bio ethanol

Can 156's be converted to run on bio ethanol ?, i hear the octane of 85% bio ethanol is 206 !

I am pretty sure it could be done, I think you will need to change most of the seals in the fuel system though, and possibly fit bigger injectors. Also you will only get about 1/2 to 2/3rds of the MPG you get with petrol due to the lower energy content of Bio ethanol.

The octane rating won't give any advantage unless you are running a turbo with serious boost or a normally aspirated car with very high compression ratio.

Tesco high octane (99) is 5-10% bio ethanol. It qualifies for a reduction in fuel duty due to a sufficient amount being from a renewable source. It should actually be cheaper than unleaded because of this, but once again we are being fleeced by big businesses pretending to be our friend.

I wonder how it's calorific value compares to 95 octane. Perhaps it is lower, and it is simply its superior anti-knock characteristics which allow more efficient use of its energy?

Originally Posted by ally

Tesco high octane (99) is 5-10% bio ethanol. It qualifies for a reduction in fuel duty due to a sufficient amount being from a renewable source. It should actually be cheaper than unleaded because of this, but once again we are being fleeced by big businesses pretending to be our friend.

Their 95RON unleaded is also 5% Ethanol.
So you wouldn't end up with the 99RON costing less than the 95RON...

In reality you want the lowest octane fuel possible (dependant on the compression ratio of the engine and avoiding pinking). The knock sensor in the engine is set at the octane rating recomended by the car manufacture (to suit to the normal pump fuel available in that country) then if it detects detonation it retards the ignition until it stops. It doesn't advance the ingnition to allow you to get any benefit from higher octane fuels.
"Super" grade petrols often give better performance becasue they are more refined and give a cleaner burn.
Calorific values are another can of worms that i haven't looked into yet.

The Stoichiometric ratio of bio ethanol to air is around 9.5:1 as opposed to petrol which is around 14.5:1

So for any given size of engine at a set RPM you will be using a lot more fuel just to get the engine to run.

I would have thought that the calorific value of the fuel would affect the power and torque, which would also affect the fuel consumption, due to the need to press the accelerator more to go the same speed.

Originally Posted by ally

Tesco high octane (99) is 5-10% bio ethanol. It qualifies for a reduction in fuel duty due to a sufficient amount being from a renewable source. It should actually be cheaper than unleaded because of this, but once again we are being fleeced by big businesses pretending to be our friend.

I wonder how it's calorific value compares to 95 octane. Perhaps it is lower, and it is simply its superior anti-knock characteristics which allow more efficient use of its energy?

Originally Posted by David C

Their 95RON unleaded is also 5% Ethanol.
So you wouldn't end up with the 99RON costing less than the 95RON...

By law the super unleaded doesnt need to have ethanol blended.... I think tesco are the only group that do this.

Oh and by the way at 90% off UK petrol stations V-power and BP Ultimate are the same product.

Bet you didn't know that. Now can you explain why BP's is more expensive?

Wouldn't know whether to run my car on it or drink it !!!