Motorcycle Engine in a Car - Here's Why and How

hi I'm Matt Brown this is my 1964 Honda s600 under the hood or mostly under the hood is a Honda cbr1000rr motorcycle engine today I'm going to talk about why I did this how I did this and some other ways that you can make a motorcycle powered car it's pretty well established that a hot rod is just taking an engine from a larger vehicle and putting it into a smaller vehicle taking a 1.8 liter and putting it into your Honda CRX mild hot rod taking a space shuttle solid rocket booster and putting it on your peel p50 the hottest of rods putting a motorcycle engine in a car seems to be a violation of this equation it's a small engine in a big car but it's not and for a few important reasons first of all motorcycle engines actually make a decent amount of power a lot of the bigger sport bike engines make about 200 horsepower which is a ton considering that they weigh about a hundred and fifty pounds with the transmission transmission that is a 6-speed sequential shift best of all used you can usually get these engines for around $1,000 all-in engine transmission ECU intake exhaust the key to this whole thing working is kind of one of the main keys to hot writing in general which is low weight you really want to stay below 2,000 pounds ideally you want to stay below about 1,500 pounds the perfect car for this is the Honda s 600 they're super small and super lightweight but they also have a history behind them that a 600 was Honda's first major production car also it still jives with the Afro mentioned hot rod equation because the original engine only had 47 horsepower this one has about 170 okay so how do we do this it's actually not as hard as it looks especially if you carry over as much of the motorcycle as possible things like the fuel tank certainly the fuel pump and fuel sending unit the exhaust carrying over all that stuff will make your life a lot easier really there's only two steps put the engine in the car and attach the output of the transmission to the wheels super simple kind of actually there's some sub steps in there and some sub sub steps so the whole thing actually kind of looks like this okay that's not so bad that's a doable list of things right most of these things exist in the knowledge base of your average hardcore gearhead so let's get started the first thing you need to do is remove everything that you don't need I actually just removed everything including pulling the body off of the frame I kind of recommend this approach if you're gonna get into this it just makes it easier at the very least you need to remove all of the internal-combustion stuff that you're not carrying over when you're done with that get your motorcycle engine and just kind of drop it in there I had a floor jack under the engine bay and I had a friend help me drop the engine in there and then I just sort of moved around and adjusted the jack and put some wood in there to prop it where I wanted it the three things you should kind of think about when you're putting the engine in there is the weight balance of the car the driveshaft output angle and efficiently mounting it to the frame I put the engine about as far back in the engine bay as I could get it and about as far to the left side as I could get it this is a right-hand drive from Japan so if my way it's gonna be on the right I want the weight of the engine to be as left as possible this also helped keep the drive shaft straight the transmission output shaft is biased to the right side of the engine in this orientation so shifting it to the left helped keep the output in line with the rear differential we'll talk about this more in a moment once I had the engine in roughly the place I wanted it I started designing the mounts the engine is held in the motorcycle with six mounts but I'm only using four in the car because two of them are at the top of the engine and there's really nothing near the car to attach it to the bottom rear mounts are super simple and easy they go directly to the frame I used quarter inch steel plate and welded it in sheer with some big gussets on there so it's really constrained well down there the two front mounts are some tubes that look a little precarious but with the rear mount being as rigid as it is the two front mounts should just be in tension and compression the engine is constrained from tumbling around the engine bay under aggressive driving but it's also mounted with some concern for the reaction torque at the output whenever you mash down the throttle the engine is trying to rotate around the sprocket this is because Isaac Newton decided a few hundred years ago that actions need to have equal and opposite reactions if you draw concentric circles around the output sprocket any mount tangential to those circles will be in tension or compression and any mount radially will be in bending that's the super simplification but generally you want things to be in tension in compression the mounts at the rear of the engine that I said were quarter-inch thick plate those are kind of in but it's not too bad because they're really close to the output and they're very heavy and thick and they're mounted directly to a mainframe member I have a really bad picture of the frame before I installed the engine here you can see the mounts in the front and the rear and a close-up of those mounts torque is of course force at a distance so if you know the torque at the sprocket and you measure a distance away from that you know the force that's there whether it's bending or tension you can do the appropriate equations to figure out how strong that needs to be I threw a pretty huge safety factor on all of these because I really don't want my engine to just rip out of the mounts also the weight increase is not really that substantial okay that's about it for getting the engine in the car now let's figure out how to attach the engine to the wheel there are a few different ways to get the power from the transmission to the wheels but most of them fall into one of two categories the first one is sort of just running a sprocket to a differential and then having your output shafts come from the differential you see this in a lot of motorcycle engine powered race cars formula 1000 stuff like that there's a company called Quaife that makes a unit that just bolts right up to the motorcycle engine that has all of that stuff all in it already it's about six thousand dollars last time I checked it's a little pricey also it doesn't really work well if you have the front-engine rear-wheel-drive layout that i have the other common way to get the output from the transmission to the wheels is to just use a driveshaft and that's what I did I have the engine up front longitudinally mounted and the output just goes straight to a driveshaft which goes all the way back to the differential and then to the wheels there's a lot of good information from the low-cost crowd low cost is whenever people make a lotus 7 replicas and a lot of them are powered by motorcycle engines so if you dig around on the forums there's one based in the US and one based in the UK there's a ton of really good information on putting motorcycle engines in cars and specifically how to get the drive output to the wheels I'll put the link to these forums in the description including a link to a specific thread that will be really interesting if you're trying to do the differential chain Drive thing okay