45 replies to this topic

[ZoRG]

Hi

After seeing the 1.5L BMW engine on Bill Sherwoods website I contacted BMW to get some more info on the engine.

They confirmed 1400HP, and said that the engine ran steel springs up to 10500RPM, had a bore of 89mm and a stroke of 60mm, made 4 bars of boost and 5.5 bar on qualifying...

Does anyone know what kind of turbo must have been used? If I look at the pic on Bill's page the turbo does not seem extremely large as some drag cars I have seen that does not even produce over 1000HP...

Any other thoughts on this engine?

[Cociani]

My understanding was that the fuel used in 1983 was very high octane and fairly high cylinder pressure was not a problem. The other technology BMW used was a fully integrated electronic engine management system.

[ZoRG]

I see, what do you mean by fully integrated engine management system?

Thanks for the reply.

[Cociani]

I watched a BMW propaganda film on Speedvision a few years ago and they didn't go into detail into the engine managment system but from what I remember the system integrated ignition timing and fuel enjection in one central processor. The system is similar to what road cars use today but at that time was fairly unique.

As you probably know the engine block was based on a production engine. Imagine that today!

[random]

Having been in the paddock from time to time in the late 80's, I can attest that the fuel they were burning smelled like nothing less than a chemical factory.

I've heard it said that the nitro methane drag racers use was tame in comparison to the chemical cocktails run in those cars.

[Wuzak]

Originally posted by ZoRG
They confirmed 1400HP, and said that the engine ran steel springs up to 10500RPM, had a bore of 89mm and a stroke of 60mm, made 4 bars of boost and 5.5 bar on qualifying...

Does anyone know what kind of turbo must have been used?

You have already stated what turbo pressures were used:

4 bar (58 psi) boost in the race.

5.5 bar (80 psi) in qualifying.

That is a quite phenominal level of boost!

I have read that the fuel used for the BMW engines was a mix used by the Luftwaffe in WW2, and that, like many of the fuels, was extremely toxic.

[ZoRG]

So what would you say would be the limit in boost as well as HP if they were to be forced to run normal 102.6 racing fuel?

[Todd]

Typically, an engine management system controls fuel delivery and ignition timing. In some turbos, it also controls the waste gait, and therefore the level of boost. What makes an EMS so effective is its ability to adjust these parameters based on real time data about combustion. There are a few ways I know of that the EMS measures the effectiveness of what is going on in the combustion chamber. An oxygen sensor in the exhaust can measure how complete combustion is. If there is too much oxygen remaining, then you may have a lean condition where not enough fuel is being injected to burn all the air. An exhaust gas temperature sensor can sense a rich mixture, where too much unburned fuel might cool the exhaust gases a bit. These two sensor allow for a good mixture to be achieved. Ignition timing is keyed to a knock sensor. There are a few types of these, and I don't remember the particulars. Essentially, they can tell when combustion is occuring at a time other than when the spark plug is initiating it. By advancing or retarding the ignition timing, relative to the time when the piston is at the top of it's travel on it's compression stroke, the EMS will try to eliminate knock. In engines where fuel is directly injected into the combustion chamber, an EMS can also time this variable to maximize combustion efficiency and minimize the destructive forces and heat of random combustion.

I've got a great article somewhere about the mystery fuels. If I find it, I will try to cull out some useful information.

[Todd]

Originally posted by random
Having been in the paddock from time to time in the late 80's, I can attest that the fuel they were burning smelled like nothing less than a chemical factory.

I've heard it said that the nitro methane drag racers use was tame in comparison to the chemical cocktails run in those cars.

I've heard it said that nitrometh is tame compared to unleaded. It actually contains less energy by volume. The magic is that it requires a much lower volume of air to burn. Therefore, the engines can use a multiple of the volume of fuel that they could burn if they were burning gasoline, more than making up for the lower energy content by volume.

[Scoots]

Originally posted by ZoRG
So what would you say would be the limit in boost as well as HP if they were to be forced to run normal 102.6 racing fuel?

That's somewhat impossible to answer, but for comparison ... I have a friend who is a professional tuner whose Mitsu Evo 8 makes 500bhp at 25lbs of boost on 93 octane in street tune with a mild turbo, cat, air filter, and full exhaust on the stock block, rods, pistons, intake, only the injectors, fuel rail, turbo, exhaust, cams, and intercooler have been changed. For this he charges around $7000 ... if he can get 500bhp out of a mostly stock, mild street drivable, mass produced car, I can't imagine what $100 million and an F1 race team could accomplish today.

[random]

Originally posted by Scoots
That's somewhat impossible to answer, but for comparison ... I have a friend who is a professional tuner whose Mitsu Evo 8 makes 500bhp at 25lbs of boost on 93 octane in street tune with a mild turbo, cat, air filter, and full exhaust on the stock block, rods, pistons, intake, only the injectors, fuel rail, turbo, exhaust, cams, and intercooler have been changed. For this he charges around $7000 ... if he can get 500bhp out of a mostly stock, mild street drivable, mass produced car, I can't imagine what $100 million and an F1 race team could accomplish today.

