93 replies to this topic

[bigleagueslider]

Actually, low fuel octane is not as much of a problem in modern automotive engines as it once was. Modern automotive engines have very sophisticated closed-loop digital control systems with multiple knock sensors. Once detonation is detected, the ECU quickly ******* ignition timing, makes the A/F mixture richer, and alters valve timing to prevent detonation.

Of course, this still may not be enough to prevent detonation with a gasoline-kerosene mixture.

Most modern oil refineries are set up to maximize output of the distillate that yields the highest market value. One might logically assume that the crude oil distillation's higher yield, heavier fractions, such as kerosene, diesel and jet fuel would be cheaper than a lower yield, lighter fraction product such as gasoline. But in many places (such as the US market), there is a much greater demand for gasoline. So the refiners optimize their distillation process to maximize gasoline output, and as a result diesel and jet fuels end up becoming more expensive.

Markets and commodities are very interesting things.

slider

[Lee Nicolle]

gruntguru, on May 25 2011, 07:43, said:

They must have pinged their brains out. I ran a stock 850 mini on kero/petrol once and it knocked violently if you so much as breathed on the throttle.

Home heat kero or power kero. Differnt stuff.
In the 40s to 70s a lot of tractors ran on power kero, and it was not an uncommon fuel.

[Lee Nicolle]

[quote name='Spaceframe7' date='May 26 2011, 23:03' post='5050482']
[quote name='Canuck' post='5026971' date='May 20 2011, 04:04']

Hi Canuck, and to the North American contributors to this forum. Apologies if this has been questioned before, but is there any research that you know of, or advice you can provide on the maximum compression ratio that should be considered for a road going sports car - using Super unleaded gasoline - in Canada? The engine, in the process of being re-built, is a 1600 c.c. Ford Crossflow fitted with Weber carbs and the head has been professionally modified for use with unleaded fuel (hardened exhaust valve seats, and higher grade valves). I have searched a number of sites from the U.K., but have noted that U.K. fuel and fuel rating is different from that in N. America. I do not want to burn a hole in the pistons (not yet purchased), or damage any other part of the engine by going overboard with too high a c.r. I read an article in our local paper some time ago that Avgas is not recommended for road cars as it is intended for an engine that normally runs at a constant rpm, and stays at those revs for most of its running time. (note: the article quoted some aero engines running on Avgas at possibly 3600 - 4000 rpm max., but I may be right out to lunch on this as I've used these numbers from memory).

Would approx. 10:1 be considered the max., for a road use engine, or does anyone suggest lower c.r. than this? I would think that the F.F. racers here in N.A., running with mandatory 9.3:1 using a double choke Weber carb, would be using Super unleaded (are they allowed to use hardened exhaust seats and valves or perhaps fuel enhancer?) or do N. American racers have access to leaded fuel somehow? Advice please.


98 Octane ULP is fine with 10-1, though be very carefull with the advance curve. Hardened seats for a short life motor is really unesecary, use flash lube in the correct dosage in the fuel and you should have no troubles. If doing high miles maybe yes then.
Actually I hate inserts as they often either 'strike water' when they cut the seats or crack the head [and on occasion then fall out] And generally lose flow also.

Edited by Lee Nicolle, 27 May 2011 - 09:01.

[Lee Nicolle]

Greg Locock, on May 26 2011, 23:56, said:

I'd be inclined to use that newspaper for some other function than supplying information. AVGAS is extensively used as a cheap form of high octane fuel for mototrsport in the USA and Australia at least.

