Is E5 a ticking bomb for high power???

[muddle84]

Well with the bad weather at the start of the year and work just being quite my brother was at home for 4 months approximately( he works for a construction company in england). He has a 05 wrx running at 340bhp. he normally runs v-power when in the uk so when hes over here he was prickin about with octane booster then he read up on E5 and used that there after until he returned to the uk. About a month ago he was out for a spin then bang, detonation, engine dead. head gaskets, bent con rod, pistons ****ed, up pipe split, big ends ****ed and a few other bits i can't remember. he is getting it re-built at a subaru specialist and when he asked what would have caused it the fella reckons the E5 would have done the damage to cause the det and you need to run leaner with ethanol in it. So i'm putting this up as a warning or just to get other opinions, is this the case that e5 is a bad idea if your not mapped for it or is it all a load of bull???

[Tetra]

They are 2 completely different fuels so I would say it was a bit of mistake using full boost on a Super unleaded map with non super unleaded fuel. The other thing to consider is, it might not be the fuel to blame.

All that I know is, my car was mapped on e5, it's seen peeks of 1.4 bar at times and it has yet to explode and hasn't seen excessive knock. I would imagine the maps would be different, as you say, the ethanol content of the fuel would make it run marginally leaner.

I'm not an expert but the only thing I would say is map for the fuel and stick with it, what ever it might be. The map is key, there are loads of lads running 95RON maps making good power, anything is possible with the right map.