Which is why more than a few have long suggested F1 move to 2 or 3 liter 4 banger turbos. The technology is much more applicable to what it being used in road cars, which equals a lot more take aways for the big car manufacturers.

Perhaps the direct tech transfer wouldn't be huge. But it would certainly be greater than the current near worthless technological dead-end of ridiculously high revving V 10's...

[McGuire]

Originally posted by Wuzak


You have already stated what turbo pressures were used:

4 bar (58 psi) boost in the race.

5.5 bar (80 psi) in qualifying.

That is a quite phenominal level of boost!

Here 4 bar and 5.5 bar refer not to boost but to manifold absolute pressure (MAP). To illustrate, a normally-aspirated engine runs at one atmosphere of absolute pressure, or at a theoretical maximum MAP of about one bar, 14.7 PSI, or 29.9 inches of mercury. [These measures are not quite exact relative to each other as they are rooted in slighty different definitions of one "standard atmosphere."]

In other words, "boost" is simply one atmosphere less than MAP. So an engine running 4 bar of manifold pressure would be running at a boost of approximately 3 bar, or about 44 lbs boost. 5.5 bar of manifold pressure is around 80 PSI in absolute pressure, or 66 PSI of boost. Yes, that is still a lot. In CART where they describe manifold pressure in inches of mercury, they would say this engine is running at "162 inches."  In CART they may refer to their figure as "boost," but it's really not -- it's absolute pressure.

Boost is also referred to as gauge pressure or differential pressure, to distinguish it from absolute pressure. Obviously, if a mechanical pressure gauge has sample pressure on one side and atmospheric pressure on the other, it will read the differential of the two. However, not all gauges need register in "gauge" pressure. A piston aircraft pilot constantly watches his manifold pressure gauge, which here is calibrated in inches of mercury absolute. If the engine is normally aspirated, the higher the altitude the less manifold pressure is available.

It is also important to distinguish manifold pressure from manifold vacuum, which is a different concept, inverted if you will. Generally, at minimum throttle opening an engine is at minimum manifold pressure but maximum manifold vacuum. Sounds obvious when stated thus, but people still manage to get the two mixed up...perhaps because manifold vacuum is typically described in inches of mercury as well.

[Chevy II Nova]

Originally posted by Todd


I've heard it said that nitrometh is tame compared to unleaded. It actually contains less energy by volume. The magic is that it requires a much lower volume of air to burn. Therefore, the engines can use a multiple of the volume of fuel that they could burn if they were burning gasoline, more than making up for the lower energy content by volume.

You are thinking of Methanol, which makes up about 10% of the mix that Top Fuelers use.

Gasoline requires about a 12:1 Air/Fuel ratio. Methanol is closer to 4:1. 3 times as much fuel more than makes up for the difference in energy, as you pointed out.

Nitro on the other hand contains a ton of energy and is rather volitile.

[McGuire]

Originally posted by random
Having been in the paddock from time to time in the late 80's, I can attest that the fuel they were burning smelled like nothing less than a chemical factory.

I've heard it said that the nitro methane drag racers use was tame in comparison to the chemical cocktails run in those cars.

Not really. Drag racers of course use nitromethane (CH3NO2) which is a monopropellant.  That is, it does not require oxygen for combustion. Technically, nitromethane meets the DOT's definition of several classes of explosives. If you pour a bead of nitromethane on the floor and strike it with a hammer, it will detonate. In past practice nitromethane was sometimes blended variously with picric acid, propylene oxide, and hydrazine, with unpredictable results [or maybe not]. However, these fuels are now prohibited in NHRA. There they now use a "spec" fuel of 90% nitro blended with methanol [methyl alcohol, CH3OH].

The fuels used in F1 before its exotic fuel ban were gasolines blended with olefins, diolefins and various aromatics [hence the odor], mostly tolouene, aka methyl benzene.  Potent but nothing truly outlandish, or as powerful as nitromethane.

It should probably be noted here that plain old unleaded pump gasoline is toxic, and also contains several known carcinogens. If you cup a teaspoon of gasoline in the palm of your hand it can be detected in your bloodstream within 60 seconds. We used to wash our hands and kill weeds behind the shop with gasoline, but today we know better.

[Scoots]

McGuire, while I can't really disagree with what you are saying, you sure use alot of words to say it

Do you know that when CART says Boost they mean MAP and not boost? I know when I said boost I meant pressure above atmospheric.

[McGuire]

Originally posted by Scoots
McGuire, while I can't really disagree with what you are saying, you sure use alot of words to say it

Do you know that when CART says Boost they mean MAP and not boost? I know when I said boost I meant pressure above atmospheric.

Often I don't have time to employ brevity.

