PART 2: AV gas in a turbo 2 stroke:

[Scott]

Holy crap, Bill. Lol. That's a long winded post.

Btw, there is a thread about a yami mtn max and his homemade turbo with a straight header pipe, no chamber. You might like to poke your head into that one.

 

[d1100t]

Update please

Is there any update on the av gas/race gas/mixed gas debate?
How are you guys making out with av gas on your turbo 2 strokes?
Who or how many has switched to av gas?
What elevation and how much boost?

Any experience and more info here woud be greatly appreciated.

 

[Sparx]

I hate to say it but in the end the only answer that will be the best answer is to say try it for yourself. I couldn't tell you how many nay sayers I have personally ran into in the last year alone just because of Snowest "chat".

When it comes to tuning and modifying, get yourself a good set of gauges you can trust, learn to read piston, plug, and combustion(color) readings off your pipe and exhaust system. Always start rich and work yourself to lean, if it feels too good to be true, work back to rich settings then back down a notch to be safe.

I personally chose to go this route as it's hard to sift out the internet BS out there about the whole AV gas 100LL is too dry for anything but a plane theory. My experience, awesome results. Watch Burandt in his newest video's (Dentention), there's a reason he runs 100LL Av gas in his sleds as well. It gets expensive after a while and AV gas is the best bang for your buck next to propane out there especially when you put on the miles he does in a season.

Saying that he runs it isn't gospel alone. There are extra precautions in case your super paranoid like everyone else and you can always add in your own lubricants or additives. I have tried adding injector oil for extra lube last trip with no visible benefits. The only damage the "dry" AV might have caused is my transfer hose cracked next to the drum and I had to cut 2" off and the hose seems a bit stiff. For all I know, it could totally be unrelated to AV and just needed replacing due to age. Everything on my sled is fine and haven't had to replace any hoses, and everything works as though it was factory. I have personally burnt over 500L of AV gas alone, and +200L of race in the last season alone in my 2010 TM8 OVS Tial setup. Here are my details:

2010 162 M8 SP
- 2009 M8 stock cyl head
- OVS Turbo Tial setup with Garrett turbo
- Factory oil injection, running Amsoil Interceptor oil
- 10-12lbs boost, up to +14lbs boost trials
- 4-8500ft give or take 1000ft, mainly 5-6000ft mostly
- TDR Turbo reeds
- 850miles now, turbo'd from day one, never changed reeds, pistons or anything else other than Turbo oil (planning to do reeds as a precaution)

You pretty much can run as much boost as you want until your charge temps get too hot on my setup then you will detonate even if you have straight 118, no benefit over AV. On straight AV at 4000ft and 10lbs on a really hard pull on the trail hitting over 85MPH I only once hit DET sensor. Just after the last trip +800miles did I take out the factory pipe sensor code 17. My '07 M1000 lasted +2000 miles on premium fuel before it went through a pipe sensor in the same riding conditions.

I don't have bad throttle response everyone complains about with straight AV. It runs awesome and consistant with no tuning, as good or better than any of the stock sleds in our group and has been the easiest sled I've ever had to tune with the PL box. I can't even believe the reeds have lasted the torture I put them trough the end of last season trying to run +14lbs without an intercooler.

I run a 55gal drum in my V-nose of my trailer and have an electric pump, I'm setup better than anyone in my trailer for having enough fuel for a 3 day riding trip and can fill up faster, anywhere...

I wish I could tell people more, but in the end you have to try it for yourself. I AM going to propane, just because it's more available than race or AV gas anywhere, it's cheaper, and not much to convert it over and I'm doing and intercooler conversion anyhow so it's really win/win to me. It'll be tough to tear down this sled because it runs so well on straight AV 100LL and 10lbs boost though!

http://www.youtube.com/watch?v=QvdTryzvbiI&feature=related

 

[pinit]

i have read this post and hear is one thing to consider on fuel quality. If av gas goes bad or is not the quality it is supposed to be and someone takes off in there plane and motor goes down people die. If you put bad race fuel in your race car or bike or sled etc etc and motor goes down your lost a motor. I guess what I'm try to convey is av gas is highly monitored and regulated for obvious reasons. Just something to think about

 

[Boyko]

heres a good chart

http://www.smithtex.com/racing/fuelcomp.html

Wow great thread! Lots of important info.