but how do you get the drive shaft attached to the sprocket well there's a few companies that actually make adapters this is not super uncommon there's some mini sprint cars and some other race cars that use motorcycle engines so if you're using a Japanese leader bike engine there's probably an adapter that's already made out there that you can just buy I made my own partly because this is a weird combination of driveshaft and engine but mostly because I'm cheap I welded a tube to a sprocket and then welded a adapter plate on the other end once it was welded together I chucked it up in a lathe and laid out the centering land so that the drive shaft could centre correctly on it this is kind of important you kind of have to have a lathe to be able to do this if it's not concentric then no matter how much you balance your drive shaft you're always going to have vibration so earlier when I was talking about shifting the engine over and minimizing the drive shaft angle that's important for a couple of reasons one the u-joints aren't really designed to be run at really high angles mine's at 13 degrees which is honestly a little higher than I'm comfortable with but I went with bigger u-joints much bigger than the power that I'm running through it i greased them frequently I checked them often and I have driveshaft loops which you should definitely have because you know if you're making this crap in your garage who knows what's gonna happen if you do have to run some kind of an angle with your driveshaft try to make sure that your rear angle is the same as your front and that your u joints are phased correctly and you'll get rid of any vibration there chances are pretty good that your driveshaft is not gonna be the correct length anymore so measure the correct length take it to a local driveshaft guy have them re-- weld it and balance it and you're good to go it's a little pricey but you kind of need the equipment to balance the driveshaft anyway so you might as well have somebody else do it the differential I'm using is from a BMW I got it because it had limited slip had the gear ratio I wanted and it was super cheap at the time it's not really the best solution for this car it weighs 80 pounds it can handle way more power than I'm ever going to put through this thing but the price was right since I have that diff I'm just using the driveshaft that came out of the same car that the diff came out of it's a two-piece driveshaft which is kind of nice because my tunnel is a little too narrow and the output shaft of the motorcycle is shifted a little bit to the right so I kind of need it to bend in the middle to make it all the way to the back here you can see the adapter that I made from the output of the engine to the driveshaft the drive shaft itself shortened and balanced the center carrier mounted to the frame and dirty sock so the cool thing about doing a lightweight car is that you can just grab junkyard solutions from something like a Miata and their performance upgrades the brakes from this thing are from an enemy otta and their way over built for this car this kind of goes along with a whole hotrod equation you take not only the engine from the bigger car but some of the other components the performance components show them on a smaller lighter car your better all-around so an easy and cheap solution would be just to get a Miata drive shaft to a Miata differential half-shafts Miata brights brakes and you know what let's just put the engine in a Miata no no too far but with all the complexity of the drivetrain that $6,000 quafe unit is starting to look pretty good now isn't it no because we don't solve our problems with money because we're adults and because we don't have that much money if you can manage the fabrication to adapt uprights or all-new suspension from a donor car it might be in your best interests you just to do that especially if you're going with a horsepower upgrade as big as this there are some easier solutions like you could just get a solid axle like a Ford nine-inch or something like that get it adjusted to the length you need throw it onto the back with some Springs and you're good to go I had those shortened the half shafts because of course this car is so narrow that those half shafts were way too long I did it myself by just cutting them to length and welding on a couple of sleeves be sure to drill some holes to plug weld also any decent driveshaft shop could do this for you I should note that the limited slip differential from the BMW did not work super well in terms of limiting slip that's probably because you can't just take the differential out of a car that's three times as heavy with twice the horsepower and expect it to work who knew I ended up getting the angles recut to the most aggressive angle I could and now it works out really well like I said before I have a drive shaft loop I highly recommend that if you're doing some crazy stuff like this there's always some stuff you're not going to think about you want to be safe so throw a drive shaft loop in two if you have a two piece driveshaft like me some of you are noting that motorcycles don't have reverse and cards usually do so what do I do just get out and push well that was actually my first solution turned out to be kind of a pain in the ass especially because this car is a little bit difficult to get into so I'd be in a parking lot and I'd push the car back and then I'd open the door and kind of squeeze my way in and get the five-point harness and buckle it all up and then put it in neutral and then start the thing and by that time there's just a row of cars laying on their horn waiting for me to get out of the way so recently I put in a reversing gearbox and a reversing gearbox is basically just a two-speed transmission where one of the speeds is reverse there are a few different companies that make these Quaife ever mentioned the one that I bought is from a company called Nova Racing transmissions it's pretty nice it seems to be really well built reverse is chain drive so it's a little bit loud but it's only when you're going in Reverse so where do you put it well anywhere between the transmission output and the differential since I had the two-piece driveshaft I just put it in the middle of the two pieces the reversing gearbox is securely mounted to the frame and then I just measured the distances to have two new drive shafts made to activate reverse I use a push-pull cable that's on the right side of the steering wheel and I did this because I didn't want to lever in the middle that the passenger or me could accidentally bump throwing it into reverse while driving down the road and exploding all my this setup is really nice because you just pull backwards to go in Reverse push forwards to go and drive it's out of the way you're never gonna grab it unless you need it so we have the engine in the car and we have the output of the transmission going to the rear wheels we're done right no not exactly we still have the fuel system the cooling system electrical exhaust we're actually pretty far from finished but we're making good progress [Music]

Channel: SuperfastMatt

Views: 910,791

Rating: 4.9060822 out of 5

Keywords: motorcycle engine car, Bike engine car, BEC, engine swap, s600, cbr1000rr, Jay Leno, Hot Rod

Id: IU98_D2sE1U

Length: 12min 28sec (748 seconds)

Published: Tue Oct 15 2019

Reddit Comments

[u/Fuze911]

Sick! Well done and great overview of the work.