Gasoline question - will Regular harm the Spyder?

[SportsterDoc]

PMK: "Higher altitude results in less dense air, so less air compressed into the cylinders, corresponding to a lower compression ratio, which requires less octane."

Less air compressed corresponds to or has the same effect as a lower compression ratio.. I did not state that it changed the compression ratio.

Please advise if you need further clarification.

 

[BajaRon]

This question has actually been answered many times over the years.

1. Will regular octane fuel hurt your Spyder (Rotax) Engine? - No. It will not.
2. Which fuel octane is best for the Spyder? - Premium is best.
3. Why is premium best.
The Rotax engine is a high compression, high performance powerplant. Under some conditions, (Heavy loads. Steep grades. High ambient temps. Hard riding. High RPM). Lower octane can, and probably will, pre-ignite (knock). To prevent this, the on board computer can sense this condition before it occurs and will retard ignition timing to prevent this dangerous and destructive pre-ignition issue. The engine is completely protected, which is the 'Why' to answer #1. But retarding the ignition reduces power output and will decrease fuel mileage.

People say they notice no difference. Can't argue with that. But on a 6,000 mile cross country trip on my 998 Spyder. I averaged 3+ MPG better on Premium than I did on Regular. That's about a 10% difference. I kept very accurate records and did not count transition tanks of fuel (when I would switch from one grade to the next).

I wish I could have done this test with non-ethanol fuel. I think I would have gotten even better results.

 

[VegasDan]

Around here, it is about $.50 - $.55 more per gallon.

If $1,500 difference over a 100,000 mile term is a deal breaker - it's your bike and your choice - and perhaps you're 100% correct.

But...
Premium fuel runs cleaner, provides better mileage, provides a HP increase and is the recommended fuel.
At 1.5 cents per mile cost difference (using your 50 cent difference number) - Ill just have to buy one fewer candy bar per fuel stop (my fat butt doesnt need yet another Snickers bar anyways) (of course; maybe if I eat fewer candy bars - I wouldnt need the extra HP; its a quandry)

 

[SportsterDoc]

? ? ? .....I don't 85 octane is even sold in the US ...... jmho .... Mike :thumbup:

Common in Utah and Colorado, where 87 is mid grade and typically 91 is high octane.

 

[SportsterDoc]

With respect for Bill's request "Not other rider's "opinions or preferences" Thank you"; I tried to state only facts. But for the record I ran 91 octane, except where not available (Stovepipe Wells, Death Valley).

 

[SportsterDoc]

At 1,000 miles per month and 33 MPG, the price difference for 30 gallons of fuel would be less than $15...a small price to optimize performance..not that I was concerned when 91 was not available...it will NOT "screw up the bike"

 

[BLUEKNIGHT911]

We have E-85 here in Minnesota.

Interesting ..... So do you think E-10 is rated at 10 octane ???? ..... Mike

 

[Knizar]

Interesting ..... So do you think E-10 is rated at 10 octane ???? ..... Mike

No Sir, I believe that E-85 is 15% Ethanol, and I have No idea what the octane it is!
Our ethanol produced 5 miles down the road, (non-food grade corn whiskey)
They also produce Shakers Vodka there. (Some bad sh-t to my liking)
:thumbup:....Bill

 

[Peter Aawen]

No Sir, I believe that E-85 is 15% Ethanol, and I have No idea what the octane it is!
Our ethanol produced 5 miles down the road, (non-food grade corn whiskey)
They also produce Shakers Vodka there. (Some bad sh-t to my liking)
:thumbup:....Bill

Here in Oz, the E-10 we get has an octane rating (ie, anti-knock rating) equivalent to your 91 (I think - cos you lot use a really weird octane measuring system that the rest of the world just can't be bothered with! ) and it's up to 10% ethanol mixed with 90% unleaded petrol; while our E-85 is a blend of between 70% and 85% ethanol topped up with unleaded petrol, with a RON octane rating of 105 - but the ethanol in either/both packs only about two-thirds the BTU's of unleaded petrol, so unless your engine has been specifically designed & tuned to run an ethanol mix, you'll always get less mpg no matter how good the octane rating means the fuel is at avoiding engine knock! :banghead:

 

[Mikey]

Mechanics and experts? Does anyone on this site actually no more than the BRP/Rotax engineers who designed the 1330cc motor? Yes, the manual RECOMMENDS 91 octane fuel. NO WHERE in the manual does it say "minimum 91 octane required". In what world would the legalize folks of BRP state "a minimum of 87 octane" if they thought it would harm the motor? Why would BRP want to pay the cost of motor repairs if caused by 87 octane fuel? I'm sure all this would only apply to a STOCK 1330cc motor. Cat deletes? Aftermarket exhausts or intakes? FI changes? Nope .. All bets would be off with BRP.

