Carburetor Doubt

[raptor93]

Does FSAE have any restrictions for the use of a four cylinder engine which has four corresponding carburetors attached to them.
If it is not allowed,is it okay to convert the system to a single carburetor engine with a manifold leading from the carburetor to the four cylinders.

[Chevalier]

The question you need to ask yourself would be why?

Why would you want to fit 1970s technology to a "racing" car? There is a reason why nothing runs carbs these days.

You will have to mount the carb upstream of the restrictor. The restrictor is of a size that limits the airflow to the engine. Using a carb you are adding the fuel before the restrictor, meaning even less air can get through!

You would have to be incredibly desperate to run carbs!

Malcolm.

[Jon Burford]

Malcolm,
Yes I agree that it is not the perfect solution, but if you had a real problem getting to a dyno, the Carb is potentially a good option.
The university of Dundee have been running a half blocked Webber for a good few years now. The first time I saw that car in 2011 it did pretty well out on track and was running really nicely.
I agree that you can get even less air through the restrictor with the carb but you don't really need all that much power to do well, so I would call your bluff on that argument.
As you say, I would have to be desperate, but I'm just saying that it can be done and you could still do very well.

[Chevalier]

Yeah I would agree that out and out power isn't too important hence the "if you are desperate" proviso. But is not a good solution other than "easy to sort". Even then (I know, I have a '76 MG Midget) they can still be a PITA to get running sweetly.

An intangible "easy to fit" excuse isn't really a justifiable option in an engineering competition so expect to take some flack from judges if you fit a carb.

http://www.formulastudent.de/a...esign-judging-stuff/

Cheers,
Malc.

[Jon Burford]

yeah the key wording from Pat there is "the exact number being relative to how well the team have incorporated the carburetor into their design"
With regards to the points loss.
If you were planning on running EFI, failed, and just said "S##t, we have 2 weeks left, lets stick an SU on there" then yeah, you should take the points hit.
If you intended on using the Carb (preferably not an SU) from the beginning and designed accordingly, then I don't see there should be a "massive" points loss as long as you have gone about it in the correct way.
As you say, there is no less work involved, it's just cheaper, simpler to design and package potentially, there are a lot fewer bits and pieces on the back (or front ) of the car and dare I say it, less to go wrong.
I am not advocating it at all and I definitely don't want to drag anything back from the dead; I hate the things.
All I am saying is that we should think things through and try and see things from the other side sometimes.

[Goody]

Originally posted by raptor93:
Does FSAE have any restrictions for the use of a four cylinder engine which has four corresponding carburetors attached to them.
If it is not allowed,is it okay to convert the system to a single carburetor engine with a manifold leading from the carburetor to the four cylinders.

I believe as long as you ran all four carbs to a single 20mm restrictor/19mm-E85, you're good to go. As mentioned, it's not ideal, but if you can get it to run happy and it's what your resources allow for, go for it.

I don't believe the rules dictate anything about fuel distribution to the engine, as long as the fuel system plumbing passes tech, there are no restrictor-bypassing ports/ the intake air is restricted per rules, you could run a tunnel ram with dual quads on that thing if you wanted!

[Jon Burford]

I would ask for Clarification before bodging 4 carbs into one restrictor.
The Rules use the word "carburetor" implying singular.
Which in itself I don't really recommend, let alone some kind of multi carb restrictor duct jumble.

[X Charger X]

I understand use of carburetor isn't a good idea but due to lack of resources we had to buy CBR 600 F2. Now to replace carbs with fuel injection system what should be taken care of and is it a good idea to meddle around with such an old engine?

[Charles Kaneb]

The main disadvantage is that you'll have to go with a 19mm or smaller carburetor in order to not have to have two venturis in the system. You'll be seriously hurting for peak power - I doubt you'll get much more than 30 hp with a 450 breathing through it. Maybe an XR600 would do a little better?

What you will get in exchange for mounting the tiny Tillotson pumper carb and a lawnmower magneto ignition is a significant simplification of the wiring system. No fuel pump, no need for armored fuel lines, no worries about sensors (a manual "start/run" switch between two advance settings wouldn't be bad), etc. If you combine this with an aircooled engine and eliminate the fan, your entire wiring harness could be under ten wires. The battery would only be used for starting and you would not have to run a charging system.

Think about all of the trouble everyone runs into with wiring and electronics. Put your wiring harness on a scale. Watch some old FSAE cars, particularly the singles, that have gone back to carburetors.

If your car concept doesn't rely on your having much power, there is an advantage there to exploit. You'll save weight and you'll probably spend more time driving and less time fixing.

How much power do you need?

[Will M]

Originally posted by X Charger X:
I understand use of carburetor isn't a good idea but due to lack of resources we had to buy CBR 600 F2. Now to replace carbs with fuel injection system what should be taken care of and is it a good idea to meddle around with such an old engine?

-X Charger X


The PE engine controllers seems to have some features the would really help when converting from carbs to EFI.
Specifically the 'Pulse to Sync' feature.

http://fsae.com/eve/forums/a/t...607348/m/97020897151

Originally posted by Charles Kaneb:
If you combine this with an aircooled engine and eliminate the fan...

Yeah ditch the F2 and grab the engine from a TRX400EX.
Air/oil cooled, dry sump, lots of after market parts.
Whats not to love? (besides having no EFI)

-William