Avgas beats any ULP hands down for performance. Better starting, more power, more throttle response, good mileage,,,,,,,,,,,,, and far more price and taxes. Last I bought was $2.60 a litre in March.
I used to use it in my 10-1 Ford Galaxie and it loved it, but then the price near doubled so I am stuck with using 98 ULP, with flashlube for the valve seats and top rings.. A Crane multispark ignition has helped light the stuff and it goes ok, but not the same as Avgas

[24gerrard]

Quote

Hi Canuck, and to the North American contributors to this forum. Apologies if this has been questioned before, but is there any research that you know of, or advice you can provide on the maximum compression ratio that should be considered for a road going sports car - using Super unleaded gasoline - in Canada? The engine, in the process of being re-built, is a 1600 c.c. Ford Crossflow fitted with Weber carbs and the head has been professionally modified for use with unleaded fuel (hardened exhaust valve seats, and higher grade valves). I have searched a number of sites from the U.K., but have noted that U.K. fuel and fuel rating is different from that in N. America. I do not want to burn a hole in the pistons (not yet purchased), or damage any other part of the engine by going overboard with too high a c.r. I read an article in our local paper some time ago that Avgas is not recommended for road cars as it is intended for an engine that normally runs at a constant rpm, and stays at those revs for most of its running time. (note: the article quoted some aero engines running on Avgas at possibly 3600 - 4000 rpm max., but I may be right out to lunch on this as I've used these numbers from memory).

Would approx. 10:1 be considered the max., for a road use engine, or does anyone suggest lower c.r. than this? I would think that the F.F. racers here in N.A., running with mandatory 9.3:1 using a double choke Weber carb, would be using Super unleaded (are they allowed to use hardened exhaust seats and valves or perhaps fuel enhancer?) or do N. American racers have access to leaded fuel somehow? Advice please.


98 Octane ULP is fine with 10-1, though be very carefull with the advance curve. Hardened seats for a short life motor is really unesecary, use flash lube in the correct dosage in the fuel and you should have no troubles. If doing high miles maybe yes then.
Actually I hate inserts as they often either 'strike water' when they cut the seats or crack the head [and on occasion then fall out] And generally lose flow

Our machine shop fitted thousands of valve seat inserts during the original faze over in the UK to lead free petrol
I do not remember one case of the inserts falling out or cracking the heads.
I have burned out standard exhaust seats with non leaded petrol in under ten laps racing.
I have also build many A series Leyland performance engines and Fords ranging through the Kent pushrod, through to the V6s and even BDAs.
It is an interesting thread on the comparisons between fuels around the globe, so my opinion may not be valid in the USA etc.
In the UK, IMHO 10:1 would be a sensible top figure for a road engine and 12:1 for a full race engine.
I have used both for either 100+ Avgas and 'Super' pump petrols without lead.
It used to be possible with leaded petrol to go slightly higher.
Of course these are 'average' figures.

[MatsNorway]

wouldn`t a cross flow config add some heat to the intake air?

I love the comment from Grunt about asking for details about the cam. i think the cam is the main reason street bikes can run 12:1 comp on 98 octane.

[desmo]

Might have more to do with the typical operating rpm range.

[24gerrard]

MatsNorway, on May 27 2011, 15:13, said:

wouldn`t a cross flow config add some heat to the intake air?

I love the comment from Grunt about asking for details about the cam. i think the cam is the main reason street bikes can run 12:1 comp on 98 octane.

I would think the 'A' series siamese ports would add more temperature to the intake air (charge).
although the A series has a 'Weslake' kidney shaped combustion chamber in the heads and most 'Kent' Ford engines were 'bowl in piston'.
There were some heads on the Kent with the oval combustion chamber in them.
The A series chamber gave far superior swirl and even mixture, IMHO this could add at least half a compression figure i.e 12.5 rather than 12.
The siamese ports (three primaries on the exhaust manifold) and non crossflow, kept the A series 20 to 30 bhp behind the Kent at a comparison capacity and level of tune. It was not the A series three bearing crank, which actualy reved better than the Kent five bearing and was probably better balanced and stronger.

Race cam comparisons in mind are the 649 Leyland for the A series and the Cosworth A1 for the Ford.
Most other race cams available are slight variations on these two.

On the A offset rockers added lift and worked better for higher sustained rpm with downdraft IDA carbs, (sidedraught 40/45 DCOEs without).
I do not know of any offset rocker ratio increases on the Fords to increase lift.
Not sure if there was enough room to use them.

