Small port vs Large port head

[Lemon S3]

I've tried searching for this but I never have any luck with the search option for some reason.
Would someone be able to tell me the size difference between a small port and large port head, and how much extra the large flows.
Also what are the pros and cons of going from a small port to large?

 

[aragorn]

On a standard engine its not really worth it. The small port head flows enough for the standard turbo, and gives better low down torque etc, which is why Audi fitted them.

If your planning on fitting a larger turbo, then its worth it, as the stock head starts becoming restrictive after 300hp.

 

[beachbuggy]

Also the inlet manifold is small port as the S3 never came with a large port manifold, so you then have to go from a small port manifold to large port head, as this happens the air speed drops but volume increases. Which as stated isn't good for low down torque unless u have a big bhp setup.

 

[badger5]

wellys goes all right with its largeport

remembering audi's design criteria was 225bhp tops

modded cars, remapped with mods... Does this still apply?

 

[Lemon S3]

I will be hybridding it soon so will be aiming for the same sort of power as Welly.

Does anyone know the actual dimensions of the large port and flow rate?

 

[Dane]

I'm gonna stay small port and go hybrid, like Steve, if that doesn't come up near Welly's I'll think about a big port head, but, I reckon small port should see a hybrid reach good figures.

 

[<tuffty/>]

I will be hybridding it soon so will be aiming for the same sort of power as Welly.

Does anyone know the actual dimensions of the large port and flow rate?

>head info from some blokes build thread<

<tuffty/>

 

[Dane]

lol

 

[Andrew@A.L.D]

Fourtitude.com - Dyno: GT3076 Unitronic 630cc Force Fed Engineering


Over 450bhp on a small port head

 

[Welly]

wellys goes all right with its largeport

remembering audi's design criteria was 225bhp tops

modded cars, remapped with mods... Does this still apply?

lol, my old 145000 mile bus become the new hybrid benchmark...

It's not just about the head in all fairness, it's also about all the other flow related mods that help out in general. The thing has a colossal cooler, big pipework to fill, and the large port head as well.

Ideally I think people looking for the hybrid should be aiming to try and keep the boost at sensible levels personally. Tried and tested.

 

[Lemon S3]

Does anyone know the width n height of the inlet ports as I've found a head but the owner doesn't know much about it but said the inlet port is about 55mm x 25mm.

 

[<tuffty/>]

Does anyone know the width n height of the inlet ports as I've found a head but the owner doesn't know much about it but said the inlet port is about 55mm x 25mm.

What engine code is the head from?

<tuffty/>

 

[<tuffty/>]

<tuffty/>

 

[Welly]

I so want one...

 

[<tuffty/>]

I so want one...

I think I need one!!!

<tuffty/>

 

[badger5]

Fourtitude.com - Dyno: GT3076 Unitronic 630cc Force Fed Engineering


Over 450bhp on a small port head

does'nt mean **** all tho does it... forcing it to do that on american dyno's vs a higher flowing head which will flow more for less boost is for me far more sensible approach. you neglected to also mention c16 fuel and 32psi of boost... hmmmm.. yea right!

BT cars need large ports in their lives - lol

 

[Lemon S3]

Thanks for the info guys, the head was a large port then. It didn't have an engine code on it for some reason.
If I got a bare large port head, could I transfer all the parts from my small port over to it?

 

[S3 Nattie]

Think you got to ask yourself what you want from your engine. Runinning a large head will shift your torque curve over a bit giving lower low end torque but give you better flow at high engine speed as it wont choke as soon as a small port head. Bigger isn't alway best.

Ye, as far as I know everything is transferable

 

[Lemon S3]

Well he has another bare large port head which apparently hasn't got many miles on it and he wants £100 plus £15 p+p for it. Wondering if that's a good price, the brand new head with cams went for £165 on the bay.

 

[Roadtrain]

<tuffty/>

Why BAM (225 PS )has small port intake, instead AGU (150 PS) has large one? Thank you.

 

[<tuffty/>]

Why BAM (225 PS )has small port intake, instead AGU (150 PS) has large one? Thank you.

All the later engines after the AGU was stopped being produced are small port... it increases low down torque...

<tuffty/>

 

[badger5]

On a standard engine its not really worth it. The small port head flows enough for the standard turbo, and gives better low down torque etc, which is why Audi fitted them.

If your planning on fitting a larger turbo, then its worth it, as the stock head starts becoming restrictive after 300hp.

your 300bhp it becomeing a restriction number is way too low.

From what I've seen and run smallport is the right size for up to 400-450bhp for optimum torque.... there after largeport will flow more overall but you will loose some torque onset at the same time.

 

[Roadtrain]

All the later engines after the AGU was stopped being produced are small port... it increases low down torque...

<tuffty/>

Ok thank you. This is because a "narrow" intake be of use for a turbo engine (instead aspirated one)?

 

[<tuffty/>]

Ok thank you. This is because a "narrow" intake be of use for a turbo engine (instead aspirated one)?

not really... smaller intake increase airspeed and subsequently cylinder fill rate to improve torque... this is the same on both turbo and NA engine... laws of physics and all that

<tuffty/>

 

[Roadtrain]

So Venturi effect?

 

[Erikn89nl]

So Venturi effect?

No, Venturi effect explains the drop of pressure associated with an increase in flow speed.

This is the continuity equation of flow dynamics:
https://en.wikipedia.org/wiki/Continuity_equation#Fluid_dynamics

 

[badger5]

So Venturi effect?

more of this>> http://www.pistonheads.com/gassing/topic.asp?t=1096171

 

[Roadtrain]

Thank you both