Clarification on JASO FC vs FD 2-stroke oils

[GardenKit]

If I am honest I don't know about the flame front, but as the fuel is much purer than petrol I believe the flame front to be much cleaner and therefore more uniform. The incredibly clean upper cylinder and plug would certainly point to this being the case.

 

The higher H/C ratio actually results in more water vapour from combustion making it more efficient.

 

The lower Vp can result in the engine being a little less responsive.

At idle the flow through the carburetor is low. Some of the fuel is evaporated and some remains liquid at the bottom of the intake pipe.

Suddenly opening the throttle will give an immediate air flow increase to the cylinder. The evaporated fuel follows the air flow, but the liquid fuel takes longer to increase its speed. This means that the first second after opening the throttle, the engine will get a lot of air but very little fuel and the response is bad.

This is normally compensated for by an acceleration pump in the carburetor. With alkylate fuel only 15 % is evaporated at 70°C compared to 30 % for normal fuel. This can be compensated for, by opening the “L” screw 1⁄4 turn.

 

But WOT is hardly effected by the lower density as the higher H/C ratio and lack of oxygenates compensates most of it.

 

Although it is generally appreciated that engine may run slightly lean on Aspen when compared with pump fuel it must be remembered that this comparison is with ethanol free petrol, which we no longer have. Aspen in fact runs as lean as normal petrol with 5-10% ethanol which is now our norm at the pump.

[Piston Skirt]

I've just received a load of bedtime reading from the Oil company whose oil I am a dealer for.

 

I knew in the back of my mind that JASO FD spec was supposed to be higher performance than FC but apparently not necessarily...

 

It comes down to basestocks vs additives again... and not just 1-2-3 as in Mineral-Semi Synthetic-Fully Synthetic.

 

Wiki and BITOG will rightly tell you that FD is the same as FC with even higher detergency.

 

Stihl HP Mineral (Red) for instance is JASO FB but ISO-L-EGD; talk about confusing; ISO-EGD is the roughly equivilent grade to JASO FD but the tests are different; some argue that one is more concerned with lubricity and heat and another ash content and detergency... Wierdly the next oils up Stihls pecking order (HP Super and Ultra) are both FD and EGD but semi and full synthetic respectively. I would expect Ultra to outperform Super despite the same ratings. Likewise Echo Power-blend is FD but "synthetic blend" whatever that means. Dolmar is certainly FD but Shavey will have to confirm whether it's semi or full syn.

 

Anyway, some FC oils don't need to be FD certified since they have a superior basestock and therefore don't need the (FD) detergents; not all synthetics are the same remember

 

It is a bit simplier and at the same time might seem more complicated than that

 

1. JASO and ISO standards actually are very close (FD is nearly equal to LEGD)

2. Many oil makers (and re-badgers) use standard names on bottles without actually having the certificates or being certified. Yes, even the big names do that, I will just avoid naming them

3. The semi-synthetic (or "synthetic blend"=mineral based+synth.additives) oils can easily have a better set of characteristics and be superior to synthetic based oils. The reason is not really complicated - the oil has to have certain set of important characteristics of lubricity, carbon/ash deposits, detergency, smoke amount etc. If one of them is lower than required by standard - it has lower rating

4. The beauty of JASO procedure - the oil maker/brand can always be checked even online (which is not so easy with ISO). Also, in most cases you can find a square symbol on oil bottle with actual certificate number given for that oil. The list of oils that are actually certified can be found here:

http://www.jalos.or.jp/onfile/pdf/2T_EV_LIST.pdf

The description of application and AFAIR testing procedures can be found here:

JASO Engine Oil Standards Implementation Panel

 

Now check the thread and your own post and you may notice that some names/pictures of oils mentioned actually are not JASO certified although you can find the "statements" on the bottles. Same story is with ISO ratings, however it's very hard for average Joe to check if certain oil is actully ISO certified.

This is the reason why many non-sponsored kart and 2-stroke bike racers stick to FD oils (and yes, they fight over which one is better )

 

Happy reading!

[TimberCutterDartmoor]

The lower Vp can result in the engine being a little less responsive.

 

What I guessed

 

It is a bit simplier and at the same time might seem more complicated than that

 

1. JASO and ISO standards actually are very close (FD is nearly equal to LEGD)

2. Many oil makers (and re-badgers) use standard names on bottles without actually having the certificates or being certified. Yes, even the big names do that, I will just avoid naming them

3. The semi-synthetic (or "synthetic blend"=mineral based+synth.additives) oils can easily have a better set of characteristics and be superior to synthetic based oils. The reason is not really complicated - the oil has to have certain set of important characteristics of lubricity, carbon/ash deposits, detergency, smoke amount etc. If one of them is lower than required by standard - it has lower rating

4. The beauty of JASO procedure - the oil maker/brand can always be checked even online (which is not so easy with ISO). Also, in most cases you can find a square symbol on oil bottle with actual certificate number given for that oil. The list of oils that are actually certified can be found here:

http://www.jalos.or.jp/onfile/pdf/2T_EV_LIST.pdf

The description of application and AFAIR testing procedures can be found here:

JASO Engine Oil Standards Implementation Panel

 

Now check the thread and your own post and you may notice that some names/pictures of oils mentioned actually are not JASO certified although you can find the "statements" on the bottles. Same story is with ISO ratings, however it's very hard for average Joe to check if certain oil is actully ISO certified.

This is the reason why many non-sponsored kart and 2-stroke bike racers stick to FD oils (and yes, they fight over which one is better )

 

Happy reading!

 

Agree with all of that. Internal testing - can it be trusted?

[Piston Skirt]

What I guessed

Agree with all of that. Internal testing - can it be trusted?

 

Well as far as I remember JASO reserves the right to purchase a sample of certified oil at any moment and re-test if it is the same spec as it was given for certification. This is one of the reasons why their certification itself is not cheap - for sample testing they use lab-spec engines under heavy conditions for 180 minutes for sole sample.

 

Typically it's easy to see if modern engine was using FB grade (this means pretty basic) oil - heavy carbon deposits are very clearly visible everywhere after as little as 20-50 hours of actual work. The cleanest engines that I've seen were the ones that used Aspen or FD oils.

 

And answering to your question - it's up to You IMHO independent testing always says the most. The only exception is when manufacturer's machinery suffers from certain problems and a spec-formula as a solution has to be developed. This was remotely similar when VW tried to solve DSG gearbox failures by changing the tranny oil to synthetic spec (and it did not help that much:) )

Edited February 4, 2016 by Piston Skirt

[TimberCutterDartmoor]

Well as far as I remember JASO reserves the right to purchase a sample of certified oil at any moment and re-test if it is the same spec as it was given for certification. This is one of the reasons why their certification itself is not cheap - for sample testing they use lab-spec engines under heavy conditions for 180 minutes for sole sample.

 

Typically it's easy to see if modern engine was using FB grade (this means pretty basic) oil - heavy carbon deposits are very clearly visible everywhere after as little as 20-50 hours of actual work. The cleanest engines that I've seen were the ones that used Aspen or FD oils.

 

And answering to your question - it's up to You IMHO independent testing always says the most. The only exception is when manufacturer's machinery suffers from certain problems and a spec-formula as a solution has to be developed. This was remotely similar when VW tried to solve DSG gearbox failures by changing the tranny oil to synthetic spec (and it did not help that much:) )

 

slight derail! Do VAG DSG gearboxes give trouble then? Is the 8-speed in a touareg such?