Hi,

I am running about 13 psi of boost with various supporting modifications. And the ARF on full load is in the high 10's.

It's been suggested mid 11's is a better place to be, but I also understand these engines do prefer to run on the rich side, and would prefer to run slightly rich rather than lean.

My question is - would running this rich be causing me too much loss of power and if so much?. On my piston engined Suburu getting the car to run as lean as possible (but within safe ish limits) and made a big difference to the power. Whilst mapping you could actually feel the difference after a threashold point between rich to lean. The difference was not linear it was like a light switch once you got past a certain point.

Can I expect a similar scenario on the RX7. ? The car feels plenty quick enough, but can't help but wonder that perhaps there is still more to come.

You can currently pyshically smell the fuel on full song where its running so rich at the top.

 

You should be running low 11s:1 with good pump fuel at 13 psi. You could safely lean it up a little bit.

A safe tune on 91 octane (R+M/2, not RON) would be very low 11s:1 at 13 psi.

 

I would say as long as you stay under 11.6-1 you should be fine Especially with such low boost. Even if you want to be safe you can run it around 11.3-1. To answer your question you might be restricting a small amount of power but nothing crazy with the richness. What it will effect the most is throttle responce and turbo lag should get a little better. Good Luck

 

When I was still running the twins I noticed a big difference in the but dyno between mid/high 10's and high 11's.

 

11.2 at 14psi
11.5 at 12psi
11.7 at 10psi
12.1 at 0-10psi
This is what I have been running for over 6 years,

 

Thanks all - you confirm what I thought and I am running way beyond the side of safe, and will get a little braver and lean off, subject to everything else being well.

I have resisted the temptation and still running about 10.6 AFR. So have plenty of scope to keep creeping this fuel back slowly and carefully. Leaning in the past on other cars I have owned has made a dramatic difference. But I guess there is a fine line, and just don't want to cross it.

Thanks for all the input - I feel more comfortable playing more with the fueling now.

 

Wow just dun the first WOT runs with my LM-1 wideband and at 10psi im averaging 9.7 in 3rd to redline, looks like i got a way to go.

 

It depends on the octane. Chuck (cewrx7r1) is using 93 (R+M) octane fuel. I'm running 91 octane and therefore run slightly richer. I don't know what octane fuel is available in England.

 

Well iv been doing some diging on ron and mon and i know that i run on 95-99 octain petrol all the time (thats with the ron+mon figures).

http://www.petrolprices.com/about-fuel.html

Search for the word tesco and thats what i run my car on.

Paragraph above shows that its worked out R+M.

 

lol at 9.7 you are probably loosing loads a power. If it anything like my other cars once you get in the 9's the power is drained away.

With regards to fuel above - we must get te good stuff over here, and 96ron on cheap fuel and 99ron on the good stuff which is what I run.

 

Yer guess i am loosing power but only just got the LM-1+LMA-2 Wideband O2 so i can tweak a little.

Power FC is soon to grace my car so that combined with the LM-1 will let me get closer to my fule targets.

BTW Tescos fuel rating of 99 is suposed to be calculated on RON+MON so is not just a RON rating, As stated before by Rynberg RON duznt mean octain.