Unleaded or super unleaded?

[Swifty]

Here's something to ponder.

If I use unleaded I can pull 34Kn @ 5000 RPM and get 1.2 MPL. If I used super unleaded any idea how much extra vroom could I get and would the extra cost of SU payback with a better MPL.

Has anyone tried SU?

Tim'mers.

[Richard B]

No, but I'd have my money on "no difference at all"

[myndit]

I thought that the super unleaded was just a 'marketing ploy' till I put some by mistake in my bike.
I noticed the increase in power within 1 mile of leaving the station. It wasn't just noticable, it was very noticable.

Try some, what have you got to lose (a few quid maybe) and report back to the forum with your findings.

I for one would be interested.

[timw]

Never done any mathematical calculations on this, but I switched to Super unleaded a while back...and I'm sure I get a bit more vroom now

[Rogue Wave]

I know a bit about this as I sometimes work for a company that prepares fuel stations for switching to Super Unleaded and then goes back to the stations about six months later and starts to sort out the problems with the tanks!

Firstly yep you will get more woomph cos it is a different blend of fuel
Thats the good bit,

The blend contains a lot more Ethanol than normal petrol and whilst this is good for whoomph it is also much more hydroscopic and causes clotting , to a degree, of the fuel which can have an adverse effect on your injectors.

So if youare gonna run it then ensure you take the normal condensation prevention steps and you should be fine. better still run it from daytanks!

If memory serves me right Esso, Total, Jet, Texaco amd all the supermarkets all use fuel from Vopak terminals. So its all the same stuff so you can shop on price without worry about the quality.

of all the fuel companies Tesco by far has the best tank maintenance policy so their fuel is usually pretty good.

BP and Shell use propritry fuel

[roycruse]

never tried it in a boat but i tried a tank full of shell optimax in my hyundai v6 coupe once. very noticable on acceleration not sure of effect on fuel consumption or top end.

does any one know of the boat engine manufacturers stance on these "high performance fuels". what do the engine handbooks say...

[timw]

Originally Posted by Rogue Wave

Firstly yep you will get more woomph cos it is a different blend of fuel
Thats the good bit,

The blend contains a lot more Ethanol than normal petrol and whilst this is good for whoomph it is also much more hydroscopic and causes clotting , to a degree, of the fuel which can have an adverse effect on your injectors.

That's interesting Rogue "Rock n Roll" Wave,

I stick it my old Aston with which has Weber carbs...any deteremental effects there do you think?

[Swifty]

Rogue, it is going in an oldish Mercury 3 carb unit which would probably run on camels p*** if it had too. I was interested by the fact that I heard you get about 10% increase in power but it is only 5% more expensive than ordinary unleaded.

I have worries that my unit may not take to higher octane fuel. The book says "Regular leaded, Premium, Low lead and lead free auto gas with a min octane of of 86" but they dont give a max...

[Bilge Rat]

Originally Posted by Swifty

Rogue, it is going in an oldish Mercury 3 carb unit which would probably run on camels p*** if it had too. I was interested by the fact that I heard you get about 10% increase in power but it is only 5% more expensive than ordinary unleaded.

I have worries that my unit may not take to higher octane fuel. The book says "Regular leaded, Premium, Low lead and lead free auto gas with a min octane of of 86" but they dont give a max...

Tim - wouldn't worry mate, with your current costs can you honestly afford to be adding extra cost to your fuel bill

PS made to Allington and back inside the island on 35 litres at 17 nautical miles, running at 25-30 knots all the way there and back

PPS see you mid channel ish

[hard1]

I never heard of a higher octane fuel causing any problems. I used to run race cars on AVGAS and occasionally bunged it in my road ride with no side effects. Mind you, they were different motors then for sure. High octane fuel probably a waste of money in many motors not tuned to take advantage of it. In any event, you could hardly call todays "high performance fuels" such with a straight face. Compared with what we had 20 years ago, it's like weak antelope tinkle.

[Hightower]

And don't forget that if you use a different octain fuel than that used during your tune up or service you might be risking your ignition timing being off.

[Jackwabbit]

I’ve used it in my bike a few times, & yes I do get a few more miles to the gallon.
I put this down to the extra performance, so to stop pulling wheelies I’m not wrenching the throttle back so quickly. BUT as soon as I get used to it the grin factor sets in & I’m back to normal mpg.

[slimtim]

I believe the zapcat racers use it for racing, so I guess it must give better performance. They have 50hp Tohatsu carb motors with boston reed valves.

Tim

[Swifty]

Well it looks like the proof of the pudding and all that. Going to Dunkirk over the weekend and dont want to tempt trouble, but upon my return will fill 1 tank with normal and the other tank with super. Will post the results as soon as.

Bilge Rat: Go on rub it in and yes you will see me mid channel... changing tanks.

Thanks to all.
Tim'mers.

[CJL]

Does the new Verado 275 ONLY run on Super Unleaded?

I thought MR HMS was banging on about that in his mag.

Chris

[lc0021]

interesting thread this... I just 'accidentally' filled up with super unleaded (98 octane..) last week - and I thought there was a noticible difference for the better (on my old Yam 50) .. but I was wondering if it had been my imagination... (perhaps trying to justify paying 1.68 euro for it on a lake in France!!...)

[gtflash]

Originally Posted by Hightower

And don't forget that if you use a different octain fuel than that used during your tune up or service you might be risking your ignition timing being off.

very true, all depends on ur engines, i drive a fastish jap motor, its original speck was designed to run on higher octane fuel from its home country than we have here, the timing and fuel/air mixture is then compensated to run on the minimum recommended 95ron for uk cars. The highest octane roadside fuel is currently optimax (about 98ron) and then esso etc at 97ron or there abouts!!! one tank of optimax makes little difference to the motor but after three or four it really starts to brighten up. Switch back to cheap stuff and its performance lags for a few tanks until the ecu has compensated for shite fuel again! But i was once told that uk cars dagy dustbins and vauxhalls etc are happiest with the 95ron as thats what theyre made to run on out the factory!

[Rogue Wave]

Originally Posted by timw

That's interesting Rogue "Rock n Roll" Wave,

I stick it my old Aston with which has Weber carbs...any deteremental effects there do you think?

I neither know or give a shit about cars!

[codprawn]

Well you should - most modern 4 stroke outboards are basically car engines and I believe the Verado is also based on a car block.

Higher octane will help most engines if they are set up for it but many other factors to take into account - for example compression ratio etc.

Used top be the case that you could buy 5 star petrol - think it was about 105 octane!!!

Despite what most people think proper leaded petrol has NOT been banned - just restricted supply. Ther is a British company still producing it - and it's nearly 100 octane - that's what you need for your Aston!!!

http://www.bayford.co.uk/leaded_petrol.asp

Still wish I could get hold of some petrol from WWII - Spitfires ran on 150 octane stuff............

[timw]

Thank you Codprawn,

I shall investigate.