Super Unleaded

scrapbook

Well-known Member
Does anyone here fill there car up with Super Unleaded petrol?

It the price difference supposed to pay for itself in fuel economy?...or is there only an improvement in performance?
 

Layne RIP

Active Member
I use Super Unleaded in my car.. but only for the performance aspect.... i don't see that there is any difference in fuel economy.
After all that would come from a different map in the ECU... and as the fuel is regulated to how much air is being draged in, the fuel consumption would stay the same.
 

Layne RIP

Active Member
All the extra Octane gives you is a better burn / bigger explosion.... so a couple more BHP.. it also helps to prevent pinking.
 

The Dude

Distinguished Member
I think Optimax is a clear winner all-round..

certainly in my last few motors you get a smoother, quieter running engine, and more power at less revs therefore better mileage, unless of course you just hammer it everywhere..

AND it's still cheaper than Diesel.. :devil:
 

ConfusedTA

Standard Member
I put Tesco 99ron fuel in my Honda Prelude, it runs a bit smoother, and has a little more grunt, and it's cheaper than Optimax, which does the same job! ;)
 

Ed Selley

AVF Reviewer
I found Optimax gave a bit more per tank but it didn't completely offset the cost. I do use it every fifth tank as it seems to clean things out a bit.
 

alexs2

Well-known Member
Super unleaded simply has a higher octane rating than ordinary(premium) unleaded,as a result of a higher benzene content,and is becoming more difficult to obtain.

For most cars,most of the time,it simply isnt necessary,but will be useful for some tuned cars,and especially turbocharged cars with higher boost setting than normal...the performance gains on a normally aspirated car will be small at best.

Both my Cosworths were set up to run Super Unleaded,to give a slightly higher maximum boost level,with less risk of preignition,with one running 3 bar and the other 2.5 bar,at which super unleaded is a necessity rather than a luxury....
 

alexs2

Well-known Member
eviljohn2 said:
I don't view it as necessary in this country. The fuel over here is consistently of a high quality so going up to higher octane values won't provide a huge step up, in other parts of the world paying for better petrol can be an excellent investment to prevent the engine seizing up. :)
I'd agree with that,with the exception of high boost turbo engines as above.
 

mason

Active Member
Tons of fun said:
I found Optimax gave a bit more per tank but it didn't completely offset the cost. I do use it every fifth tank as it seems to clean things out a bit.
Thats what I do with my car as I have done with all my cars in the past.

I have a new 320 BMW and it runs why why smother with optimax in the tank- extra power and smother run!
 

Layne RIP

Active Member
On the whole most people wouldn't even notice the difference on their run around.. as it would be small anyway... Jap cars (especially imports, as Japan has 100 Octane) sometimes need the super unleaded... but this is only the high performance ones.
I think if you have a high performance car especially turbo's running high boost you'd be a fool not to use super really.
 

Ed Selley

AVF Reviewer
mason said:
Thats what I do with my car as I have done with all my cars in the past.

I have a new 320 BMW and it runs why why smother with optimax in the tank- extra power and smother run!
I think mine doesn't really care as long as it isn't sambuca.
 

alexs2

Well-known Member
eviljohn2 said:
How would people go about actually doing a direct test of the 2 different fuel types?
Easy enough to do assuming that the car's ECU mapping takes it all into account,and doesnt offer any advantage to one as opposed to the other,as would be the case with many turbo engines,but quite honestly,for any normal road car,the performance gains other than as listed above would be relatively small.
 

Ed Selley

AVF Reviewer
I can only really monitor MPG. I fill at the same place and then do exactly the same journey each day so aside from a slight condition change its pretty constant
 

alexs2

Well-known Member
Tons of fun said:
I can only really monitor MPG. I fill at the same place and then do exactly the same journey each day so aside from a slight condition change its pretty constant
About all that most of us can monitor without a data logger and PC,and performance/power outputs require a rolling road or similar....not really worth it!
 

The Dude

Distinguished Member
I do fairly consistent mileage, and last year was doing almost identical, high mileage, fast paced commuting every week...

I found that Optimax/SuperPlus gave me at least an extra 30 miles per tankfull, which didn't save me any money but is a handy bonus considering you get noticably better mid-range power and a smoother, quieter engine.

I've had a Rover VVC, a Rover/Honda VTEC, and a Mazda Rotary over the last few years, and found high-octane fuel made easily noticeable improvements in each...

I didn't conduct double-blind placebo trials though... so i could have just been imagining the extra performance, and driving slower as a result to produce the extra mileage... :D

Didn't know about the Tesco 99oct stuff, will be giving that a go..
 

alexs2

Well-known Member
Shell Optimax etc do contain detergent additives designed to keep the injectors clean,which may be the answer.
 

lovegroova

Well-known Member
IIRC Shell regular also contains the detergent additives, so using Optimax just for its cleaning properties is probably not worth it.

Honda recommends using 98RON for my S2000 but it still works on 95. Can't say I'v used enough 95 to be able to say whether there's a performance difference.
 