I would not increase C/R above 10:1 on either engine with road cams.
Not so much because of pre-ignition but because of losses in tractability.
They would become difficult to start and prone to stalling.

Edited by 24gerrard, 27 May 2011 - 17:06.

[J. Edlund]

MatsNorway, on May 27 2011, 16:13, said:

wouldn`t a cross flow config add some heat to the intake air?

I love the comment from Grunt about asking for details about the cam. i think the cam is the main reason street bikes can run 12:1 comp on 98 octane.

I would say that the high engine speed and the small bore are the main reasons for high compression ratios being possible.

[Spaceframe7]

24gerrard, on May 27 2011, 17:04, said:

I would think the 'A' series siamese ports would add more temperature to the intake air (charge).
although the A series has a 'Weslake' kidney shaped combustion chamber in the heads and most 'Kent' Ford engines were 'bowl in piston'.
There were some heads on the Kent with the oval combustion chamber in them.
The A series chamber gave far superior swirl and even mixture, IMHO this could add at least half a compression figure i.e 12.5 rather than 12.
The siamese ports (three primaries on the exhaust manifold) and non crossflow, kept the A series 20 to 30 bhp behind the Kent at a comparison capacity and level of tune. It was not the A series three bearing crank, which actualy reved better than the Kent five bearing and was probably better balanced and stronger.

Race cam comparisons in mind are the 649 Leyland for the A series and the Cosworth A1 for the Ford.
Most other race cams available are slight variations on these two.

On the A offset rockers added lift and worked better for higher sustained rpm with downdraft IDA carbs, (sidedraught 40/45 DCOEs without).
I do not know of any offset rocker ratio increases on the Fords to increase lift.
Not sure if there was enough room to use them.

I would not increase C/R above 10:1 on either engine with road cams.
Not so much because of pre-ignition but because of losses in tractability.
They would become difficult to start and prone to stalling.

Hello 24 Gerrard, and thank you - and others - very much for the information so far.

As requested by another forum contributor, the camshaft (a Holbay item, recommended for street use), has the following specifications:

Lift at cam=.286";
lift at valve=.435";
angle of relationship=107 degrees;
Inlet period with .022" clearance= 142 degrees;
exhaust period with .025" clearance= 142 degrees;
Full lift at 105 degrees A.T.D.C;
inlet lift at T.D.C. (running clearance)= .099"
Inlet timing at .022" clearance in degrees = 37/67;
exhaust timing at .025" clearance in degrees = 71/33
Running clearances cold - inlet.016" - exhaust .019"
This is using standard Ford timing procedure.
Twin 40 DCOEs are recommended with this camshaft, but it can be used with a 'standard' GT Weber downdraught carb (i.e. 28/36DCD, 32 DFM, DGV, DGAV etc).
Pistons require deeper valve cut-outs due to much higher lift than the standard Ford GT camshaft.

If this is too much info - my apologies, but I do not know what is relevant and what is not. BTW, the info is taken from the Holbay camshaft specification sheet. Holbay ran with a 10:1 c.r. after deepening the pockets in the forged Hepolite Powermax pistons (unavailable for ages unfortunately), but this was probably in the 681/2737E engine with the small chamber in the cylinder head as you mention above.

Accralite/Omega (U.K.) forged pistons are approx. 11.7:1 as manufactured - which seems rather high for road use with our lower Canadian gas octane, and Formula Ford forged pistons (from Pegasus or Ivey engines in the U.S.) are 9.3:1 on a standard 1600c.c. engine - but would be less if deeper pockets were cut. I realize some machine shops in the U.K. have used cast pistons from the 1300 c.c. Ford Cortina, (providing approx. 10.3:1 after deepening the valve cut-outs), but a couple of articles in an out-of-print U.K. magazine (Cars and Car Conversions) indicated that this is not always a wise move, as the pistons may not last too long even for a road engine (not sure why though, they didn't reveal this in the article unfortunately?). I realize that I do not have a lot of choices, but opinions as provided on this forum may provide the answer. Cheers.

Edited by Spaceframe7, 28 May 2011 - 02:27.

