Fuel octane and break-in procedures - just an observation

[Ray R]

I find it interesting that when folks are talking about what octane to use in their Spyders, everyone references the manual and says 87 is the way to go. The BRP engineers would have called for higher octane if the Spyder needed it.

But when folks ask about break-in procedures, BRP engineers don't have a clue and folks should "run it like you stole it!". Disregard the manual because "other engines" have been thought to run better and/or longer with a more "harsh" break-in.

My opinion, for the $.02 that it's worth, is that the engineers that built the vehicle are likely the most knowledgable about the materials and components that went into it, and therefore are the best source for proper operating procedures.

I've never heard of a vehicle that failed because the instructions in the manual were followed.

 

[Danimal]

Removed in protest of censorship. All of my tips will only be availabe elsewhere online.

 

[Magic Man]

Danimal is correct.

The lower compression of this series of 990 Rotax as compaired to the 136hp version coupled with the higher flash point of the 93 octane fuel can actually make the Spyder have some driveability problems at lower RPMs. This we actually have experienced first hand in our own test on our Spyder last weekend.

We filled up an almost empty tank with 93 and drove the bike. After a few minutes when the 87 fuel was completely out of the fuel rail and lines the bike began to have a low speed "miss" or "stumble" that was not there before.

We went back to the shop siphoned out the fuel till no bars were shown went and refilled the tank with 87. Again after a few minutes when the fuel lines and rail were clear of the 93 the "miss" or "stumble" was gone.

There have been several automotive tests and service bulletins on this topic for just the same reason. The higher octane fuel can indeed cause drivability problem in todays engines designed to use the lower octane, lower flash point fuel. Higher octane fuel that is designed to "resist engine knock" or detonation, also has a reluctance to burn properly at low engine speeds because of the lower compression chamber pressures in todays low compression motors.

The higher a fuels octane number the greater it's resistance to pre-ignition it has. Diesel fuel has an octane number over 600 but would not even run in a Spyder as you all know. Unfortunately that higher octane of 93 fuel can also make the flame front spread too slowly in low compression motors causing these types of problems. Especially, at lower engine speeds when compression chamber pressures are at there lowest due to reduced volumetric efficiency of the motors at these engine speeds.

I did this test this last weekend to finally be sure once and for all that indeed it was running worse on the higher flash point 93, and to tell you the truth it really does not run as well at all.

MM

 

[Danimal]

Removed in protest of censorship. All of my tips will only be availabe elsewhere online.

 

[Magic Man]

Dan,

This problem is not a "mapping" problem in the software of the computer like other problems sometimes can be. This is one time that it is a real life "hard parts" condition due to the low compression ratio of the motor and the high flash point of the fuel. The adaptive computor of the Spyder can "learn" to make adjustments to the mapping for fuel ratio and timing, but in this case the size of the compression chamber is a hard parts condition.

MM

 

[Danimal]

Gotcha.... makes sense to me.

So now everyone has no excuse to NOT run the 'cheap' 87 gas... ;D

We're @ $ 4.15 right now!

 

[Way2Fast]

Since when is a motor with 10.8-1 compression considered low ???

By the way, the computer can take some time to adopt to certain changes, but ignition timing is not one of them. The moment the ECU senses detonation, (knock, pinging...call it what you will) steps are immediately taken to prevent it.

 

[NancysToy]

Since when is a motor with 10.8-1 compression considered low ???

By the way, the computer can take some time to adopt to certain changes, but ignition timing is not one of them. The moment the ECU senses detonation, (knock, pinging...call it what you will) steps are immediately taken to prevent it.

10.8:1 is not low, but it is lower than the Aprilia at 11+ to 1. Same motor design. The important thing is actually compression pressure, which is also a product of the cam timing. The combustion chamber shape and spark plug location can have a great effect on the tendency for an engine to detonate, also. Good fuel management, and a hot spark will reduce detonation. In short, while a Chevy 283 will likely detonate badly at 10.8:1, the Spyder apparently has a design that does not.

As I understand it, the Spyder does not have a knock sensor. Therefore, it will not be able to retard the spark upon detonation. You can get the Spyder engine to knock. I have had it happen under load, at too low rpm. Downshifting was necessary to cure it. There was no ECU response. This engine really wants to be above three grand or more under load.

We have had no trouble with regular fuel in our Spyder, and have not seen any benefit in performance or mileage with premium (stock exhaust). My wife's HHR, on the other hand, will run OK on regular, but is designed for premium, and runs noticeably better on the high grade fuel, and gets better mileage. Bottom line, neither fuel grade will likely hurt the Spyder engine or the performance much. Use what makes you happy. It will only cost you $40 a year more for premium if you ride 12,000 miles at 30 mpg.
-Scotty

 

[bjt]

You can get the Spyder engine to knock. I have had it happen under load, at too low rpm. Downshifting was necessary to cure it. There was no ECU response. This engine really wants to be above three grand or more under load.

Been there, done that. ;D

 

[spyderme]

In Australia we have 98 ron, 95 ron and 91 ron. I initially ran 98, as per my dealers advice. I changed to 95 on my last tank and I noticed the difference straight away. Much smoother power delivery and a lot less popping when throttling back through the gears. 95 for me from now on.

 

[bjt]

Being I was curious about Australia's RON octane rating vs. the United States rating system, I looked it up. Here's what Wikipedia says....

In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90-91 US (R+M)/2, and even deliver 98 (RON) or 100 (RON)

So you went from what we call Premium in the U.S. to Mid-grade, still a notch above Regular. I wonder why your dealer told you to run 98 RON when, according to our North American standards, you could be running 91 RON?