Scooby Jonni

Hi,

I’m just wondering if anyone could give me some known good target AFRs for 99ron fuel running a maximum of 1.35bar. The car is a 2.0ltr V3 GC8 STI Type-RA with a standard VF23 turbo, induction kit, turbo back decat exhaust, FMIC, stainless headers and a Walbro 255.

Thanks in advance

Scooby Jonni

Anyone? Pretty please

I'm thinking about 11.3 at full boost, 14.6 at idle. Maybe about 13.8 at atmospheric pressure and linear interpolate the rest?

Slowboy Racing

It’s a starting point, though richer at atmo. Aim slightly richer at WOT until you have your fuel line flat and clean, trim from that point if you want to run leaner. But be warned OE Pistons don’t like getting to hot.

What works best for your car can vary from others so there is not always a consistent, unless of Corse it's a reflash

Scooby Jonni

Thanks very much for sharing your expertise. Its greatly appreciated.

I've been looking at quite a few dyno graphs and taking into to account your suggestions I think my new targets will be:

14.6 at idle
12.8 at atmo,
11.1 from 4000 - 6400rpm at maximum boost
then linearly heading down to 10 at the red line. I'm also thinking of reducing the boost down to about 1.1 bar at the red line so as not to put the compressor out of its range of efficacy.

Unfortunately I don't have access to a dyno so finding the optimum AFR for power is going to be very difficult. My plan is to setup my AVC-R on my stock (chipped) ECU then find MBT at very low load with my mappable ECU in closed loop mode. Once this is done, i'll switch to open loop, start rich and bring up the AFRs to my targets then slowly keep increasing the load maintaining the target AFRs until I hit det. I'll then reduce timing to 2* before this happened.

After spending countless hours reading up on the subject, thats the best approach I can come up with Of course, any comments would be more then welcome.

dynamix

iTrader: (3)

Books and reality differ somewhat though so be prepared to change your way of thinking from your own experience and from viewing logs.

Det cans are a very worthwhile DIY project for you

What ecu have you got?

Scooby Jonni

Hi Duncan,

True, everything I read on the subject seems to suggest a slightly different approach; there seems to be no optimum procedure. I’m trying to learn as must as possible but information on mapping seems a little thin on the ground. I have acquired all the parts necessary to build some det cans and just need to glue them together.

I have a Power-FC, no FC-DataLogIt unfortunately but luckily I’m quite patient.