Avgas is it safe to use

[orsum]

My car and its mods.
The car is located on the east coast of South Africa at sea level.
Its an S2 ABY Coupe
The mods are: 440cc injectors, R8 coils, RS2 turbocharger, "RS2" Exhaust manifold from a group buy, 3" DP and exhaust system, RS2 intercooler and the ECU was sent to Prj to be mapped, according to the info on the ECU its his Stage three software.

Firstly has anybody any experience with these types of fuels.

Avgas 100/130

Small piston engine aircraft.

A leaded fuel.

Avgas 100LL

Small piston engine aircraft.

A low-lead version of Avgas 100.

The issue I have with my car is at high revs it appears to be holding back/pulling back at high rpm. About 5500rpm upward in 3rd gear and about 5000rpm in 4th 5th and 6th gears.

This pulling back is less noticeable on a cold day or if I add an octane booster.

I was at a tuner 2 days ago who said it is the South African low octane petrol that is most likely the issue and that its more than likely the boost etc will needs to be reduced. He also said do not change the software just try Avgas first and see how the car runs. I have no experience with Avgas and I am also concerned that messing with the present software may not be a good idea.

I have located a local airfield that will sell me some Avgas all be it 25% more expensive than pump fuel. If it works and its safe my intension would be to find a mix ratio that eliminates the pulling back and if I had to I would use just 100% pure Avgas.

What do you guys recommend? is it safe short and long term should I give it a try or is there an alternative I should be looking into.

Thanks

ORSUM aka Steve

[Lago Blue]

Hi Steve,

It's good to see you on here again sir! Here's a link to a conversation which (as an ex flight engineer I believe) may best answer (particularly the detail in post #4) your Avgas questions. I'd suggest you look elsewhere, but as I don't share your motor, I'm just guessing - perhaps it is reacting just as it should? Is there an alternate auto fuel brand that might suit? Are there any codes for pulling? Maybe a knock sensor is duff or not well connected?

https://bobistheoilguy.com/forums/th...-in-car.19939/

[orsum]

I think the ECU is doing its job with the petrol we have in SA and I am sure it could be tuned to stop this pulling back. The issue for me is the lack of trust I have with guys in South Africa who have never worked on this ECU before. I mean that in the nicest way possible.

Pity I dont have the funds to fly Prj to South Africa to sort it out for me

I am always logging in will send you an update on the mounts one of these days.

[Tractor Dave]

I think your car needs proper road testing using high grade UK super unleaded petrol here in Wales for 12 months or so. Send me the car and I will perform these test for you free of charge

[orsum]

Just the mention of Wales brings back so many great memories of my days and nights rallying through the forests and roads of a great part of the UK.

Driving my Mini Cooper S from Liverpool to Llyn Trawsfyndd, Blaenau Ffestiniog, Wales to do some trout fishing in the snow and rain. Great times I miss them.

Getting back to your offer. My son has moved to my old stomping grounds and we were chatting about a drive I would love to do in the S2. Reluctantly I will have to decline your offer but if our trip ever happens then I will take you up on a few beers.


IMG-20210320-WA0014.jpg

[Tractor Dave]

Nice trip that would be!
If you pass my way, I do quite a bit of trout fishing myself and would enjoy your company

[JariP]

How are your intake air temperatures? Can you fit a bigger intercooler?

[orsum]

I have the RS2 intercooler fitted but I have not checked the air intake temperatures. As for fitting a bigger intercooler I have not idea of how much bigger I would need to be nor do I know if it will fit without modifying the front bumper which I would prefer not to do.

The air temperatures the car operates between 22 to 40 deg cel winter to summer. When we do have cooler days the car starts to run better at about 18 deg cel or less. The cooler the better

[Ian Simmonds]

Just a thought reading this, have you looked into Water/Methanol injection? 20Vcqdriver on here has run it for several years on a 20vT engine without major issue (I believe).

[orsum]

I am aware of what is available and have not ruled out any additional mods or changes to the car. I do not at this stage wish to do any additional work.

My question is more aimed at Avgas and the alternatives I have asked for are all aimed towards using a petrol additive.

I can get a stock RS2 map, replace the injectors with the stock RS2 and the coil packs and put back the standard ignition system. I am not sure that this would help as I still have the petrol octane issue. South Africa stopped supplying the 97 Octane Jan 2006.

If Avgas or an additive works and its safe then I will most likely us one of them.

I have all the part I took off my standard ABY. I could just put everything back to as it came out the factory and then there would be no more issues and a lot less power.

An after market ECU is also a possibility as I should be able to find a competent tuner but I will still have the 95 Octane issue to deal with.

If I can get a safe reliable fuel that works then that would be my first choice.

Prices in South Africa. Race fuel is 50 Rand a Ltr and standard 95 pump fuel is 16 Rand a Ltr.

[Bowie69]

You can get bottles of octane booster over here, do you have anything similar over there? Normally sold in small bottles in service stations with the oils.

May be worth trying that before doing much else mechanical/tuning wise.

[orsum]

Yep we have additives that claim they will give you the world on a plate

I have sent emails to several companies asking for info on the products.

Seems like Avgas so far is a product that is not being used by many in the S2 Forum

[johne]

Avgas isn't used much in cars in the UK because it's difficult to get hold of and is very expensive. That said classic cars run very well on it because there's no ethanol in it and the high octane means you can advance the ignition. I suspect an S2 would run very well on it as long as you haven't got a catalytic convertor which the lead in Avgas would destroy.

[newsh]

Get a wideband O2 controller on it and make sure it’s not leaning out at high revs. That would be my first move.
As far as the Avgas goes, why not add some to a tank of basic petrol to start with.
Say 10:1 mix, see if there’s an improvement, keep an eye on temps. Then try 5:1.
Go for the full fat leaded one if you’re not running a cat.
If you hook up Vagcom you can watch the temperature sender in the back of the head to see what the ECU sees.
I run 99 in my coupe when I can get it and I’ve had 105 in Germany near the Ring.
Never any issues.
Higher octane means a little less energy from the burn but more power at high boost as the ECU never pulls timing.
Avgas would be illegal for us due to the lead.

[fish]

Just a thought, will the injectors be happy with leaded fuel? And the valves?