When CART mandates a popoff valve limit of say 40," that means the engine gets 40" of manifold pressure, no more [unless you whistle the valve eh]. CART folks often call that number "boost," but it's really MAP. 40" of MAP allows for 10" above atmospheric, or not quite 5 PSI of boost.

[ZoRG]

surely that can't be so? Are you saying that if you put a pop off valve of 10 on, it will be permanently open?

[McGuire]

Originally posted by ZoRG
surely that can't be so? Are you saying that if you put a pop off valve of 10 on, it will be permanently open?

Yes, it is so: 40" MAP is definitely 10" above atmospheric pressure. However, you are asking a different question as to whether a 10" POV would be permanently open. The short answer is no, but that's rather misleading. Do you want the long answer?

[ZoRG]

Maybe in Cart... but according to this sentence in the email, it does not seem that way:

"In 1986 we were able to achieve a charging pressure of 5,5 bars in the qualifying, in combination with a waterspray cooled intercooler there was the mentioned power output of app. 1400 hp."

[Cociani]

McGuire,

I certainly appreciate your thorough complete answers. It is fantatic to have such knowlegable people to bounce ideas off of.

[VAR1016]

In his book, "Ir was fun" Tony Rudd describes the demonstration run performed by Graham Hill at Kyalami in 1968 in the 1.5 litre V-16 BRM.

For this demonstration Rudd replaced the 4.5" air intake with the Rolls-Royce-designed 6" iris throttle. allowing 50% more air to be ingested.

With the rev counter running "off the clock" (clock limit 12,500) Rudd calculated that the engine was developing 780HP. Unfortunately he does not state the amount of boost, but goes on to mention that with the "intermediate 75 psi (= 5Bar) setup the engine would make 610HP. It was calculated that for a mooted land-speed record attempt, that the engine would give 1000 BHP on sprint fuel.

Very fair going for what was basically a 1946 design - albeit with a "few" modifications!

PdeRL

[BRIAN GLOVER]

Howdy,

You sure know a lot of stuff, McGuire. Do you write for a tech magazine? I found a error in your text.;)

This morning at 9am at the Daytona airport, ATIS reported 30.24" and 63'f. (I went to the Turkey Rod Run at the speedway.) A 'standard ' day is 29.92 " and 56'f or 14.7 psi. Performance tables for all aircraft are corrected to these values. Florida in the winter, just after a really cold front has gone thru, like today, the air is extra heavy and pressures way over standard is normal. The HP gains are noticeable as is the performance of the wing.( That's why F1 cars have pitot tubes )
So, consulting one's tables you will find that you need a lot less runway to take off and your climb rate will be considerably higher than in mid summer. Before you even start your airplane, you will notice that your manifold pressure will be what ATIS has reported. Your altimeter's Coleman window will display the ambient pressure if you set it to airport elevation if it is calibrated correctly.
As you climb out after take off you reduce first the manifold pressure with the throttle to 25" and then the prop rpm to 2500rpm if you have a naturally aspirated engine with a constant speed prop.. . As you continue to climb on a day like this, you will be able to carry that MP till 7 or 8 thousand ft. The prop rpm, which is the same as the engine rpm will remain at 2500. By this time the throttle is wide open. In summer you would be looking at 19" or less at this altitude. You may not be able to even take off in Albuquerque NM on a mid summer day. It is not good to run a air-cooled engine below 65% of its power because of engine component clearances, so if you want your aircraft engine to last, keep it at high power settings. To determine a cruise altitude, you would climb to the altitude that will give you not less than 65% power. Change in altitude requires mixture changes. As you descend, the throttle is constantly reduced to maintain 25" and the mixtures are made richer. If you don't do this, 30" MP will put too much load on the prop governor if the prop is set at 2500 rpm. Its like going up a hill in top gear.
A fixed pitch propeller aircraft does not have a MP gauge. The engine won't have the HP to reach max rpm at altitude and if the pressure is high at take off, the prop will have too much drag to exceed engine rpm limitations. At cruise, you would generally have the throttle wide open. You also get better combustion with a wide open butterfly. Remember 65% rule. In a decent you would prevent the RPM from going into the red with appropriate mixture changes.
In the case of a turbo charged aircraft engine, or the Atmospheric carburetors on supercharged Merlins, the manifold pressure and prop rpm is set by the pilot at all phases of flight and will stay there for all altitudes. Mixtures are set for cruise EGTs. If you have a pressurised cabin, it is still good to monitor outside air temp to determine cruise altitude. Your cylinder head temps may be fine, but your piston clearances may be excessive.
On air cooled engines, it is not good to operate them below 20" for long periods. For landing, you would hold those settings to flair and control speed by increasing drag with flaps and landing gear. IE: if you are paying the bills.
Econo gauges on cars are nothing more than vacuum gauges. The lower the pressure, the less gas you will use. Saving gas in an airplane will cost you engine repairs in the long run and maybe your life.

Type slowly, because I can't read fast.

