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R31Nismoid

By R31Nismoid,
in Victoria

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xALmoN Grand Master

xALmoN

Posted
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Nah Adam, ethanol does burn slower than petrol. It also burns cooler due to the hydrogen bonds in etOH, which requires a lot more energy to vapourise than petrol. Explains the lower EGTs when running etOH huh? Fact in point is bubble point of etOH which is only C2 is 70degrees, it is a trend that the more the carbons, the higher the bubble pt (high school chem i assume).

Petrol is basically C8, with various isomers and aromatics added in to increase octane rating, but they all have roundabout 6 to 8 carbons, and no oxygen in the molecule itself. Petrol itself boils at 90degrees, but the components are largely C8.

We can look at vapour pressure and heat of vapourisation to understand volatility. 896kJ of energy is required to vapourise 1kg of EtOH vs 298 for octane, which is the closes to petrol. This, is why it burns cooler and slower. Or at least why i understand it burns cooler and slower. I'll have to look up activation energies to further explain why etOH burns slower but i cbf now.

And that is why, it is probably better to go a hotter plug when you're using etOH as a fuel.

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joeyjoejoejuniorshabadoo
joeyjoejoejuniorshabadoo

probably worth more than your D1R's

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i kinda want one. name him al pacacino.

Birds
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You laugh now, but when I'm at a formal occasion with a shitty DJ and they need someone to drop Dre beats...I have something up my sleeve.

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alr33x Grand Master

alr33x

Posted
Posted

Nah Adam, ethanol does burn slower than petrol. It also burns cooler due to the hydrogen bonds in etOH, which requires a lot more energy to vapourise than petrol. Explains the lower EGTs when running etOH huh? Fact in point is bubble point of etOH which is only C2 is 70degrees, it is a trend that the more the carbons, the higher the bubble pt (high school chem i assume).

Petrol is basically C8, with various isomers and aromatics added in to increase octane rating, but they all have roundabout 6 to 8 carbons, and no oxygen in the molecule itself. Petrol itself boils at 90degrees, but the components are largely C8.

We can look at vapour pressure and heat of vapourisation to understand volatility. 896kJ of energy is required to vapourise 1kg of EtOH vs 298 for octane, which is the closes to petrol. This, is why it burns cooler and slower. Or at least why i understand it burns cooler and slower. I'll have to look up activation energies to further explain why etOH burns slower but i cbf now.

And that is why, it is probably better to go a hotter plug when you're using etOH as a fuel.

Had a headache by the end of the first paragraph you Kent's are too smart for me

Sunkist Grand Master

Sunkist

Posted
Posted

Lol Alex, I was about to say the same.. Lol the only reason I know that ethanol burns slower is because I set it in fire at Scott's lol

I like fire

But yeh the bigger arc/gap makes sense!

Rekin Grand Master

Rekin

Posted
Posted

Awesome thanks for the /skylinesaustralia discussion in the wasteland.

Thinking of buying bcpr7es-11 to see if misfire caused by heat range of plug. If issue still occurs, I'll drop them to 8mm?

Thoughts on this? Cheers

kaitoukid Veteran

kaitoukid

Posted
Posted (edited)

B2YH-vat_original.png

About to happen to me... very hungry so call my mate to go Subway/Schnitz.

Then Pho is brought up. Also very acceptable. Nek minnit his missus also coming (which is no problem... the problem is that she doesn't live *close* and now I have to wait longer until my food is in front of me :'( ).

tl;dr

getting pho, but have to wait :'(

Edited by kaitoukid
Sunkist Grand Master

Sunkist

Posted
Posted

Awesome thanks for the /skylinesaustralia discussion in the wasteland.

Thinking of buying bcpr7es-11 to see if misfire caused by heat range of plug. If issue still occurs, I'll drop them to 8mm?

Thoughts on this? Cheers

I'm still gonna say go to .8mm. I don't think you are chasing 350+kw I mean mine were .8 on all my cars. Never had an issue with making powerz

Rekin Grand Master

Rekin

Posted
Posted

http://www.ngksparkplugs.com/techinfo/spark_plugs/faq/faqpregap.asp?nav=31200&country=US

Another consideration that should be taken into account is the extent of any modifications that you may have made to the engine. As an example, when you raise compression or add forced induction (a turbo system, nitrous or supercharger kit) you must reduce the gap (about .004" for every 50 hp you add). However, when you add a high power ignition system (such as those offered by MSD, Crane, Nology) you can open the gap from .002-.005".

Interesting...

Birds Grand Master

Birds

Posted
Posted

Nah Adam, ethanol does burn slower than petrol. It also burns cooler due to the hydrogen bonds in etOH, which requires a lot more energy to vapourise than petrol. Explains the lower EGTs when running etOH huh? Fact in point is bubble point of etOH which is only C2 is 70degrees, it is a trend that the more the carbons, the higher the bubble pt (high school chem i assume).

Petrol is basically C8, with various isomers and aromatics added in to increase octane rating, but they all have roundabout 6 to 8 carbons, and no oxygen in the molecule itself. Petrol itself boils at 90degrees, but the components are largely C8.

We can look at vapour pressure and heat of vapourisation to understand volatility. 896kJ of energy is required to vapourise 1kg of EtOH vs 298 for octane, which is the closes to petrol. This, is why it burns cooler and slower. Or at least why i understand it burns cooler and slower. I'll have to look up activation energies to further explain why etOH burns slower but i cbf now.

And that is why, it is probably better to go a hotter plug when you're using etOH as a fuel.

It does burn cooler, but from what I'm reading, not slower. Google has some conflicting results...some say faster, others say slower...and this also seems to change depending on AFRs too. Ethanol does have a higher autoignition point, making it less prone to detonation and harder to ignite than gasoline...but from what I understand, once ignited, will burn faster. I would like to know which one is correct, is there a way to test it without blowing ourselves up?

One thing is for certain...ethanol is awesome.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Ethanol burns slower but an increase in pressure changes it's burn rate drastically. There is also more oxygen to help it burn.

I have seen nearly 1000 degrees C in my manifold, so it certainly doesn't burn cold, just colder than dino 98. This is mainly due to extra timing though, as adding timing gives the fuel more time to burn in the cylinder, not in the exhaust.

One thing is for certain...ethanol is awesome.

^^ This. :)

xALmoN Grand Master

xALmoN

Posted
Posted

well, burning both fuels at atmospheric would be very different to burning both fuels under cylinder conditions, cylinders have pressure between 160 to 200ish psi? that's from 10 to 15x atmospheric pressure.

mr aero engineer, any input?

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