Fuelling and Octane Booster - roadtrip dilemma

[stevekoz]

First of all I'm not 100% on whether this is in the correct forum or not so apologies beforehand if not.

I've got a bit of a fuelling conumdrum

I have a car that is modified and as such mapped to run 99ron fuel.

On the other hand i have a road trip planned and it appears high octane fuel is few and far between.

Given my car gets roughly 200 miles per tank and given petrol stations selling 99ron fuel are sparse (250miles + apart). That means i could legitimately run out of fuel.

As this is a driving holiday. I could take a large jerry can with me. But for safety reasons alone that worries me... The whole crash and fire thing. However i was wondering are there other solutions??

I know you can buy the usual (often crap) fuel additives from the likes of Halfords. But. Are there any out there that actually would work to increase the octane of 95/97ron fuel to within safe limits to run in a 99ron car.

It's an very well living in the city where 99ron is every where, but, I'm only taking outer hebrides currently not timbuktu. On the continent fuether you drive in sure the same must be said.

So is there an answer to what must be quite a common scenario out on the market and available in the UK or do i seriously need to contemplate buying a new car??

[Smurfsarepeopletoo]

What car is it? and what modifications?

The way I understand it is that although mapped to 99RON, this will be for the peak performance, the car should run on normal fuel, but just wont have the same performance.

I could be wrong though lol

[anonymous-user]

The critical fact is do you have knock control?

If you do (as all modern OE cars do) then reduced octane simply leads to less power, as the engine management retards spark and adds more fuel to keep things cool.

But on an aftermarket ecu without knock control (or an aftermarket ecu with knock control but one that is badly mapped...) then running at high load on lower octane fuel with spark settings for a higher octain fuel could cause knock or pre-ignition (actually worse, because you can't hear it happening...)

Realistically though are you going to be driving at high loads ie could you simply drive carefully if you have to fill up with a tank of lower octane fuel?

[E-bmw]

^^^^ Wot 'e said.

100% good advice there, shouldn't be an issue if the above pans out & you aren't wringing its neck on high load on lower octane fuel.

[stevekoz]

The car is a megane r26 mapped for 99ron. Running 24psi (1.6bar). The engine does have standard knock sensors. Running off a standard ecu. In normal condition the knock sensor would retard timing to cope with detonation. I don't think it's the same for a car mapped to a single high octane fuel.

I've seen the damage detonation can cause from incorrect fuel, to a piston,over yards not miles. It's not pretty. I'm ultimately unwilling to entertain that.

In addition, I'm not sure Its practical to drive off boost (below 2800rpm - 30mph) for what could be up to 250miles. Effectively half the trip. The point of it is to drive the cars. Not stupidly of course but with spirit, at the same time, long stints even uphill is enough to do the damage needed and we'll be well into mountain country.

Alas that seems a bit final.

[E-bmw]

stevekoz said:

The car is a megane r26 mapped for 99ron. Running 24psi (1.6bar). The engine does have standard knock sensors. Running off a standard ecu. In normal condition the knock sensor would retard timing to cope with detonation. I don't think it's the same for a car mapped to a single high octane fuel.

Mapped correctly it is the same, get in touch with who mapped the car. This is the only way you will confirm whether it will do it or not.

Your only other options are as you say take it with you or use a booster, but personally, I wouldn't rely on them.

[stevieturbo]

stevekoz said:

The car is a megane r26 mapped for 99ron. Running 24psi (1.6bar). The engine does have standard knock sensors. Running off a standard ecu. In normal condition the knock sensor would retard timing to cope with detonation. I don't think it's the same for a car mapped to a single high octane fuel.

I've seen the damage detonation can cause from incorrect fuel, to a piston,over yards not miles. It's not pretty. I'm ultimately unwilling to entertain that.

In addition, I'm not sure Its practical to drive off boost (below 2800rpm - 30mph) for what could be up to 250miles. Effectively half the trip. The point of it is to drive the cars. Not stupidly of course but with spirit, at the same time, long stints even uphill is enough to do the damage needed and we'll be well into mountain country.

Alas that seems a bit final.

OEM ecu should always retain good working knock detection.

But if it's really such a concern, speak to whoever supplied the map, and if necessary remap it for fuel that is readily available.

Or just don't drive like a moron. It's a driving holiday yes....but presumably you're not going on a race track ?

[stevekoz]

There may be a track(s) involved unsure as yet.

But i also dont think its moronic to assume driving under 3000rpm on mountain roads and on national speed limit roads, maybe a bit inverse to the whole point of the trip.

It is entirely possible to enjoy a spirited drive whilst not being a moron. At least I'd hope it was. But doing so off boost - that's alot harder than it sounds. I'm aware detonation will occur much higher in the rev range but still. There's risk there even driving sedately.

A change of map seems the best route bar biting the bullet and buying yet another car.

Which in itself offers an interesting conundrum given many performance cars and hot hatches now recommend 97/99ron. Whole different topic i know but it's another interesting point.

