What determines the limit of cylinder pressure?

[Jared_80]

Ok let me re-phrase that if I could somehow control internal temps and knocking what would be the pressure limits be on the block/rotating assembly be??

[ivymike1031]

I've seen engines running successfully (reasonable durability - 400hrs+ at full load) with peak cylinder pressures as high as 2750psi. Piston strength and piston undercrown cooling get to be an issue. These engines had a floating cast iron cylinder liner, iron block, and iron head, which had no trouble whatsoever with the pressure. The head bolts had to be "beefed up" a bit vs the original design.

[Jared_80]

Do you know what the pre-ignition pressure was? And what fuel they were using?

[Corbin]

xylene has excellent anti-knock qualities. Stuff is hella poisonous though. but toluene and xylene dont like to vaporize at lower temps. and can corrode any plastic or rubber in the fuel system, Supposedly adding ATF to the tank can help. Propane injection's good too. Propane has an octane rating of 103 and has a cooling effect when vaporized.

[ivymike1031]

Originally Posted by Jared_80

Do you know what the pre-ignition pressure was? And what fuel they were using?

The fuel was diesel, and I don't know precisely what the pressure before injection was, but it was probably in the neighborhood of 700psi.

[Jared_80]

Originally Posted by Corbin

xylene has excellent anti-knock qualities. Stuff is hella poisonous though. but toluene and xylene dont like to vaporize at lower temps. and can corrode any plastic or rubber in the fuel system, Supposedly adding ATF to the tank can help. Propane injection's good too. Propane has an octane rating of 103 and has a cooling effect when vaporized.

Propane has an octane equivlent (it has no octane in it) of 105. Which is alot more resistant than any street gas. I am considering using it as my secondary injectors, which engage at a set boost level. The toluene trick is cool but I have yet to find a cheap supply the stuff costs like $20 for 500ml, when you consider using 10% toluene you are talking about alot of money. If you know of a cheaper source I would love to hear about it.

[Sluttypatton]

The cheapest I have got toluene for is 2.50/gallon at a paint supply store.

[Evil Result]

Do you see BMEP as a pratical means in which to derive theoretical power figures.

[Jared_80]

Originally Posted by Sluttypatton

The cheapest I have got toluene for is 2.50/gallon at a paint supply store.

Is that pure Toluene? If not what % is it? I read the other day that if you add 10% Toluene to 90% (91 oct) gas you will have 118 octane fuel!

[ivymike1031]

Originally Posted by Evil Result

Do you see BMEP as a pratical means in which to derive theoretical power figures.

There's nothing theoretical about calculating power from a known BMEP, although usually BMEP comes from a torque or power measurement, not the other way around. BMEP is a mathematically derived quantity directly related to the torque output and displacement of an engine. It is a good gauge of how "hard" an engine is working, since it takes engine speed and size out of the picture (ie, two BMEP figures from different size engines are directly comparable).

[Sluttypatton]

I can't remember, I haven't used Toluene to boost my Octane for about two years. Since I bought a stock Dodge Neon (and it has remained pretty stock) I have had very little trouble with detonation. I'll see if I can find out.

[quaddriver]

Originally Posted by Sluttypatton

I can't remember, I haven't used Toluene to boost my Octane for about two years. Since I bought a stock Dodge Neon (and it has remained pretty stock) I have had very little trouble with detonation. I'll see if I can find out.

I just read this, I would not, and advise the same to not use ANY arene in your fuel.

First of all, its tempting because its RON/MON is appx 118 iirc and its autoignite is about twice that of iso-octane. however, octane numbers do NOT neccesarily translate into power - its NETT caloric content is about 10% less than other fuel components.

But, and here is the kicker, its a felony to add. You are in violation of the clean air act of 90, carb phase 2 of 96 as well as provisions of the complex model of 98 - in other words, dont get caught. Enviro cops like taping $50K fines to your forehead for fun. (im also surprised you got toluene from anywhere, its now controlled in many places and what is sold over the counter is not pure toluene to boot)

Why is it bad stuff? the arenes (aromatics) have been phasing out of modern gas simply because they are highly toxic. toluene is not as toxic as benzine, but it is co-soluable in water over an order of magnitude than other fuels and reacts with NOx compounds not as bad as olefins but 3-10 times more than alkanes and 2-4 times more than popular oxygenates which themselves have already been shown to cause health problems in normal use.

I know, you only use it during racing right? well it didnt do what you thought it would... because arenes are unsaturated hydrocarbons, they burn very unstably...they ALWAYS produce soot. They also consume beneficial radicals during the combustion process (contrary to laymans belief fuel just not magically become water and CO2, it goes thru hundreds of transformations when the first c-c,c=c, or h-c bond is broken simply because the remaining compound is DIFFERENT) At any rate if you did this on an OBD2 motor, the post-catalyst O2S bank would detect the low oxygen content and the PCM will do two things: pump more air if equipped, and lean the mixture, which reduces power which reduces combustion temp which reduces octane requirement.

Instead Id look for a replacement, TEL is out, because while the soot from the arenes plug the converter in short time (and no they cannot be cleaned) the TEL destroys the catalyst. I would use methanol or MMT...the PCM will attempt to put the motor back into 'balance' and in doing so will give more fuel (part of the reason fuel mileage suffers in the winter - a portion of your 'gas' is not gas, but rather oxygenate with poor btu/lb rating, and you burn more to go back to stoich) of course you could always just remap the fuel curve and stay with methanol which is the least harmful solution save the creation of formeldahyde. NOw if this was a carbed engine, my answer would be different, but I am under the belief this was done on an EFI motor.

[quaddriver]

Originally Posted by SaabJohan

Yes.

