Merlin power with Modern Tech but Unleaded Petrol

[Deleted member 68059]

Hi pbehn,

Making a block strong enough for the bores has been with us since internal combustion engines. They knew the strength of the metal they were using, certainly.

When Chevrolet went from a 350 cubic inch V8 to a 400 cubic inch V8 on the same block, the metal was strong enough, but they then didn't have room for coolant spaces between the center wo cylinders, so the 400 always ran hot there. Being strong enough and being able to cool it sufficiently are not the same subject.

I think the DB 605 overhaul times were fairly low, I seem to recall they started at something like 100 hours and got to something like 200 hours. I am NOT very sure why German engineers set the overhaul interval so low, but I have seen quality of metal out forth as one reason. Whether or not that is the real reason is another question. The engineering for the DB series engines was first class; ditto the Jumos. Perhaps it was just being conservative.

Maybe our German members know, or maybe Snowygrouch knows ... ?

It's a bit complicated for a full a story as a forum post, but broadly device intervals in Germany went from 200 h in say 1939 to less than 50h in 1944/45. Mostly materials and oil related. Jumo 213 is the only one capable of tuning for something like Reno. 3000hp would be very easy indeed. I think something to win Reno would need the 4 valve 213j head to be used. 4500rpm should be viable with 213j parts (of which there is probably one set in the world left, and no drawings...

 

[Koopernic]

Hi pbehn,

Making a block strong enough for the bores has been with us since internal combustion engines. They knew the strength of the metal they were using, certainly.

When Chevrolet went from a 350 cubic inch V8 to a 400 cubic inch V8 on the same block, the metal was strong enough, but they then didn't have room for coolant spaces between the center wo cylinders, so the 400 always ran hot there. Being strong enough and being able to cool it sufficiently are not the same subject.

I think the DB 605 overhaul times were fairly low, I seem to recall they started at something like 100 hours and got to something like 200 hours. I am NOT very sure why German engineers set the overhaul interval so low, but I have seen quality of metal out forth as one reason. Whether or not that is the real reason is another question. The engineering for the DB series engines was first class; ditto the Jumos. Perhaps it was just being conservative.

Maybe our German members know, or maybe Snowygrouch knows ... ?

The issue with the DB605 seems to have been that they changed from roller bearings in the DB601 engine to sleeve bearings in the DB605 without providing a sufficiently improved lubrication system to support this type of bearing. Junkers did have a good lubrication system on its engine. There was a period that they thought the DB605 engine was frothing the oil at high altitude and so a deaerator was fitted. It's possible that had Daimler Benz stick with the bearing technology it was familiar with we wouldn't be hearing of the DB issues.

The other issue is that had a paucity of alloying elements for wear parts and also includingthose on spark plugs.

 

[Koopernic]

It's a bit complicated for a full a story as a forum post, but broadly device intervals in Germany went from 200 h in say 1939 to less than 50h in 1944/45. Mostly materials and oil related. Jumo 213 is the only one capable of tuning for something like Reno. 3000hp would be very easy indeed. I think something to win Reno would need the 4 valve 213j head to be used. 4500rpm should be viable with 213j parts (of which there is probably one set in the world left, and no drawings...

How did Junkers develop an engine capable of such high piston velocities? I came across an old German text (google books I think) once which used pistons of the DB604 as an example. They weren't cylindrical but slightly convex and possibly ovoid.

 

[Deleted member 68059]

How did Junkers develop an engine capable of such high piston velocities? I came across an old German text (google boobs I think) once which used pistons of the DB604 as an example. They weren't cylindrical but slightly convex and possibly ovoid.

Principally by employing an oil centrifuge and nose fed crank oil system.

