Leaded Fuel

[Faheemo]

Hi ,
I own a 96 S2 down here in S.Africa, My Second one. First was a 3B.
My car has been decated.
I believe the knock sensor is limiting boost, Due to low octane ratings wher i live . Is it possible to use leaded fuel??
What will the consequences be ?
the fuel available is 97Octane Leaded and 93 Octane Unleaded.
97 Unleaded is available but not in my location.

[Jas11n]

If I remember correctly, leaded fuel will kill your lambda probe..

[Billman]

and the cats that you removed

[Jas11n]

and the cats that you removed

[S2central.net]

This is a real problem alright - the best solution (if quality pump fuel is not available) is octane booster - something with MMT additives like the products from Millers are good.

The alternative is to hook up with a paint shop and secure a supply of Toluene - search the forum for Toluene and you'll get some more info. Its got a much higher RON & MON rating than pump fuel... but you can't run too high a concentration in the tank or you'll have problems with cold starts.


Paul

[GandalfS6]

Hi Faheemo

Welcome to the Forum! From what you are saying you live up in Gauteng (only 93 available)?

The solutions - you can buy leaded Shell or BP racing 102.6 octane - pm me if you want to know where to get some. It is more expensive than normal fuel and It costs about R6.50 (GBP 0.59) per litre. If you mix that 50:50 with 93 you have 98 octane. You can also buy unleaded racing fuel at the Sasol at the Kyalami race track on a Wednesday afternoon. It costs R7.00 per litre.

You can get Toluene at Protea Chemicals - do not use more than 10% with normal fuel, work in a well ventilated area and use gloves (it is carcinogenic) It has an octane rating of 121 so 10% would give 95.8. My S2 does not like more than 10% (too cold a flame front).

Personally I think the best long term solution to our problems up in Gauteng (poor 93 fuel, high altitude (1700 m above sea level) and high temps) is too fit water injection. It costs GBP300 for the Aquamist 1s system and water is free You can happily use 93 octane without worrying about knock.

I use WI with racing fuel but I have quite a strong S2. My car loves the water - it was running at intake temps the same as ambient on a dyno!

BTW Leaded fuel will reduce the life of the lambda probe and the plugs, generally half the normal life - which is not too bad

[S2central.net]

Ain't it Benzene that has carcinogenic risks ? Toluene is similar but different. Tis my understanding that handling of Toluene is no worse than good old octane from the fuel pump.

Paul

[4WheelDrifter]

Petroleum's not exactly the safest thing you'll ever handle. I guess wearing protective clothing and breathing apparatus at the pumps is a little too much trouble. But Toluene is thought to be less carcinogenic than benzine.
It sounds like the general motoring public may one day have to handle hydrogen. That sounds like fun!

[Beetie]

Or if you were on the m6 today burning carbon dioxide......

[Faheemo]

Thanks a lot for all the info,
But i dont think i'll be mixing hydrocarbons all that often.
Rather sacrifice and drive the distance for the correct fuel whenever possible.
i dont think anybody complains of driving an audi s2.

[S2sedan]

Gandalf,

Can you tell me more about water injection ???

In Brazil we have problem with fuel too, so i run on ethanol. (alcohol) we have it at fuel stations. In cold start i have a system that injects gasoline

[GandalfS6]

Can you tell me more about water injection ???

Have a look at www.aquamist.co.uk

We have pretty extreme conditions up here in the Highveld of South Africa. Best fuel = 93 RON (and crappy at that), we are 5000 feet above sea level and the ambient temps in summer get up to 35 degrees. Water injection was first used in World War 2 fighter planes. At the moment I think all WRC teams use WI.

Basically, you inject water at high pressure through a small jet into the intake sytem, just after the intercooler. This results in a fine mist which then mixes with the air and fuel. It cools down the air quite effectively and does a great job at stopping knock. If you tune the car for water injection you can increase power quite a bit, but be careful - if the water injection stops for some reason (blocked jet etc) and the car is tuned to run with it, EGT's goes sky high and you tend to melt engine parts. My tuner prefer not to tune for WI unless you have boost blowoff valves that kicks in if the water injection stops.

What it would do if you didn't tune for WI, is that your car will feel the way it does on good octane on a cold evening - but all the time!