I always like how companies peddling race fuel knock 100LL (no pun intended), like the typo in the smithtexs chart, 100ll is a min of 99.5 mon, ron is usaly around 10 point higher so avgas would be around 110 ron not 100

http://en.wikipedia.org/wiki/Octane_rating

 

[sledbreak]

Not to add fuel to the fire. im running a 08 D8 Pump gas i usually add about 2 gallons of 110 and non eth. pump gas per tank. think of switch to straight av gas. i run about 8-10 psi and ride anywhere from 3 to 8000 ft should i tone it down or add an additive? any comments are welcome.

 

[TurboMatt]

This might be a silly question but it relates to 100LL so I'll ask:
Is there any issues with storing a sled for the summer with 100LL in it?
Should I use any Stabil or anything?

 

[theshadowrider]

This might be a silly question but it relates to 100LL so I'll ask:
Is there any issues with storing a sled for the summer with 100LL in it?
Should I use any Stabil or anything?

I haven't had any issues and don't use stabil on anything else.

 

[srosscojw]

av gas in a turbo 2 stroke

Anyone try running this type of fule in modded or turboed polaris cfi engines? Pros, cons?

 

[jeepin270]

Wrkin real good...

 

[2XM3]

I'm still runnin 100% av gas at 10-12 psi, no issues at all

 

[XP860]

I'm still runnin 100% av gas at 10-12 psi, no issues at all

X2 for me as well with my Silber Kit!

 

[TurboMatt]

X2 for me as well with my Silber Kit!

X3. same here

 

[N.A84]

100% AV here, 10.2 comp head and 13-14 psi at sealevel. It rips!

 

[Race]

Heres a good video on what you should look for in higher octane

http://m.youtube.com/watch?v=HCVL8dMqoiU

 

[River Ratt]

storing over summer

I was also curious about the life of Av gas so I called my friend who owns a Helicopter Company, Jim trained on the little R22 and R44's Robertson gasoline helicopters, so I figured he would know. Jim told me that Av Gas is good to use in an aircraft up to three years old. This is open drum. The fuel has very good stability as it should because a lot of planes sit around for quite awhile between flights. I am currently burning 100 LL that was bought 2.5 years ago in my 2011 Pro HM turbo at 10 lb psi, and it runs fine on it.
IMO it is definitely the best bang for your buck. Race Gas is ridiculously over priced even if your mixing 50\50 with pump gas. I personally have had bad pump gas and had Det. on an older Mtn.Sled a few years ago, so I don't trust pump gas myself.
As per throttle response, yes pump gas is better down low rpm, and Av gas takes a few more pulls to start when engine is cold, to me this is not a big deal and I will live with this knowing I have a good quality and consistent fuel in 100 LL.

 

[av8er]

AVGAS

I have been running it for over 15 years in my sleds, it is very consistent

 

[tree climber]

i had 10 gallons in my shop that was 2 years old i was just going to dump but after reading around the internet and reading that a guy whos job it is to test the fuel at airports where it sits longer than normal say they tested a 2 year old sample and found zero degradation i decided to risk it i had another 15 gallons on the way at 5.25$ a gallon compared to over 10 i thought i would ease the first tank then boost up after replacing with fresh. well got talked into a drag race which i thought was pointless but cranked up to 15psi and held it pinned for a good while where poor fuel would have melted for sure at that level of boost. my local airports wont let me buy it so i have to depend on my friend to bring it in from the next state over

 

[BILTIT]

On 2 stroke mercury race engines 5 motors, 4 stroke...lol...maybe 1000+ at least... My good friends shop builds nothing but 2 strokes,n/a and turbo..hes done maybe 300 motors. You find after years of testing that all motors tend to perform very similar with respect to fuel, air temp, ect ect. We even did a couple of turbo mazda rotary motors (strange beasts) I did a huge amount of dyno time on blown gas deals, we had the fuel octane dialed in pretty good after 20 years. You can actually figure out the aproximate required octane needed if you know the true running compression on a engine, Quick and dirty formula for this is:
Final Compression Ratio (FCR) = [ (Boost÷14.7) + 1 ] x CR for sea level Note: the (+1) is dropped when boost and atm pressure are >1

Where cr is true static compression,14.7 is atmosphereic pressure at sea level. (final compression numbers have NO corelation to static compression numbers ie 12-1 FCR noes not = 12 -1 static !




Now Air pressure above sea level can be calculated as (just use a chart..lol)


p = 101325 (1 - 2.25577 10-5 h)5.25588

where

p = air pressure (Pa)

h = altitude above sea level (m)


final compression can be determined and octane needed can be picked. Now its important to remember that the number you get for final compression does NOT in any way compare to the "normal" number you see for static compression, ie 12-1 does not = fcr 12-1. This is only used as a ballpark # to see where you are at. Many things play into effect here, ignition,intercooler,port timing.exhaust flow, ect ect ect but as a starting point a FCR of 12-1 is good for 91octane, somewhere around 16 to1 for 100ll or C12, above that C16 or C25 till about 25-1+ where things get touchy...lol..

So for our motor at sea level running 12 pounds of boost and 12-1 true static(polaris dragon 800) whats are running compression? well:

[ {12.0 / 14.7} +1] x 12= 21.7 to 1 running compression under load

now same engine at 10000 feet

[{12.0/ 10.245}] x 12 = 14.00 running compression (10.245 is atm at 10,000 ft)

So we see that 12 pounds SHOULD be safe at 10,000 feet on 100ll blend and at sea level better have some C16 in it.

Is it safe? well we now look at what guys are running, ummm , many running 12 pounds boost on 100ll with no issues so we conclude by our formula and real world data that is should be OK.

Remember THIS IS A STARTING POINT ONLY. THERE IS NOTHING AS ACCURATE AS YOUR OWN PLUG READING,EGT'S,PISTON WASH,BURN PATTERN,AFR ECT ECT TO DETERMINE OCTANE REQUIREMENTS. Different chamber and about 1000 more things...Every motor has its own requirements and you learn what to do by years of experience and testing. NEVER put a motor near the "edge" unless you are totally willing to accept the FACT that it can melt to the wrist pins in a split second no matter what/who is tuning it thats just a fact when pushing the limits. Thats why I don't get to upset if I blow the rods out the bottom of the block...$hit happens or as they say "thats racin bub" lol.

Other guys figure all this different ways, first thing you learn in engine building is that nothing is the same..lol...and only trust your own data..are others correct?? Maybe, are there methods better? Maybe, the only thing I ever cared about is who's kissin the trophy girl at the end......................................







The "snappyness" of a motor you can tell pretty easy on the dyno fron the rate of acceleration over a given load, ie, the computer on the dyno is programmed to apply a fixed load over a time interval, then you can see how long the test engine takes to accelerate this load to the spectified rpm.
Or the dyno can be set up to give you a reading of how fast it has to open the water break in order to hold the motor, then apply this data to a acceleration curve you can look at.
Before we had all this computer stuff to control the break (way back when) you operated the brake with a wheel, primative as it sounds it was pretty easy to feel how fast the motor gained rpm by how fast I would have to apply the load...lol...and let me tell ya you crank that baby pretty dang quick on a blown alcohol deal..hahaha.

Very good info, is there any such formula for non-boosted applications? Just compression/elevation changes?

 

[Hardass]

To each his own but i know quite a few people including my self running Maxima hitest octane booster and it works no if or ands about it. I cant supply any teck data but it works and is super easy to use no more airport or race for us. Good luck.