[XJSJohn]

few years ago i did a road trip from Singapore around SE Asia (including Laos, Cambodia and Myanmar) in a 370Z that had a few modifications including uprated ECU and injection system so was not very happy running on grotty old mystery fuel.

Whenever i was filling up in one of teh more rural of filling stations (hand crank pumps or filling up from glass whisky bottles in some cases) i had a very fine filter funnel and topped up with HKS Octane booster.

I cannot comment if this helped, but i can say that by doing this the car managed to do the whole trip without feeling like it was having fuelling problems, but i do not know if it was suffering any performance issues as i certainly was not using all 400+bhp on the back country roads where i was getting this fuel either .....

[untakenname]

Best bet would be to fit a boost controller so it's capped at say 16psi instead of 24 when running lower octane fuel, I carry some Silkolene Pro Boost in the boot of my Subaru that's mapped for 99, adding 2% to the fuel should raise the octane rating 2 points.

[stevekoz]

XJSJohn said:

few years ago i did a road trip from Singapore around SE Asia (including Laos, Cambodia and Myanmar) in a 370Z that had a few modifications including uprated ECU and injection system so was not very happy running on grotty old mystery fuel.

Whenever i was filling up in one of teh more rural of filling stations (hand crank pumps or filling up from glass whisky bottles in some cases) i had a very fine filter funnel and topped up with HKS Octane booster.

I cannot comment if this helped, but i can say that by doing this the car managed to do the whole trip without feeling like it was having fuelling problems, but i do not know if it was suffering any performance issues as i certainly was not using all 400+bhp on the back country roads where i was getting this fuel either .....

Yes you are right. Appreciate the story and sounds similar certainly.

I won't be using the all of the 350bhp i have available either but I know that I'll have the opportunity to at least use a chunk of it.

I have emailed a tuner about this and they don't recommend anything but a new map or switchable maps.

We haven't yet talked about octane booster and i see demon tweeks offer a product that will seemingly increase Octane by up to seven to eight numbers. Not sure if that's enough of a hike needed in real world terms.

[stevekoz]

untakenname said:

Best bet would be to fit a boost controller so it's capped at say 16psi instead of 24 when running lower octane fuel, I carry some Silkolene Pro Boost in the boot of my Subaru that's mapped for 99, adding 2% to the fuel should raise the octane rating 2 points.

I hadn't considered a boost controller... D'oh.

Thanks. I'll investigate. Also good to know the pro boost is good add the two points needed but combined with a controller may allow a safer bet.

Thanks sir for the idea.

[stevieturbo]

untakenname said:

Best bet would be to fit a boost controller so it's capped at say 16psi instead of 24 when running lower octane fuel, I carry some Silkolene Pro Boost in the boot of my Subaru that's mapped for 99, adding 2% to the fuel should raise the octane rating 2 points.

If it has been mapped for optimal performance at 16psi, and knock control safeties removed then the same risks are present.

Fitting an external boost controller could change boost everywhere, and would still need the map rechecking at least, and possibly modified.

Again, a lot depends on what the person tuning it has actually done.

Some tuners bodge the fk out of things, some actually do decent work

[Evoluzione]

The only way to do it properly is to load a different map for different fuel if the ECU can't sense it and adjust.
Turning down the boost will not work, if it's happy at full load, at 1 bar on 99 it will knock like buggery with 95 in it. Det does not just occur at high boost pressures.

[XJSJohn]

stevekoz said:

XJSJohn said:

few years ago i did a road trip from Singapore around SE Asia (including Laos, Cambodia and Myanmar) in a 370Z that had a few modifications including uprated ECU and injection system so was not very happy running on grotty old mystery fuel.

Whenever i was filling up in one of teh more rural of filling stations (hand crank pumps or filling up from glass whisky bottles in some cases) i had a very fine filter funnel and topped up with HKS Octane booster.

I cannot comment if this helped, but i can say that by doing this the car managed to do the whole trip without feeling like it was having fuelling problems, but i do not know if it was suffering any performance issues as i certainly was not using all 400+bhp on the back country roads where i was getting this fuel either .....

Yes you are right. Appreciate the story and sounds similar certainly.

I won't be using the all of the 350bhp i have available either but I know that I'll have the opportunity to at least use a chunk of it.

I have emailed a tuner about this and they don't recommend anything but a new map or switchable maps.

We haven't yet talked about octane booster and i see demon tweeks offer a product that will seemingly increase Octane by up to seven to eight numbers. Not sure if that's enough of a hike needed in real world terms.

if you are going somewhere as daft as i was, your bigger issue is fuel age / quality / dirt / water / ethanol / bio mix

As your tuners have said, they could put a switchable map in which may be the way to go. i forget are you on teh stock ECU? its an expensive option but you can get after market ECU's that can have up to 4 maps (maybe more nowadays)

[Inline__engine]

nulon pro strength octane booster works