The Rolls Royce Merlin: WWII Fighter Plane Engines Modified For Hydroplane Racing!

You're looking at 4,000 horsepower. When we were racing, the guys used to say, "Well, why are you running this old junk?" Back at that time, this old junk was what they were calling speed equipment. I mean, I could get into it if you if you really want to know. This is out of Huey helicopters of the Vietnam era. Why don't I go get one of the engine guys that really knows that that rebuilds these? Oh, yeah. That'd be awesome. Let me let me go get So, this is one of the Allison's. A quick way to tell between Allison and the Rolls-Royce is the Allison's got this real funky looking intake manifold. Almost kind of looks like a modern diesel truck manifold or something up there. And this is Dan Hy. He is the biggest authority we have in long time. You are my friend. And he is been a a crewman and a crew chief on the unlimited since the early 80s. So he he knows these engines very very well. I know Merlin better than I know Griffins and Allison, but I'll answer what I can. So what are the technical specifications of a Merlin? Of a Merlin? Uh 1,650 cubic in. Um I believe in the airplane it turns somewhere in the neighborhood of 2800 RPM, but in a race boat we would try and turn them over 4,000 RPM. In the uh airplane, I believe they pulled somewhere in the neighborhood of 80 in of manifold pressure. Racing trim, we tried to pull 120 plus in. So that's about uh 45 lbs of boost. That's pretty stack. Yeah, it is. And in race trim with nitrous oxide, which all the race boats ran, um we estimated that you've made around 3,000 horsepower with them. And that's all happening with like the original 1940s pistons. Well, it is, but um speaking to the Rolls Merlin, pretty much every part in a Rolls Merlin that was being used for racing had to be modified. The case, the banks, the valves, the valve springs, the cams, the blowers. I mean, every part, the wheelhouse, the blower, which is a blower drive, everything was modified. I mean, you can make plenty of horsepower just make it live. So, interesting. Allisons are are a little different. Um, there's one boat that continues to run an Allison today. I don't know exactly what they pull for manifold pressure. The Allison's just a little bit bigger engine, 1710 cubic in. Um, it whereas the Merlin is u mag uh aluminum, the many of the parts on an Allison are magnesium. Um, is that the same Allison that makes transmissions today? Uh, I believe so. Yeah, it was Allison GM. Mhm. Wow. The interesting part about some of these engines, at least on the Merlin, um back during the war, uh there were a lot of US manufacturers uh building parts for the engines. So, you might see an intake manifold that had cast in it general or may tag or stuff like that. It's pretty interesting. So, there all kinds of stuff going on. Yeah. How often did you have to rebuild after a race? Was it after every race or when we were racing the Merlin's the blower drive assembly? And you probably heard maybe heard the term quill shaft. So it was common to break a quill shaft, which was a blower drive shaft. Um was pretty common. By the time I was involved in racing, they had pretty well beefed that particular piece up, but the blower drive assembly was still the weak link, especially on the earlier model engines, which down the road we were forced to use as the years went by. After every time that we ran a boat, it didn't matter if it was one lap, three laps, five laps, every time we ran an engine, I should say, we took the blower off and checked the blower drives, checked the gears and whatnot to to make sure all that stuff was good. Don't you have some parts in there? The engine shop here at the museum is is working on uh a Merlin engine right now. We've got some polished valve covers. We're real close. We're real close. We got to put the harnesses on. And there's some plating we have left to do. Obviously, put the valve covers and then we have to plum it. And so anyway, so this is the blower. This is the thing that really differentiates the horsepower output between an Allison and a Merlin. So there's two stages. There's one impeller here and one impeller here. And so the air comes in and it blows out and comes back down the middle and blows out. And then it gets thrown out. It's a centrifugal. It looks like a turbocharger. Mhm. This tube actually replaces on the airplane was an an after cooler to cool the intake charge other to keep it from detonating. But um since you spray nitrous or well the nitrous used to go in the bottom of the blower right here with extra fuel. So you can't just put nitrous in cuz that's just air. You have to add fuel with it. So we'd put uh nitrous and then fuel in here. aftercooler actually intercooler was removed and replaced by this uh chrome tube when they we the they started running uh water alcohol injection for what we call ADI or anti-detonation injection. So race cars do that too. You can get rid of the intercooler if