Layne RIP

Active Member
Well with my GT4 Celica.. you definately feel a difference between the 2.. it feels much more resposive on 98ron.. than 95ron.
 

alexs2

Well-known Member
Layne RIP said:
Well with my GT4 Celica.. you definately feel a difference between the 2.. it feels much more resposive on 98ron.. than 95ron.
A lot of that may come down to the ECU type,plus boost and fuel mapping,as the only limitation I had on either of the Cosworth engines was to keep the maximum boost below 2 bar if I had to use unleaded,to avoid preignition...the engine response and power up to that limit was unchanged.

Both of those had Pectel ECUs,which go somewhat beyond the usual road car electronics,and are much more flexible,but not really practical for everyday use.
 

Layne RIP

Active Member
My car is completely standard at the mo... i'm currently trying to source the best parts for it.. i.e Induction / Exhaust.. looking at ECU's and Hybrid turbo's too... there is a 2.1 stroker kit for it.. but i think i'll stick with the standard crank for the mo.
 

alexs2

Well-known Member
Layne RIP said:
My car is completely standard at the mo... i'm currently trying to source the best parts for it.. i.e Induction / Exhaust.. looking at ECU's and Hybrid turbo's too... there is a 2.1 stroker kit for it.. but i think i'll stick with the standard crank for the mo.
At risk of dragging this thread OT,I'm sure you know there are plenty of Toyota tuners out there,but do beware of some the cheaper/nastier ones at the bottom of the market.
What you'll get there is a reasonable amount of power,but with no capacity to deliver it for long periods without problems....most turbo engines are ok for about a 15-20% power increase without significant modifications other than to the ECU,as all you're doing really is to use up the manufacturer's margins in terms of limits in the engine.

Once you get above that,you really do need to pay attention to uprated oil and water cooling,plus crankcase and head breather systems,or you will raise the crankcase pressures and lose oil!

Above that,as you've said,a hybrid turbo will almost certainly be necessary to give you sufficient airflow,but you may also need to consider a set of higher lift cams and to port the head as well to use that......it all comes down to cost.

As far as the YB engine goes,it's all relatively cheap until you get over 300bhp and begins to rise exponentially thereafter,but 500-600bhp can be extracted quite reliably from a 2 L engine if it's done right....OK...enough off topic there!
 

Layne RIP

Active Member
Yeah i've done a lot of research on tuners and Fensport seem to be the best when it comes to Toyotas.... i'm gonna start off mild to begin with, just get the breathing sorted (oh and a decent bypass / dump valve) as the standard ECU will handle that no worries.. should give me approaching 260bhp too (fairly easy 20bhp)... and then see what to change next, the 3SGTE lump is quite strong.. but i will be looking at ways to keep it that way before getting too serious with the power. Oh i'm gonna lag the bottom of the intercooler too... to cut down on the heat soak you get on these from the engine.. obviously i'll be looking at changing it out at some point for a bigger front mounted one... Although i don't want to go too big on the Turbo or give the air too far too travel.. so i don't get too much lag.
 

SeanT

Well-known Member
Fensport do seem to know their stuff yeah.
I use normal unleaded all the time now in my 24v Cosworth XR4x4, because the engine was designed to run on it so super gives no benefit (it's normally aspirated)
However I put super in my (unleaded converted) 90 BHP 1.3 MK I Fiesta as the engine is a little highly strung and carbureted (plus the original engine was designed to run on four star and now has a higher comp ratio...)
Definitely notice the difference in this car, and in my old Capri, although Optimax never gave as much benefit as proper super......
 

chedmaster

Active Member
dad's evo 8 300 needs super, and he likes playing jeremy clarksons game where you let it run right down then go on to the next station, trouble is not as many stations seem to have super any more :D
 

skap7309

Banned
Dave-S said:
I have found that super unleaded can cause problems on older cars. My L plate mondeo 2L injection has reall problems with super unleaded causing the car to have a reall judder at higher speeds. switched back to normal unleaded and its no longer a problem :)
This may be due to the additives in optimax etc that clean the engine, it'll be taking the sludge out of all the hairline cracks in your engine in a high milage car. I found this out when i asked about switching to synthetic oil, its the same thing. hope this makes sense
 

alexs2

Well-known Member
skap7309 said:
This may be due to the additives in optimax etc that clean the engine, it'll be taking the sludge out of all the hairline cracks in your engine in a high milage car. I found this out when i asked about switching to synthetic oil, its the same thing. hope this makes sense
Synthetic oils and high mileage engines which have previously used ordinary oils are definitely a bad combination,as stuff like Mobil 1 will remove all the deposits left around the engine,often with nasty results.

If however,you use a synthetic from day 1,the engine wear is much reduced,and makes an immense difference to turbo engines,esp if uprated.
 
T

trashbat

Guest
lol had a bad experience with super unlead once. because it burns quicker and fiercer the exhaust gases couldn't get out quick enough resulting in £80 for a new backbox and fitting and £100+ for recovery. Not good :devil:
 

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