[Lee Nicolle]

24gerrard, on May 27 2011, 11:50, said:

Our machine shop fitted thousands of valve seat inserts during the original faze over in the UK to lead free petrol
I do not remember one case of the inserts falling out or cracking the heads.
I have burned out standard exhaust seats with non leaded petrol in under ten laps racing.
I have also build many A series Leyland performance engines and Fords ranging through the Kent pushrod, through to the V6s and even BDAs.
It is an interesting thread on the comparisons between fuels around the globe, so my opinion may not be valid in the USA etc.
In the UK, IMHO 10:1 would be a sensible top figure for a road engine and 12:1 for a full race engine.
I have used both for either 100+ Avgas and 'Super' pump petrols without lead.
It used to be possible with leaded petrol to go slightly higher.
Of course these are 'average' figures.

I have seen no end of inserts fall out or crack heads. Holdens, Chevs, Fords, Mopar, 4 6 and 8 and even VWs. One shop I use will not do it, as they have had too much drama, and they have very good equipment and machinists. 1 insert to repair damage maybe. A head that was never designed to have an insert is generally very thin in that area, and a 90 deg cut is setting a total stress riser. 70s onwards engines were worse from all manufacturers. Alloy heads designed to have inserts are generally trouble free though I have seen several of those come out too under hard and hot conditions, eg heavy towing.Or a boiled badly engine, and that is the brinnel on the head surface. Some manufacturers use fairly poor alloy, more akin to the 70s instead of this century.
As for 10 laps to burn seats it must have been stupidly lean, what did the pistons look like? Ashtrays probably.
LPG and methanol engines are far harder on seats than unleaded. And the worst I have seen there is 50000km and the heads were stuffed. 410 Sprintcar engines do a season @ 8500 rpm+ and the seats just get a lick for the next season with a new set of valves. [titanium has a very short life] Some 360s just get a seat lick and reuse the stainless ones for another season.

[24gerrard]

Lee Nicolle, on May 28 2011, 06:54, said:

I have seen no end of inserts fall out or crack heads. Holdens, Chevs, Fords, Mopar, 4 6 and 8 and even VWs. One shop I use will not do it, as they have had too much drama, and they have very good equipment and machinists. 1 insert to repair damage maybe. A head that was never designed to have an insert is generally very thin in that area, and a 90 deg cut is setting a total stress riser. 70s onwards engines were worse from all manufacturers. Alloy heads designed to have inserts are generally trouble free though I have seen several of those come out too under hard and hot conditions, eg heavy towing.Or a boiled badly engine, and that is the brinnel on the head surface. Some manufacturers use fairly poor alloy, more akin to the 70s instead of this century.
As for 10 laps to burn seats it must have been stupidly lean, what did the pistons look like? Ashtrays probably.
LPG and methanol engines are far harder on seats than unleaded. And the worst I have seen there is 50000km and the heads were stuffed. 410 Sprintcar engines do a season @ 8500 rpm+ and the seats just get a lick for the next season with a new set of valves. [titanium has a very short life] Some 360s just get a seat lick and reuse the stainless ones for another season.

Plenty of cast iron in the old engines and I cannot remember one case of a job returned with 'dropped' seats or cracks.
Of course we had cracked seat jobs which included cracked heads but never AFAIR on original jobs.
I agree, machine shop tuning is all but dead these days because the modern engine has too little metal to work with.
Seats etc are often held in with 'faith' and how clever the guy on the computer was.
Few of them have ever spent days grinding ports and matching combustion chambers by hand.
Pity, they remain ignorant of the basics.
Chip it she said

[MatsNorway]

J. Edlund, on May 27 2011, 20:09, said:

I would say that the high engine speed and the small bore are the main reasons for high compression ratios being possible.

exactly...

Me thinks..

you get less air cyl fill at low rpms taking the engine to go past it critical rpms before it starts to work properly. (you could say it never really works better it just does more work..giving more power)

Edited by MatsNorway, 28 May 2011 - 11:22.

