Formula IV

jsharpphoto

Coast to Coast
I know there really isn't such a thing as Formula 4, but I don't care. I want to build a car. My father has some history in Formula Vee, which is where I got my idea.

I want to build a small single seater car, powered by a water-cooled motorcycle engine. Imagine if the KTM Xbow had been designed in 1980. Steel tube frame, like an oversized golf cart. I want to use as much motorcycle parts as possible, including spoked wheels.

Here's what I've decided so far…
1. Rear wheel drive
2. Left foot activated clutch, with a suicide shift lever
3. Chain drive
4. I figured I can make an electric-motor powered reverse gear that I can engage/disengage with a handle, that can interact with the chain.

Here's what's undecided…
1. What's the ideal motor for this situation. I've seen the shifter carts with a GSXR motor, I don't want that. Too much power. I was leaning towards a gold wing motor, but that wouldn't work because it's shaft drive. Unless I made some sort of small chain & sprocket system that used the rear axle of the shaft drive to turn what would be the front sprocket. I don't want too much power. I know that's a silly thing, but I don't actually intend on racing this thing. I don't have the time to invest in a real contender of a race car, even if there was a class that I could compete in. I just want to build something fun and ridiculous to ride around in my neighborhood, and occasionally trailer it out to a race circuit.

2. What's the maximum distance I can mount the radiator from the motor. I'm assuming this will end up as rear-engined, but the radiator would be at the front. It works for Porsche and VW, right?

I'm sure I'll have lots more questions, but I wanted to start getting ideas for what motor I should be looking for.

I KNOW THIS IS A DUMB IDEA/ILLEGAL ON THE STREETS/MONEY PIT. But isn't that what doing the ton is all about?

I'll leave you with a little bit of my visual inspiration…

1950_6_Whitehead.jpg
 
I have always wanted to do this so I am following along for sure.
My plan eventually is to put a busa motor in one.
I don't get your "i don't want too much power" argument.....Its a steel tube frame(heavy) and its 3-4 times the size of a motorcycle, with twice the wheels to power....seems like you'd want as much power as you can get.
100hp gsxr engine is still only 100 horses, which isn't a lot in a car...

My plan is to built a very small scale offroad version, think hopped up gokart, with the ability to swap for some street tires for burnouts :D

As far as a GL engine, that actually may be a good plan, it seems for what youre after you're going to want torque over peak power.
 
SONIC. said:
I have always wanted to do this so I am following along for sure.
My plan eventually is to put a busa motor in one.
I don't get your "i don't want too much power" argument.....Its a steel tube frame(heavy) and its 3-4 times the size of a motorcycle, with twice the wheels to power....seems like you'd want as much power as you can get.
100hp gsxr engine is still only 100 horses, which isn't a lot in a car...

My plan is to built a very small scale offroad version, think hopped up gokart, with the ability to swap for some street tires for burnouts :D

As far as a GL engine, that actually may be a good plan, it seems for what youre after you're going to want torque over peak power.



That's actually dead on. The more I think about it, the more 80-100 HP with a target weight (including driver) to be about 700 lbs. I can fabricate a sprocket to go the rear axle of GL hub, and then do a short chain to the rear axle of the car. If i'm doing that, I could have still use the rear brake on the GL hub as sort of a transmission brake. If I did that, and had rear brakes on the car, I might be able to ditch the front brakes. Maybe.

I'm thinking it'll be better to keep the HP to a manageable level, but increase the torque, since it's likely that i'll never see the top speed of this thing unless I take it to an air strip. Also, I don't know how it would handle with more than 100HP with skinny motorcycle tires. Bikes lean through a turn, but a car can't.
 
Look up Formula SAE or for faster cars check out Formula 600 and Formula B.

These are all race cars, but they are also all motorcycle engined race cars. Motorcycle engines have huge challenges with oil scavenging when placed under lateral loads. That can mean expensive dry sumps, or at a minimum a good bit of work on oil pan baffles.
 
Sav0r said:
Look up Formula SAE or for faster cars check out Formula 600 and Formula B.

These are all race cars, but they are also all motorcycle engined race cars. Motorcycle engines have huge challenges with oil scavenging when placed under lateral loads. That can mean expensive dry sumps, or at a minimum a good bit of work on oil pan baffles.

Thanks! That's something that I hadn't considered, at all.
 
Holy super replies batman.....

Sounds like you have thought it out..
Do you have a tube bender and notcher? Those are the 2 biggest hurdles, along with a GOOD welder (I'd TIG it personally, but a good mig would work too)

As far as ditching front brakes....thats a huge no no....your front brakes in a car are doing maybe 70% of the work, you could never race without them, you'd just lock up the rear tires all the time and spin out of control.
 
Also, if you ever expect to drive on a real circuit you will likely need to meet some safety regulations. That means a roll structure built to specified design, likely a minimal fire system, and almost certainly a fuel cell.
 
I was lucky enough to do a full-day racing experience thing in an F2000 car at Mosport. 125HP in a 1000 pound car gets you going gangbusters.
 
Sav0r said:
Look up Formula SAE or for faster cars check out Formula 600 and Formula B.

These are all race cars, but they are also all motorcycle engined race cars. Motorcycle engines have huge challenges with oil scavenging when placed under lateral loads. That can mean expensive dry sumps, or at a minimum a good bit of work on oil pan baffles.

I had also never considered that, I suppose a motorcycle engine is always nearly parallel to the centripetal force in a turn from the leaning, forcing the oil downward in the pan as opposed to to the side like a car....hmmm
 
duh on the front brakes. i don't know what I was thinking.

As far as racing on a "real circuit" i don't think that's in the cards, honestly. I wouldn't have anyone to race against, I also have no racing experience. this is more likely to be a sunday driver, screw around car.

I think the biggest hurtle now is figuring out this oil situation.
 
Tim said:
I was lucky enough to do a full-day racing experience thing in an F2000 car at Mosport. 125HP in a 1000 pound car gets you going gangbusters.

I raced a Pro 2 Liter event at Mosport. Easily a top 3 track in North American. And the fans... don't even get me started. Mosport fans are the best!

I was .001 off the all time lap record and finished second twice despite leading the majority of both races. I just wish I had the opportunity to go back and get the win or the lap record. One of the two would be enough.
 
Rich Ard said:
Lots of Vtwin motors out there...

I was thinking the same. Lots of low end torque.
But are there any with decent HP ratings that aren't really expensive? I'm not well versed on anything "V"
 
Agreed. I know shit about vtwin or v4 motors. I was thinking about a ninja motor in the 500-650 range. I've heard those things are super reliable.

How do old VW bug engines stay cool?
 
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