Other uses of v-12 in boat airplane

On YouTube you’ll find videos of a Mazda Miata with a Jaguar V12.

Where do I get a mental image of a centrifugal super charger off the aft end of an Allisson in a P40?

Yeah, although the Cobra lacked a blower, t did feature a fast firing 27mm through the prop shaft. The Allison was housed behind the pilot. Great balance equaled to high maneuverability.

Carl

Where do I get a mental image of a centrifugal super charger off the
aft end of an Allisson in a P40?

Dunno. That describes the supercharger on the Merlin.

BTW, the P-40 itself had an interesting development. Originally designated
the P-39, if I recall correctly, with a radial air-cooled engine. It was a dog.
Then someone got the bright idea to fit the Allison instead, which made it
much better even though the hp apparently wasn’t significantly higher. The
aerodynamics of the radial were messed up somehow. Anyway, with the
longer Allison engine fitted, the CG was shifted forward, and the plane had a
nasty tendency to roll over on its nose. So the tail was lengthened to
compensate. With all those changes, it was decided a new designation was
in order and the P-40 was born.

Yeah, although the Cobra lacked a blower, t did feature a fast firing
27mm through the prop shaft. The Allison was housed behind the
pilot. Great balance equaled to high maneuverability.

It also had guns in the wings, but the Russkies started removing them! The
cannon through the prop shaft was plenty, and removing all the weight way
outboard in the wings made the plane yet that much more maneuverable.
One of those Russians holds the record for most kills by an allied ace.

After WWII, Bell went on to build the first aircraft to break the speed of
sound, and eventually decided to focus on helicopters.

– Kirbert

the owner/builder said any one with the nuts to drive it dont need more than 5/7 psi pressure!

it has 2500hp at only 2800rpm(Crankshaft), 6 psi would put it over 3000hp , now that would deffinatly get your attention!

this stuff is all a joke anyway, but its interesting to see it real life(at least for me).

i have a hard job believing anything the Brits say, of course i’m Irish so that explains things somewhat!

and like already said,today they USA Allison is the preferd engine ,realtive to the Merlin, for serious power!

you may not be aware,but back then Brits would never say USA did anything good!

thank heaven for Wikipedia, read more,and they couldnt get the Merlins to do flying manuvers they would stall and crash in the Spitfires, untill USA BENDIX gave them some properly pressureized carburetors, so they could fly upside down!

another thing brits would not believe, is the RR Merlins that were made in USA BY Packard motor co. Detroit Mich.

and shipped to GB ,the pilots would pull strings to get them in the Spits., they said the were smoother and more dependable!

GB assembled them by hand fitting filing , where Packard merlins were built by FORD designed MASS production machinery, using USA standard threads, not those silly witworth threads.

Kirbert:

Yeah, sorta, CW produced standard fighters before the P40. it evolved from them. An early one was a biplane. Then a mono, P36, as I recall, all radial engines. And, the latest, the P40. More power!!!

The ones that went to China were diverted from their
original destination, Sweden.

The P39 designation was for Bell’s Aerocobra.
I mistyped, it was a 37 mm gun. A marvelous weapon, but, intricate, and a bit fussy. One of my army assignments was as a platoon leader in an AA SP unit. I had four half tracks with buckets featuring them. The gun flanked by two 50 cal.
Deadly when they worked. Jammed easily…
As that was 54, they had seen service in N. Africa in WWII. Worn out, I suspect. After I left, the unit was rearmed with the 75mm “skysweeper”. Radar and fire control all on the same mount. I got to see them at my new assignment, a firing range. Cut the tow target to ribbons.

Carl.

1 Like

Further thinkings: New word!!

  1. As we know, there are various means of forcing more air into an IC engine. All fall into the familial term, “blower”. The “fiined” wheel can and was driven in at least two ways. One, by exhaust, ie “turbo”. Another is mechanicaly. This is termed centrigual, a bit
    mislewading. .The Allison and the Merlin used the latter. Large clue. 12 exhaust shortie stacks off the left side of the engine.

  2. Design and build of a V12 was no mystery to Packard. The fabulous PT boats of WWII were powered by three each.

The design team eagerly undertook production of the Merlin. supposedly, made some changes to up the output, and to make production simpler and thusly faster.

  1. Our brass also messed with the P38. “It isn’t a high altitude fighter, so supercharging not needed”.
    Ignorance prevailed in some production???

  2. Other “compressors” were the positive displacement that found fame in Hot Rods, And an odd spiral tyoe that seemed to work,but lost out somewhere along the line.