I did a test with my car one evening - the ambient temp was 18 Celcius. Driving nicely the intake temp (shown by the ECU) was 20 C - If I stop and nail the car to redline in 1st,2nd and 3rd, the intake temp would increase to 37 C. With WI it only increases to 22 C.

I must post my WI install in the "Guides and Top Tips" forum

HTH

[S2sedan]

please do that, as Brazil is as hot as South Africa, but the only good thing is our alcohol on pump, alcohol is very very cold.

Gandalf, does the engine suck the water thru the intake ?
Does it make the combustion worse ?

[S2central.net]

Have a look at www.aquamist.co.uk

We have pretty extreme conditions up here in the Highveld of South Africa. Best fuel = 93 RON (and crappy at that), we are 5000 feet above sea level and the ambient temps in summer get up to 35 degrees. Water injection was first used in World War 2 fighter planes. At the moment I think all WRC teams use WI.

Basically, you inject water at high pressure through a small jet into the intake sytem, just after the intercooler. This results in a fine mist which then mixes with the air and fuel. It cools down the air quite effectively and does a great job at stopping knock. If you tune the car for water injection you can increase power quite a bit, but be careful - if the water injection stops for some reason (blocked jet etc) and the car is tuned to run with it, EGT's goes sky high and you tend to melt engine parts. My tuner prefer not to tune for WI unless you have boost blowoff valves that kicks in if the water injection stops.

What it would do if you didn't tune for WI, is that your car will feel the way it does on good octane on a cold evening - but all the time!

I did a test with my car one evening - the ambient temp was 18 Celcius. Driving nicely the intake temp (shown by the ECU) was 20 C - If I stop and nail the car to redline in 1st,2nd and 3rd, the intake temp would increase to 37 C. With WI it only increases to 22 C.

I must post my WI install in the "Guides and Top Tips" forum

HTH

Interesting info there - I have often thought the idea of WI to be absolutely fine in theory but I've never seen documented before/after results like you describe. Any photos of how & where you installed your Aquamist system ?

Mapping the Motronic ECU with WI would be absolutely fine... as it all the fallback mechanisms to retard timing and reduce boost in the event of knock detection / very high air temps. Motronic is fundamentally a failsafe system - it would automatically compensate for a blocked water injector - or an empty bottle.

Talking of which - what is the water consumption like ?


Paul

[GandalfS6]

@S2sedan - as the water is pumped through the small jet (I use a 0.7 mm jet) at high pressure (7 Bar on my Aquamist race pump). This creates a very fine mist, that as soon as it hits the hot air (even after the intercooler - Paul's turbo spreadsheet shows that with 86% compressor efficiency the temp of air exiting the IC when ambient is 20C would be 41C) the mist is turned into (mostly) steam. In the process the intake air temp is reduced drastically.

@Paul, I will see if I get some time over the weekend to post a install guide. I basically placed the water pump behind the LHS headlight (near to the washer tank and a relatively cool place) and tapped the jet into the pressure pipe in the front cross member (just after the IC). This has the advantage that the water is injected almost 2m before the throttle body and has lots of time to mix properly with the air fuel mixture. I use the washer fluid tank which takes about 7 litres of water so the water lasts quite a while. The 0.7mm jet flows at 260 mm / minute but it only kicks in if the boost goes over 0.9 bar. (I'll talk about that a bit more in the install guide).

The problem for tuning with water is that the water drops the EGT's significantly. As I understand it, you would advance the timing untill the EGT's get up to normal levels. If the water then stops as result of a blocked jet for example, the timing is so advanced that the knock sensors can't pull the timing back fast enough not to destroy the engine. Minhea should be able to explain this much better. In South Africa a few agressively tuned Scoobies burned holes in their pistons when this happened. My tuner prefers not to tune for WI unless you have a boost blow off valve linked to a water flow monitor. I have installed the Aquamist DDS2 water monitoring system but I am still wating for the blow off valve that is linked to it.

I am considering upgrading the Aquamist 1S system which is the basic system that starts pumping at a pre-set boost level and is thereafter linked to boost pressure to a 2d system. It is more advanced in that it monitors the fuel flow of the fuel injectors and supply water proportional to the fuel flow. You can then set the system to for example always flow water at 10% water : fuel ratio if the boost is over say 0.5 bar. The 1S system flows a bit too much water at high revs.

HTH