Now you've open another can of worms! Changing the system, with aftermarket toys!!! Oh boy!!!:clap:opcorn:

 

[PMK]

:clap::agree::chat::bdh:opcorn::banghead:

The animal lovers are very likely offended by you beating that horse with a stick.

 

[Knizar]

The animal lovers are very likely offended by you beating that horse with a stick.

He's DEAD! Just tenderizing it!:b2b: Ever had a Piece?:bbq:
AND, That's Not a Horse, It's a Mule, Donkey, or an Ass!

 

[Mikey]

opcorn: I love a good gas thread!!!!

 

[SportsterDoc]

Even with 300+ HP under the hood of a Datsun PL620, I advanced distributor when above 6,000 feet elevation.

 

[bikerchris1270]

opcorn: I love a good gas thread!!!!

The oil preference thread are a hoot too!
Hey….It’s winter, we’re bored.

 

[IdahoMtnSpyder]

Actually, Sporsterdoc, you did state in a previous post that altitude lowers compression ratio which is not correct and misleading.

PMK, not to be argumentative but I believe you are thinking of the word "corresponding" as being equivalent to "changing", which of course cannot occur with the compression ratio. I agree with Sportsterdoc that he intended to convey the meaning as "is equivalent to". So, as you state in your comment, the internal chamber pressure will be greater at sea level with a 9:1 compression ratio, about 14.7 x 9 = 132 psi, than it will be in Wyoming at a 9:1 compression ratio, or 12.3 x 9 = 110 psi. The resulting compressed A/F mix pressure at 5000 ft elevation, 110 psi, would be equivalent to the compressed A/F mix pressure of an engine with 7.5:1 ratio at sea level, 7.5 x 14.7 = 110 psi. So, because of the thinner air in Wyoming the chamber pressure there will correspond to, or be equivalent to, a lower compression ratio of 7.5 at sea level, the design altitude of the engine.

You are both correct when taking into consideration the definition you are undoubtedly each applying to the word "correspond".

 

[obiwanbill]

He's DEAD! Just tenderizing it!:b2b: Ever had a Piece?:bbq:
AND, That's Not a Horse, It's a Mule, Donkey, or an Ass!

I heard that phrase in the military for the first time :bdh: It's meaning was when at transfer, a sailor took out 3 month's advance pay, he had to "pay it back" by a 50% cut in pay for the next 6 months. It's called beating a dead horse because on 1/2 pay, feels like you're dragging a dead horse behind you.

 

[BajaRon]

opcorn: I love a good gas thread!!!!

I'd rather talk about it... Then have it! :yikes:

 

[PMK]

PMK, not to be argumentative but I believe you are thinking of the word "corresponding" as being equivalent to "changing", which of course cannot occur with the compression ratio. I agree with Sportsterdoc that he intended to convey the meaning as "is equivalent to". So, as you state in your comment, the internal chamber pressure will be greater at sea level with a 9:1 compression ratio, about 14.7 x 9 = 132 psi, than it will be in Wyoming at a 9:1 compression ratio, or 12.3 x 9 = 110 psi. The resulting compressed A/F mix pressure at 5000 ft elevation, 110 psi, would be equivalent to the compressed A/F mix pressure of an engine with 7.5:1 ratio at sea level, 7.5 x 14.7 = 110 psi. So, because of the thinner air in Wyoming the chamber pressure there will correspond to, or be equivalent to, a lower compression ratio of 7.5 at sea level, the design altitude of the engine.

You are both correct when taking into consideration the definition you are undoubtedly each applying to the word "correspond".

Yes, Sportsterdoc has it 100% correct, I shall edit my posts to reflect my stupidity on the subject.

 

[SportsterDoc]

Yes, Sportsterdoc has it 100% correct, I shall edit my posts to reflect my stupidity on the subject.

No worries, sometimes that happens to me when I post past my bedtime!... Especially as 75th birthday is less than 2 weeks away!!

And a self-application of stupidity is not at all correct.

Perhaps I should have chose a synonym to corresponds... I did not use same as, since it's not exactly the same... so corresponds seemed to fit.