  3. The use goes way back in auto design. Circa 1939, Graham-Paige used one on its Continental 6. Small, low PSI, more for show. But, KF reverted to it Circa 54, seeking to prolong the use of a similar 6, in a world of new OHV V8’s. More PSI’s did up the HP!!

  4. Studebaker acquired the McCullough, nee Paxton and applied it to it’s modern, but a bit short
    in CI’s to match the competitions big V8’s. That and the Avanti were Stude’s last gasp.

Carl

I drag raced against a super charged Studebaker I had a Mercury with tri-power…early 60s…he shot away from me so fast I thought I was standing still.

I was told that a super charger went under the carburetor and a blower was before the carburetor. …tech terms I guess

I was told that a super charger went under the carburetor and a blower
was before the carburetor. …

No, that’s incorrect. A turbocharger is powered by the exhaust while a
supercharger is mechanically driven. Either one can be either before or after
the carburetor, if you still have a carburetor. The problem with putting it
before the carburetor is that it pressurizes the carburetor, so the carburetor
has to be properly sealed with the float bowls vented into the throat and the
fuel supply pressure controlled accordingly. The problem with putting it after
the carburetor is that the blower, either a centrifugal wheel or a pair of
Rootes impellers, is moving a dangerously explosive mixture.

The big difference between supercharger and turbocharger is in operation.
The turbocharger doesn’t really kick in until the throttle is pretty wide
because there’s not enough exhaust flow to spin it, and when there is there’s
a bit of a lag while the impeller spins up. Once going, though, the
turbocharger is more efficient because it’s not a load on the engine, it’s
utilizing “wasted energy” from the exhaust stream. A Rootes supercharger
gives you boost at idle, so you’ve got gobs of torque from the get-go. The
centrifugal supercharger also has no lag, but its performance increases with
engine speed while the Rootes has a flatter performance profile.

– Kirbert

Another is mechanicaly. This is termed centrigual, a bit mislewading.

It’s called centrifugal to distinguish it from the positive displacement type.

.The Allison and the Merlin used the latter. Large clue.

No, the Allison used a turbocharger. That was the problem; it worked fine,
but didn’t fit in most airframes.

12 exhaust
shortie stacks off the left side of the engine.

Another 12 off the right! One per exhaust valve, and there were two exhaust
valves per cylinder.

The design team eagerly undertook production of the Merlin.
supposedly, made some changes to up the output, and to make production
simpler and thusly faster.

The Merlin was designed as a handmade racing engine for the Supermarine
racers. When WWII approached, the bright idea was to start producing a
production version – and the Spitfire itself also derived from the
Supermarine. To put an engine designed to be a one-off into mass
production requires a lot of little revisions, including that the displacement
was reduced somewhat to ease the casting accuracy requirements.

  1. Our brass also messed with the P38. “It isn’t a high altitude
    fighter, so supercharging not needed”. Ignorance prevailed in some
    production???

As we well know, the P-51 Mustang sucked mightily until the Allison was
ditched in favor of the supercharged Merlin. But after WWII, North American
went on to develop the P-82 Twin Mustang which saw some service in
Korea. The prototype P-82 had Merlins but for production they switched
back to Allisons! Of course, the P-82 fared poorly against the MiGs. I knew
a P-82 pilot; he said that when a MiG approached, the best you could do was
to try to pull up and try to get a few shots at him as he zipped past – just
before you ejected, as there was no question that you were goin’ down. This
guy was shot down 3 times.

  1. Other “compressors” were the positive displacement that found fame
    in Hot Rods, And an odd spiral tyoe that seemed to work,but lost out
    somewhere along the line.

It’s called a Rootes blower, and I’m pretty sure it’s still used in some
applications – including Top Fuel dragsters. Bradley Smith installed a pair of
them in his XJ-S. Neat thing is, if you want to increase boost, you just
change the pulleys on the belt drive.

– Kirbert

Nah. Six per side. The twin exh valve throats per cylinder merge just after the valve and before the manifold faces of the head. So you have one oval-hole port and oval hole flange held by 4 fasteners per stub exhaust stack. Even when the six stubs per side were internally split in two by a wall inside the casting, the separate paths only commenced an inch or two beyond the manifold face, where the merged outflow split into two parallel tracks. On a normal engine you’d look to gain something from having full ports/pipes per valve and gain something from resonant effects and extraction but presumably on a supercharged fighter you gain more by dispensing with the drag and weight of a piped exhaust system?

1 Like

one of these days all the mechanical engines and appurtenances will become obsolete and then electric or nuclear power maybe…Today’s youngsters never had to make an engine run to go for a ride and most couldn’t with the high tech stuff that takes lots of $ to buy equipment to repair them…we made our own motor scooters and Whizzer motorbikes and then progressed to Model A s and V-8s etc. a different world isn’t it…even the xjs has more on it than I like to deal with although I do understand the motives of why they do all this without getting into theory and all.

