marco, intake manifold question

[timucin]

i will start doing my own intake manifold on monday. but i dont know what should be the size? cc?
can you pls help me

thnx

[timucin]

any help..

[zlobo]

I builded my @ ¨3.3L i think

[timucin]

oops..
quite big, how to fit it there?!?!

do you have any pics ?
thnx for help

[timucin]

just visited your web page.. amazing car ,excellent project!!!

[Pisobiker]

Timucin,
consider RS2 IM is about 4.2 liters including the runners.
So the plenum should be about 3-3.2 Liters I think (which should be good enaugh).
Anyway much more important than volume (unless you make it far too small) is balancing flow through it to have each runner fed by the same air mass.
This of course to maximize performances for many reasons:

1) If one of the cylinders receives more flow mass, it will start knocking earlier thus inducing you to tune the global engine upper limit lower then max possible;

2) If one of the cylinders receives more flow mass and you are tuning A/F ratio through a single WB Lambda on the collector, you might tune your engine to have an average of 12.2:1 at WOT while having leaner mixtures in the cylinder with higher flow (thus again knock problems and temperature raise) and richer in the other ones. Both those conditions result in less power output.



Marco

[timucin]

you think i should leave the current one as is..
does the current cause any restriction at 500 hp^s?

[Pisobiker]

No, I'm not saying you should keep yours. At least I have actually not experimented if the OEM one will run out of specs at higher than 400 Hp mass flow rates.

I think the easyest way to check it would be putting one boost gauge per each runner and go for a 4 th gear blast with the "500" hp setup. Using "peak boost memory" boost gauges will then allow you to see eventual differences among the runners.
Only problem would be costs, since those kind of boost gauges, of the required precision) aren't cheap...... and you'll need 5 !


Marco

[Audi_CQ]

Here are a couple of pictures of my homemade manifold (under construction ) . Long runners and large volume, but requires some work. I've moved my servo and redesigned the coolantpipe.

Fitted in a "wannebe S2" Coupe Q

[Pisobiker]

Looks good. Aluminum welds are really "professional". My respects for the job. I wish I had a TIG welder and the skills to make that good looking welds on aluminum....

I see you used a cilindrical pipe as plenum, which means same cross sectional areas through its lenght.... how did you get to the definition of this layout?


Marco

[timucin]

every pic i see gives me a new idea;
very nice job bro
good luck!

[audiman]

@Audi CQ, got any pics of that ex. manifold? Looks a bit mental from what i can see. Nice Inlet manifold tho. Top welding. Nice and light weight too.

BTW is that a 3B block with a ABY/ADU/AAN head? Cambelt is tensioned via the water pump and not separate tensioner, just an observation.

[Mark Halligan]

Yep lovely work, I too wish I could do that, looks like some of the IMSA type manifolds that I have seen. Very nice .

Mark.

[Mark Halligan]

Just thought....wanna make me one , how much?

Mark.

[Audi_CQ]

I also wish I had a TIG welder and the skills to make that good looking welds on aluminum Welding done by a local tuning company (ES tuning).

The plenum isn't 100% cylindrical. Get's a bit smaller at the back.

The design came by trial Wanted something like the IMSA-manifold with longer runners then original S2. Bought some 90 deg. bends and a plenum pipe and tried to get it all together with smooth curves.

Another picture with fuel rail, throttle body and modded coolant pipe :