 

[NevadaK]

This is an interesting question. I'm not an A&P or fuel guy so take this with a grain of salt. This reminds me of a TV show my son and I used to watch on Saturday mornings which was focused on hot rodding and auto performance. Not one of those lets make it look cool shows, these guys were very much focused on the technical aspects of performance. They did a multipart series on "modernizing" a 1950's era performance engine and seeing what the possible improvements would be. They stuck with the block, the basic architecture of the engine, but that was about it. They were able to improve the crankshaft by making it lighter, but the real improvements were all found in areas where science has given us a better understanding of fluid dynamics or advanced control. After each improvement they ran the engine on a dynamometer to see what had been achieved. The biggest jump came with improved cylinders, cylinder heads and the manifold. IRIC correctly, that more than doubled the HP output. Later, they modded the engine from carburetor to injection also with an improvement and then supercharging. Each subsequent step brought improvements but at a lesser rate. The last episode my son and I watched they were planning on trying to convert it electronic ignition and control which they pointed out was the biggest improvement in engine technology in the last couple of decades. My guess is that with a similar mindset you could get your target of 1800 HP but the merlin might look a bit different. I imagine that a modernized Merlin would involve similar steps.

 

[special ed]

I seem to remember many years back, a group in Minnesota began restoration of a D-9 and it's Jumo. The goal was to return it to flight. As I remember, the comment about the engine was it had babbitt bearings and was going to require much machining to get it to take replaceable bearings. The article said that may be why a 25 hour TBO by the Germans was required.

 

[Deleted member 68059]

I seem to remember many years back, a group in Minnesota began restoration of a D-9 and it's Jumo. The goal was to return it to flight. As I remember, the comment about the engine was it had babbitt bearings and was going to require much machining to get it to take replaceable bearings. The article said that may be why a 25 hour TBO by the Germans was required.

Jumo213 does not have in-situ babbit bearings, both crank and cams have replacable shells. For the documentary, its possible some minor accessory shaft somewhere had a babbit bearing surface.

 

[Koopernic]

This is an interesting question. I'm not an A&P or fuel guy so take this with a grain of salt. This reminds me of a TV show my son and I used to watch on Saturday mornings which was focused on hot rodding and auto performance. Not one of those lets make it look cool shows, these guys were very much focused on the technical aspects of performance. They did a multipart series on "modernizing" a 1950's era performance engine and seeing what the possible improvements would be. They stuck with the block, the basic architecture of the engine, but that was about it. They were able to improve the crankshaft by making it lighter, but the real improvements were all found in areas where science has given us a better understanding of fluid dynamics or advanced control. After each improvement they ran the engine on a dynamometer to see what had been achieved. The biggest jump came with improved cylinders, cylinder heads and the manifold. IRIC correctly, that more than doubled the HP output. Later, they modded the engine from carburetor to injection also with an improvement and then supercharging. Each subsequent step brought improvements but at a lesser rate. The last episode my son and I watched they were planning on trying to convert it electronic ignition and control which they pointed out was the biggest improvement in engine technology in the last couple of decades. My guess is that with a similar mindset you could get your target of 1800 HP but the merlin might look a bit different. I imagine that a modernized Merlin would involve similar steps.

My fascination is 1930s and 1940s electronic and mechanical computation. I've wondered what would have been possible if a lambda sensor were available. The lamda sensor was commercialised in the 1970s by someone at Robert Bosch to help with catalytic converter control but was soon used by hot roders. The lambda sensor is simply a nernst cell which has been around since the 1890s.

It would be straightforward to display the 'lambda' on a galvometer gauge in the cockpit but it would only require one or two audio frequency vacuum tubes to provide a linear output of voltage to adjust a small say 5W electric motor to adjust the mixture of the engine. Such vacuum tubes could easily survive 50G and operate for 30,000 hours.

It would be immensely valuable to obtain good cruise consumption and also to make efficient two stroke direct injection petrol engines viable such as the Rolls Royce Crecy (which used prechambers)

The other tech that might have worked is the 'knock sensor'. That's simply a crystal microphone turned to a specific frequency (about 44kHz of the top of my head) and it might have been possible to set your boost confidently to 28psig on the Merlin or 1.98 ata on the DB605 confident that if knock started to occur due to say bad fuel, high ambient temperatures or whatever that the sensor would detect it and progressively reduce boost limit until it stopped and then very slowly increase it again.

The technology of the day was to represent numbers as shaft turns, add/subtract as via differentials and multiply/divide/square root by converting to logs with cams, adding/subtracting and then converting back with anti log cams. Ballistic data was encoded onto 3D cams. There was a lot that could be done and in an engine a cam can be caste or copied on a cam copying machine and doesn't have to be ground to sub micrometre precision like the ballistic cams for a battleships main guns.

