Multiple engines legal in racing?

[Philabuster]

I did not wish to hijack the Super Mini thread.

What are the rules concerning multiple engines in racing (SCORE, BITD, ect)?
Does this automatically throw the buggy into the unlimited classes if it sports more than one power plant? I have some ideas. :shock:

[K-fab]

I just went through the SCORE 2006 - 2010 rules book and I don't see anything that specifies one engine only. It would put you in Class 1 - the unlimited cars that haul major arse (130 mph)

[bdkw1]

Or sportsman buggy, They don't have a rules section for them, you just have to fallow the general saftey rules. There were a couple of snowmobile engined 4X buggys that race about 15 YR's ago. One was for sale recently, I wish I had kept the pics of it.

[Rorty]

Multiple engined cars are very popular for grass racing in the UK and there are some very ingenious methods of hooking them up together. The result of 2 Busas in a light car is nothing short of devastating! 8)

[Philabuster]

I have a powertrain idea for a Trophy Truck type vehicle. I think it would be too large for a Class 1 buggy though. This is probably the wrong forum to post this idea, but I figured WTF. :lol:

I don't have the skills to draw it on the puter though. :roll:

My idea is to use four RX-1 engines coupled together with a custom 'combiner gearbox' of my own design utilizing a separate CVT transmission for each engine. The gearbox will have forward, neutral, and reverse, along with low-range capability if desired. It will have forward and reverse facing outputs similar to a divorced transfer case in a 4x4 truck (think NP205). This will allow 4x4 applications with no modification to the gearbox. Final reduction will be at the live axle differentials.

The idea behind the design is cost, simplicity, and reliability with redundant, relatively inexpensive engines. The vehicle will still be able to drive with only one engine should the other three fail. Most breakdowns in the desert seem to be from the automatic trannies burning up followed by engine failures. Hi-po V-8s can cost upwards of $30,000 and when they blow, you start over from scratch. :shock:

Also, there is no better trans than a CVT for ease of operation. Mash the skinny pedal and go!

This idea has been on the drawing board for a while, but I wanted to share.

Thoughts?

[Rorty]

Originally Posted by Philabuster

I have a powertrain idea for a Trophy Truck type vehicle. I think it would be too large for a Class 1 buggy though. This is probably the wrong forum to post this idea, but I figured WTF. :lol:

I don't have the skills to draw it on the puter though. :roll:

My idea is to use four RX-1 engines coupled together with a custom 'combiner gearbox' of my own design utilizing a separate CVT transmission for each engine. The gearbox will have forward, neutral, and reverse, along with low-range capability if desired. It will have forward and reverse facing outputs similar to a divorced transfer case in a 4x4 truck (think NP205). This will allow 4x4 applications with no modification to the gearbox. Final reduction will be at the live axle differentials.

The idea behind the design is cost, simplicity, and reliability with redundant, relatively inexpensive engines. The vehicle will still be able to drive with only one engine should the other three fail. Most breakdowns in the desert seem to be from the automatic trannies burning up followed by engine failures. Hi-po V-8s can cost upwards of $30,000 and when they blow, you start over from scratch. :shock:

Also, there is no better trans than a CVT for ease of operation. Mash the skinny pedal and go!

This idea has been on the drawing board for a while, but I wanted to share.

Thoughts?

Are your parents super rich?
What happens if you loose an engine or trans?
How do you maintain all engines at the same revs? (Be realistic)
That's all I can think of at this time of night as to why not to do it.
You'd be better off with a central engine and run a hydraulic pump and then have an hydraulic motor at each wheel. You'd have to come up with a means to keep all that fluid cool - and the weight penalty would be huge too, but hey it's no worse an idea! :lol:

[masterfabr]

All engines tied together thru central gearbox. They dont know they are separate and act as one.Just like unlimited pulling tractors.In the UK this is more common than you think. Probably not practical for a buggy but for a mini trophy style truck???????Quite a few people there run 2 busas, one for the front and one for rear that are computer rpm controlled w/o any physical connection at all! :wink: I'm not saying that I think this is practical for any of us but it's not a dumb idea.

[tenaja]

It's the "Separate CVT transmission for each engine" that's going to really make it impractical. If you have four engines rigidly connected--like with a gearbox--then they are all forced to run the same RPM. If you tune the throttle exactly the same, then it wouldn't be too far off.

This won't work well with a CVT on each engine, though--CVT's aren't consistant and precise enough to run them together. If one belt is .005" longer or shorter than the next, then its output will be different. If your pulleys are .005" off in distance from each other, then the output will vary. If one belt is worn more than the next...if one engine is just a bit stronger than the next...if one spring is just a bit weaker...if one weight is just a gram heavier...etc, etc... too many variables.

The attractions to CVT's--their tunability, variability and imprecision--are the exact same reasons they shouldn't be coupled together.

Now, if you were to couple your four engines, then add just one CVT, that's a different story...but have fun finding a CVT up to the task. (I haven't heard of them that large.)

[masterfabr]

didn't catch the cvt part.I fooled around with cvt 30 years ago on the old honda odysseys. I hear what you're saying!

[Philabuster]

Originally Posted by tenaja

It's the "Separate CVT transmission for each engine" that's going to really make it impractical. If you have four engines rigidly connected--like with a gearbox--then they are all forced to run the same RPM. If you tune the throttle exactly the same, then it wouldn't be too far off.

This won't work well with a CVT on each engine, though--CVT's aren't consistant and precise enough to run them together. If one belt is .005" longer or shorter than the next, then its output will be different. If your pulleys are .005" off in distance from each other, then the output will vary. If one belt is worn more than the next...if one engine is just a bit stronger than the next...if one spring is just a bit weaker...if one weight is just a gram heavier...etc, etc... too many variables.

The attractions to CVT's--their tunability, variability and imprecision--are the exact same reasons they shouldn't be coupled together.

Now, if you were to couple your four engines, then add just one CVT, that's a different story...but have fun finding a CVT up to the task. (I haven't heard of them that large.)

I hear you on things not being PERFECT, but what is perfect? In a V-8 engine for example: are all cylinders seeing the EXACT same air and fuel flow? How about exhaust headers? Do they scavenge all the same or are some primaries more efficient than others. Get my point?

The vehicle clutches will be optimized to run full out when all engines are pumping. In the event one engine dies, it will be decoupled from the rest automatically. You could remove the dead engine's drive belt quickly during a race and the other three engines would compensate via the CVT transmission. The engines would not shift out the same as before (shift RPM would be lower), but they would all still shift in relation to each other. Also having separate engines will make swapping out a bad motor a piece of cake in comparasion to R&R a V-8.

Now with the same scenario with only one engine. The load on the clutches will be far higher with only one engine driving. The vehicle will never hit top speed with one engine, so the clutches will not allow the engine to shift out beyond what it is capable of running, but again, the vehicle will still move under its own power. Being that the CVT transmission is TORQUE SENSITIVE, it will always put each engine in the proper ratio for the load. If one clutch is calibrated a little differently, it will attempt to shift out sooner than the rest--I got it. But, it won't shift as fast until the other clutches take their share of the vehicle load and catch up. There is no way one clutch will be fully shifted out while the other clutches are still in low range. They will in effect balance out with each other close enough not to matter.

Current belt-drive CVT technology is reliable for moderate HP and torque loads. I don't forsee a big block V-8 with a CVT hanging off the back of it anytime soon. Maybe in the future, Trophy Trucks will be running some kind of high HP CVT like Nissan is running in their luxury cars.