Originally posted by McGuire


Here 4 bar and 5.5 bar refer not to boost but to manifold absolute pressure (MAP). To illustrate, a normally-aspirated engine runs at one atmosphere of absolute pressure, or at a theoretical maximum MAP of about one bar, 14.7 PSI, or 29.9 inches of mercury. [These measures are not quite exact relative to each other as they are rooted in slighty different definitions of one "standard atmosphere."]

In other words, "boost" is simply one atmosphere less than MAP. So an engine running 4 bar of manifold pressure would be running at a boost of approximately 3 bar, or about 44 lbs boost. 5.5 bar of manifold pressure is around 80 PSI in absolute pressure, or 66 PSI of boost. Yes, that is still a lot. In CART where they describe manifold pressure in inches of mercury, they would say this engine is running at "162 inches."  In CART they may refer to their figure as "boost," but it's really not -- it's absolute pressure.

Boost is also referred to as gauge pressure or differential pressure, to distinguish it from absolute pressure. Obviously, if a mechanical pressure gauge has sample pressure on one side and atmospheric pressure on the other, it will read the differential of the two. However, not all gauges need register in "gauge" pressure. A piston aircraft pilot constantly watches his manifold pressure gauge, which here is calibrated in inches of mercury absolute. If the engine is normally aspirated, the higher the altitude the less manifold pressure is available.

It is also important to distinguish manifold pressure from manifold vacuum, which is a different concept, inverted if you will. Generally, at minimum throttle opening an engine is at minimum manifold pressure but maximum manifold vacuum. Sounds obvious when stated thus, but people still manage to get the two mixed up...perhaps because manifold vacuum is typically described in inches of mercury as well.

[berge]

Originally posted by Cociani
I watched a BMW propaganda film on Speedvision a few years ago and they didn't go into detail into the engine managment system but from what I remember the system integrated ignition timing and fuel enjection in one central processor. The system is similar to what road cars use today but at that time was fairly unique.

As you probably know the engine block was based on a production engine. Imagine that today!

not only that, BMW engineers used blocks from high mileage cars in junkyards.

[McGuire]

Originally posted by BRIAN GLOVER
Howdy,

You sure know a lot of stuff, McGuire. Do you write for a tech magazine? I found a error in your text.;)

By all means spell it out, in exquisite detail. I wouldn't want to steer anyone wrong. Gloating is permitted if you feel it is appropriate.

[dosco]

Originally posted by BRIAN GLOVER
Howdy,
Florida in the winter, just after a really cold front has gone thru, like today, the air is extra heavy and pressures way over standard is normal. The HP gains are noticeable as is the performance of the wing.( That's why F1 cars have pitot tubes )

Well......sort of. More like it's a simpler task to map the engine and aerodynamic performance as a function of airspeed rather than groundspeed.

BTW, it seems you are a private pilot. What are your thoughts on the switch (for GA aircraft) from 100LL to "heavy fuel" (ie diesel)?

[dosco]

Originally posted by ZoRG
Maybe in Cart... but according to this sentence in the email, it does not seem that way:

"In 1986 we were able to achieve a charging pressure of 5,5 bars in the qualifying, in combination with a waterspray cooled intercooler there was the mentioned power output of app. 1400 hp."

Is that not because F1 turbo cars didn't have the same boost limitations as CART cars?

Interestingly, I have a friend who used to design turbo wheels used by the CART folks back in the mid 1980s....he told me there were ways to defeat the "official" pop-off valves mandated by the CART tech guys. He said one way was to "spin" the air around the valve....the resultant vortex created a low-pressure zone on the valve face, but allowed higher overall system pressure. Interesting.

[Scoots]

Originally posted by dosco


Is that not because F1 turbo cars didn't have the same boost limitations as CART cars?

Interestingly, I have a friend who used to design turbo wheels used by the CART folks back in the mid 1980s....he told me there were ways to defeat the "official" pop-off valves mandated by the CART tech guys. He said one way was to "spin" the air around the valve....the resultant vortex created a low-pressure zone on the valve face, but allowed higher overall system pressure. Interesting.

IIRC they called that "whistling", and there was a big stink about it between Ford and Honda. It contributed to the current sorry state of CART.

[BRIAN GLOVER]

Can you elaborate on the function of the pitot in to regards engine mapping, please?
I understand the aero performance part. I know the wing performance will even change if a cloud goes over the field let alone wind direction. I know you will need less incidence on a cold day and there will be less drag for the same amount of lift. A different section also. Obviously one would need different gear ratios and in the case of Kyalami, a different cam.

Since the mid 80s, 100LL is all that is avaiaible for GA. There were 3 grades before that. Aircraft built earlier than that have problems with bromide deposits and short plug life with their low compression ratios. The FAA has approved auto gas on some aircraft since then.
I'm not familiar with diesel engines in GA. might tell you something. Do you mean an engine change or just the fuel?