[Lee Nicolle]

J. Edlund, on May 27 2011, 21:09, said:

I would say that the high engine speed and the small bore are the main reasons for high compression ratios being possible.

And all alloy engines which do absorb some detonation. Plus ofcourse a combustion chamber designed around that fuel. EFI helps a lot too as it properly atomises the fuel unlike carbs.And the computer limits the advance. Put 100 in it and it will make more power.
But then you have to find a servo that actually sells proper 98, that is fresh and not contaminated with 91.
That has happened to me several times. Drive into a retail petrol outlet with a car running fine, pay far too much for the product [15c more] and get a km down the road and the car is pinging its brains out.
Thios commercial brought to you by BP, substandard fuel on many occasions .And reputedly they have the best plant in Oz to make the stuff

[24gerrard]

Lee Nicolle, on May 31 2011, 00:44, said:

And all alloy engines which do absorb some detonation. Plus ofcourse a combustion chamber designed around that fuel. EFI helps a lot too as it properly atomises the fuel unlike carbs.And the computer limits the advance. Put 100 in it and it will make more power.
But then you have to find a servo that actually sells proper 98, that is fresh and not contaminated with 91.
That has happened to me several times. Drive into a retail petrol outlet with a car running fine, pay far too much for the product [15c more] and get a km down the road and the car is pinging its brains out.
Thios commercial brought to you by BP, substandard fuel on many occasions .And reputedly they have the best plant in Oz to make the stuff

I have always considered cast iron engines to be more capable of absorbing detonation.
Perhaps we should ask BMW.

BP in the UK has IMO been the best fuel distributer in the UK.
It is their refining that also goes to most supermarket outlets etc.
Shell and Total always seems to smell different and burn the skin more.
I found that out when doing some fuel tests.

I keep hearing criticism from those in OZ on the fuels available, including LPG etc.
Are your controls less stringent?

[Catalina Park]

24gerrard, on May 31 2011, 22:07, said:

I keep hearing criticism from those in OZ on the fuels available, including LPG etc.
Are your controls less stringent?

There was an independently owned service station near me that got caught for substituting diesel fuels with inferior fuels. Because it was a big place on the highway the Government went out to make an example of him and threw all the strength of the law at him.
The Government lost.
There is no actual specification for what makes up diesel fuel (or even petrol) in Australia.

Edited by Catalina Park, 31 May 2011 - 10:59.

[24gerrard]

Catalina Park, on May 31 2011, 11:58, said:

There was an independently owned service station near me that got caught for substituting diesel fuels with inferior fuels. Because it was a big place on the highway the Government went out to make an example of him and threw all the strength of the law at him.
The Government lost.
There is no actual specification for what makes up diesel fuel (or even petrol) in Australia.

Realy!!!

I now realise why there is so much controversy coming from the engineers and experts in OZ about octanes etc.
Sorry fellas but if you have no way of confirming what makes up the fuel you put in your vehicles, it makes your comments on the subject based on experience of OZ fuel of no import.

[J. Edlund]

MatsNorway, on May 28 2011, 13:17, said:

exactly...

Me thinks..

you get less air cyl fill at low rpms taking the engine to go past it critical rpms before it starts to work properly. (you could say it never really works better it just does more work..giving more power)

At low speeds you can always decrease ignition advance if knock is an issue. But some low speed knock can usually be allowed during engine acceleration, it tends to be more of a cosmetic problem.

[Greg Locock]

24gerrard, on May 31 2011, 22:06, said:

Realy!!!

I now realise why there is so much controversy coming from the engineers and experts in OZ about octanes etc.
Sorry fellas but if you have no way of confirming what makes up the fuel you put in your vehicles, it makes your comments on the subject based on experience of OZ fuel of no import.

Oh dear. You seem to have swallowed Lee's little story hook, line, sinker, and rod. We have Euro 4 emissions standards here with concomitant fuel quality standards eg http://www.environme...ards/index.html . Min Octane in Oz is 91, rather better than the USA was when we introduced it. However I'm sure your faith based approach to engineering will continue to amuse us.

