Shell V-power racing 100 problem (EU)

[Przemek]

Hi,


I am experiencing the following issue with two of our GT2 AWD Stingers (HKS 45 plugs gapped at 0.23, aftermarket mid pipes and exhaust).

We had started using Shell V-Power Racing 100 octane gasoline (European specs) and everything was OK for a while and then both cars started behaving weird.

When starting from a complete stop (only then) with full throttle (pedal to the metal) the cars loose boost (it is cut off) around 4000 rpm (looks like over-boost protection is on) then when you release the accelerator and push it again all is fine. It happens only from a complete stop.
It is not referred to a specific gas station - we filled the same type of gas on different Shell stations.

When we start using regular 98 unleaded gasoline everything is fine.

I just wonder what the problem might be - can certain fuel additives in this specific gasoline cause this issue or maybe too high octane causing over-boost? I thought that the higher octane the better...
It is defiantly not an issue with the cars because it is a very small chance that both of them would start behaving like that at the same time.

Have you come across as similar issue? Any ideas what it might be?

BTW it is the same with JB4 (map0/1/2) and with/without BMS intakes.

Looks like this specific gasoline doesn’t like our cars...or maybe a combination with HKS plugs?

 

[eflyguy]

I thought that the higher octane the better...

.. and there's your problem.

 

[Przemek]

.. and there's your problem.

I am not sure... JB4 recommends high octane fuel for higher maps... and the problem occurs with the jb4 as well. It is not always but more or less happens at the same time to both cars (refueled on different Shell stations)... we cannot figure out whether it is the weather or something else...

 

[turboAWD]

I've heard a similar thing being described, not sure if it's related: really good octane allows for highest boost, really good spool, etc. It gets to a high enough power level that transmission-torque safeties kick in and cut the power (throttle closing?). This is something jb4 cannot change (yet?), and you need an actual flash to remove some of those safeties, AFAIK.

 

[eflyguy]

I don't have JB4 (I have ECU flash) but my understanding is that for a given tune/setup, higher is not always better - i.e. there is a limit, a point at which you won't see any benefit and in fact might get worse results than a slightly lower octane.