you have something else to Exactly. What's the difference between a Merlin and a Griffin? Uh the Griffin is pretty much a a big Merlin. So whereas the Rolls Merlin is 1,650 cubic in, the Griffin is 2239 cubic in I believe um this particular model has a single stage blower on it which means it has one impeller whereas the Merlin uh Rolls Merlin and this is the thing that that made it so much faster has a two stage uh blower. So it has a 12-in impeller I believe it is and then and followed by a 10 in. So it's like having two blowers in one. The version that ran in the Budweiser during racing also had a two-stage uh blower, so it could put out looking at 4,000 horsepower close to it. So, they were taking the larger Griffin and putting the Merlin's two-stage blower on. No, I'm sorry. The the model that the model of Griffin that the Budweiser guys would run when they were racing came that particular model came with a two-stage uh blower on it. This is a different version, different model, and it has happens to have a single stage on it. Okay. Yeah. Hard to come by. The two-stage are hard to come by. I believe they're even hard to come by when Budweiser was racing them. That makes sense why the Budweiser guys had them cuz they were the ones with the resources and the backing to Well, they actually Bernie acquired some of his at least some of his engine parts um when he acquired another team. That somebody is Bernie Little, eighth grade dropout, self-made billionaire, a man with a very winning personality. Harris Club team uh were the first ones I know of. There may have been others, but the first ones I know of in 1968 that were running Griffins and Bernie ended up buying that equipment and it and I believe the boat ran as Michelob Michelob draft or something like that. And and but but but that's I believe that's how Bernie got at least some of his Griffin engines. They're not going to say to me, uh, well, you wouldn't buy this or you wouldn't buy that. I'll buy whatever they have to have to win. Is the Hera's team the Tahoe miss? Yes, we saw that one. That was one of the Yeah, that boat that boat that you saw actually ran a Griffin in 1968 after the Allison current forms. Was it an Allison? Current form. What they were running there yesterday was was an Allison. A stock what would be considered a stock Allison. Um they also are working on the boat when it raced um ran what they called an ox stage Allison where there was actually an additional blower that was gear driven that sat in front of the engine. So you basically ended up with a two-stage uh blower system. And so they currently are working on configuring that that they wanted to run the boat first in in a stock form with a stock. Mhm. So, the two-stage blower is kind of like a compound turbo in a a diesel truck or something. Exactly. You know, the more more wind you can make, the more horsepower you can make in in a lot of ways, just looking at them. Uh the the Allison and the Merlin are pretty similar. Um 12 cylinders uh overhead cam uh shaft drive up to the cam. Oh yeah, look at these rocker arm setups in here. That's that's really neat. Yeah, this is actually this is not as nice a setup as an Allison because basically you have the cam rubbing on top of the fingers. The fingers are the the rocker arms, if you will. Yeah. U the Allison actually has a roller here. So, they have a I'm sorry, roller on the rocker arms and and a little different setup. You have uh one roller runs two valves, whatever. But both engines have four valves per cylinder. Um the Allison has a pent roof design whereas the the um on on the Merlin the valves are vertical but but really similar in that way that are gear driven both. Is that driven off of like a like a planetary gear off the It's driven off of the crank through a set of gears. The planetaries actually drive the blower. Um but but set of gears drives the mags and the cam. That's really these are the magnetos and on a Merlin the magneto and distributor are integral. Uh one of these runs the exhaust plugs and one of them runs the intake plug. So intake side. So there's two plugs per cylinder on both the Allison and the Merlin and the Griffin. There's some thick valve stems. Uh the Allison's are quite a bit bigger and sodium filled exhaust valves. I mean, we when we were racing and the guys used say, "Well, why are you running this old junk?" Well, back at that time, this old junk was what they were calling speed equipment. Four valves per cylinder, pin roof design, overhead cam. I mean, you know, sodium filled valves, you know, to still do that. Yeah. Yeah. You know, so it wasn't, you know, and that gives you more appreciation. And it's kind of hard to see here, but if you looked at the machine work for the time, the quality of the machine work, which is absolutely fantastic for the time and the machinery that was being used and the rate at which they were trying to build these things, it it's just like you you just go I mean, there's no way