Piper 270 or 285?

[Martinsalharris]

So I am considering my next stage of tuning for my S2 K-Series...

I already have a Maxigen Induction, sports exhaust and cat, throttle bodies and flowed head - so was thinking of getting new cams and an Emerald fitted - but which cams to go for?

I like the extra grunt and sound my last mods gave but hanker for more power...

Its a daily driver so don't want it un-driveable if I go for the 285 cams - anyone got these fitted? Is the extra top end worth it and how much worse is the bottom end going to be?

Any advice welcome?

Cheers

[lukefreeman]

285's require springs and a bit of fettling of the head.
270's don't.

Don't forget verniers too!

I'd go 285's, plenty of people run them.

[thegreenhell]

My understanding is that 285s aren't happy if you are running a plenum, and 270s are much better in that scenario. 285s can be made to work nicely with Jenvey ITBs and an Emerald. I'm not clear from your post if you have the standard plenum setup or ITBs, as you mention throttle bodies but also an induction kit and current lack of Emerald ECU.

[lukefreeman]

I assumed iTB's as he said "throttle bodies"

285's won't idle or behave at low Rpms with a plenum.

[Martinsalharris]

Yes I have 52mm Throttle Bodies

[Martinsalharris]

And Luke - what do you mean by some work on the head? I know you should change to solid followers but hear there is a 285H option that allows keeping the current ones.

[thegreenhell]

Martinsalharris said:

Yes I have 52mm Throttle Bodies

You mean you've changed the standard 48mm single throttle for a 52mm, but still have a plenum? Unless you're running Jenvey or similar multiple throttle assembly with an Emerald ECU then I would fit 270s rather than 285s. The 285s will idle like a bag of spanners, and without head work (porting and bigger valves) and a 421 exhaust manifold then you won't really get the benefit of the top end potential of the cams either.

Another point to consider is that if you're going the Jenvey/Emerald/285 route (with the other matched mods I mentioned) then you're in the power range where you start to need forged pistons.