Their fuel was toluene based but contained some even nastier stuff. The fuel was the biggest reason for the increased power output (and therefore increased cylinder pressure). The synthetic fuel could however cost as much as $300 per liter but was 60% more dense than normal gasoline and contained a lot more energy.

The actaul composition was more closely guarded than thermonuclear devices but here is one recipe:

Up until the end of 1957 it was possible to choose freely what fuel you used. Mercedes, for example, relied on the following recipe: 45% benzene, 25% methyl alcohol, 23% aviation fuel, 3% acetone and 2% nitrobenzene. The remaining two percent remain a secret until this day. The explosive mixture was so aggressive that remnants left over from training and races had to be drained off and the engine rinsed out with conventional petrol. This was the only way to prevent the engine from suffering damage overnight!

Im wondering if the 2% had bromine in it or some other organomettalic

[Sluttypatton]

Toluene is the primary aromatic in many of todays gasolines. Chevron's aviation fuel (it's the best example I could find) contains 0-20% Toluene. Toluene is used in automotive fuels too, however I am unsure of the exact content. I have read that the specifications for spark-ignition engine fuel say that gasoline may have a total aromatic content of 20%-45%. So if one were to add Toluene to the fuel, it would likely still be within the specifications for total aromatic content as much of todays fuel contains somewhere around 20%-45% aromatics, much of which is Toluene. My previous car was EFI, and it still had the stock, functioning, catalytic converter the day I sold it.

You are quite knowledgeable in this subject, probably more so than me, but please loose the diminutive tone in your writing. You don't have to explain things as if I were stupid, I am not. And the fact that you would include "and no [catalytic converters] cannot be cleaned" is somewhat insulting. I didn't call you stupid, please don't imply that I am.

As for the law behind adding Toluene to your gasoline, I have no clue what it is. I live in Canada, where it is likely similar, but I haven't done the research. Not to say that I don't think it's everyones responsibility to keep the air clean.

By the way, I am now experimenting with Methanol and Ethanol, but before I can use them I need to find out where to buy Benzine so I can break the azeotrope and remove the 4% water in the Ethanol. Is Benzine even available to the public?

[quaddriver]

Originally Posted by Sluttypatton

Toluene is the primary aromatic in many of todays gasolines. Chevron's aviation fuel (it's the best example I could find) contains 0-20% Toluene. Toluene is used in automotive fuels too, however I am unsure of the exact content. I have read that the specifications for spark-ignition engine fuel say that gasoline may have a total aromatic content of 20%-45%. So if one were to add Toluene to the fuel, it would likely still be within the specifications for total aromatic content as much of todays fuel contains somewhere around 20%-30% aromatics, much of which is Toluene. My previous car was EFI, and it still had the stock, functioning, catalytic converter the day I sold it.

You are quite knowledgeable in this subject, probably more so than me, but please loose the diminutive tone in your writing. You don't have to explain things as if I were stupid, I am not. And the fact that you would include "and no [catalytic converters] cannot be cleaned" is somewhat insulting. I didn't call you stupid, please don't imply that I am.

As for the law behind adding Toluene to your gasoline, I have no clue what it is. I live in Canada, where it is likely similar, but I haven't done the research. Not to say that I don't think it's everyones responsibility to keep the air clean.

By the way, I am now experimenting with Methanol and Ethanol, but before I can use them I need to find out where to buy Benzine so I can break the azeotrope and remove the 4% water in the Ethanol. Is Benzine even available to the public?

I meant no offense. of the most popular arenes, toluene is less unsaturated than benzine because of an extra carbon, hence it is not as 'evil' to our EPA. (benzine addition to motor fuels in the US is prohibited) However, the concern is in the advance reactions benzine is formed and emitted. What I mean by advance reactions...as the flame front progresses thru the combustion chamber, temp and pressure rise on the remainder - sort of like a bomb blast - easy to visualize if you slow down the event in your head, anyways, that extra carbon might get broken first and then the exhaust valve opens and that molecule might get exhausted as benzine... benzine is a known carcinogen in the US and if it is available to the public, I am unaware of it. You being in Canada, your emissions laws are quite different than ours so you can prolly disregard that portion of my post. Last I ever heard US fuels were at 20% toluene circa 1996 and falling. (sometimes the EPA mandates good things, sometimes they dont, replacing toluene with another good AKI component leads to a whole new set of fleas.)

btw, I did my personal research on fuels from say 91-96 ( I was racing managed EFI vehicles then), if you can get archives, 'Circle Track' mag did an article in 1993 called 'Race Gas Secrets' that is an EXCELLENT source. I have a so-so xerox of this I can ATTEMPT to fax...there is also a FAQ from the UK that used to float on usenet from circa 93 or so. I think it was part of a thesis from a guy who worked at BP - Ill try and see if I can resurrect a link from the old alt.rec links - also a good source of what not to burn and why. At the same time I was living in beacon ny and my neighbor was a research chemist at the texaco fuel research facility in fishkill - an invaluable source of info, basically his take was, the govt mandates the fuel composition and distillation curve. the manus use a reference fuel and tune the motor to get cert - at no point does anyone have your desires in mind.

Again, I meant no offense at all, a lot of times I use sarcasm and tic that does not come across on a BBS

ps - in the states, we have 'octane boosters' that you can buy in 12oz cans (roughly) for $5 or so to treat 10-20 gallons or so, they used to be simply toluene, then they were toluene and MMT, then Methyl only...the 'contains petroleum distillates' label on the can is pretty obscure. if you are racing a managed motor, I have found that the best way to grade your effort is run with a scan tool hooked up and look at the KS counts and the advance values from the run. if it passed, your work is done.