Optimax, Ultima etc

[EFA]

Mick,

 

4* will damage a CAT not a lambda sensor. You can set up a carb engine on 4* with a wide band lambda and a rolling road for example.

 

Myles, The plug on the old VX was a hardware jumper which would allow pre-set changes to the ignition map to increae/reduce advance as required.

 

The statement that ECU's do not have a setting for Octane is true in such that it is not a default map, but you could use one of the inputs on the ECU to change a global timing value from a simple in dash switch if you really wanted to.

 

More on topic...

 

K2 RUM's been mapped for Optimax. All engines are mapped (if mapped well) to cope with the lack of combustability of lesser fuels, (12.5:1 air fuel ratio) so if you run on 95 and the a/f ratio drops to 12.8:1 you'll still be OK. You will however get more margin of safely for long high load throttle openings and marginly more power.

 

A knock sensor allows an engine to dynamically adjust the advance to allow manufacturers to sell cars in countries with much crappier fuel than the UK (I'm tempted to say France here, but actually the US is a good candidate). Even with the knock sensor, a large margin of error is incorporated into the mapping, but the dynamic nature of the ignition map means you CAN feel the difference particularly where the effective factoring of the ignition parameter on a turbo is taken into consideration, hence why the effect is far more noticable on turbocharged engines.

 

 

 

 

 

Fat Arn

 

Slay the K.

 

 

Edited by - Fat Arnie on 30 Apr 2004 09:18:54

[Mick Day]

Arnie

 

Have a look here: http://www.picotech.com/auto/lambda_sensor.html

"A lambda sensor's normal life span is 30,000 to 50,000 miles. But the sensor may fail prematurely if it becomes clogged with carbon, or is contaminated by lead from leaded petrol or silicone from an antifreeze leak or from silicone sealer."

 

Maybe wide-band sensors are more robust.

 

Mick

[Jason Plato]

Nifty - your car - or any other SS is not set up specifically for super unleaded .

 

I'd blame the management for this too ......

[Nifty]

Only repeating what Caterham told me..and the handbook tells me to use Super unleaded too.

 

Keep off the straight and narrow 😬

[edmandsd]

Fact: Leaded fuel significantly shortens the life of lambda sensor compared to unleaded fuel.

 

Home of HTR700

[Slipper man]

I don't know about the SL, but Minister told me that they mapped the R500's for 95 octane. Having said that, I use 98 on track to give a greater safety margin, but you cannot tell the difference to drive the car

[Bafty Crastard]

Mr. Lambert has some relevant comment about Otimax on the Bookatrack web site, might be worth a read!

 

Original R300 NUT

 

Edited by - Bafty Crastard on 1 May 2004 22:57:41

[Mick Day]

I've copied the following from the Booka Track site; I seem to remember reading this somewhere else as well:

 

"Engine lubrication - Oil temperature

"With the track day season in full swing and warmer weather here, we have received a large number of queries from various quarters regarding acceptable oil temperatures on k series Supersport cars and Superlights.

We would expect the oil temperature to reach in excess of 100c when driven enthusiastically, but not reach the red.

What has become apparent is that the single most important factor affecting the temperature is the fuel being used. We believe that the quality of 95RON unleaded has detiorated recently, possibly as a side affect of price competition, and this is causing poor combustion at sustained high rpm. This is generally not felt by the driver.

Experience has shown that cars run on Super Unleaded or other high octane fuels (such as Shell Optimax) do not experience this problem. In tests, the oil temperature has been significantly lower under hard use (though it will be similar in general road driving). Note: Whilst our guage only reads to 120c, the engine is rated to a much higher temperature (as is any good quality oil).

Therefore, to safeguard your engine from lubrication related problems, Caterham Cars strongly recommend the use of Super Unleaded or equivilant fuel for track days and racing." - Simon Lambert"

 

Coming back to this argument of tuning the engine (ecu) for higher octane fuel: it's all down to the ignition advance mapping. Use higher octane & the ignition can sustain more advance. Vice versa with lower octane.

 

So if you're inadvertantly using fuel of a lower octane number & give it some stick, poor combustion may occur resulting in higher oil temperatures etc. Not to mention what any associated detonation may do to the engine.

 

From what I gather Optimax is a fuel produced to a standard rather than a budget. So it has a proper dollop of detergent & is 98RON. incidentally Super Unleaded in the UK is 97RON but in France it's 98RON.

 

Mick