Originally posted by dosco


Well......sort of. More like it's a simpler task to map the engine and aerodynamic performance as a function of airspeed rather than groundspeed.

BTW, it seems you are a private pilot. What are your thoughts on the switch (for GA aircraft) from 100LL to "heavy fuel" (ie diesel)?

[dosco]

Originally posted by BRIAN GLOVER
Can you elaborate on the function of the pitot in to regards engine mapping, please?
I understand the aero performance part. I know the wing performance will even change if a cloud goes over the field let alone wind direction. I know you will need less incidence on a cold day and there will be less drag for the same amount of lift. A different section also. Obviously one would need different gear ratios and in the case of Kyalami, a different cam.

Well....basically all the engine functions revolve around air pressure.....the airbox, intake trumpets, fuel-air mixture, spark timing, etc etc. At the beginning of the race, if the car didn't have a pitot probe, the race engineer could measure the relative air pressure, humidity, etc and try to "set" the engine for that measured condition. The race engineer would also have to use that atmo data to fit an airbox designed for that atmospheric condition. The engine could then be controlled via RPM (or wheel RPM, or whatever).....of course, if the weather (humidity, temp, etc) changed during the race, the engine, airbox, etc., would not be performing at it's optimum level. Additionally, assumptions would have to be made regarding manifold pressure, etc., as a function of the car's speed (recall that drag, ram pressure, etc., change as a function of velocity squared). As the car changes speed, the airbox pressure changes.....if the engine mapping is based on RPM only, and the atmospheric conditions change, the engine might not perform optimally as the car changes speed.

Now....if you have a pitot probe on the car, the engine control system can take the probe data and continuously control the engine performance. The airbox could still potentially have problems (it doesn't have variable-geometry), but the engine would function optimally for any given atmospheric condition and car speed.

Originally posted by BRIAN GLOVER
Since the mid 80s, 100LL is all that is avaiaible for GA. There were 3 grades before that. Aircraft built earlier than that have problems with bromide deposits and short plug life with their low compression ratios. The FAA has approved auto gas on some aircraft since then.
I'm not familiar with diesel engines in GA. might tell you something. Do you mean an engine change or just the fuel?

Well, as I understand it, the FAA has mandated a change (in the near future, I don't know exactely when) to abolish 100LL and use "heavy fuel" (diesel). Lots of research is going on to convert GA piston engines to diesel. I was curious about your thoughts in the matter, since it's a pretty major change and undoubtedly will cost most GA operators some serious cash.

[BRIAN GLOVER]

In a previous thread, it was determined that there is little ram effect below .4mach if my memory serves me well. compressibility factors are only taken into account at about .7 mach on airplane wings. Also the airbox has a small entrance and then widens, which would reduce pressure at the trumpets if it ever reached that speed. I cant see the pitot being used for engine mapping. Sensors in the engine and intake would be sufficient information for the ECM.
I think it would be used to compare actual shaft speed to airspeed real time so that they can optimise downforce adjustment in the pits.

[QUOTE]Originally posted by dosco
[B]

Well....basically all the engine functions revolve around air pressure.....the airbox, intake trumpets, fuel-air mixture, spark timing, etc etc. At the beginning of the race, if the car didn't have a pitot probe, the race engineer could measure the relative air pressure, humidity, etc and try to "set" the engine for that measured condition. The race engineer would also have to use that atmo data to fit an airbox designed for that atmospheric condition. The engine could then be controlled via RPM (or wheel RPM, or whatever).....of course, if the weather (humidity, temp, etc) changed during the race, the engine, airbox, etc., would not be performing at it's optimum level. Additionally, assumptions would have to be made regarding manifold pressure, etc., as a function of the car's speed (recall that drag, ram pressure, etc., change as a function of velocity squared). As the car changes speed, the airbox pressure changes.....if the engine mapping is based on RPM only, and the atmospheric conditions change, the engine might not perform optimally as the car changes speed.

Now....if you have a pitot probe on the car, the engine control system can take the probe data and continuously control the engine performance. The airbox could still potentially have problems (it doesn't have variable-geometry), but the engine would function optimally for any given atmospheric condition and car speed.

[dosco]

[QUOTE]Originally posted by BRIAN GLOVER
[B]In a previous thread, it was determined that there is little ram effect below .4mach if my memory serves me well. compressibility factors are only taken into account at about .7 mach on airplane wings. Also the airbox has a small entrance and then widens, which would reduce pressure at the trumpets if it ever reached that speed. I cant see the pitot being used for engine mapping. Sensors in the engine and intake would be sufficient information for the ECM.
I think it would be used to compare actual shaft speed to airspeed real time so that they can optimise downforce adjustment in the pits.

[QUOTE]Originally posted by dosco
[B]

Agreed.....the pressure difference (at isentropic stagnation condition) is about 4% between 50 mph and 180 mph.

With that said, though, I still contend that in F1, where every percent of performance might make a difference, that the pitot is used for engine mapping.