1 Like

well looks like we beat this thread all to sh$t:

the new terminology that has been agreed by most engine builders, is POWER ADDER.

thats simple enough,or is it ?

a power adder is any device or method to increase power /torque.
we all know that to increase power is add more air(along with a proper aif/fuel ratio).
the air has to get into the cylinder(not the combustion chamber,contrary to what most think the comb. chamber is only to direct air traffic into the cylinder).

the older term was forced induction, which is a positive air pressure in the inlet manifold, and called supercharging!
devices to make a pressurized inlet are many types. all these were driven by the engine itself,with a slight drop in useful power!
1st and kinda oldest was the ROOTES blower,because many were just laying around many truck junkyards,after WW2,(they were actually a scavanging pump to pump air into the cylinder and blow out the burned combustion gases thru a set of valves ,2stroke diesels,GM.) many variations are available ,make your own choice.

#2 along came the engine driven centrifugal compressor type air pump, kinda looks like a turbo cold side compressor pump! but still driven by the engine, some talk parasitic this and parasitic that, your choice.
again many variations.

#3 then we have the little DARLING TURBOSUPERCHARGER(shortened to turbocharger), very simple in theory, very complicated in design!

and every time we think they have reached a limit, someone comes up with a new development, in any of the types of power adders! just gotta love these new thinking guys!

as of today the most power ful engines are turbocharged!! of course thats open for debate, but many car companies are using them, they are also less cost the big fancy engine drive super charging!

OK then there are CHEMICAL INJECTION power adders, like the famous N2O,(nitrous oxide spraying,nitrous for short).
along with alcohol.methanol,.

that brings up something of importance ,ALL these engine modifications /power adders are limited by the BASIC INTEGRITY of the engine it self, how much it can handle with increased INTERNAL STRESSs.

a qiuck way to understand is a theoritical % of power increase, just say you make a 25% power increase, no problems.
torque is ADDTICTIVE believe me,i’m hooked on it !
some guys are happy with a 50% , some want 100% or more /more /more!!

all of it is just simple right?

enter the KING of power adders, NITROMETHANE INJECTION , how about 1000% increase and more, so far nobody knows the limit!
Nitromethane makes its own oxygen and fuel as it burns/vaporizes in the cylinder, it only uses manifolding and blower pump to carry the nitro into the cylinders, i guess to help force unburned combustion out of cylinders also.

can be very dangerous, also very expensive ,and last i heard was illegal to manufacture in USA, but can be had from CHINA(imagine that,LOL).

i hope you can make something out of what has been said here!

Well…i guess enuff is enuff

1 Like

kirby , just checked comparision of allison 1710,vs, RR merlin 1650 engines!

very interesting the allison is a 4valve percylinder engine. probably why turbocharging reacted better to them.

the RR merlin is a 2 valve percylinder engine. and why 2 valve needed more manifold pressure , and then two stage supercharger to make up more HP, because it didnt breath as well as 4 valve.

i was not aware of that
both are single overhead cam , but the allison has roller rockers(way back when).

where the merlin has COB,(cam on bucket).

both use tounge and fork con rods, rarely explained is why today the hi-output merlins are using allison rods?

more useless knowledge!!

Time to do a little more reading. Production Merlin had 48 valves and was not cam on bucket. You probably saw details of a parallel-valve version?

1 Like

the RR merlin is a 2 valve percylinder engine. and why 2 valve needed
more manifold pressure , and then two stage supercharger to make up
more HP, because it didnt breath as well as 4 valve.

Remember that, for these aircraft applications, the boost isn’t so much for
generating more power as for maintaining power output at higher altitudes.
The 2-speed blower, for example, is just to allow the Merlin to operate that
much higher.

– Kirbert

I am wailing for this convo to gravitate to the “WAR EMERGENCY” switches.

1 Like

hey george, now that you mention it!

back maybe 25yrs ago , i had a WW2 PT boat engine come thru the rebuild shop, well on top of engine was the speed control lever.

it read on side positions, “STOP, IDLE , 1/2 SPEED, FULL OUTPUT”, but just below normal lever had a small lever that said “BATTLE CONDITIONS”.

like many things we collect in life ,when moving to Texas, it got lost in the shuffle.

you are correct peter, but after looking at the Allison overhead roller rocker arraingment , it is for a pentroof/hemi design, far superior to the vertical Merlin design with flat chamber. my opinion.

and kirb , turbo compensate automaticly for altitude pressure changes, without having a complicated gear setup, that can go sideways at the wrong time!