Edited by Greg Locock, 01 June 2011 - 00:09.

[gruntguru]

Doesn't Australia use the RON scale and the USA the (RON+MON)/2 scale?

Regulation works fine for ensuring the product leaving the refineries meets a spec but its a lot harder to regulate against adulteration by retailers (as would equally be the case in the UK).

[24gerrard]

Greg Locock, on May 31 2011, 23:37, said:

Oh dear. You seem to have swallowed Lee's little story hook, line, sinker, and rod. We have Euro 4 emissions standards here with concomitant fuel quality standards eg http://www.environme...ards/index.html . Min Octane in Oz is 91, rather better than the USA was when we introduced it. However I'm sure your faith based approach to engineering will continue to amuse us.

I am glad my posts amuse you Greg, although I thought that perhaps with the state of OZ politics and economics at present.
it would be you guys considering a 'faith' approach to life, let alone just engineering.

It was not your governments regulations on fuel that I was drawing my conclusions from,
it was Lee's comment that the retailers can do what ever they wish with the fuel without fear of prosecution.
A bit like the fizzy beer you drink.

[Lee Nicolle]

We may have so called standards but really they are seldom enforced.The government does not have any testing facility in Oz. The Industry self regulates. Even weights and measures are being scaled right back. That is why AVGAS is a consistent fuel. if it was like normal petrol planes would fall out of the sky very regularly. Because the stuff IS made to the standard.
Fact LPG does vary in ingredients widely. Hence economy and power differences.
Fact, what we buy at the local retail petrol outlet [no service whatsoever] varys widely in quality depending where it is made. we still have some refinerys left [though none in South Oz] but a lot of fuel comes from SE Asia. According to several people I know in the Industry some of it is very good, and some is CRAP. As is the local stuff and to a small degree depends on the crude it is made from.And it is VERY annoying to buy the so called premium product at 15c a litre more and get crap. EFI cars will mask it to a degree as the computer just ******* the engine but with old school you know almost immediatly.
The ethanol blend stuff seems to vary quite a lot too.
As does diesel though my experience with that stuff is very small. A personal dislike as you can seldom even refuel without getting filthy hands. And to work on they are very dirty, and heavy.
Great for trucks and industry but the rest, forget it.

As for iron absorbing detonation better than alloy. Get a hammer and tap iron. Very hard and unforgiving. Tap alloy and a diferent tone as it is a far softer metal.And absorbs some detonation. Though any detonation is bad, both for the components and the metal also. Detonate an alloy head engine and the metal goes soft eventually with the extra heat. Even iron will to a small extent.Though it will crack under those conditions.

[Magoo]

gruntguru, on May 31 2011, 19:28, said:

Doesn't Australia use the RON scale and the USA the (RON+MON)/2 scale?

Exactly. 91 RON = 87 (R+M)2 octane, more or less. Our "regular" pump gasoline here in the USofA is 87, while "premium" pump fuels range from 89 to 94 on the (R=M)/2 scale, also known in some parts as AKI for anti-knock index, or PON, pump octane number. 94 (R+M)/2 is approximately 98-99 RON, depending.

Blabbering on... Research octane (RON) and Motor Octane (MON) numbers are both obtained using bench engines with adjustable CR, etc. However, the MON method (aka "aviation lean") is somewhat more tortuous, producing lower octane numbers. MON will generally be around 8-10 points lower than RON, roughly speaking. However, some fuels can have a high RON with a relatively low MON, hydrogen for instance.

[24gerrard]

Quote

As for iron absorbing detonation better than alloy. Get a hammer and tap iron. Very hard and unforgiving. Tap alloy and a diferent tone as it is a far softer metal.And absorbs some detonation. Though any detonation is bad, both for the components and the metal also. Detonate an alloy head engine and the metal goes soft eventually with the extra heat. Even iron will to a small extent.Though it will crack under those conditions.

I think the increased problem of detonation in alloy engines is the huge reduction in the actual mass of metal used due to the results of CAD and CAM.
The units are now far lighter and better made.
Much better control over the timing using computers reduces the chances of detonation and is used to instantly compensate, which hugely reduces any damage resulting.

