100+mph with new Optimax & Booster ?

[paul_honthy]

Since owning the car I've been very careful not to drive over 100mph (on private roads of course) for any length of time to avoid running lean coz of the crappy fuel we have.

 Now that im running the new 100 Ron Optimax plus octane booster is it mechanically safe to go above 100 mph for a longer period of time?

Surely this combination is equal to the Jap fuel making it safe to run the car like its meant to be without fear of melting a piston !!??

Any ideas people ?

[colin_ross]

What kind of intercooler do you have?

Evidence suggests that it isn't the fuel that causes high speed det but the fact that the tmic's are not effective at higher speeds. The air that should be directed down the scoop and through the i/c gets blasted over the scoop and leads to high charge temps which leads to fubar'd engines.

[harvey_smith]

At high speed the air is still going into the scoop. Put some bits of wool on your bonnet with sticky tape and prove it for yourself. The TMIC is not big enough or efficient enough to cool the compressed air charge.

Anything above .2 bar of boost on my STi3 Wagon and the charge temperature will rise very slowly. From fully warm and 0-100mph and the charge temp. is 50 +, some spirited driving to 80 mph and then a sprint to 100 and the charge temp is 65 Deg C!!!

In the cruise at say 80mph with Charge temp under 30 C (varies due to ambient ) and apply throttle for a max speed run and by the time you get to around 135mph the guage is reading --. It stops reading at 69.9.

Before I had a charge temp guage I have seen 165 on the clock and still rising. Probably neare 155.

The high charge temps are what kills Scoobs and even uprated TMICs cannot cope.

Consider getting a charge temp guage, about £45 and drive accordingly to preservr the engine.

Ignorance is bliss but it could all end in an expensive BANG.