high octane ratings.
    Since 1925, about 150 different racing outboards have been made.


  4. #24
    Team Member
    Join Date
    Jul 2009
    Location
    Indianapolis
    Posts
    136
    Post Thanks / Like

    Default

    Rotax says that at 50:1 the oil cuts two points off of the typical octane rating. Do the math, the octane rating of oil alone is pretty low. If you are running 10:1 you have lowered the octane rating more than just a couple of points...Jet fuel has an octane rating of 20, just saying...

  5. #25
    Team Member zul8tr's Avatar
    Join Date
    Oct 2008
    Location
    Orlando, Fla
    Posts
    690
    Post Thanks / Like

    Default

    Found this over at a motorcycle site and interesting read about how the oil in the fuel works for lube and oil ratios.

    ----------------------------------------------------------------------------------------------------------------------------------
    05-24-2006 03:34 PM #1 Yamaha Tri-Moto
    Location:Canada

    All About 2 stroke Oil Ratios. Interesting find
    I was Browsing the net and came across this, figured ive seen so much talk about oil ratios this may help some people out. I sure found it interesting.

    *I did not write this, Spanky over at mx.com did*

    Pre-mix 101

    OK, looks like it's time for a little pre-mix 101. I don't usually get into ratio discussions, because mix ratios are like religions to most people, and they tend to be closed-minded on the subject, but I'll put in my $.02 here anyway.

    There is a prevailing myth that less oil is better, and that the oil in the fuel is what lubricates the engine. Both are wrong.

    *less oil is better* People think that if they have a plug fouling problem or a lot of spooge, they need to run less oil. Wrong! Both problems are caused by rich jetting, and have nothing to do with the mix ratio.

    *the oil in the fuel is what lubricates the engine* The engine is lubricated by the residual oil that builds up in the crankcase. All the oil in the fuel does is replenish this oil.

    The best way to determine if you are running enough oil is to check the level of the residual oil in the crankcase. If the ratio you run leaves enough residual oil in the crankcase to cover about 1/8" of the bottom of the crank wheels, then you are fine. If you don't have that much residual oil in your crankcase when you pull the top-end off, you aren't running enough oil for your riding style and conditions.

    With that said, to have that amount of residual oil in the crankcase at 50:1 (a ratio made popular by magazines and oil bottles), you can't be riding very hard, or your bike is jetted richer than necessary simply to deliver enough oil. I arrived at 26:1 for my bike with my riding style because that is the amount that gives me the proper amount of residual build-up. Small-bore engines require greater oil concentrations than larger engines to achieve the proper amount of residual build-up, because they rev higher and have higher intake velocities. Along the same lines, someone that pushes the engine harder, and keeps the revs higher, also needs to use higher oil concentrations to achieve the proper residual build-up.

    To understand why the residual oil is so important, you have to understand what happens to the oil in your fuel when it goes into the engine. While the oil is still suspended in the liquid gasoline, it can not lubricate anything. It has about as much lubricity at that point as straight gasoline. When the gasoline enters the engine, it evaporates, dropping the oil out of suspension. Now that the oil is free, it can lubricate the engine, but it must get to the parts to lubricate them. The way it gets to the bearings and onto the cylinder is by being thrown around as a mist by the spinning crankshaft, and the droplets are distributed by the air currents moving through the engine. Ever wonder why there are two small holes in the transfer port area of the crankcase, right over the main bearings? These are to allow some of the oil droplets being flung around inside the engine to drip down into the main bearing area.

    Some of the oil eventually makes it into the combustion chamber, where it is either burned, or passes out the exhaust. If the combustion chamber temps are too low, such as in an engine that is jetted too rich, the oil doesn't burn completely. Instead, some of it hardens into deposits in the combustion chamber, on the piston, and on the power valve assembly. The rest becomes the dreaded "spooge". The key to all of this working in harmony is to jet the bike lean enough to achieve a high enough combustion chamber temperature to burn the oil, but also still be able to supply enough oil to protect the engine. If you use enough oil, you can jet the bike at it's optimum without starving the engine of oil, and have excellent power, with minimal deposits and spooge. At 50:1, you simply can't jet very lean without risking a seized engine due to oil starvation, unless you're just putt-putting around on trails without putting the engine under much load.

    With the high oil concentrations that I use, I tend to get far more life from my cranks and rings than most of my friends that run leaner oil ratios. The high oil content also produces better ring sealing, so more of the combustion pressure is retained.

    One small point. No one ever broke an engine by using too much oil.


    __________________________________________________ _______________________________________________

    Pre-mix ratios and power production

    I have run Dyno tests on this subject. We used a Dynojet dynamometer, and used a fresh, broken in top-end for each test. We used specially calibrated jets to ensure the fuel flow was identical with each different ratio, and warmed the engine at 3000 rpm for 3 minutes before each run. Our tests were performed in the rpm range of 2500 to 9000 rpm, with the power peak of our test bike (a modifed '86 YZ 250, mine) occuring at 8750 rpm. We tested at 76 degrees F, at 65% relative humidity. We started at 10:1, and went to 100:1. Our results showed that a two-stroke engine makes its best power at 18:1. Any more oil than that, and the engine ran poorly, because we didn't have any jets rich enough to compensate for that much oil in the fuel, and the burn-characteristics of the fuel with that much oil tended to be poor. The power loss from 18:1 to 32:1 was approximately 2 percent. The loss from 18:1 to 50:1 was nearly 9 percent. On a modern 250, that can be as much as 4 horsepower. The loss from 18:1 to 100:1 was nearly 18 percent. The reason for the difference in output is simple. More oil provides a better seal between the ring and the cylinder wall.

