Ski-Doo Snowmobiles Forum banner
1 - 20 of 45 Posts

·
one fast 98 mach-z
Joined
·
1,328 Posts
Discussion Starter · #1 ·
I get mixed answers from riders you meet on the trail. most say the extra money for the best fuel is cheaper than a engine that comes apart.


But in canada the axtra cost for fuel adds up real quick.

anybody know?
 

·
2011 RMK PRO 155
Joined
·
8,136 Posts
edlund said:
I get mixed answers from riders you meet on the trail. most say the extra money for the best fuel is cheaper than a engine that comes apart.


But in canada the axtra cost for fuel adds up real quick.

anybody know?
[snapback]717407[/snapback]​
My Cousin Had 3500 Trouble free miles on His 600 HO SDI running 87 Octane Gas.
 

·
Registered
Joined
·
1,756 Posts
Doo a search, there is a lot on this topic. I will say that the SDI adjusts for 87 octane fuel. You will be fine.
-Good luck
 

·
Registered
Joined
·
81 Posts
I run 87 Octane in my '05 GSX Limited...with know problem.That's what Ski-Doo recommends in the operators book. Good luck!!
 

·
Registered
Joined
·
94 Posts
In the '06 oper. manual it states 87 for SDI. 91 for Power Tek. Seems like they keep changing their minds! Depends on riding conditions, Wide open on a lake is different than woods riding.
 

·
Registered
Joined
·
603 Posts
Read an article written from BRP stating the SDI MPEM automatically adjusts the timing for 87 octane....So I'd say don't waste your money on 91
 

·
Registered
Joined
·
413 Posts
The sdi system does not adjust to octane. I asked that question in corporate corner a year ago. The detonation sensor retards the timing from its set point when denonation is encountered. The next time you start the sled it goes back to the set point if no detonation is experienced. I was hoping the brp used a similar system used on performance cars that adjusts to octane so I ran premium for the first 4000 miles in my 600 sdi. For the past 2000 plus I have run nothing but regular (87). The sled runs better now. I had to set the clutch to 1 because of high rpm. I was at 2 and 3 with premium. Do some research and what you will find is that an engine only benefits from higher octane if it can develop the pressure necessary to completely burn the fuel. The way to get this pressure is with higher compression or advanced timing that raises the pressure in the c-chamber as the piston moves to compress the already ignited air fuel charge. If you have enough compression or timing that you experience detonation with 87 then you will benefit from the premium, otherwise it is a waste of money. Again, don't take my word for it. Do some research. If you come up with a different answer I am eager to debate that issue. The bottom line is try the regular if it detonates and the timing is retarded you will know. Otherwise the regular is the better option..
 

·
Registered
Joined
·
1,756 Posts
dooman92 said:
The sdi system does not adjust to octane. I asked that question in corporate corner a year ago. The detonation sensor retards the timing from its set point when denonation is encountered. The next time you start the sled it goes back to the set point if no detonation is experienced. I was hoping the brp used a similar system used on performance cars that adjusts to octane so I ran premium for the first 4000 miles in my 600 sdi. For the past 2000 plus I have run nothing but regular (87). The sled runs better now. I had to set the clutch to 1 because of high rpm. I was at 2 and 3 with premium. Do some research and what you will find is that an engine only benefits from higher octane if it can develop the pressure necessary to completely burn the fuel. The way to get this pressure is with higher compression or advanced timing that raises the pressure in the c-chamber as the piston moves to compress the already ignited air fuel charge. If you have enough compression or timing that you experience detonation with 87 then you will benefit from the premium, otherwise it is a waste of money. Again, don't take my word for it. Do some research. If you come up with a different answer I am eager to debate that issue. The bottom line is try the regular if it detonates and the timing is retarded you will know. Otherwise the regular is the better option..
[snapback]717671[/snapback]​
That sounds like a valid argument. I am also a believer that the SDI's may benefit from using 87 octane due to the fact that it burns hotter thus preventing plug fouling and running more efficiently - cleaner.
 

·
Registered
Joined
·
1,484 Posts
Northbound said:
Hey nbrenegade,
Were you running 87 when we went for the last ride? I seem to remember have to tow you and you blamed the gas. lol
[snapback]718013[/snapback]​
Well that's too funny as I was just thinking about that when reading my post just now and though I should mod it to read "Until I sucked the mag side piston out of it and Northbound had to tow me 10miles out of the woods"

Anyway 9000 kms trouble free running leads me to believe it wasn't the octane.....
 

·
Registered
Joined
·
413 Posts
Buds, what that article says is true. The sled/engine starts at its most advanced setting. If vibration/detonation is noticed then the timing is retarded to the lower setting. If you are using 87 and no detonation is encountered the timing does not retard and you do not lose power. If you do not have enough compression or timing to cause the detonation then you will get at least as much power from the regular fuel... There are several systems used in high performance automobilies that advance the timing until detonation is noticed and then back down slightly. With those system you benefit from the increased octane because the timing is advanced as for as the fuel will tolerate. I was hoping the brp system acted that way but through testing and questioning brp I learned that the sdi system does not continually advance, but rather works from a set point. What is misleading about the article is implying that the engine knows the octane of the fuel. It does not know the octane only when the fuel used can not support the timing and pressure of the engine.
 
1 - 20 of 45 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top