....... yes, I may be grasping.....

[Felix]

The rocket fuel used - yes, it had been developed during WW2 for use in V1 and 2 rockets - was made by BASF subsidiary Wintershal and specially impregnated gloves and clothes were worn when handling it. At the time more than one journo remarked how the eyes smarted when standing close to a running engine.

Wonder, thus, how the poor mechanics stayed sober enough to refuel it, for it was this M12 engine in Gordon Murray's Brabham BT52 which introduced us to the practise of numerous short sprint races equalling one 320 km grand prix...

I was privileged enough to see this engine at the (No Entry Unless By Prior Arrangement) BMW Mobile Tradition warehouse in July, and was told it ran 7,5:1 compression, had a bore of 89,2mm and stroke of 60mm, and delivered 540Nm @ 8500 rpm.

[dolomite]

Originally posted by Felix
The rocket fuel used - yes, it had been developed during WW2 for use in V1 and 2 rockets - was made by BASF subsidiary Wintershal and specially impregnated gloves and clothes were worn when handling it.

No it was not the same fuel used for the V1 and V2 (in any case, the V1 was not a rocket).
The fuel in question was developed to give increased power in piston engined aircraft.

[dosco]

Originally posted by Felix
The rocket fuel used - yes, it had been developed during WW2 for use in V1 and 2 rockets

V2 fuel......liquid oxygen and methyl alcohol.

What's so special about that fuel? And when did an F1 car run on either?

[dosco]

Originally posted by Felix
The rocket fuel used - yes, it had been developed during WW2 for use in V1 and 2 rockets

V1 pulsejet fuel......acetylene.....

I don't think an F1 car ran on that, either.

[dolomite]

http://forums.atlasf...p?postid=664506

[McGuire]

Originally posted by BRIAN GLOVER
This morning at 9am at the Daytona airport, ATIS reported 30.24" and 63'f. (I went to the Turkey Rod Run at the speedway.) A 'standard ' day is 29.92 " and 56'f or 14.7 psi. Performance tables for all aircraft are corrected to these values. Florida in the winter, just after a really cold front has gone thru, like today, the air is extra heavy and pressures way over standard is normal. The HP gains are noticeable as is the performance of the wing.( That's why F1 cars have pitot tubes )
So, consulting one's tables you will find that you need a lot less runway to take off and your climb rate will be considerably higher than in mid summer. Before you even start your airplane, you will notice that your manifold pressure will be what ATIS has reported. Your altimeter's Coleman window will display the ambient pressure if you set it to airport elevation if it is calibrated correctly.
As you climb out after take off you reduce first the manifold pressure with the throttle to 25" and then the prop rpm to 2500rpm if you have a naturally aspirated engine with a constant speed prop.. .

Brian,
Thanks for the explanation of atmospheric and manifold pressure from the aircraft perspective. I'm sure car-oriented folks found it enlightening. The automotive industry has traditionallly described things in manifold vacuum and gauge pressure -- while often also using MAP as well, especially in boosted engines.  The term "manifold absolute pressure" might be misleading to the unitiated. The key is "absolute." In a normally aspirated engine, manifold pressure is almost always less than atmospheric, that is: "negative" pressure or "vacuum." 

Returning to the interesting question posed at the top of the thread, of a popoff valve set at 10" absolute: This valve will be open when the engine is not even running, because the setting is roughly 20" less than atmospheric pressure. The only way to get this valve closed is to somehow keep the engine running at under 10" of manifold pressure.  That is, more than 20" of manifold vacuum, which most automotive engines will have trouble maintaining except under closed throttle decel. Essentially, this engine has a vacuum leak.

Picture a manifold pressure gauge, calibrated from zero to 30" hg absolute pressure. Next, picture a manifold vacuum gauge, calibrated from zero to 30" hg gauge pressure. Both gauges are reading essentially the same thing, but their dials are calibrated in opposite directions. I will attempt to draw schematic MAP and vacuum gauges for comparison, MAP on top, vacuum on the bottom, in inches of mercury:

0" - - -   5" - - - 10" - - - 15" - - - 20" - - - 25" - - - 30"

30" - -  25"- - -  20"- - - -15"- - - -10"- - - - 5"- - - - 0"

So manifold vacuum and MAP are essentially mirrors of each other. On a normally aspirated engine in "standard air" running at 100% throttle opening and at exactly 100% volumetric efficiency, the MAP gauge will read somewhere around 30" -- in other words, atmospheric pressure. Meanwhile, the vacuum gauge will read around zero inches -- again, atmospheric pressure. Inside the intake manifold of an NA engine running at full throttle, the mean air pressure is close to atmospheric, or relative to ordinary human POV, "no pressure" at all. Meanwhile, a nice idle for a passenger car engine will show around 18-19" of manifold vacuum, give or take.

