172 182 cylinder head

[ShaunG]

hi can any one tell me why on the 172 cylinder head the exhaust ports are drilled out and matched to the exhaust manifold whilst the 182 cylinder head exhaust ports are untouched and dont match the the exhaust manifold?

 

[Dan@SJM]

as for revision purposes you dont want the exhaust ports to match the manifold.

 

[mikey_172]

because the matching gives you the 10 bhp more thats why the 172 gets done and the 182 dosenti think the 182 is on the limit it matched if that makes sense

 

[Dan@SJM]

Its a different exhaust manifold and fuel map that gives the extra 10bhp (if that).

 

[drhowser]

surely a 4-1 gives more bhp, i thought that the 182 mani improved torque?

 

[drhowser]

sorry, and for the original question. i've no idea i'm afraid.

 

[Gray]

If your talking about a PH1-172 i thought the exhaust ports were slightly larger on those engines anyway, compared to the PH2's?

 

[edde]

If your talking about a PH1-172 i thought the exhaust ports were slightly larger on those engines anyway, compared to the PH2's?

Yep.

182 gains were due to the exhaust manifold the remap as such and the exhaust system and cat.

 

[ShaunG]

yeah i know the 182 manifold gives the extra bhp, jus wonderin if i stick a head on with the ports drilled out or not and which way round will help the engine breath better. i'm still unsure as to why the 172 to ports are huge and the 182 ones arnt, basically which combination do you think will be best the ports drilled out with a 182 manifold or the exhaust ports untouched with a 182 manifold:banghead:

 

[Tigger]

Are you having your exhaust ports matched as well as matched inlet plenham/manifolds ?

 

[ShaunG]

Are you having your exhaust ports matched as well as matched inlet plenham/manifolds ?

yeah i'll port the inlet thats a must but unsure what to do with the exhaust ports weather leaving small like the 182 heads or oepening up like the 172 heads unsure which will help the engine breath better:S

 

[Andyman]

surely a 4-1 gives more bhp, i thought that the 182 mani improved torque?

Other way round im sure (4-1 = better low down torque, 4-2-1 = more top end power) ?

Either way its not / dosent to make much difference on stock 182's vs 172's


Due to keeping the car on the road at the time, i bought a ph2 head (same as a 182?) and had that polished and ported and bolted to my ph1 172. Not sure if iv gained or lost in terms of power and torque by doing this but it goes well enough