unleaded debate - very confused
Discussion
Guys, i am confused - this is taken from the steve heath guide to TVR's regading the use of unleaded 95 RON in a 4.0l Chimp
"All Rover V8 engines were fitted with hardened valve seats and therefore the only problem with running unleaded is the lower octane that unleaded fuel provides. This can cause pinking and predetonation which can cause engine damage if ignored. This can be cured in most cases by simply having the ignition adjusted. The less performant engines are less susceptible to pinking and thus it is common for the 4 litre engines to often require no adjustment at all."
So can you or can't you use 95 RON unleaded ?
"All Rover V8 engines were fitted with hardened valve seats and therefore the only problem with running unleaded is the lower octane that unleaded fuel provides. This can cause pinking and predetonation which can cause engine damage if ignored. This can be cured in most cases by simply having the ignition adjusted. The less performant engines are less susceptible to pinking and thus it is common for the 4 litre engines to often require no adjustment at all."
So can you or can't you use 95 RON unleaded ?
I used 95 RON for several tank fulls and my 4.0HC pinked quite a lot. Was much better with 98 RON. However i never had the engine timing adjusted for the lower RON. As the ECU only adjusts the fuel it cannot compensate for the change in fuel. A more modern fully mapped system can also adjust the timing and with suitable sensors can compensate.
When I first got my 4.0HC I only used Shell VPower or Tescs 99 Ron.
One day I needed fuel and there was no VPower at my local Shell so I stuck some 95 in it.
The car didn't pink and to be honest I really couldn't notice any loss of performance.
So its been running happily on 95 ever since.
I spoke to Rob at V8 Developments about this and he said the Rover V8 is a relatively low compression engine so is absolutely fine on 95.
Rob recently set the ignition timing after fitting a new cam and just like before it doesn't pink at all on 95.
The unleaded debate is a completely different thing, the heads are aluminum so they must have had hardened valve seats from year dot.
This should mean you don't need leaded fuel, not even sure you can buy it these days anyway.
In summary put regular 95 in, if it pinks retard the ignition timing by a couple of degrees and it will be fine.
One day I needed fuel and there was no VPower at my local Shell so I stuck some 95 in it.
The car didn't pink and to be honest I really couldn't notice any loss of performance.
So its been running happily on 95 ever since.
I spoke to Rob at V8 Developments about this and he said the Rover V8 is a relatively low compression engine so is absolutely fine on 95.
Rob recently set the ignition timing after fitting a new cam and just like before it doesn't pink at all on 95.
The unleaded debate is a completely different thing, the heads are aluminum so they must have had hardened valve seats from year dot.
This should mean you don't need leaded fuel, not even sure you can buy it these days anyway.
In summary put regular 95 in, if it pinks retard the ignition timing by a couple of degrees and it will be fine.
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