    Now, I realize that 18:1 is impractical unless you ride your engine all-out, keeping it pinned at all times. But running reasonable ratios no less than 32:1 will produce more power, and give your engine better protection, thus making it perform better for longer.


    As a side note, I no longer run 26:1, I now run 32:1. I'm not a young man any more, and I just can't push as hard as I used to, so I don't need as much oil now. 32:1 is enough oil to do what is needed for me now, since I'm getting slow...

  6. #26
    Team Member
    Join Date
    Nov 2008
    Location
    Horseshoe Bend, ID
    Posts
    749
    Post Thanks / Like

    Default Now we're cooking with (Av)gas!

    Thank you for the data! The motorcycle article speaks volumes: 2-stroke mechanics routinely see evidence of the "river" oil that flows through an engine. Though crank wheel references don't apply to vertical crank engines, the concept is the same. It's interesting that 18:1 appears to be a magic number (relative to power output). Perhaps the factories knew something about the subject after all.

    It should be noted that duty cycle has a lot to do with ratio requirements. This is why my race motors run absolutely clean compared to the Merc 500 pontoon boat example. They are always hot, running high RPM, which doesn't allow carbon or lead buidup to form. BTW: Higher oil concentrations seal rings, labyrinth seals, and reeds better than lower concentrations. These are reasons for more delivered power.

    Tim

  7. #27
    Team Member
    Join Date
    Jul 2009
    Location
    Indianapolis
    Posts
    136
    Post Thanks / Like

    Default

    Great stuff Z, nothing like real data to put things into perspective, and no question Tim you need enough oil to help seal the rings, but too much oil is likely to cause power reduction too, so you want the right amount, not too much or too little.

    Also remember that every engine is different. An engine with better inherent ring sealing might be able to run on less oil than one with a piston with fewer rings, so while this is great stuff it may not be perfect for our engines. Question now is, if you run a Merc 44 at 16:1 will you have any issues with ring scuffing, bore sticking or big end bearings??? And how fast can you run it that way for how long??

  8. #28
    Team Member
    Join Date
    Nov 2008
    Location
    Horseshoe Bend, ID
    Posts
    749
    Post Thanks / Like

    Default 16:1 forever

    Quote Originally Posted by Yellowjacket View Post
    Great stuff Z, nothing like real data to put things into perspective, and no question Tim you need enough oil to help seal the rings, but too much oil is likely to cause power reduction too, so you want the right amount, not too much or too little.

    Also remember that every engine is different. An engine with better inherent ring sealing might be able to run on less oil than one with a piston with fewer rings, so while this is great stuff it may not be perfect for our engines. Question now is, if you run a Merc 44 at 16:1 will you have any issues with ring scuffing, bore sticking or big end bearings??? And how fast can you run it that way for how long??


    Hey Yellowjacket: The test Z refers to indicates power begins to suffer under 18:1 to a limited degree, but without fear of bearing, ring, and cylinder damage. Most of us would rather suffer 1-2% power reduction than a set of blued bearings, crank, or scored pistons/bores.

    Many years ago a well known factory engineer confided in me the fact that max power/durability testing was conducted at 16:1. Since that day dozens of my engines have run 16:1 or heavier oil. These engines have won numreous local, regional, divisional, national events. BTW: My world record setting OMC triple uses one ring pistons. Yet none have ever failed a bearing, ring, or piston due to lubrication failure.

    Even engines with burnt pistons (due to bad fuel, too much spark, or too lean mixture) never exibited a bearing problem. And the only time bore sticks occurred was due to inadequate cooling (cooling system starvation, etc) or low/zero oil. Poor cooling only leads to a hurt piston and bore. A low/zero oil destroys pistons, bore, rods, and crank.

    Oil quality not withstanding, duty cycle should dictate oil ratio. The only reasons to use less oil is for extended low speed operation, less smoke, or if you're trying to economize. It's well known that the 50:1 (and taller) ratios have been pushed by marketing types to reduce cost of operation, smoke, etc, but at what cost? It all sounds good until you remember that oil is cheaper than parts!

    Tim

    BTW: I too, love the smell of Klotz, Blendzall, and castor in Methanol.......

  9. #29
    Team Member
    Join Date
    Jun 2005
    Location
    Eastern PA
    Posts
    753
    Post Thanks / Like

    Default

    Am I wrong (hah!) but isn't that YZ-250 air cooled? If so, his results are out the window when discussing water-cooled outboard engines.

    Jeff

  10. #30
    Team Member
    Join Date
    Nov 2008
    Location
    Horseshoe Bend, ID
    Posts
    749
    Post Thanks / Like

    Default

    Quote Originally Posted by Fastjeff57 View Post
    Am I wrong (hah!) but isn't that YZ-250 air cooled? If so, his results are out the window when discussing water-cooled outboard engines.

    Jeff
    Why would air vs water cooling make a difference?

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. 2 Stroke Wizard Expansion Chamber Program
    By John (Taylor) Gabrowski in forum Technical Discussion
    Replies: 13
    Last Post: 12-24-2017, 12:25 PM
  2. FS: 2003 Mercury 40hp 3 cyl 2 stroke
    By biggdave92 in forum Motors and Powerheads
    Replies: 3
    Last Post: 09-07-2014, 12:30 AM
  3. 25hp 2 stroke 3 cylinder Johnson
    By speedfreak in forum Technical Discussion
    Replies: 27
    Last Post: 12-17-2013, 08:31 AM
  4. 8hp 2 cylinder 2 stroke MODS FOR POWER
    By microbream in forum Technical Discussion
    Replies: 1
    Last Post: 07-19-2011, 03:03 PM
  5. Max timing advance
    By Boatnut in forum Technical Discussion
    Replies: 31
    Last Post: 04-03-2009, 08:15 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •