Oxygenated fuel, oh my!

[1976RD400C]

I normally buy a jug of VP110 to mix with non-ethanol pump gas for my modified bike. Went to the local bike shop and they didn't have any more but they had VP2+. The label says for 2 strokes and comes with oil mixed at 40:1, 105 octane, 5.9% oxygen enriched. I thought let's try this stuff straight up with a little Yamalube 2R to get the ratio at 25:1. I kick it, with the chokes on, and it starts right up and then stalls. Odd, but it has done that before, it floods. Take the chokes off, crack the throttle open, kick, vrooom, it's ready to ride. Off I go and notice it is running as smooth as can be. Get to the back roads and start to give it some juice, oh yeah, seems like more power. It never skipped a beat on a 25 mile ride and the cylinder head temps were lower than most of what I see, 285f max. On the way back I wacked it through the lower gears a few times and it does have more punch. It wants to go to 10K but I keep it at 9.5. After hitting that turkey, I got a little wimpy about the back road through the woods high speed stuff. The rest of the jug will be mixed 50:50 with pump gas with oil at 25:1. I like this bike (RD400) better than my RZ because it is more stable, corners better, stops way better, and will probably walk away from the RZ in a straight line. Thanks to John Ritter for working my cylinders, heads, and reeds, this thing runs perfect.  

[85RZwade]

Hmmm, I thought I was all done buying race gas...

[RDDave]

Oxygenated gas makes power; https://www.youtube.com/watch?v=ryqyTPfNj1Q

[quocle603]

Sounds expensive.

[RDnuTZ]

coming from CA, they always had different blends of fuel mandated for different times of the year to fight pollution. My recollection on this (could be imperfect) is that the "Summer Blend" was more "oxygenated" and this was achieved by blending in higher % of Ethanol. It always resulted in higher prices at the pump and we got less MPG at the same time as it burned quicker.

[1976RD400C]

This is the stuff I bought. Next ride will be 50/50 with 91 non ethanol pump gas.  https://vpracingfuels.com/products/vp-t2-plus-fuel

[RDnuTZ]

yeah I always ran straight VP leaded non-ethanol in my dirt racing bikes. The mandate I was referring to was the state mandate for pump gas. They always used the seasonal changeover to justify spiking pump prices due to "low refinery supply" each time they changed blends.

[JKV45]

Make sure you know what you are using if you go the race gas route.

We run VP MR12 in our KTM race bike, and it does provide a bump in power, but it needs to be flushed after every use.

Probably not something anyone would use on the street, but if you did use it without being familiar with it, you would cause all sorts of problems with your fuel system.

[teazer]

MR12 is great for a 4 stroke, but I wouldn't recommend it for a 2 stroke.

Back to the thread though.  More alcohol in the form of ethanol or methanol carries more oxygen but burns at a proportionately richer air:fuel ratio. Race gas is designed to resist detonation and some race gas burns slower than pump gas to achieve that result, but not all.

My favorite race fuel so far is VP U4.4 because it seems to be the most responsive to throttle input. Regular race gas is really safe in terms of detonation protection but often has a flatter throttle response. I have tried all the Sunoco blends and some VP, and few of them actually make much of a difference to power on a street motor.

That Engine Masters video made it abundantly clear that on that motor, 87 pump gas made as much power as 91 or anything else except methanol or E85 and they really run much richer than street or race gas. Their value, like all race gas is resting detonation.  If you have more than say 150PSi of cold cranking pressure, you might want to think about higher octane gas and if you are closer to 200psi, you must use race gas to prevent a melt down.

To put it all in perspective a 5% power improvement on say a 50HP RD is 2.5HP at peak. Nice to have but at less than peak revs, you get the same power with a slightly wider throttle opening and on the street, it is really not worth the big bucks.  That said, I just got a pail of Q16 to test.

[RDnuTZ]

I only saw the intro on the video and didn't have 19 minutes to spare on the whole thing. Did they happen to mention the elevation they were testing at? At near Sea Level living in San Diego 87 was our Regular and 91 was Premium. Living here in CO now at 6200' 86 or even 85 is Regular, 87 is Mid-Grade and 91 or 93 is premium depending on gas station. I bought a 2013 Jeep Grand Cherokee in San Diego and it recommended minimum 87- no problem that's Regular. I recently bought a 2024 Nissan Frontier that also recommends 87 minimum, but here that forces me to spend 20cents more per gallon. I always use the 87 and also top tier gas because there is a noticeable seat of the pants difference in the way both my vehicles run with 87. The Jeep is a Flex fuel motor and can run E85, but I've been wary of using even though it is the cheapest of all up here.