View Full Version : 447 or 503 SIDC?

profqwerty - n/a
28-Dec-07, 05:20 PM

Can anyone tell me the spec differences between:

-447 SCSI

-503 DCDI

-503 DCSI

I'm running the 447, but it's getting a bit worse for wear now; so am looking into upgrading it. I'm thinking a 503 for F1x, so what's different between the DCDI and DCSI power/weight wise?


Don83000 - n/a
29-Dec-07, 02:09 AM
All the info you should need

http://www.ultralightnews.ca/rotax503/index.html (www.ultralightnews.ca/rotax503/index.html)


Iceman - n/a
29-Dec-07, 03:01 PM
S ingle C arb - S ingle I gnition

D ual C arb - D ual I gnition

D ual C arb - S ingle I gnition

Most (if not all) 447's you will come across are single carb, some have the Bosch points ignition, or newer engines have the Ducatti electronic ignition.

503's are usually twin carb and again have either Bosch or Ducatti ignition, however with the 503 the Ducatti is twin ignition i.e. 2 plugs per cylinder.

As regards power and weight, there is no significant difference.

profqwerty - n/a
29-Dec-07, 04:48 PM
The thing I really need to decide is if it's worth upgrading from an old 447 to a 503 DCSI engine, or waiting around for something else...?

What is the taper on the 503 crankshaft? Is it the same as the 447?

I'm running the 447 through a belt reduction drive - I can alter the frame as the data sheets show the mounting studs to be slightly farther apart.

I shouldn't need to change the belt/height at all though?

Iceman - n/a
29-Dec-07, 05:00 PM
The crankshafts have the same taper so no problem there.

However, becuase the 503 has more power, you will need to change ratio or fan setup. If you keep the ratio the same then the belt centres obviously won't change, but you will need to increase blade pitch and/or number of blades.

The choice to upgrade will lead to more issues (e.g. twin throttle cable, higher fuel consumption) so you need to decide what you want from your hovercraft and look at options available.

There is no reason why your 447 can't be serviced and continue to give you good service, do you know how many hours the 447 has run?

profqwerty - n/a
4-Jan-08, 12:51 PM
Yah it's a tricky one..as it actually works now I think I might leave it a bit - if it floods and the hover is in bits (again!) I will be royally peed off.

As long as it's not tooo complicated swapping them over later on I will do.

Ideally I would race it at somepoint; is there definitely F1x novices now at all?

The blades are pitched fairly flat anyway, so pitching up / adding another one isn't too difficult (it's 5z 3/12 at the moment).

I have no idea about the hours!

It's going to have about 13L fuel tank so that's not a problem; but does it use ethe saem muffler as the 447?

Do people tune 503's or just use the standard rotax exhaust?

There is plenty of room for the extra carb.

sixpackpert - n/a
4-Jan-08, 01:10 PM
Formula 503 specifies a standard engine with standard exhaust.

Formula F1x specifies:

The engine for thrust is to be aircooled, up to and including: 500cc 2-stroke, 750cc 4-stroke.

Have a look at page 8 here...

Racing Regs (www.hovercraft.org.uk/downloads/files/block_4/hc1152007.pdf)

profqwerty - n/a
4-Jan-08, 02:52 PM
I have a separate lift engine, so I'd have to do F1x.

What I meant was for F1x (or perhaps F2?) do people tune their 503's or just use the standard exhaust?

sixpackpert - n/a
4-Jan-08, 02:57 PM
I have a separate lift engine, so I'd have to do F1x.

What I meant was for F1x (or perhaps F2?) do people tune their 503's or just use the standard exhaust?

At the moment everyone just uses standard exhausts in F1x IIRC.

You can't do F2 because the limit is 500cc total capacity (lift engine included)