Hi all,

Could somebody help me cast some light on the differences on the heads on the phase 1 and the phase 1.5 engine?

Thanks in advance

 

castings are different.. the rocker covers from one won't fit the other..

cams are different I believe altohugh not compared side to side..

I believe that most if not all the phase 1.5 cams are slightly wilder than the phase 1.. sti3 being the wildest and with longest duration, followed by sti4 and then phase 1 sti.. I am not 100% sure which phase 1 got the solid valves, seen it on some RA and some STi.. but they are the ones I mean when I say phase 1 sti.

The head castings for all phase 1 are the same, they are the same for all phase 1.5 too.. ie. uk = sti.. just the cams and valve train are different.

Simon

 

so are phase 1 and phase 1.5 heads identical then apart from cams and the valvetrain or is it all phase 1 heads are the same as each other and all phase 1.5 are the same as each other but different between the phases

 

same as each other.. phase 1 and phase 1.5 casting are different.. but all phase 1 are the same casting.. and all phase 1.5 are same castings afaik.

Simon

 

so you can swap parts between the 2 phases then?

Also with head work, is it possible to get the same/similar flow characteristics from the phase one as the phase 1.5?

 

I would have thought so, What power are you aiming for? I've had 2 quotes to do mine, 1 was 950 + vat and the other was 700 + vat, so decided to leave it alone as the outlets are matched to the manifolds so see no point in spending near to 1 k for a pair of CNC flowed heads at this level, i have more important things to spend my money on and have to draw a line somewhere.

 

Not looking for specific power levels, I have got hold of a phase 1 engine that has ring damage (bores not damaged) which I am going to rebuild over a period of time. Was thinking about doing a bit of work on the heads myself (not bothered if I mess up as I have my existing heads on my running engine anyway), just thinking that with the rebuild which will include uprated rods/pistons etc, I want heads that are capable of utilising the internals and allow a higher rev limit.

 

swap which parts specifically? inlet manifold foot print is the same phase 1 and phase 1.5.. I have phase 1.5 heads on my phase 1.

I don't believe the phase 1/1.5 head parts are interchangable.

You could get similar if not the same flow I guess, but not tried.

Simon

 

I was meaning can you swap the whole valvetrain etc to get rid of the hydraulic type lifters and the cams if they are better.

 

no I beleive they are different.