Petrol

[lust2luv]

Okay, bearing in mind I'm running a (comparatively) lowly N/A...

 

I'm using regular unleaded at the moment.  Am I crazy?

 

Should I be using super-unleaded?

 

Is the only difference the temperature at which detonation occurs?

 

I have an American friend who says that  _occassionally_ using a higher grade of petrol (or rather "gas") provides some lasting benefits to her engine - is she right?

 

Oh and does that Shell Optimax stuff have added benefits other than a higher octane rating?   Any idea how much that stuff is at the moment - regular petrol seems to have dropped somewhat recently.

 

Would Optimax be likely to give me any noticable performance benefit / loss?

 

What are other NA'ers running on?

 

Apologies for all the questions - Thanks in advance for any advice.

 

Cheers

 

[AJI]

I always run on optimax, being jointly developed by Shell and Ferrari it is a lot better grade of fuel over 'normal' unleaded. Aswell as a higher RON value there are 'cleaning' additives mixed into it, so aswell as a performance increase there is also an engine 'cleaning' benefit. (Cleans out built up carbon residue from engine)

 

I think (but don't quote me) that the average BHP increase for a 3.0L Twin-Turbo engine is something like 6-8HP. But not sure what it will be for a N-A engine. There are also fuel additives that you can add to increase BHP by about 5HP, I think they cost about £2 from Demon Tweeks.

 

AJI

[Ring Master]

 

Whether your car is NA or blown, it will be mapped

for a certain grade of fuel.

 

If your car is a jap import , chances are it will be mapped

for 100ron fuel, ie ignition timing will be advanced enough

to the point where detonation doesnt occur. Run 95 ron

and chances are your ECU will pick up knock, take a big

chunk out of your ignition timing, this will cause a loss

of power and fuel economy.

 

Give Optimax a go and see if it helps, dont 4get to reset

the ECU by disconnecting the battery for an hour.

 

 

Justin

[lust2luv]

(please bear in mind I'm a complete duffer when it comes to tech stuff)

 

I was worried Optimax might be too high a RON for my engine, didn't realise Jap cars were configured for such a high rating.

 

Sorry, but why do I need to reset my ECU... and come to think of it, what is an ECU?!  (see disclaimer above!)

 

Could disconnecting my battery cause problems with my alarm (a Clifford, I know it has back-up power and don't want to drain it).  I guess I can just deactivate it first.

More to the point, anything to watch out for when disconnecting the battery?  I do know you have to remove the clips in the correct order (negative first?) but is there anything else Supra specific to watch for (like the starting the ignition with the dash off thing)

 

Finally is mixing fuels problematic?  Presumably I should switch grades with as empty a tank as possible?

 

Again sorry for being such a dunce!  Thanks for your patience!

 

Cheers

 

[Guest Martin F]

Quote: from lust2luv on 5:10 pm on Nov. 2, 2001[br

 

I do know you have to remove the clips in the correct order (negative first?) but is there anything else Supra specific to watch for (like the starting the ignition with the dash off thing)

 

 

No Offence Lust, but that one always makes me laugh.

 

I have heard of this one many times before, but whoever came up with removing the terminals in a RIGHT order ?????

 

As far as i know, it makes sod all difference.

 

 

[lust2luv]

The way I heard it the negative earthed the battery, so if you removed the positive and then were dumb enough to drop it against something metallic you'd be completing a circuit with nasty side-effects.  Maybe it's nonsense then?

 

[Guest Martin F]

Maybe not then in that case.

 

Makes a sort of sense, but you'd have to be pretty silly to drop it for long against something that shorted it out!!!

 

I was trying to think of an electrical\technical reason why to do it a certain way.

 

 

Don't try this at home kids!

 

 

 

 

(Edited by Martin F at 5:40 pm on Nov. 2, 2001)

[lust2luv]

Ah see, but that's just the sort of dumb thing I'd be likely to do!

 

 

I know computing and operating consumer electronic (if anyone needs a hand programming their video), but my motto is "if you need to remove a screw to access it, it was never intended for my fiddling"!

 

[Gareth Davies]

When I had my NA, putting super in it really did help, I don't think it's possiable to have too high a ron fuel (ok within reason) since we're all after the magical 100 ron.

 

I believe a better way to reset the ECU is to pull the EFI fuses (1, 2?) for 30ish seconds. They're labeled in the fuse box in the engine bay. That way you don't have to worry about the alarm, radio etc. The point of this is so the ecu has to 're-learn' and thus picks up the better ron immediatly. There are side effects of this, i.e. floating idle etc. but it should have relearnt within about 15 minutes of varied driving. Otherwise it takes it about a tank (and you don't need to play with the ECU).

 

Trust me, some optimax and millers will do wonders for the humble NA.

[lust2luv]

Okay, I'm giving the Optimax a try - 74.9p, very nice, cheaper in fact that super unleaded at most garages around here, I was under the delusion it was much more.

 

Anyway I took Gareth's advice to pull the EFI 1 fuse (don't seem to have an EFI 2) for half a minute.  [bTW the way the fuse is fitted  the '30' on it is upside down, is that unusual?]

 

Problem: I was hauling in a speeding black 911 this afternoon when I noticed something weird.  Hitting 100 the red warning triangle in the speedo starts flashing and it stays lit above 115, although the car's still delimited.  (all on my private test track, natch)  

 

Presumably this is a feature of the speed limiter when it's working?

 

Any easy way of deactivating it?   Although I guess I could learn to live with it.

 

Cheers

[Gareth Davies]

Have you never seen this before? When the warning triangle came on did any of the other lights come on? I believe a functioning speed limiter doesn't trigger any warning lights, just a loss of power.  Also I don't believe the large warning triangle is supposed to flash. I definatly did not see anything like this in my NA, which had managed signifigantly more than that (we're talking km officer...). However I did see a similar problem in my TT when the speed signal was duffed.

 

AH's speedo does all kind of fruity stuff over a certain threshold, I don't recall were you got your car from (if you've mentioned it before). But as you assume it, does sound like a duff speed conversion / speed limit  defencer (SLD).

 

If this is the case though there isn't an 'easy' fix (see Paul Booth's epic thread on speed coversion elsewhere on the board). I believe Pete Betts does a good unit ( http://www.trlperformance.com ) for about £80 the harder bit is sorting out the old conversion properly.

 

Maybe it's worth opening another thread as many of the more knowledgable people on this subject have very little time and will probably not recheck a thread on petrol types.

[Rob]

My N/A supra used to flash the triangle when I hit the speed limiter (now delimited) and really curiously, the first time I ever hit 180kph was at night, and the interior lights flashed as well. How weird is that?

 

But, Lust2Luv, do tell us if you notice any performance benefits from using Optimax. I sometimes run Super if I'm feeling flush, but haven't really noticed any difference.

[lust2luv]

No, it never did it before I pulled the fuse, so hopefully it can't be that hard to remedy, although as I say I guess I could live with it.

 

Rob, I think I'll definitely be sticking with Optimax (unless fuel prices go through the roof again).  Don't know yet if the performance is noticably improved, it's only supposed to be a few BHP anyway, but I did run down that 911!  

 

Starting a new thread as suggested...