However, any changes made to fuel or mechanical changes like compression ratio, has to be very carefuly considered.
The old cast iron engines were massive by comparison and allowed a lot of experimentation before damage occured.
Many of the problems I encountered with tuning them was a result of bad manufacture rather than from metal strength.

[ArtShelley]

24gerrard, on Jun 1 2011, 09:49, said:

I am glad my posts amuse you Greg, although I thought that perhaps with the state of OZ politics and economics at present.
it would be you guys considering a 'faith' approach to life, let alone just engineering.

It was not your governments regulations on fuel that I was drawing my conclusions from,
it was Lee's comment that the retailers can do what ever they wish with the fuel without fear of prosecution.
A bit like the fizzy beer you drink.

What's wrong with Oz economics? I got back from a holiday to the U.S late last year - now they've got problems. Was in Europe and U.K earlier last year on a work trip for 10 weeks and though some parts of Europe were ok, the U.K was in a sad state. Am sure they'll pick up though. But yes, Oz is quite good. Of course we have our whinging chicken littles here too, but the economy is doing well, admittedly almost entirely on the back of a booming resources (mining and oil/gas) super-cycle.

Sounds like you know even less about Oz economics than our beer. Understandable though since you guys drink the Fosters **** that we export over to you

[Tony Matthews]

24gerrard, on Jun 1 2011, 13:08, said:

Much better control over the timing using computers reduces the chances of detonation and is used to instantly compensate, which hugely reduces any damage resulting.

They'll be using them for the same reason in gearboxes before long, mark my words...

[24gerrard]

Tony Matthews, on Jun 1 2011, 18:27, said:

They'll be using them for the same reason in gearboxes before long, mark my words...

Have you bought one to hold your pencil yet Tony?

[Tony Matthews]

I no longer use a pencil, Gerrard.

[gruntguru]

Magoo, on Jun 1 2011, 21:46, said:

However, the MON method (aka "aviation lean")

I haven't heard that before. Aviation fuels are normally rated using the supercharge method which is quite different. Is the lower Avgas number obtained using a MON test?

[24gerrard]

Tony Matthews, on Jun 1 2011, 22:44, said:

I no longer use a pencil, Gerrard.

Not even for sketching Tony?
Digi pics I suppose. (same safety net?).

I organise the odd art show for local artists Tony, I wonder if there will be any such artists at all left in 30 years?
I wonder what Turner and Constable would think of all the modern bells and whistles?

Sorry off topic, back to toxic fuels.

Edited by 24gerrard, 01 June 2011 - 23:56.

[johnny yuma]

[quote name='Spaceframe7' date='May 26 2011, 22:03' post='5050482']
[quote name='Canuck' post='5026971' date='May 20 2011, 04:04']

10.5 :1 with an "old school" points distributor will need 98 octane and some booster,a cooling system that NEVER runs hot ,and some timing compromise at either middle or high rev output,and always a sacrifice at low rev output if its a racer.

[cheapracer]

Lee Nicolle, on May 25 2011, 14:12, said:

About 35 years ago during a National Fuel Strike the place
That drum got us out of trouble in the worst of Goughs years.

Me and my teenaged mates went around all the car yards milking - when I got home with a jerry can full my Dad didn't know if to thank me or give me a flogging

[bigleagueslider]

Geometric compression ratio is only one variable to consider whether an engine will suffer detonation. As noted, fuel octane rating (whether RON, ROM, or RON+ROM/2) is also important. Other relevant factors would include, combustion chamber geometry and surface area-to-volume characteristics, intake charge motion and turbulence, intake charge temperature, latent heat value of the fuel, mixture stratification of the intake charge, trapping efficiency, and EGR rate.

