TVO formula

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Ajax123
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Location: Lincolnshire

TVO formula

Post by Ajax123 » Wed Mar 14, 2018 12:02 am

Just wondering if there is a standard formula for tvo. My db25 runs on petrol tvo and the Best recipe is 15pints paraffin to 1 pint petrol and on pint diesel. Is this fairly standard or doe it vary widely from tractor to tractor. Just curious really

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db2d
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Location: Monmouthshire

Re: TVO formula

Post by db2d » Wed Mar 14, 2018 11:53 am

Kerosene is what most people use, either straight or with petrol added. Paraffin and diesel is a very low grade fuel. DB did have engines adapted to run on Lamp Oil. What is the reasoning for adding diesel ?
There are also DB engines that use petrol only.

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rid54
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Re: TVO formula

Post by rid54 » Wed Mar 14, 2018 12:58 pm

This was interesting. Both the question and the comment, but from different views. English is not my native language, and in school we were taught that the americans prefer kerosene over paraffin, which is what the british use, but it is the same substance.

Diesel sounds a bit odd to add. The octane value of diesel is low and would be expected to lower the octane value of even a petrol/paraffin (or kerosene?) mixture to some extent. Perhaps that doesn't matter in that particular engine?

Mr dino
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Re: TVO formula

Post by Mr dino » Wed Mar 14, 2018 6:44 pm

4 parts kero to 1 part petrol is what I used in my old fergie
It's sort of yellow and rust

Ajax123
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Location: Lincolnshire

Re: TVO formula

Post by Ajax123 » Wed Mar 14, 2018 11:09 pm

rid54 wrote:
Wed Mar 14, 2018 12:58 pm
This was interesting. Both the question and the comment, but from different views. English is not my native language, and in school we were taught that the americans prefer kerosene over paraffin, which is what the british use, but it is the same substance.

Diesel sounds a bit odd to add. The octane value of diesel is low and would be expected to lower the octane value of even a petrol/paraffin (or kerosene?) mixture to some extent. Perhaps that doesn't matter in that particular engine?
It's the recipe I got from the guy who had it before me. He got it from the original owner who bought it apparently in 1953...he is reported to have played with various recipes and found that to be best. I do know that the paraffin we have in this area is particularly clean so maybe it just needs dirtying up a bit... it seemed a bit odd to me too but it seems to work fine. No soot on the plugs no lumpy running so...

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cobbadog
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Re: TVO formula

Post by cobbadog » Thu Mar 15, 2018 5:44 am

Our 30C is a TVO model but Kero is dearer to buy petrol so we only use petrol. Some guys with old stationary engines classed as being oil engines run of all sorts of mixes from diesel/petrol, kero/petrol but the fuel to get if you can is aviation fuel as it is far higher octane reading. In some areas aviation fuel is stored in 200 litre (44 gallon) drums but has a shelf life and once expired cannot be used in aircraft.

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rid54
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Re: TVO formula

Post by rid54 » Thu Mar 15, 2018 8:51 am

Found this, I suppose you have seen i too:

https://en.wikipedia.org/wiki/Tractor_vaporising_oil

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KevinC
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Re: TVO formula

Post by KevinC » Thu Mar 15, 2018 3:08 pm

Someone once told me that Duxford imperial war museum used to run a taskmaster on aviation petrol but the continued use burnt the pistons as the octane rating is way to high. These engines have a very low compression ratio compared to modern vehicles and were. designed to use only the relatively poor quality fuel available at the time

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db2d
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Re: TVO formula

Post by db2d » Thu Mar 15, 2018 8:46 pm

David Brown had a range of engines deigned to run on petrol and many of these were in tractors supplied to The Military. They had high compression pistons and running on petrol was not an issue. Some of these tractors that were first made in 1939/1940 are still running as good as the day they left the factory.

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rid54
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Re: TVO formula

Post by rid54 » Thu Mar 15, 2018 9:00 pm

Very generally, the octane rating of a fuel is a way to rate the ability of the fuel to withstand compression, without igniting. High-compression engines require high-octane fuels, that's the general idea. The fuel, when it comes to otto engines with carburettors, is vaporized and, in practice, turned into a gas in the carburettor, while being mixed with air. The mixture should withstand being compressed in the cylinders, without igniting, until the spark plug starts the combustion process. Using high-octane fuel in low compression engines is not a problem. Low octane fuel in a high-compression engine will probably lead to pinking (pre-ignition; detonation) and engine damage. An engine that runs on paraffin (kerosene?) will not be damaged by high-octane petrol.

KevinC
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Re: TVO formula

Post by KevinC » Thu Mar 15, 2018 10:13 pm

A brief bit of research on the Internet produced this information.
AvgasLL100 low lead 100 octane fuel contains tetra-ethyl lead added to raise octane (ten times the amount in leaded petrol if it were still available in the uk) Deposits left after burning are corrosive and damaging to valves, valve guides, seats and cylinder heads. Spark plugs will likely foul rapidly. It has a chemical package added to allow it perform at high altitude. These aromatics can damage automotive rubber hose. It has a lower volatility so part throttle response and cold starts may be compromised.
Also it has a lower specific gravity which means the fuel air ratio may need changing.
It sure ain't going in any of my vehicles. Oh and in the uk it is probably not legal to use because of the fact that has no duty paid on it and because of the high lead content.

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rid54
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Re: TVO formula

Post by rid54 » Fri Mar 16, 2018 7:47 am

Just to eliminate any misunderstanding:

With "high-octane" petrol I mean something like 98 unleaded, a automotive fuel that you would find readily available. Compared to low-octane (87-93) petrol, or paraffin/kerosene with even lower octane. I was not referring to fuel for airplane engines.

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skyrydr2
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Re: TVO formula

Post by skyrydr2 » Fri Mar 16, 2018 8:38 am

OCTANE is a retardant agent added to gasoline (petrol) to control pre-ignition. Cetane is added to diesel to make it more combustible and burn with a tick more vigor or energy.
Jet fuel is VERY high in cetane thus making it very volatle and burn HOT.
Av gas or "low lead100" is not at all good for any automotive type engines and an extreme waste of money.
10:1 or higher requires 90 plus octane or you WILL burn pistons and or crack piston rings.
When I rebuild petrol tractor engines I volume check a cylinder and head to calculate compression. Then machine head and or block to get as close to 9:1 compression ratio if it is a normal 7.5:1 .
This gives more torque and much better fuel economy as well as instant governor response. It will also run a bit hotter in high heat of summer so we just add a higher octane fuel and it runs normal.

KevinC
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Re: TVO formula

Post by KevinC » Fri Mar 16, 2018 12:54 pm

Understood. I WAS referring to aviation fuel as that was what was discussed earlier in the post. I have always used pump fuel in my tractors without any problem. I wouldn't bother with super or optimax or whatever as there is nothing to be gained from it. I now use a lead replacement additive in those that don't have hardened valve seats. Avgas has been looked at as a replacement for race fuel as it is cheaper but with poor results due to the lead content

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GeoffDEAL
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Re: TVO formula

Post by GeoffDEAL » Tue Mar 20, 2018 8:35 pm

Used aviation petrol for many years in race engines,plugs and combustion chambers remained perfectly clean no problems the only difficult part is pouring it in mixes fine with petrol. Ran out of petrol one day with the old combine harvester so poured in a can of av gas and ran perfectly and the smell reminded one of race day. Only difference here it is very pure fuel with 110 plus octane rating and nice smell both burnt and un burnt.

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