2.8 vs 2.4 vs 2.7 Heads and Cams

[chackalucka]

Collected some measurements from the heads I have here in Australia.
I know US didn't get the 2.4 but it looks like they have roughly 2mm wider ports than 2.8 heads, I measured every port and the sizes were within .5mm.
Even though the 2.4 has wider ports the 2.8 still had higher lift cams.

2.7
Intake port: 43x28mm
In.P cross-section: 1035mm^2
Exhaust port: 36mm
Ex.P cross-section: 1018mm^2
Surface area gain: RS4 (16%)
Intake Cam: 7.6mm
Exhaust cam: 10mm

2.4
Intake port: 56x27mm
In.P cross-section: 1355mm^2
Surface area gain: 2.8 (4.5%) & 2.7 (23.6%)
Exhaust port: 36mm
Ex.P cross-section: 1018mm^2
Surface area gain: RS4 (16%)
Intake Cam: 8.4mm
Exhaust cam: 10mm

2.8
Intake port: 54.5x26mm
In.P cross-section: 1293mm^2
Surface area gain: 2.7 (20%)
Exhaust port: 36mm
Ex.P cross-section: 1018mm^2
Surface area gain: RS4 (16%)
Intake Cam: 8.6mm
Exhaust cam: 10mm

Rs4
Intake port: 56x27mm
In.P cross-section: 1355mm^2
Surface area gain: 2.8 (4.5%) & 2.7 (23.6%)
Exhaust port: 33mm
Ex.P cross-section: 855mm^2
Intake Cam: 8.4mm
Exhaust cam: 10mm


I've never seen a post that actually puts this info into one post. If there is more info on the rs4 heads please chime in.

Updated info on RS4 heads and added Surface area and percentage gains of each port.

I took the width measurements at shortest points to get a more accurate surface area but max width of the port excluding 2.7 is 1mm larger at the dip. (Pictures give perspective)



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[KiwiRider]

Hey mate! Nice to have another person from this side of the world (I'm a Kiwi).

I have my RS4 engine out at the moment so have taken the measurements you're are missing.

RS4:
Intake port - 55.8mm x 27.8mm
Exhaust port - 32.8mm

Interesting that the exhaust is noticeably smaller on the RS4 heads!

[chackalucka]

Man you are an absolute legend! I'm a South African so we probably would get along even more.

I'll add that in and find out the cross-sectional area of each as well to get a better size number.

I think they really wanted to get those ko4 turbos to ramp up as quick as possible, I don't think as much of a problem with ko3 and maybe why the s4 would feel a bit more doughy and less responsive IMO.

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[chackalucka]

I also created a 2.7 page on Facebook for the Australia NZ guys separate to the general b5 page.

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[Kamil P]

Check the casting part numbers on the 2.4 and 2.8 they are probably the same

[chackalucka]

I'll do that and add them into here.

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