Modern engines with digital control of fuel and ignition, closed loop controls, and high frequency data acquisition from lambda, knock and mass airflow sensors, rarely suffer from detonation. Even when supplied with low octane fuels. If the engine is supplied with low octane fuel, once detonation is detected, the ECU will immediately ****** ignition timing, richen the fuel mixture, and reduce the throttle opening. The engine will naturally produce less power, but it will not suffer from detonation damage. Even 10.5:1 CR's are possible (and safe) with modern N/A engines using 89 octane pump gas. New street bike engines run at 12:1 or more on 91 octane pump gas.

[Magoo]

gruntguru, on Jun 1 2011, 19:00, said:

I haven't heard that before. Aviation fuels are normally rated using the supercharge method which is quite different. Is the lower Avgas number obtained using a MON test?

Yep, the lower, first number ("lean") in the ASTM XX/XX scheme is similar/equivalent to MON, while the higher, second number is MON but rich mixture, high temp, high manifold pressure. Takeoff settings, in other words. So with 100/130 avgas, the 100 is MON, sort of, while the 130 is the "supercharge" octane rating.

[gruntguru]

So a "pseudo" MON performed using a supercharge method engine. Thanks Magoo. I did have a copy of the appropriate ASTM manual but made the mistake of lending it once too often.

[Magoo]

The lean half of the avgas dual rating and MON are the same ASTM test standard, but there can be differences in the way the results are interpreted. Not that it matters much anymore.

[Lee Nicolle]

cheapracer, on Jun 2 2011, 05:48, said:

Me and my teenaged mates went around all the car yards milking - when I got home with a jerry can full my Dad didn't know if to thank me or give me a flogging

I am surprised you got any! Most yards, including my own ever leave much fuel in cars. If they come in with plenty they are used until there is not much, or occasionally sucked to refuel all the otheres with none!

[Catalina Park]

I discovered that my fuel economy improved when I parked my Torana with the back bumper against the fence.

[Lee Nicolle]

Catalina Park, on Jun 5 2011, 03:15, said:

I discovered that my fuel economy improved when I parked my Torana with the back bumper against the fence.

[cheapracer]

Catalina Park, on Jun 5 2011, 10:15, said:

I discovered that my fuel economy improved when I parked my Torana with the back bumper against the fence.

Thats really weird, just yesterday before I even read this I was trying to remember what ever happened to my Torana fuel cap collection!

I had them all and you may think GTR XU1 was the hardest to get, nope, damn 2250 was the hardest.

[Catalina Park]

cheapracer, on Jun 5 2011, 20:20, said:

Thats really weird, just yesterday before I even read this I was trying to remember what ever happened to my Torana fuel cap collection!

I had them all and you may think GTR XU1 was the hardest to get, nope, damn 2250 was the hardest.

You know, I still have a 2250 one in the shed. I think I have a couple of Lion logo caps still. They are now worth a lot less since there are reproductions on the market but I did manage to sell the XU1 tank before the reproduction of them hit the shops.

It was an LX that had the filler behind the numberplate that I backed up against the fence to stop overnight evaporation.

[cheapracer]

Catalina Park, on Jun 5 2011, 18:39, said:

to stop overnight evaporation.

Strange how the worst evaporation seems to happen at 1 am at night rather than in the heat of the day..... one of science's mysteries.

[Grumbles]

A friend of mine had trouble with fuel being milked at night from drums he carried in the back of his ute. He had his suspicions but no proof, so added some engine oil to the fuel, like a rich two-stroke mix. Sure enough, young neighbour was spotted driving his old Commodore past leaving a thick trail of smoke a couple of days later. My friend, a big bloke, had a "quiet word" with him and no more problems.

[Lee Nicolle]

Catalina Park, on Jun 5 2011, 11:39, said:

You know, I still have a 2250 one in the shed. I think I have a couple of Lion logo caps still. They are now worth a lot less since there are reproductions on the market but I did manage to sell the XU1 tank before the reproduction of them hit the shops.

It was an LX that had the filler behind the numberplate that I backed up against the fence to stop overnight evaporation.

A locking cap may have been a easier alternative.
I have had a complete collection of those LC LJ caps,,, attached to the various cars!

Edited by Lee Nicolle, 07 June 2011 - 10:30.