Carburettors and Fuel inject of the day was sophisticated and complicated. Had the first jet engies used similar techniques to meter fuel according to air flow they would have been a lot less troublesome. It was a mistake the UK, Germany and US all made.

 

[GreenKnight121]

There were several reasons for lead being added to fuels.

As mentioned above, first was as an octane booster. As discussed, there are alternative octane booster chemicals available.

Second (also mentioned in-passing earlier) was for lubrication - in particular for the valve stems... the lead built up on metal surfaces in contact with the fuel and/or its fumes, and formed a self-shaping & self-repairing seal to reduce oil loss. This was an issue in older automobiles when leaded fuel was abolished - my 1968 Cadillac Sedan deVille required lead fuel for the lubricative/sealing properties, and when the last stations in Southern California that offered leaded fuel stopped selling it, I had to add a "lead-replacement" additive to the fuel tank every time I filled up. If I had rebuilt the engine as I had planned to, it would have received new "no-lead" valve fittings... but I ended up selling it instead.

The third reason for lead was as a stabilizer for the fuel, to both prevent "knock" and to lengthen the amount of time fuel could be stored, or a carburetor or engine could sit dormant with fuel inside, before the fuel began to separate and form a "varnish" coating (and even a gummy sludge) on metal surfaces in contact with the deteriorating fuel. Again, there are stabilizing additives sold for unleaded fuel that enable fuel to be left in cans and engines for several months (a snowmobile or snowblower over the summer, a lawnmower etc over the winter) without the fuel deteriorating or leaving undesirable deposits.

 

[SaparotRob]

I learned to drive on a '68 Sedan deVille. I named her Star Ship Potemkin. When carrying passengers, I would imitate Lt. Pavel Chekov when speaking.

 

[Koopernic]

I learned to drive on a '68 Sedan deVille. I named her Star Ship Potemkin. When carrying passengers, I would imitate Lt. Pavel Chekov when speaking.

 

[SaparotRob]

Oh Baby, you're BEAUTIFUL!!

 

[SaparotRob]

Okay. I spent way too much time looking at this picture.

 

[GregP]

Somehow, they managed to make it look like it had tail fins when it really doesn't. If I recall, it had a settable "bug" for cruise control. You'd set it to, say, 65 mph and, if you exceeded that speed, a buzzer would sound. Maybe I'm thinking of 1965 or so, though. We had it in a Buick Electra 225, but I rode in a Cadillac and it had the same buzzer.

 

[SaparotRob]

I don't remember if the cruise control had a buzzer. I never used it.
A friend of mine had a "deuce and a quarter". I liked those too!

 

[GregP]

1964 Buick Electra 225:

 

[SaparotRob]

I'm also very fond of the '66 GTO. ( Peeking through the Buick's backlight)

 

[BiffF15]

I'm also very fond of the '66 GTO. ( Peeking through the Buick's backlight)

My cousin had a 67 Goat, 400, 4BBL, 4 speed. It would leave a nice set of parallel strips on the pavement.

 

[GregP]

The 67 GTP "Tri-Power" was one of the quickest production cars made for more than a decade after it sold out. The "Tri-Power" part meant three two-barrel carburetors and the engine was 389 cubic inches. The tires I recall the best were Uniroyal "Tiger Paws." They did, in fact, have very good grip, but it was due to them being made out of a very soft rubber compound. You could literally leave two black lines around a corner or when you pressed on the gas pedal, not necessarily hard enough to break loose, but hard enough to leave a layer of rubber everywhere you went. Needless to say, a set of Tiger Paws didn't last too long!

1967 Pontiac GTO Tri-Power:

389 Three-Deuces engine:

I had one of my most embarrassing events happen in a 1964 GTO. A friend of mine bought one and it had a suitably impressive stick shift in it. He came by and stopped outside in the street and walked around to let me drive it. I got in, put it in first, and proceeded to take off backwards! The shifter had an unmarked white knob on it and he had bought a manual, floor-shift, 3-speed! He laughed, I turned red, and I never assumed anything about a shifter after that day.

Stood me in good stead when I got into the military and there were some REALLY weird shift patterns in some of the 2 1/2 ton trucks the military used.

 

[SaparotRob]

Beautiful, beautiful car.