you could reproduce this engine today. You just no way. This is really Oh, it'd be unbelievably expensive. This stuff really is like the the pinnacle of innovation relative to resources. Like the output versus what they had is it's just unbelievable. It really is. I mean this is this looks like some really precise well-made stuff. There's little clips on everything. All the casting um the machining the and they go in any deeper all the aircraft parts. Some of the stuff there was a later version of this engine that was ended up putting in the a bridge tank because they were looking for something with more horsepower. or it didn't have a blower on it. Uh so they made a carbureted version of it. But and those they didn't have to spend the time and energy or the money frankly on a tank engine that they wanted for an aircraft engine. Yeah. Like they all this safety wire on here cuz if you know one of these bolts pops off, it gets in there, it's gets screwed up, pilot dies or ends up in enemy territory. You have you have two two mags and that I believe is pretty common on aircraft. So if one mag fails, you've got the other one. You can still get to the ground, right? I mean, and um in in the in the case, um let's go in here. Do you have any uh blower parts taken apart? We can see like uh I can't think of any off top my head. But here's what the rods in a Merlin look like. Oh, wow. So you can see here that the rod that goes off to the a bank is a blade. They call it a blade rod and it sits in between on the fork rod and the fork rod sits actually on the crank journal. That's common to the Allison and the Merlin that setup. Um the Allison's a little different, but but in general it's it's similar. Is that so they don't have to have the um the banks offset? I I believe that's part of it. So, they It looks a little bit offset, but not very much. It's not offset. No, I I believe that part of it. They didn't have to make the engine longer. Uh I don't know if it gained weight or saved weight so far as the whole rod assembly. I'm sure there was other advantages. I don't, you know, know of. Um but but I mean, here again, look at look at the quality of that that crank, you know, the rods. I mean, it's they're just it's beautiful. This looks like a modern high performance crankshaft like you know. Yeah. Take an old cup engine apart. This is kind of what the crank looks like. Yeah. You know, it's for the time. Nothing Nothing's new. It's like the whole hot rod industry is like born from the military. I'll show you one other thing that that now I I think I mentioned to you earlier that everything we pretty much did was to keep the engine together. And this is some of the stuff that you do to a Merlin boat race. Um, this this is a plate that's been being added to this wheelhouse because this is the planetary setup that you were talking about. Mhm. There's a center gear that runs off the crank. That gear there drives the mags in and the two shafts that go up to the uh cam shaft. Uh, and then there's three gears here. Those little gears right there sit in here and are driven by this center gear. And then they in turn drive that planetary system that you're talking about, which those are parts four down there. So now you've got a center gear that's pushing on these three gears. Well, they want to go out that way, right? And this is a a -7 uh wheelhouse or blower drive, if you will. And and so it's lighter duty than the later series. So to beef it up for racing, we started adding these plates. And these plates hold these three bearings. And and there's also a matching plate. uh for this side and it keeps those three gears from wanting to go go out, you know, out out uh radially. Is that due to the higher RPM? You would turn these things over what the airplane was doing. RPM and it just more of a load on the blower drive, more of a like I said, we were pulling 45 in 45 lb of boost, which Yeah. How many engines, you know, pull 45 lbs of boost? You know, that that's a lot of manifold pressure. And so now you're you're working that blower really hard. Well, it takes horsepower to do that and all it's all going through those three little gears and so they're wanting to go out, you know, go leave. Yeah. They don't want to stay in there. Uh-uh. So to finish That's the kind of stuff that we did and still do to to make things. This is this is actually the stock um drive gear that goes into the crank. And that thing they called the quill shaft slid down in the middle and it kind of like took some of the shock but it would snap. This would is a an an aftermarket. Here's the matching plate for for uh those three bearings. The gears sit right in here that sits inside that. And you can see the difference between this aftermarket uh blower drive gear. Can you change the boost level by method with the ratio inside this box? We we we don't we never changed them there. There are two different uh sets of blower gears. Blower gear these end up drive finally driving the