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Author Topic: Watchout using VP 110 with 927  (Read 361 times)

Offline RUn2it

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Watchout using VP 110 with 927
« on: March 20, 2019, 10:14:48 pm »
It was cold at Glamis and went through 25 gal of Sunoco Standard (110 using R+M/2) in the LT500, so a buggy trip to across the highway from the Glamis store and bought a 5 gal can of VP 110 (using R+M/2) and happy as VPs M (Motor octane) is 109 and Sunoco M is 106, for those that are not familiar with fuel chemistry M is what makes power, the R component is tested with a small 1 cylinder 4 stroke at idle for a period of time then checked for carbon buildup etc So mix 927 with the VP (no pump gas) and as I finish dumping mix in tank a little stringy dribble drops on the plastic, it looked thick for pre-mix so touched it and it appeared to be straight 927, drained the residual from the can and it was oil. Got the glass olive jar and put some VP and roughly equivalent of 32:1 927, shook it and watched the oil go to the bottom. Instant replay with some Sunoco scavenged from 5 Sunoco containers and no separation. I've heard for years that 927 could separate but it didn't get much thought since I was using a lower motor octane with no problem then looked closer at the 927 label and it says separation at 35 deg but was around 45, then I see specific gravity of the fuel, if lower than .735 separation can occur. Sunoco lower M octane is .729 (.006 low) and VP higher M octane is .705 (.030 low). In my case if I had not seen the oil dribble I might have not have ruined the engine since the oil goes to the bottom and possibly filled the carb bowl with oil and likely would not have started but I had the fuel shut off and I didn't want to experiment with what would happen. Sorry for the term paper but this way you can see and be reasonably certain that this isn't BS or assumption. Oh yeah, the Maxima 927 says you can "lower the temp at which separation occurs by adding 4oz per gal of Maxima Hi-Test", doesn't say how low of a temp so test to be sure. I added a gal of Chevron premium to the VP mix and it stays suspended. Lee

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Offline Q2W

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Re: Watchout using VP 110 with 927
« Reply #1 on: March 21, 2019, 08:56:37 am »
Nice catch!

If i remember right, there was some old forum chatter about 927 separating at lower temps back in the day.  Nice to see the numbers now.
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Offline MotorGeek - Jerry Hall

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Re: Watchout using VP 110 with 927
« Reply #2 on: March 21, 2019, 12:49:14 pm »
I look at specific gravity to get a general idea if the castor oil will separate from the gasoline and or at what fuel temperature separation may occur.  Some of the fuels like 100LL av-gas may separate at 80 F unless some type of blending agent is added to the base fuel.

The "jar" test is the best way to test the fuel for separation.

I think 100LL has a specific gravity of around .68 to .70.  Fuel with low aromatic content typically has more problems mixing with castor oil.  Fuels with a specific gravity around .74 or higher, most often have higher aromatic content and castor oil will usually stay mixed in the fuel to around 50 F.

Unleaded pump gas has a high aromatic content and can be used as a blending agent in leaded race fuel or 100LL av-gas with out appreciably affecting the octane rating. For most of my customers, I advise them to mix  one gallon of pump premium to 4 gallons of race or av-gas.
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Offline RUn2it

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Re: Watchout using VP 110 with 927
« Reply #3 on: March 21, 2019, 09:38:09 pm »
Harry Klemm use to recommend avgas for 2 strokes, then backed off as he discovered the avgas has no heavy end/ long chain/high aromatics and has a high paraffin content. I tried avgas/premium pump 50/50 in the XP Seadoo mod as I couldn't find race fuel, no matter how rich or lean I set it the plugs were always gray. I didn't have heat or deto problems but it was slow accelerating, didn't launch hard as it would with race fuel. It felt like it had pump gas with octane boost, all octane boost does is slow the burn, retard the flame front so it doesn't deto. Sure, it doesn't deto but you don't get your $ worth of all the high $ parts and work you put into the engine, and once you ride something really quick anything less is ... boring x boring. Oh yeah, the R+M/2 is actually the AKI of pump gas, the anti-knock index. If you get gas at AMPM I'll tell you how to spend more for gas per gal and save you $ at the same time, Check your mileage with a tank of whatever "octane" you use from AMPM then go to Chevron and get the same 87 or 89 as AMPM. I've been told by people that I said this to that they got between 30 and over 100 miles more per tank. And 1 of the persons I told this to was 1 of the fastest Trophy truck drivers and had the most wins and championships in the Mickey Thompson stadium series back when. He says when he goes by an AMPM now he want's to yell at the customers "YOU MORONS" LMAO!

PS AVGAS 100LL and non aviation 100LL don't use the same method for calculating the "octane" rating

 

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