what should the air fuel ratio on a new age stippp be?
martin

 

How are you measuring it? At what load/revs? Short answer, 14.7:1 idle/cruise, rising to low 11s or richer on full boost I would think.

 

it is for a friend (honest) who ran his car at dastek and was told his car was running rich at 10:1 during the dyno run
it is an stippp with tsl grou n bb,centre section and sti air filter

martin

 

10:1 doesn't surprise me. It is very safe.

 

fair enough,you probably know more than some subaru specialists
thanks
martin

 

No, just I've seen a lot of STi ECU maps (not the PPP, but I expect it is still rich) and the requested AFRs are rich +++.

Prodrive are engineering it to be suitable for hot weather conditions hammered continually without monitoring tools and potentially suspect fuel whilst keeping the pistons cool and will have tested it in those conditions I expect.

10:1 will probably lose about 10 BHP at most (pulled that number out the air from rough testing on non-STis) from running 11:1 which is probably lean enough with cats in place.

 

it was gerry saying it was running "very" rich,i know that prodrive do run their cars that way-the first thing i noticed on long journeys with the remap was an improvement in economy! i thought it sounded ok but was not 100% sure
thanks
martin

 

Think yourself lucky, mine was 9:1 on my bugeye WRX........... now thats rich
Spooks

 

especially considering your results!
martin