blower and the early ones are a lower gear ratio than the later ones. But you you also have in aircraft use, you could switch the blower from a low blower ratio to a high blower ratio based on this ratchet gear assembly. Was that easy to access or do you have to take the whole front drive apart to do that? The pilot had a button. He could go from high blower to low blower. So there was like a transmission inside there. Um almost it was a is hard to describe, but it was a hydraulically activated clutch assembly that would change the ratio. That's probably the easiest way to say it. Sort of like an automatic transmission. Uh different but similar I guess. No clutch pack. No clutch pack. But when the clutch pack um I mean I could get into it if you if you really want to know. So there's no like like a manual transmission in a car has got synchronizers and forks. So So these three low gears are driving this blower, right? Yeah. Okay. So now uh in blow blower the there there inside uh there's an assembly here that this sits in. There was a clutch pack and it either grabbed onto the shaft if you will via clutch pack with splines on it or it didn't grab onto the shaft. If it doesn't grab onto the shaft, now this blower gear is driving at the same rate that this gear is driving. Right. Mhm. When you would activate uh the button there, open a valve, the oil pressure would close the clutch pack and now it would grab this shaft. And now you can see that that gear is turning at a faster ratio than this drive gear. Yeah. Mhm. That's high blower. That's freaking cool. Mhm. Pretty smart guys, huh? Yeah. Um, historically, at least in my experience, most everybody would run a in racing would run a higher blower ratio gear, but in low blower h in the blow blower set. So, it would be like direct drive because uh it the the higher blower drive system was uh it could be not necessarily robust. kind of like uh when you're racing a car, your strongest gear is your one to one. So you don't have the the multiplication. So in this case, when you go into high blower, you're overdriving all this stuff. Yeah. Yeah. You don't race a drag car in overdrive. Yeah. So I have learned that. Anyway, so that's just a little tidbit. Most that's way most everybody that I knew. Now, I guarantee you there were guys, including us, a few times would try different setups, including high blower and whatnot, but we were just trying stuff, you know. Anyway, that's fascinating. So, would you like mess with stuff like like changing the boost level, like you're going out of the turn, you turn it up, and then you pull it back or something like that? We would did we did different things. There's other guys that did more than we did. I mean, we guys played with blower ratio. If they could change the, you know, if you had the the money and whatnot, you might even speed that blower up even further. And there were guys that tried that. Um, yeah, there there was some pretty interesting stuff going on. Guys tried different cam grinds just like any other racing. You're just trying to do something different, make more horsepower, make the thing. Fascinating. Were there any other things like like that plate that you would have to go in and do to beef these up for racing? you know, because of the RPM you were running and the boost levels, you increase the valve spring pressures and uh uh then you played with the cams to try and keep those to live at the higher RPM. Um the the uh case and the crankshaft you modified for the higher RPM. Of course, you take the nose case off that drives the propeller in the airplane and you put a a gearbox on. And that's that's the gear box right there. Or that's a one version of the gearbox. It's not complete, but but so if this wasn't from an airplane, what did they come from? This was custom built for hydroplane racing. Mhm. Who used to make them back then? Um there uh the company that's now called the Gear Works started out as as uh um Mantel Gear Works and and they started building and western gear. They started building the western gearbox. This is a western gearbox. And then um there's a company back east uh in the Detroit area called Fairlane Tool and and the guys that ran Fairlane Tool also raised a boat whatever and they developed a heavier duty version that was based on the western gearbox but but they made what they felt were improvements to it made it a little bit beefier and whatnot. And then so that was those the Western and Fairlanes were pretty common to the Merlin for the Allison's. Western also made a gear gearbox. Uh there was a gearbox called a Vulner Vulkar an arena box. The first guy to put one of these plane engines in a boat. Did they make something like this or do they just hook the propeller right to the crankshaft? I I believe they would have had to have a gearbox, but I I don't know who is the very first person to put this. Yeah, that's that's something you don't just like build in your garage. back in the back in the day that you…