Researching R3 Ultra 4 Possibilities

[ricosrides]

Hello All,
New to the forum and new to R3 in general...
I have been doing some research on potentially using an R3 engine in an upcoming Ultra 4 race car build that I am planning. Seems like an interesting option for light weight high torque. Things I've considered so far.
Drive train:
R3 engine re-geared to get to 3.2:1 first gear and potentially lower geared 6th.
Quaife inline reversing gearbox
Atlas II transfer case for all the 4wd needs
Mandatory upgrades:
upgraded transmission internals
upgraded output shaft to handle 37-40" tires
added 2nd stage on dry sump setup

Maybe I'm crazy thinking that the R3 can handle the abuse of a light weight Ultra 4 buggy. But seems kinda cool to potentially have a <3,000 lb race car when most others have massive 5-6k lb cars.

Curious to hear from those of you that know a bit about strength and reliability of the R3 in a really abusive environment like Ultra 4 offroad racing.

Best,
Rico

 

[TURBO200R4]

welcome from Tucson Arizona USA

 

[Kiwicol]

Gidday mate, welcome to the forum. Seems a very expensive way to slap an engine into something. Would you not be better off getting a 4 cyl Busa engine & working the magic from there? It'd be waaay easier and there's lots of go fast mods avail, you can get huge numbers out of them if you want.

 

[Jagster]

Welcome to the forum.
Can the Rocket engine do the business for your quest?.........No idea.....but I would love to find out.

 

[ricosrides]

Gidday mate, welcome to the forum. Seems a very expensive way to slap an engine into something. Would you not be better off getting a 4 cyl Busa engine & working the magic from there? It'd be waaay easier and there's lots of go fast mods avail, you can get huge numbers out of them if you want.

Thanks for the comment. I agree, the Rocket 3 isn't the most cost effective approach. I looked at the Hyabusa quite a bit, along with the BMW k1600. For the rocks, the Hyabusa just didn't seem to have enough low idle torque. The K1600 is smooth with pretty good low end torque, but a bit wider than the R3. In the end, the R3 power to weight ratio seems hard to beat.

 

[Jhortz]

I'm may be about to slaughter a few sacred cows here so hold onto your hats. Also, it would literally take volumes of books to fully explain these concepts so I'm well and truly short-handing this here, bear that in mind please.

There is nothing magic about torque, power and torque are completely interchangeable through the use of a formula, they are literally calculated from each other. In common usage the term torque has come to represent an engines ability to produce power at low speeds, which is a handy way for us to understand what power delivery would be like from the engine but it is somewhat misleading.
Torque is created and lost through mechanical advantage, power isn't. You change gearing ratios you change torque and speed outputs but power remains constant. Power largely changes with RPM (more RPM more fuel more power, the other option is forced induction which ultimately lets us burn more fuel), an engine like the rocket's is designed to provide more power at lower RPM (flattening the power curve), which results in higher torque lower and a "torquey" feel to the power delivery. But the actual power produced is less than peak power, remembering that we report engine power at peak which is another somewhat misleading way to understand/shorthand things. So basically you can produce torque through gearing, and even an engine with sharp power curves can give insane torque at the wheels if geared correctly (you would just end up with low wheel speed). The big question is can you set the vehicle up in such a fashion?

As I write this I realize how massive this explanation would have to be, and how I just don't have the time to explain it fully through a forum, not that I even fully understand it all myself (and sorry provocateurs out there, I also don't have time for internet squabbles over red herrings either). My advice is research the relationship between torque and power, then consider the delivery needs and options to find a good engine. The rocket engine is a bit unique and unusual for a motorcycle, but it is specially designed/tuned for that, it a lot of ways it really doesn't hold up against other options. But don't let that deter you, the very spirit of the rocket is taking a crazy concept and making it work.

Best of luck with the project, keep us updated.

 

[ricosrides]

I'm may be about to slaughter a few sacred cows here so hold onto your hats. Also, it would literally take volumes of books to fully explain these concepts so I'm well and truly short-handing this here, bear that in mind please.