Speaking of airplanes...the weather stations used by drag racers consist of an absolute barometer and an aircraft altimeter, so for tuning purposes they work and speak in terms of "density altitude." Consequently they also use their own "standard air" on the dyno, known as "standard corrected" (60 F and 29.92, very close to your ISA/FAA standard, while the current SAE J1845 standard is 77 F and 29.235 Hg). An engine dyno'ed in "standard corrected" air will show output about 4% sexier than under the OEMs' SAE standard. There are at least five different "standard atmospheres" in use across the industry...one more reason dyno figures are not quite portable.

Of course manifold pressure is greater than one atmosphere in a supercharged engine, which is a horse of a different color. And the source of still more confusion, over the difference between "boost" (charge pressure over atmospheric) and MAP (total charge pressure). The benefit of turbocharging is far more significant in aircraft: exhaust back pressure is directly proportional to ambient air density. The higher you fly, the less work it takes to turn the exhaust turbine.

[J. Edlund]

The turbocharger in the BMW M12/13 F4t engine was first a KKK then later a Garrett. Which model they are of is unclear, but it's probably some model made for F1 racing.

And they aren't that small
http://www.race-cars...86/benx86pe.jpg
http://m10power.320i...20stand-1-c.jpg
http://m10power.320i...20stand-2-c.jpg
http://m10power.320i...20stand-3-c.jpg
http://m10power.320i...20stand-5-c.jpg
http://m10power.320i...20stand-6-c.jpg

the turbocharger on the 5 later images are a KKK.

In interviews with Paul Rosche he claims that they thought the power was above 1400 hp, what it really had isn't clear.

BMW used a synthtic fuel specially developed by Wintershall for F1 based on their earlier research for lead replacements. The "synthetic" method was developed under WW2 since there was a shortage of crude oil, but there isn't more to the "nazi rocket fuel" rumor than that. (the long version can be found in the thread dolomite linked to)

Today it's possible to reach about 6 bar of boost, above that point the compressor will require more power than the turbine can produce. So without a multistage setup that is max.

Energy content and stoichiometric air fuel ratio of a couple of fuels (approx.
gasoline: 44 MJ/kg, 14.7
methanol: 20 MJ/kg, 6.4
ethanol: 27 MJ/kg, 9
nitromethane: 11 MJ/kg, 1.7

To find out how "powerful" a fuel is we can divide the energy content with the SAFR and compare, if we for example compare gas with nitromethane:

( 11 / 1.7 ) / ( 44 / 14.7 ) = 2.16

Running on pure nitromethane can in theory increase engine power with a little more than 100%, doing that we will have a fuel consumption of around 8 times what the gasoline engine would have.

[dosco]

Originally posted by J. Edlund
The turbocharger in the BMW M12/13 F4t engine was first a KKK then later a Garrett. Which model they are of is unclear, but it's probably some model made for F1 racing.

And they aren't that small

the turbocharger on the 5 later images are a KKK.

The *entire unit* in the pix is pretty large, but the turbo wheel itself (based on the housing size) appears to be in the 1.5" to 2" diameter range, which makes for a pretty small wheel......when I worked at AlliedSignal (previously Garrett) I knew some folks that worked with the F1 crowd and the turbo units they purchased. One person told me that the wheel was a ceramic unit, about 1" to 1.5" in OD, and spun well over 100,000 RPM. She mentioned that the teams regularly used the units well over their design limits, with the result being many failed turbos.

The unit pictured doesn't hold a candle to the huge units attached to diesel (truck) engines.

Cool.....

[J. Edlund]

Originally posted by dosco


The *entire unit* in the pix is pretty large, but the turbo wheel itself (based on the housing size) appears to be in the 1.5" to 2" diameter range, which makes for a pretty small wheel......when I worked at AlliedSignal (previously Garrett) I knew some folks that worked with the F1 crowd and the turbo units they purchased. One person told me that the wheel was a ceramic unit, about 1" to 1.5" in OD, and spun well over 100,000 RPM. She mentioned that the teams regularly used the units well over their design limits, with the result being many failed turbos.

The unit pictured doesn't hold a candle to the huge units attached to diesel (truck) engines.

Cool.....

My guess is that the compressor has a diameter of a little above 100 mm, this being the exducer diameter. The difference in inducer and exducer (trim)diameter is probably quite large because of the high pressure ratios used. The turbine is probably around 80 mm, inducer diameter that is. Based on the fact that a tip speed of around 500 m/s is required, that would be 120,000 rpm with a 80 mm turbine. I've heard that ceramic turbine wheels where used, the compressor might be of billet machined titanium since we reach high compressor temperatures.

The size is probably quite similar to the Garrett GT45 and Holset HX50 that you find in trucks with 400-500 hp. Even for a turbocharger in that size it will need to work well over its design limits to reach 1400 hp. Only some of the smallest turbochargers are using turbine diameters of around 1.5", that being enough for a little above 100 hp, but then with shaft speeds in the 200-300k range.

