Octane Requirement for a Etec

[oler1234]

I know what it says on the gas cap but... has anyone tried 89 for mountain riding?

I know with mine it develops a crazy stumble and studder at idle when i got 94. With 91 it is somewhat gone around the 5500 elevation mark. Just wondering if anyone is running 89 without any problems.

 

[moyiesledhead]

I know what it says on the gas cap but... has anyone tried 89 for mountain riding?

I know with mine it develops a crazy stumble and studder at idle when i got 94. With 91 it is somewhat gone around the 5500 elevation mark. Just wondering if anyone is running 89 without any problems.

Why would you run 94 in a sled that only requires 91?

 

[oler1234]

Why would you run 94 in a sled that only requires 91?

It says to run a minimum of 91... there is no maximum listed. And to my knowledge i have not read anything where it states to run 91

 

[Hillclimber]

When I'm up at work we don't have 91 we have 89 it runs just fine. But a little sluggish needs the 91 for the full power.

Sent from my SGH-I747M using Tapatalk 2

 

[drew562]

I have been on long rides and filled at gas stations that only have regular 87 The etec has a great knock sensor and will recognize bad fuel and tunes for it. It's not something I would do all the time and you will notice a power loss but the sled will run fine on 87 in a pinch

 

[neilsleder]

The 94 is petro can gas? If it has a stumble it might cause that 94 has ethanol in it to get the extra three octane points.

 

[hpjunkie]

Ran Shell 91 for two tanks, then 87 For two tanks @ 2000' elevation. Can't feel/see a difference. Sled pulls strong with either octane. Compression is less here @ 2000', than at sea level. Does the ignition timing vary based on atmospheric pressure?

 

[greenthumb]

Why would you run 94 in a sled that only requires 91?

FYI:
Chevron 94 does not contain ethanol. Chevron 87/89/91 may contain up to 10%. The pump says so. Also, the 94 hose is separate from the other grades, so you don't get a few litres of 87 from the previous fill up.
Shell 91 also does not contain ethanol. It is 'nitrogen enriched'. I do not know the pros/cons of this.
Esso says up to 10% for all grades. The same for Mohawk. Petro-can's wording is cryptic, but my understanding is that all grades may contain up to 10%.
From what I have read, it is strongly recommended to stay away from ethanol in etecs. I believe it.
I have also read/heard/experienced enough to believe Techron (chevron) is a significantly better and more effective additive than other brands.
I have been consistently using chevron 94 is several sleds, (including a turbo 4 stroke) with good results.
I have tried a few tanks of Shell 91, and feel (seat of the pants) that my '14 XM runs better, more consistent, and has more power on Chevron 94 over Shell 91. Just my opinion though.

Octane requirements go down as altitude increases. Using a higher octane in an engine that doesn't require it is of no benefit. AFAIK, etec octane requirements are the same for all models. Assuming they all use the same map, theoretically 89 would work at a higher altitude just as effectively as 91 at sea level. What altitude, I cannot say. One chart I have read claims 89 @ 4000' is the same as 91 @ sea level, but I would not take this as fact.

 

[Director]

Does the sled compensate for atmospheric pressure and fuel quality by measuring air density in and exhaust temp out? Should be able take a read from both sides and adjust air/fuel mixture as required..

 

[Polar_RMK]

I don't think so, seems too complicated to me.
I would say air density doesn't change much with atmospheric pressure. It's a function of temp mainly.
Moisture will have more effect on air density then atmospheric pressure.
I am talking about atmospheric pressure on constant altitude.