ALFAGTV6.COM

@MD and Bruce,
The bigger the better.

Why not calculate it:
I borrowed this from the Dutch Aflaclub, copyright Roy van Gortel.
Ok it's in Dutch but for the South-Africans no problem.

http://www.alfaclub.nl/phpbb/viewtopic. ... ilde+weten

You can use these programmes:
Klik hier om zelf rekenen
Klik hier om zelf resonanties te berekenen
Klik hier om zelf drukverliezen te berekenen

On Tab 2
You have to compensate the input variables by dividing the engine in Half.
So two 1,5 liter 3 cylinder eninges.

Then try to size up the length of the inlettubes, diameter of the inlettubes and volume of the plenum (easiest done with water if you have a plenum on stock).

The results of this calculations matched the real deal in racing...

Resonance occure:
- with a large plenum (big is big enough, above a certain value the ownfrequency doesn't come down)
- longe inlettubes
- thin inlettubes!!!

The thicker the inlettubes the higher the ownfrequency
The longer the inlettubes the lower the ownfrequency

But keep in mind: There's always an unknow empirical factor between theory and practice!

I think someone just realy wants a V12

Why does it need to be two pipes per intake
couldnt you acheive the same with one pipe per outlet using three of the 90 degree pipes to one plenum and three 90 degree pipes to the other
and by mounting one plenum per bank he would have acheived the same look
im sure i saw a yellow gtv6 once on the omain site with just that set up

In fact here it
Leif Soderstrom's GTV6 racer

darryl longley wrote:Why does it need to be two pipes per intake
couldnt you acheive the same with one pipe per outlet using three of the 90 degree pipes to one plenum and three 90 degree pipes to the other
and by mounting one plenum per bank he would have acheived the same look
im sure i saw a yellow gtv6 once on the omain site with just that set up
In fact here it
Leif Soderstrom's GTV6 racer

I agree,
It would be the better sollution, for two reasons
- First, It would be much easier to make.
- Second it would bring the ownfrequency down.

The main difference is that this design has double the surface in the inletlines to a cilinder than your idea.
A larger surface create a larger volume of the inletline(s) to a cylinder and so a higher ownfrequency.

there was one idea that I was kicking around a while ago when I was doing calcs on the intakes.
And that was to run 2 small runners to each. one per valve(this is for a 24v).
The idea was to run only one open at the low RPM and at some point start too open the other side for the rest of the RPM band.
so it would only be tumble when both where runing.

some factory cars already do run a similar setup, with a runner for each port/valve. dont know enough about it to say anymore though.

slyalfa wrote:there was one idea that I was kicking around a while ago when I was doing calcs on the intakes.
And that was to run 2 small runners to each. one per valve(this is for a 24v).
The idea was to run only one open at the low RPM and at some point start too open the other side for the rest of the RPM band.
so it would only be tumble when both where runing.

Toyota used this idea years ago and called it TVIS (I can't tell you exactly what it stands for).
Basically, each cylinder used 2 inlet runners (1 for each valve) and at low rpm/load, a butterfly valve in 1 of the inlet runners was closed to promote high inlet air speed (all air breathed thru 1 inlet valve) that helped low rpm torque.
At higher rpm/load, the valve would open to gain the full breathing potential of the 2 inlet valves.
Toyota abandoned this aproach for the simpler 'small port' inlet system. Whether this was cost or performance based I couldn't say.

ToyotaVariableInletSystem i guess .... those japanese are not very original when it comes to these names.

Giuliettaevo2 wrote:ToyotaVariableInletSystem i guess .... those japanese are not very original when it comes to these names.

Agree with the naming, but can't recall Alfa's attempt at 2 stage inlet manifold design......

Duk, Alfa 156 has variable inlet manifold (and rest twin sparks - I think from 1998->...). For example, bolted on 1.8TS 16v it produces some 5HP more...

I think the engine looks great! Kind of looks like the ford taurus HSO engine.

I think the engine looks great! Kind of looks like the ford taurus HSO engine.

Misprint above. It's the Ford SHO