In CART the regulations are:
Maximum compressor wheel diameter 91.44mm
Maximum compressor housing inlet bore 74.67mm
Maximum compressor housing discharge diameter 54.61mm
Maximum turbine wheel diameter 88.90mm

The Garrett BR74 used in CART are probably also about the same size as one of the old F1 turbos (the single units, most use twin turbo). Note that the difference in inducer-exducer diameter of the compressor is small, this is due to that CART are using high flow low boost turbos, a large inlet area is required for a high airflow and a large exducer diameter for high boost applications.

[McGuire]

Germany's mystery stuff in WWII was nitrous oxide (as in the GM1 system used on the DB 605 engine in the Me 109) which provided a kick of 25-30% over rated power for short intervals. The mystery stuff in America's fuel during the war was triptane, which is not compatible with modern fuel formulation strategies. The mystery stuff used in the BMW F1 turbo engine's fuel was toluene, aka methyl benzene.

[BRIAN GLOVER]

Howdy Bill,

I notice you don't use the word 'blow' off valve.;) As far as I know the pop off valve is located in the compressor duct or duct junction[ in the case of twin turbos on a V engine] and usually before the intercooler. It's function is to quickly release pressure when the throttle is closed to prevent choke or turbo surge. This is the only time this valve opens. You may have to resume with my education.
In the case of the IRL series a couple of years ago, a certain engine manufacturer tricked the valve to open later by creating a 'low' pressure area. In 02 the engines were only allowed 2 lbs over ambient pressure and all valves were supplied by the IRL authorities. This 'cheating' is only really possible in continuous wide open throttle conditions as found in IRL and low boost pressure ratios and low efficiencies in favor of high flow.
In rally cars the mapping is for higher efficiencies for better throttle response.
Boost is fine tuned here and the waist gate prevents overall destruction of the engine. Computer mapping of ratios and blade designs and in/exducer bores and pop off and waist valve design is mind boggling today and I regret it is not used in F1. Revving the **** out of engines that are made out of the same materials as RR Merlins V12s doesn't impress me.
The complex technology in those bi turbos[not twin turbos] used in Audis and Mazda street cars with internal pop off and waist valves, far exceeds the present thinking that goes into f1 engines and it really should be the other way round.
I like all those funny sounds that come from turbos. The waist gate dumping sound of old Turbo Porsche engines before electronic rev limiters and the chirping sound of the compressor stalling when the throttle is closed in rally cars and the chatter of the desperate attempt of the pop off valve trying to stabilize the pressure between the closed butterfly and the compressor .
You wouldn't have to wear earplugs at F1 events.

Type slowly 'cause I can't read fast.


[QUOTE]Originally posted by McGuire
[B]


Returning to the interesting question posed at the top of the thread, of a popoff valve set at 10" absolute: This valve will be open when the engine is not even running, because the setting is roughly 20" less than atmospheric pressure. The only way to get this valve closed is to somehow keep the engine running at under 10" of manifold pressure.  That is, more than 20" of manifold vacuum, which most automotive engines will have trouble maintaining except under closed throttle decel. Essentially, this engine has a vacuum leak.

[dosco]

Originally posted by BRIAN GLOVER

I like all those funny sounds that come from turbos. The waist gate dumping sound of old Turbo Porsche engines before electronic rev limiters and the chirping sound of the compressor stalling when the throttle is closed in rally cars and the chatter of the desperate attempt of the pop off valve trying to stabilize the pressure between the closed butterfly and the compressor .

If modern turbos were to be used, they now have variable geometry stator vanes......I don't think you'd hear any compressor stalls.....if you did, they'd be the exception and not the norm.

The VSVs work much the same as the VSVs in aerospace turbofan engines.....which are specifically controlled to reduce/eliminate compressor surges and stalls.

As far as earplugs......I attended several CART races back in 1995, 96 and 97. Those engines were turbocharged and loud as hell. Not as loud as modern F1 engines, but pretty damn close.

[McGuire]

I don't think there's any question that the turbo systems in contemporary production cars are far more sophisticated than any ever used in CART or F1. But then that is the general trend. Production cars continue to advance, as race cars are ever more restricted.

[BRIAN GLOVER]

It was Champ cars, you fool.

[QUOTE]Originally posted by BRIAN GLOVER
[B]Howdy Bill,

In the case of the IRL series a couple of years ago, a certain engine manufacturer tricked the valve to open later by creating a 'low' pressure area.

[random]

Originally posted by dosco
As far as earplugs......I attended several CART races back in 1995, 96 and 97. Those engines were turbocharged and loud as hell. Not as loud as modern F1 engines, but pretty damn close.

The loudest cars I have ever heard in my entire life were those of the turbo era in F1.

I can listen to CART or F1 cars without earplugs for a few seconds, it's loud but not painful. But being right at the start-line for the combined standing start of all those Turbo F1 cars went past my pain threshold. As soon as the cars rounded the bend, we few without protection ran for the nearest earplug vendor.