Italian 3 Cyl Sport Motorcyle a good donor for Throttles?

[GrantG]

Just saw this beatiful sport bike and wondered if a pair of the 3-cylinder intakes could (should) be used on a custom 911?

MV Agusta, F3 - 3 Cylinder 675

http://www.mvagusta.it/uploads/4q/CC/4qCCMciZiBc-n21TpbTn4Q/Brochure_F3_ENG.pdf

[GrantG]

Good looking machine - if I didn't think I'd only survive on this earth for a few hours with one, I'd buy it

[Flieger]

Al Kosmal (X-factory) uses Triumph Speed/Street Triple throttle bodies with a Weber manifold. He sells a kit.

Personally if I were going through all that trouble I would want ones that were separated from each other and spaced correctly for the 911 ports like the Solex carbs were.

Then there are the Rothsport ITBs. Very pricy.

[HawgRyder]

50mm throttle bodies looks a little large to me.
For individual cyliders...about 35mm to 40mm would be closer to what you want.
The larger the bore the better they are a the top end (max RPM)
but low end response and torque will suffer.
My $.02
Bob

[Schwarzeritter]

Here are some of the issues,

1. I am not sure Grant if you understood that these throttles are a ride by wire design.
Basically throttle by wire, this is add's to the cost if you intend to go this direction.
You also will require engine-management that is capable of supporting this feature.

2. The throttle diameter is one aspect, as well is injector location and spray pattern.
Beyond this you still need to consider the relationship / distance that the butterfly or throttle
is located from the port. Not to mention is this a plenum, or atomespheric set up and deciding on the style of velocity stacks and so on.

3. You also need to consider the spacing, by this I mean it is highly going to be the case that an adaptor plate 1X per bank will be needed required or some sort of manifold 1X per bank.

4. I would recommend that you honestly just go with a set up that meets your requirements.
Unless you require something custom and very specific.

5. A alternative solution, you went with individual runners that feed from one individual plenum per bank with one individual throttle body.

Last but not least, I would recommned that you develope a very well sorted ignition and fuel mapping before going with individuals and standalone.

6. I use individual throttles as tool to improve response and balence. As far as diameter,
and known un known X, Y and Z are concerned. Depends on which engine, camshafts, valve diameter, port inlet and exhuast, compression and so on you are using.

Tailor the response to your driving style and needs, you will be faster.

Good luck -

[al lkosmal]

Originally Posted by Flieger

Al Kosmal (X-factory) uses Triumph Speed/Street Triple throttle bodies with a Weber manifold. He sells a kit.

Personally if I were going through all that trouble I would want ones that were separated from each other and spaced correctly for the 911 ports like the Solex carbs were.

Then there are the Rothsport ITBs. Very pricy.

Or spaced apart like the MFI T'bodies are...........like this, perhaps

another home brew DIY/ITB/EFI .....MEFI on the way.






PS: I think that 50mm t'bodies will be too big. Hawgryder has it right IMO.

regards,
al

[Flieger]

The interesting thing is that the intake runners for MFI are not perfectly straight. The outer ones are angled inwards for some reason. The throttle bodies do appear to be straight but it is hard to tell since they are much shorter and the bore can be vertical even if the casting is not.

[stownsen914]

Originally Posted by Flieger

The interesting thing is that the intake runners for MFI are not perfectly straight.

Yeah - Porsche decided to make the air filter box attachment match the Weber carb spacing when they built the MFI stacks .... Oh well ...

[Flieger]

Guess I need some RSR style trumpets then.