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[YamahaTim]

I guess 11.5 was pretty good then. I always thought it was 12.5 but that always made me nervous. I can get 91 non oxy around here and north MN. But WI and MI seems like they just have 91 with ethanol. I will probably have something wrong with my motor or just something easy. Who knows. Bit I will be safe for sure now!

 

[suburban]

hey Tim, the 4 cyl can survive low boost and 12.5, but as Allen stated, the 3 cyl is less tolerant.
the thing to keep an eye on is if you can maintain 11.5 on a 1/4 mile plus wot pull. it may start out there and slowly fade to 12.0 plus, as stock fuel system is on the edge at 6 lbs.

 

[kviper]

Quality of fuel plays a huge factor to making these live. You never know what you are getting from the pump. With afr's on the edge, fuel systems (fuel pump, injectors) getting maxed out with the amount of boost it's better to be safe with lower afr's.
Honestly, for these to be more bullet proof there needs to be some kind of knock sensor to let you know when you've crossed the line. Yamaha's bed partner has this technology already on a stock sled.

The 11 and newer Apex has the knock censor and automatically pulls timing when deto is detected. The main reason I felt comfortable going low boost on mine. I think the Phazer also has a censor.

 

[Sledguy89]

Man reading all this is making me nervous about snow check a 15 viper an installing the turbo. As I've never had a boosted sled an my local dealer(shawmutt hills) has yet to sell a turbo an install for the new viper

 

[matt@mpi]

I guess 11.5 was pretty good then. I always thought it was 12.5 but that always made me nervous. I can get 91 non oxy around here and north MN. But WI and MI seems like they just have 91 with ethanol. I will probably have something wrong with my motor or just something easy. Who knows. Bit I will be safe for sure now!

11.5 is what you want to see at WOT. 12.5 is ok at part throttle.

 

[YamahaTim]

hey Tim, the 4 cyl can survive low boost and 12.5, but as Allen stated, the 3 cyl is less tolerant.
the thing to keep an eye on is if you can maintain 11.5 on a 1/4 mile plus wot pull. it may start out there and slowly fade to 12.0 plus, as stock fuel system is on the edge at 6 lbs.

My WOT is for sure rich! Like 10.6 rich it's the hard take off but not WOT I'm at around 11.5-11.9. And real slow speed sometimes it's up there, but that's going real slow! Once and a while heavy throttle is 12.3. Not very often is my WOT higher than 11.5.

 

[YamahaTim]

I think I'm going to run everything 11.5 and lower! Whether my engine is hurt or not! It's fast as hell at 10.6!! Can't really notice ant difference anyway!

 

[DooZ]

I guess 11.5 was pretty good then. I always thought it was 12.5 but that always made me nervous. I can get 91 non oxy around here and north MN. But WI and MI seems like they just have 91 with ethanol. I will probably have something wrong with my motor or just something easy. Who knows. Bit I will be safe for sure now!

Has anybody ever suggested an octane booster? Lucas and Torco are popular with the Cat turbo crowd. The best would be a splash of 110 if the situation allows it.

 

[Superfletch]

I have seen this on Suzuki GSXR 1000s. It was caused by a vacuum line break and leaning out the A/f ratio. Only occurred at sustained high rpm (Brainerd International Raceway) conditions. The guy went thru 3 motors before pushing the rubber line back on, oops. I think this is more of a lean issue than detonation. Running lean and having high and or excessive heat build up because of being lean can cause detonation but this is on NA motors. Can turbos cause this even with proper AF ratio? I am trying to understand as I intend to install a turbo for next season. I also believe anything over 92 octane does not help on motors that are running high rpm (8k and up)?

 

[YamahaTim]

I guess 11.5 was pretty good then. I always thought it was 12.5 but that always made me nervous. I can get 91 non oxy around here and north MN. But WI and MI seems like they just have 91 with ethanol. I will probably have something wrong with my motor or just something easy. Who knows. Bit I will be safe for sure now!

Has anybody ever suggested an octane booster? Lucas and Torco are popular with the Cat turbo crowd. The best would be a splash of 110 if the situation allows it.

I have thought of that, but I don't know what I can use. Yes I could get a little can of 110 octane. And through it into every tank, but how much would I need.

See what I mean (all good questions)right. But don't know what's safe. I don't really hold it at WOT that much, but I do, do it. So I would surly like to be safe while doing it. I also run it at 5.5-6 psi. With my clutching issues in the past it would be far and between that I would see 6 psi. Mostly 5.5 so I think I was safe there to as well.

I would like to carry a safety measure though!

 

[Farm dog]

I'm going to have to watch my afr gauge more often on my mcx kit on my Nytro and see what it runs at. I run 6lbs of boost with an Ulmer clutch kit. Unfortunatelly our snow is gone at home.
Good info guys.

 

[YamahaTim]

I'm going to have to watch my afr gauge more often on my mcx kit on my Nytro and see what it runs at. I run 6lbs of boost with an Ulmer clutch kit. Unfortunatelly our snow is gone at home.
Good info guys.

Yes let us know.

 

[stingray719]

hey Tim, the 4 cyl can survive low boost and 12.5, but as Allen stated, the 3 cyl is less tolerant.
the thing to keep an eye on is if you can maintain 11.5 on a 1/4 mile plus wot pull. it may start out there and slowly fade to 12.0 plus, as stock fuel system is on the edge at 6 lbs.

My WOT is for sure rich! Like 10.6 rich it's the hard take off but not WOT I'm at around 11.5-11.9. And real slow speed sometimes it's up there, but that's going real slow! Once and a while heavy throttle is 12.3. Not very often is my WOT higher than 11.5.

Back in my stock car racing days when every tenth of a second mattered and was on the clock I would run on the rich side and not see any noticeable drop in time. In fact every main event I won was on a cold night as other guys tried to run the ragged edge. So with my boosted sleds I always ran on the rich side not knowing what quality of fuel I would get and what the ambient conditions might be. Just my opinion though.

 

[YamahaTim]

Well im running pretty rich. hope im good!!

 

[JP270NYTRO]

my mcx 270 kit would pull 11-11.5 wot for as long as I wanted and not one problem at all...fuel these days is what is killing the engines, buy torco octane booster and you should be good or dave from hurricane has some booster as well I know on my 1100t it made a difference, I would get a knock light on some pump fuels around here and add some torco it would be gone.