Changing from Unleaded to Superunleaded

[AFTERSHOX]

I have to say that I've never used regular unleaded in the zed; as GT4 Zed is saying, the car is tuned from factory to run on super (recommended 98 RON if memory serves); and using regular is not advised (unless you use it as emergency fuel to get to the nearest SUPER pump!)

 

I was told by a 'reliable source' that all fuel comes from the same place anyway; it's the amount of additive that goes in to the tanker when they are filling it up pre-delivery;

 

Tesco's fuel is supposed to be 99 RON (which is why it poss came out TOP in the fuel compare); whereas Sainsbury's is labelled 97 RON [at the pump], but is officially rated as 98 RON.

 

Even when you switch loyalties to another brand of fuel - it is suggested that it would take 2 - 3 TANK fulls of the same fuel before you may even notice a slight improvement in smoothness; if you put rubbish fuel in your tank, and you will notice almost IMMEDIATELY; pink pink pink

 

My tuppenny-bits worth

[gangzoom]

Found this on a BMW forum, it was done by an independent tuner.

 

The 335i they tested has a N54 engine, which means 2 small turbos each feeding 3 cylinders, so a 8% gain in power...not that great to be honest and I doubt you can tell on the road. Apparently NA engines gain even less, not really sure why.

 

The recommendation from BMW is to use 95-98Ron, unlike the Z which clearly states 98Ron on the fuel cap (I think). I'm now purely using 95Ron in the 335i, but in the Z i never used 95Ron unless i was totally out of petrol and the pumps only had 95Ron.

 

[Beavis]

forgot to add, you'll need about 3 tanks through before you see a difference.

 

Really? Iirc the cars ecu re-adjusted itself to the fuel you are using took about 50-60 miles of driving. And power difference between the two fuels used on the zed is approx 12-15 bhp.

 

 

And for the record Tim (Lomoto) always ran his zed on unleaded with no issue's.

[was8v]

the apparent cost benefits using unleaded do not outweigh the risk of premature failure.

 

 

 

Do you know of any VQ35 engines (with standard, not remapped ecu) that have failed due to running 95 ron in the UK?

 

The 350z has a knock sensor so I would say its highly unlikely to cause any damage running on 95 over super unleaded. You will just get a bit less power as discussed. Because it has the aforementioned knock sensor, the engine should react instantly to changes in fuel.

 

 

I've read about a few petrol stations filling their super tanks with boggo unleaded and mis selling it - who would ever know? Super is also likely to be older and "stale" as they don't sell so much of it. I only buy super unleaded at busy petrol stations.

 

EDIT - V Power apparently smells "slightly fishy" : http://www.pistonheads.com/gassing/topi ... 1400&mid=0

[Chris`I]

Maybe Abbey can advise us of what exactly the "high det map" does, as thats what you're likely to be running putting 95RON in.

[Zugara]

if you put rubbish fuel in your tank, and you will notice almost IMMEDIATELY; pink pink pink

 

 

I tend to disagree with you here.

 

My car is pinking, whether I use 98ron,95ron any ron. Pinking does not get any better or worse regardless of fuel used.

[Leeroy]

Found this on a BMW forum, it was done by an independent tuner.

The 335i they tested has a N54 engine, which means 2 small turbos each feeding 3 cylinders, so a 8% gain in power...not that great to be honest and I doubt you can tell on the road.

An 8% difference is huge from just different fuel. I just did some maths and that would equate to 22bhp in a 276 bhp Zed, although it's likely a non-blown car would likely be less than that. That's more than you'd get from a decent exhaust (assuming you had a car which didn't cancel out any gains ).

[chrisgunton]

I go to bed and wake up to all these replies! Didn't expect to start such a discussion!

 

Still unsure of what to do really. Will have to see how much it costs for a tank of super and see if that is within my budget. Been pondering selling the car anyway :'(

[Chris`I]

Basically if you cant afford the extra cost of Super, you shouldnt really have a 350z

 

If you can afford it, put it in and forget about it

[Dblock]

if you put rubbish fuel in your tank, and you will notice almost IMMEDIATELY; pink pink pink

 

 

I tend to disagree with you here.

 

My car is pinking, whether I use 98ron,95ron any ron. Pinking does not get any better or worse regardless of fuel used.

 

Your car is broken though

[Mark@Abbey m/s]

The 350z has a knock sensor so I would say its highly unlikely to cause any damage running on 95 over super unleaded. You will just get a bit less power as discussed. Because it has the aforementioned knock sensor, the engine should react instantly to changes in fuel.

 

its only the latest 370z that has full time ignition control (knock) , all the 350Z car only have knock control up to around 5000rpm.

 

Attached is a knock control map from the stock ECU , your see there is knock control up to 5000rpm this is the RED zones , the GREN zones there is no knock control.|Where the green is there isnt any knock control.

 

 

 

Mark

[was8v]

the 350Z car only have knock control up to around 5000rpm.

 

So what does that mean for a car running on 95 over 5000 rpm? In your experience - is damage likely to occur?

[Mark@Abbey m/s]

It could cause damage , I have never had a car in with detonation damage, so maybe it is okay to run the cars on unleaded.

 

If the car see's detonation it will switch to the high detonation Ignition map it wont switch back to the low detonation

ignition map until the ignition switch has been cycled off. So the car onc eit is on the high det map will run around 6 degree's retard on the timing over the entire ignition map so it will not cause damage.

 

I am developing a unleaded map for all the 350Z car but we are just a little short on dyno time at the moment.

 

Mark

[Chris`I]

Any idea how much you expect to have to retart ignition timing for standard Unleaded Mark? Do you think it will be as much as 6deg?

 

I guess if you dont need as much as 6deg less, at least owners running standard Unleaded now are safe, just not running optimally/full power.

[Mark@Abbey m/s]

Nissan dont run a degree figure in the ignition map they run a millisecond figure before peak cylinder pressure, does the

the same thing but not as simple to tune.

 

The timing difference between high and low detonation on a DE motor is around 10 degree's but I would imagine to tune for unleaded we would run the car a little richer as well as retarding ignition timing say around 4/6 degree's Igntion timing.

[Alistair24]

Always use super unleaded in mine

[elfman]

you don't save THAT MUCH with the 5p difference tbf.

 

yesterday i filled up £84.40, i had a 5p/ltr voucher for tesco's so did it there. That was 65 litres worth of fuel, bill at the end came out at 81.10.

 

so for 5p/litre. on around £85 worth of fuel you save about what £3.50. It's nothing in the grand scheme of things, you'd spend more on a large coffee.

[Mears5]

To be honest, you are not going to see a massive increase in MPG, at best you may see enough to balance out the additional cost.

 

The car was designed to run on super so it is worth doing it anyway, just don't look at it as a cost saving.

 

I have signed up to a site that I found on Money Saving Expert which provides details of which companies are selling it the cheapest within a set radius of a post code that you set which has been useful. I have seen a difference of up to 7p per litre from petrol stations within a 5 mile radius of my home. I now tend to fill up at Sainsburys which is currently at 132.9 in my area (cheaper than what some stations are selling unleaded for).

 

May only save you a few quid each fill up but as I drive past the station once per week anyway, I make a point of using it.

 

there is also an iphone app that can show you the best price locally i think my sis said its called fuel smat uk or something but it does exist if its of any use