Consensus on 87 Octane in a Turbo

[Octanebooster]

Boosted, thank you ! WOW ! That is amazing ! Did not think to look at the fuel additive ( unleaded or not ) .
Stock ECU's ! ? Are you suggesting, my 96 850 T can have mods or different ECU ! ? Or maybe install a different
chip set ?

[boosted5cyl]

In theory you could have a custom ECU or flash that was mapped to run on x octane. It would probably be setup to allow more boost for longer with more aggressive ignition timing. Depending on how close to their limit in stock config, your motor might reach its max potiential before you make the most of the higher octane. You may need more compression or boost pressure (bigger turbo) to reap the full benefits. Especially if you went to something like 115oct. Theres a lot of variables, I'm sure someone who knows more (or anything LOL) about T5 tuning could advise on more specific scenarios.

On the subject of tuning......wife asked me today if I could have a cost no object daily driver what would I get. Had to really think about it for a while, eventually decided that I would take the V70 to a crazy mod shop and have it made into RWD config with a 6speed manual tranny and have the motor modded for max torque, maybe two small spoolers like the TD03's in the T6 or a combo charger/turbo setup. I like the sound of the 5cylinder too much to get rid of it so it would have to stay as a 5. I'd leave the appearance stock though

[gilhuly]

I've given this particular issue a fair amount of thought and speculation over the last couple years. Lower octane fuel burns faster, so in effect hotter at the moment of ignition (though total energy content is not changed - higher octane just ignites slower). I have been told by very experienced mechanics that most, not all burnt valves in turbos they see are in cars running 87. I have also witnessed this first hand. This having been said, I don't actually think this is enough on its own to burn valves. I actually think that burnt valves are primarily caused by leaky valve stem seals allowing oil down the stems and onto the valves where it bakes and accumulates. the crap on the valves acts as an insulator and inhibits the transfer of heat out of the valvesI think that the use of lower octane fuel aggravates this condition.

If I am correct, I think this makes an excellent case for sea foaming your car if you have that smoking after 10-15 mins at idle.

[kaneco]

Are you adding the sea foam to the engine oil or fuel? My 98 v70 xc has the smoking after idle problem. Car also has a rough idle, not a high/low idle just a little rough. Currently running 93 octane with Lucas octane boost.

[JRL]

A REAL bad idea

[gilhuly]

Seafoam won't do anything to fix the valve stem seal problem. Only new valve stem seals will do that. The Seafoam is fed into the combustion chamber through a vacuum port on the throttle body with the motor running. Look for a hot soak technique. There are lots of write ups on seafoaming and lots of endless threads about whether its a good idea. It is not going to hurt. I've done mine and didn't get too much smoke which means I'm pretty clean. If you get the major cloud of smoke, its working.

JRL, what's a bad idea and why? Nobody knows exactly what/who you're talking about or whether there is any solid reasoning behind your statement.