Air Fuel Ratio for TC

[Sheltie2306]

Hi, anyone can advice how lean can we push for TC car at high load and high rpm region?

I am runing about 10.5:1 and that seems safe and stable. But had seen people going at 11.5:1 or even 12:1, much better power, but is it safe for the engine ?

 

Anyone with proven experience can share ?

Edited January 23, 2005 by Sheltie2306

[Vtim]

you too hiong liao, have you check with your REX kakis in subaru club SG ????

[Sheltie2306]

Well, it's sad to say that there's very very few people in Singapore that do hobby DIY ecu tuning to this level. Those really knowledgeable few are probably in the trade to make money, and they are not willing to share.

 

I am getting most of the information from US and Australia forum, the people there are very open and friendly.

[Genie47]

Then get the info from them! I got a lot of info on Starlet 4E-FTE transplants from them. Also learned a trick or two about get incredible horsepower.

[Yeobh]

The best ratio is 14:1, too lean the chances you will burt your valve and kill your plugs.

[Genie47]

Not only that, very lean mixtures result in hotter exhaust temperatures. I have witnessed a Starlet's turbo get so hot the actuator melted off. The turbine inside has white residue which is tell tale of hot exhaust. The turbo might have suffered bearing damage as well .

[Dwoon]

Understand that 10.5 AFR is a good safe bet. I also understand that in certain places in the US, 11.0 is used but locally here in Sgp, the weather is just too hot.

 

If you wanna push it to the limit, check the knock readings as you slowly increase from 10.5 and monitor closely. But if no safety margin is given, what happens when you run into a bad batch of fuel??? I'm no expert in this area but just sharing what little I know.

[Esky]

Genie bro,

 

can share-share those incredible hp tips ah?

[Saaber]

so bro, when I can test sit your forester?... ...heard some good things from a friend abt your ride...

[Dwoon]

Shhhhh .......... , actually nothing when compared to his lah ........ his twin scroll leh...... & wait till he's done with his stuff, I smell no smoke man

 

Can let you take a spin and compare with Saab, will try to meet up with you guys during the weekly thinggy at Bishan. I've not tried Saab before leh, maybe we can try try each others ride & .

[Yeobh]

About 18 years ago I introduce a Japanese chip tuner to my friend. He was so absorbed in the new way of tuning cars that he paid frequent visits to the master and even spend time at certain Japnese racing circuit to beef up his racing skill. He was one time quiet well know in both the local and Johor circuit.

He is always trying to push to the engine to the limits - finally he went to the limit of no return.

Take care

[Saaber]

too bad...I sold my saab liao but test drive can still be arranged......but it is no normal Saab hor...

[Genie47]

Nothing but more fuel and air. The siao Starlet owners down under have bigger injectors, bigger turbos, additional injectors on the intake manifold (so 8 in total!), rising rate fuel regulator and 225lph fuel pump.

 

Of course all this is nothing if the gear cannot transmit the power so they have heavy clutches and use the toughest gearbox. In the end, the all famous Brownster from www.toyotagtturbo.com produced 240 wheel horsepower .

 

So far, 4 other Aussie Starlet owners have crossed the 220 wheel horsepower mark. All I can say is that the Aussies are F***ing crazy! Must be all that beer.

 

That is why I am enlightened. Power must come from input of fuel AND air. You cannot cheat the laws of physics. Matter cannot be created or destroyed. Unless engine is nuclear powered .

[Vtim]

Well, it's sad to say that there's very very few people in Singapore that do hobby DIY ecu tuning to this level. Those really knowledgeable few are probably in the trade to make money, and they are not willing to share.

 

I am getting most of the information from US and Australia forum, the people there are very open and friendly.

all the best man, when all is done, I hope to have a ride in your car

[Sheltie2306]

Hi all, thanks for all the infor and advice. Just to share, someone in US replied me with the following table:

 

The horizontal is the load (MAP) in %, vertical is rpm. He is suggesting to run 11.5:1 on high load side. Anyway, I will try his suggestion.

 

Another thought that I have is at 11.1:1, the flame speed is the fastest, and there will be lesser chance for abnormal combustion (detonation), and may be can run higher timing. Just my thought, will try to verify.

 

0 10 20 30 40 50 60 70 80 90 100

 

500 14.7 14 14 14 dna dna dna dna dna dna dna

750 14.7 14 14 14 -------------------------------------------

1000 14.7 14 14 14 ---------------------------------------------

1250 14.7 14 14 14 ---------------------------------------------

1500 14.7 14 14 14 ---------------------------------------------

1750 14.7 14 14 14 ---------------------------------------------

2000 14.7 14 14 14 13.5 13 --------------------------------

2250 14.7 14 14 14 13.5 13 12.5 12.5 12 11.5 11.5

2500 14.7 14 14 14 13.5 13 12.5 12.5 12 11.5 11.5

2750 14.7 14 14 14 13.5 13 12.5 12.5 12 11.5 11.5

3000 14.7 14 14 14 13.5 13 12.5 12.5 12 11.5 11.5

3250 14.7 14 14 14 13.5 13 12.5 12.5 12 11.5 11.5

3500 14.7 14 14 14 13.5 13 12.5 12.5 12 11.5 11.5

3750 14.7 14 14 14 13.5 13 12.5 12.5 12 11.5 11.5

4000 14.7 13.5 13.5 13.5 13.5 13 12.5 12.5 12 11.5 11.5

4250 14.7 13.5 13 13 13 12.5 12.5 12.5 12 11.5 11.5

4500 14.7 13 13 12.5 12.5 12 12 12 12 11.5 11.5

4750 14.7 12.5 12.5 12.5 12 12 12 12 12 11.5 11.5

5000 13.5 12.5 12 12 12 12 12 12 12 11.5 11.5

5250 13 12 12 12 12 12 12 12 12 11.5 11.5

5500 12.5 12 12 12 12 12 12 12 12 11.5 11.5

5750 12 12 12 12 12 12 12 12 12 11.5 11.5

6000 12 ------------------------------------------------------------------------

6250 12 ------------------------------------------------------------------------

6500 12 ------------------------------------------------------------------------

6750 12 ------------------------------------------------------------------------

7000 12 ------------------------------------------------------------------------

[Autocraze]

Shhhhh .......... , actually nothing when compared to his lah ........ his twin scroll leh...... & wait till he's done with his stuff, I smell no smoke man

 

Can let you take a spin and compare with Saab, will try to meet up with you guys during the weekly thinggy at Bishan. I've not tried Saab before leh, maybe we can try try each others ride & .

let him try the 1.5bar version lah.. B*LLs will not shrink, they simply melts.

[Autocraze]

too bad...I sold my saab liao but test drive can still be arranged......but it is no normal Saab hor...

---

think ground force cannot excite u anymore... go try those roller coasters with near 2G.....

[Slowpoke156]

How much boost are you running at each rpm? What is your intake charge temperature? If you have these info available, it's easier to advise.

 

For maximum power, you will need a mixture of 13:1. Problem is, our hot climate does not permit this as our ambient temperature is too high. If you can drop your charge temperature by 20 deg.C or so (by water injection or maybe a more effective intercooler with water spray), then you can lean it out a bit more.

 

There are a couple of reasons why people run super rich;

1. Rich is better than lean, detonation reduces your engine to scrap in seconds

2. When running rich, fuel is actually used as a coolant to bring down the intake charge temperature

 

Everything about the engine revolves around heat. If you can deal with that effectively, anything is possible.