There is nothing magic about torque, power and torque are completely interchangeable through the use of a formula, they are literally calculated from each other. In common usage the term torque has come to represent an engines ability to produce power at low speeds, which is a handy way for us to understand what power delivery would be like from the engine but it is somewhat misleading.
Torque is created and lost through mechanical advantage, power isn't. You change gearing ratios you change torque and speed outputs but power remains constant. Power largely changes with RPM (more RPM more fuel more power, the other option is forced induction which ultimately lets us burn more fuel), an engine like the rocket's is designed to provide more power at lower RPM (flattening the power curve), which results in higher torque lower and a "torquey" feel to the power delivery. But the actual power produced is less than peak power, remembering that we report engine power at peak which is another somewhat misleading way to understand/shorthand things. So basically you can produce torque through gearing, and even an engine with sharp power curves can give insane torque at the wheels if geared correctly (you would just end up with low wheel speed). The big question is can you set the vehicle up in such a fashion?

As I write this I realize how massive this explanation would have to be, and how I just don't have the time to explain it fully through a forum, not that I even fully understand it all myself (and sorry provocateurs out there, I also don't have time for internet squabbles over red herrings either). My advice is research the relationship between torque and power, then consider the delivery needs and options to find a good engine. The rocket engine is a bit unique and unusual for a motorcycle, but it is specially designed/tuned for that, it a lot of ways it really doesn't hold up against other options. But don't let that deter you, the very spirit of the rocket is taking a crazy concept and making it work.

Best of luck with the project, keep us updated.

Thank you for the reply Jhortz. I completely agree with your statements. I also realized that I should have been a bit more descriptive in my initial post. With that said, I am mostly interested in your opinion on the R3 transmission's ability to hold up to 4wd race abuse in a swap. I believe that the power capabilities, weight, displacement and other specs are right inline with what I am looking for.... That said, I am not certain that the RIII/R3 transmission would hold up well to 4 wheels of abuse. Heat would be a problem along with many other things. Would love your thoughts on this if you are willing.
Maybe my project is way too far out of left field and the best option would be to get a gen 1 donor for quite cheap and try it out to see how far it can be pushed until it breaks and then build from there.
Thanks,
R

 

[TURBO200R4]

Thank you for the reply Jhortz. I completely agree with your statements. I also realized that I should have been a bit more descriptive in my initial post. With that said, I am mostly interested in your opinion on the R3 transmission's ability to hold up to 4wd race abuse in a swap. I believe that the power capabilities, weight, displacement and other specs are right inline with what I am looking for.... That said, I am not certain that the RIII/R3 transmission would hold up well to 4 wheels of abuse. Heat would be a problem along with many other things. Would love your thoughts on this if you are willing.
Maybe my project is way too far out of left field and the best option would be to get a gen 1 donor for quite cheap and try it out to see how far it can be pushed until it breaks and then build from there.
Thanks,
R

the gen 1 has rock crushser gears
the 20 up has angle cut gears and should be stronger. i have not heard of any probs it the 20 up.

 

[Jhortz]

Motorcycle transmissions are generally built light, especially compared to four-wheel drives. The difference in construction and use means they will tolerate certain types of abuse better than an automotive transmission, but will also not tolerate somethings an automotive transmission would. It's impossible for me to say if the transmission would hold up, sorry. I do know the 2nd gen has a much improved transmission whereas the 1st gen did have some failure points which where largely addressed overtime with updates.

I think the big problem would be the clutch. Bikes almost always have wet clutches, which allow for more slippage to offset low power at low speeds and low rotating mass of the engines when taking off. Along with that, as clutches on bikes are hand operated the spring weight needs to be low compared to a car where you use your foot, have more leverage, and can have power assistance on the clutch. A clutch designed to slip with a low spring weight is likely to slip when placed under excessive load like the weight of a buggy and use in low speed or tyre stall situations. Mind you, it is possible to upgrade clutch springs and if you are in a buggy you could use a bigger lever with longer travel allowing for a heavier clutch.

The rocket is a good example of anything being possible in engineering. You can make anything perform like anything else if you have the time and budget to overcome inherent design issues. The question is if those inherent issues should be overcome or just avoided by choosing something else with a more suitable design base. But I'm also in full support of someone doing something nuts.