Fuel???

What fuel does everybody with an SZ use then, i have always used optimax but wonder with prices going higher and higher can i use normal 95 ron ? lova ya

I always use Optimax, or 98 Super Unleaded if stuck. Some people say the NA engine is less demanding so 95 is okay, but as I see it, it's a Jap import and hence supposedly mapped for 100 RON over there. The ECU will cope with the cheap stuff, but I like to treat my baby to the best.

Originally posted by lust2luv

I always use Optimax, or 98 Super Unleaded if stuck. Some people say the NA engine is less demanding so 95 is okay, but as I see it, it's a Jap import and hence supposedly mapped for 100 RON over there. The ECU will cope with the cheap stuff, but I like to treat my baby to the best.

 

It is also supposed to go a bit further but I have found that to not be the case with the supe. It certainly used to go about 10% further than normal unleaded in my sierra.

Cheap stuff and the word petrol can not be used together

I've run my SZ-R on 95 and Optimax and in my opinion the Optimax is a waste of money on a NA.

Its much more expensive, makes the car do lower MPG and I cant even notice any difference in performance, hence dont use it anymore.

Originally posted by toyotasuprauk

Cheap stuff and the word petrol can not be used together

 

I've run my SZ-R on 95 and Optimax and in my opinion the Optimax is a waste of money on a NA.

 

Its much more expensive, makes the car do lower MPG and I cant even notice any difference in performance, hence dont use it anymore.

I have found this with my supe. With my other cars however I do notice a difference. In my normal road cars on normal daily runs I find my fuel goes about 10% further if I use premium or optimax or super unleaded. Its a tad strange that the N/A soop is a bit strange in this respect. I think that the N/A supe is pretty much tuned as far as it can go which is why further tuning is very expensive. I think that expecting fuels to help in an environment where every tuning matter is allready optimal is being hopefull. Perhaps if the ECU was a little more programmable or perhaps tolerant then the use of optimax may prove advantageous.

Well the idea's meant to be that higher RON fuel (optimax is 98.5) is more resistant to igniting under compression, so the timing can be advanced further without pre-ignition and thus greater performance be had.

Unless you adjust the timing yourself, it needs an engine/ecu with active knock sensing/adjustment - that's a little more than just a knock sensor - it needs to be able to adjust it's timing in increments up until knocking occurs, then back off slightly.

Or so I read, somewhere, quite some time ago.

Funny thing is I certainly would have expected the Supra to have this functionality. Maybe it only does this when it's "learning", so pulling the ECU fuses for 10 seconds before filling on Optimax might help?

With regard to going further (mpg), Optimax is of a higher density than other fuels, so there's more of it if you see what I mean, however the counter argument to this seems to be that fuel is delivered by volume, so it doesn't matter. ? Maybe this explains why your older non-injected car went further on it, but fuel-injected cars don't?

(hoping someone can confirm or shed some light?)

I have run my SZ on 95 RON for the last 3 years. No problems so far.

OK I've got a TT and run it on Optimax... but my general question is that what is the best option if you cant get hold of Optimax?

Is it BP, Texaco, Esso...? Which of these has the best SuperUnleaded option?

Lots of people have said good things abour Texaco. BP Ultimate seems to be unjustifably super-expensive and personally I buoycott Esso/Exxon because of their environmental standing/political lobbeying.

As for Optimax, I've run much better drag times in my car with Optimax (and indeed Optimax + Millers) than with 95, so the octane must be giving some benefit (did reset ECU though).

Originally posted by Patrick_Devlin

Is it BP, Texaco, Esso...? Which of these has the best SuperUnleaded option?

I use Texaco if I can't get any optimax, its not supposed to me much different. I run 10% Toluene as well...

Can you remind me of the benefits of Millers again? It raises the octane level and helps reduce the possibility of det, is that right?

How much is it and where can I get it from?

i used to run my TT on only optimax but since fuel prices started to get really expensive i dropped to 95 ron fuel and i've gotta say i havn't noticed any difference apart from improved mpg:conf: i dunno whether thats cos its a uk or not though

Originally posted by lust2luv

Lots of people have said good things abour Texaco. BP Ultimate seems to be unjustifably super-expensive and personally I buoycott Esso/Exxon because of their environmental standing/political lobbeying.

 

As for Optimax, I've run much better drag times in my car with Optimax (and indeed Optimax + Millers) than with 95, so the octane must be giving some benefit (did reset ECU though).

 

How much better is "much better"?

I always use normal unleaded. I have filled up with Opti a couple of times but it just doesn't seem worth it for the small power gains achieved in the SZ. Probably worth it for a trackday - I suppose if the fuel is more dense and the injector injects a pre-determined volume then you will be getting more fuel in each stroke with optimax and therefore more power. but like I say - for motorway miles - save your money.

Originally posted by Patrick_Devlin

Can you remind me of the benefits of Millers again? It raises the octane level and helps reduce the possibility of det, is that right?

 

How much is it and where can I get it from?

Higher octane fuel does reduce the chance of det, yes. I think I am right in saying that Millers raises the octane by .2RON, making optimax 98.2RON. The packaging on octane boosters usually infers an increase of 2RON, not sure about Millers though.

10% Toluene raises Optimax to 100RON, its nasty stuff but a lot cheaper than bottled boosters.

Forgot to say that you can get Millers from Camskill and I think Envy sell it also.

it's be 98.7 RON then wouldn't it? The stuff I read (from Shell Austrailia or Shell Canada I can't remember) said it came out of the pumps as 98.5 RON.

I always figure Optimax to be 98RON, whether it is or not I don't know. That wasn't really my point, a .2 raise for £3-£4 isn't much compared to a 2.0 increase with Toluene

no your right it certainly doesn't seem worth it!

Hmmm... Toluene sounds good. I remember CW mentioning something about it on a thread not that long ago. Arent there issues with storing it? How much does it cost?

I can get this toluene through work but there is like 10 different types in the chemical catalogue. Storage wise it comes in big glass bottles and you store it like you do white spirit etc (in the shed next to the paint/fireworks/big bundles of other highly flammable gases/liquids and a heat source:D) From what I can gather though its not very freindly to rubber or plastics so long term usage probably isn't good for your fuel system but I stand to be corrected.

Just found the thread after a brief search! £6/gallon...

I wouldn't keep it in the bedroom, but it isn't that bad. I keep mine in a lock-up outside and wear gloves and goggles whenever I handle it.

I got a big drum of Toluene through work and put it in 5L Petrol cans using a rotary barrel pump. It works out at less than £1 a litre, if you buy it in smaller quantities it obviously costs more.

Chris Wilson and Envy both sell it, otherwise get it from your local chemical suppliers (Albion?). Tell them its for thinning paint if they ask

Originally posted by dangerous brain

From what I can gather though its not very freindly to rubber or plastics so long term usage probably isn't good for your fuel system but I stand to be corrected.

10% or less isn't going to do any damage, its what petrol companies themselves put it in petrol to raise octane.

Some on Supraforums run 30% toluene, with a lubricant added.