Fuel

Guest · Apr 10, 2003

Guys,
Having attended the JZ day last Saturday, I spoke with Steve at JZ. He was most helpfull, to the point where he checked the timing switch on the DME. This was set to switch 3, with 6 degrees plus. Steve altered this back to switch 1, which is 0 degrees; which gives a full 21 degrees advance.
He also said 95 octane would be OK in this set-up.
I then ran my car on the dyno, and returned 232bhp.
My trip home from JZ to Birmingham was a joy... the car flew home.[

]

ClubSport 911 · Apr 10, 2003

So, I guess the little trick with the DME settings were worth it then ? - If so, then well done. Nice to be able to help. STEVE

Guest · May 4, 2003

Sometime ago someone mentioned on titanic that most fuel injector additives contained mainly parrafin. I forgot to mention that before running on the dyno at JZ, I put half a litre of parrifin in the tank. Didn' t notice any real change, no ping, no smoke, nothing.
Also, metho in the tank will remove any water in the fuel tank.
Peter[8D]

Big_nige · Jul 7, 2008

I run either, 98 seems to give better mpg but costs more so its swings and roundabouts. I've had the car dyno'd several times running various fuels, and the power difference is barely noticeable. I run the car daily on a 40 mile round trip and have used various fuels and like I said the only noticeable difference is MPG, about 20-25 more miles out of a full tank on the stronger stuff.

mintmate · Jul 7, 2008

Thanks for the information Big_nige that is a great help.

Trevor

3.2_fordy · Jul 7, 2008

Trevor
I will all ways try to use the 98+octane if I can, and try to stay away from the supermarket stuff had a bad experience running leaded from them (blocked injectors £350)[

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But you can happily run on both

Big_nige · Jul 7, 2008

I don't put anything in other than Sainsburys, Nectar points and discounts from the instore shopping makes sure I'm a regular customer. Last dyno session the car was running on Sainburys 'Taste the difference' gave 241 and good mpg. Hear alot of bad about Tesco's fuel though. Use the car regularly and it'll be fine, personally I think alot of running problems owners have is down to infrequent use. These cars like/need to be used.

Gary C · Jun 20, 2009

I always (so far, only filled it up 4 times [

]) use super, but with no additives or lead replacement.

I believe these engines were built to run without lead, but Uk fuel octane was a little higher in 89 than it is now, so super is probably better for it.

There is a fuel quality switch on the ECU that can be adjusted to run on lower octane fuel, I suppose that could be set if you want to run normal with a large safety margin.

totsnap · Jun 21, 2009

Have tried Optimax etc and noticed no diff in mpg or bhp.... usual U/L is all I use and the car is more than happy with it
Have owned the car for 6 yrs and normal U/L has been fine, for road use.
You could prob. measure the higher grades of U/L within track use tho'......

Just my opinion of couse!

Gary C · Jun 21, 2009

ORIGINAL: SP_CS

With Vpower, Ultimate etc etc you need a few tank fulls to feel the benefit IMO

I have Tesco 99 available nearby, my car loves it .... post rebuild CR is now 10.45:1, so Tesco or Vpower 99 only for me

The car does not have a knock sensor as far as I know, and therefore does not adjust for different fuel grades. Therefore octane needs to be high enough to avoid knock, but any higher (octane) grants no benefit. Different fuels do though have different specific calorific value so they can produce more energy and therfore power.

I imagine that the margin to knock when the cars were released on UK fuels was large enough such that the small reduction is still within the safety margin, but as my car does not do many miles, filling up with super is no burden and makes me happier.

75pno · Jun 21, 2009

Had a 3.2 supersport for 5 yrs and used normal unleaded with no problems.

75 pno

adamtsobek · Jun 22, 2009

Normal U/L petrol did it for me, only once filled with the higher octane petrol but did not feel any difference.
So save some money stick with the ordinary U/L

Adam

Big_nige · Jun 22, 2009

Sainsburys boggo standard for mine. Tried higher octane stuff and noticed a marginal increase in MPG, but not enough to become anally retentive on what fuel I use.

twinny · Jun 22, 2009

Guys, our cars DME's are dumb as the engine does not have a knock sensor therefore the only way to gain any real benefit from 98+ RON fuel is to have the ECU remapped.

Gary C · Jun 22, 2009

ORIGINAL: twinny

Guys, our cars DME's are dumb as the engine does not have a knock sensor therefore the only way to gain any real benefit from 98+ RON fuel is to have the ECU remapped.

Totally true, the only question is, how near to the knock limit did Porsche set the UK cars in the 80's and how much did octane drop in the later part of the decade (I had an Astra at the time, and it needed its timing retarded slightly to stop the rattling can of pins noise).

I suppose experience is the key, no history of melting pistons or valves for the last 20 yrs so normal must be ok (just search scoobynet for fuel paranoia

)

johne · Jun 22, 2009

thanks for the advice.i had a 964 rs for 5 yrs and ran that on super all the time .but this is no track car.that 3.2 must be fun 371 bhp with a twist

twinny · Jun 22, 2009

ORIGINAL: johne
.....that 3.2 must be fun 371 bhp with a twist

Yep

nathan 1981 930 G50 · Jun 22, 2009

Considering the low cost of fuel compared to all the other expenses I only use shells finest.

Probably for short journeys it's a waste of time, but when the engine (especially the heads) get hot I think the better quality fuel is good insurance against detonation. Sitting in traffic seems to get my engine oil hotter than anything, even than on a track.
If you've ever seen pictures of 100 piece rings you won't bother penny pinching on fuel IMO.

twinny · Jun 23, 2009

ORIGINAL: nathan 1981 930 G50

Considering the low cost of fuel compared to all the other expenses I only use shells finest.

Probably for short journeys it's a waste of time, but when the engine (especially the heads) get hot I think the better quality fuel is good insurance against detonation. Sitting in traffic seems to get my engine oil hotter than anything, even than on a track.
If you've ever seen pictures of 100 piece rings you won't bother penny pinching on fuel IMO.

+1.
Still to get mine remapped to read the higher RON fuel, but run V-Power to control detonation better particularly on track days.

Nathan- Running hot in UK traffic? - Have you got an oil cooler fan fitted? I run a fan + lower temp thermostat on the switch + bumper scoop and mine's fine.