Intake manifold construction, intercoolers

[Bernd Felsche]

Rausch, Bernd tapped away at the keyboard with:

> At the moment, I have an air/air intercooler per side (twinturbo V
> engine). I have per side: three 90deg bends, about 2m piping, two
> intercooler mandifolds with 90deg bends and four silicone hoses.

> I am thinking of welding an air/liquid intercooler core from
> Spearco directly in the intake plenum. The throttle body will be
> upstream of the intercooler. With this construction I can exit the
> turbo in a straigt line, with an expanding pipe of about 0.4m to
> the throttle body. I will only need one hose (turbo has a flange
> at the outlet). This setup will save me five 90deg bends, 1.6m
> piping, three silicone hoses and two manifolds at the intercooler
> per side.

>       TB   IC     intake runners
>        |---------|------------|
>        |   ||    |------------|
> -------|   ||    |
>  ->    /   ||    |------------|
> -------|   ||    |------------|
>        |   ||    |
>        |   ||    |------------|
>        |---------|------------|
> 
> -Is there any downside of this setup ?

Your throttle response is going to suck - no pun intended.

Can't you put throttles on the end of the runners; one per runner?
These can be "ganged" using a linkage inside the plenum to reduce
the number of seals required to just one (possibly just a Bowden
cable entry). Integrating the intercooler with the plenum will
probably require a plenum split anyway - at least during
construction. Use that split to construct/integrate the throttles.

         _________ ____________.
        |         /            |
        |   ||    +------------+
 -------+   ||    |____________.
  ->        ||    /            |
 -------+   ||    +------------+
        |   ||    |____________.
        |   ||    /            |
        |_________+------------+

Don't try to run the IC piping through the split if it's a
permanent one. Keep the sealing surfaces of the split simple. A
flange with o-ring groove is reliable - but watch the temperature
and use a suitable o-ring material. The flange could also be sealed
with other materials at a pinch. Keep it flat and minimise the
stresses carried by the flange bolts.

> -How do I calculate intake plenum volume ? Only the volume on the
> downstream side of the intercooler or the complete plenum including
> intercooler ?

Without seeing how much of an obstruction the IC presents; the total
plenum volume is between the throttle and the intake valve - this
volume is used when calculating some resonance modes.  Depending on
why you're calculating the volume, the plenum volume could also be
between the end of the inlet runner(s) and the throttle valve.

-- 
Bernd Felsche - Innovative Reckoning, Perth, Western Australia
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