2.7 & 3.2 cam characteristics/swap

[mb230sl]

hi guys,

has anyone used 2.7 cams in a 3.2 or v versa?

to cut a very long story short * , i need an insight as to how 2.7 cams might alter the characteristics of a 3.2 (tiptronic).

i downloaded the manual from easymanuals.co.uk which as it turns out seems to pertain to the earlier five chain engines. the engine in question is a three chain.

nonetheless, it contained cam specs as follows (with calculated duration in brackets, using a website thing i found) -

2.7

Inlet opens 14 after TDC
Inlet closes 44 after BDC
outlet opens 141 after TDC
outlet closes 8 before TDC

(intake duration 238, ex duration 329)

3.2

Inlet opens 14 after TDC
inlet closes 60 after BDC
outlet opens 141 after TDC
outlet closes 6 before TDC

(intake duration 254, ex duration 327)

i haven't measured lift, yet.

does this suggest the 2.7 might be a torquier cam down low?

the world of cams is a dark and mysterious one !

* abridged version of the very long story as follows -

my partner had owned the car for several years back in the UK, and once settled here in australia, sent for the car. preparing the paperwork, waiting while it was on the water, then fulfilling the compliance and roadworthy requirements for initial registration here is an arduous task indeed. on the traumatic day of inspection and so forth, we jumped the final hurdle, and hopped into the car to go and get number plates. as we idled out of the car park, there was a squeak and the car stalled.

the tow truck trip back was a miserable one. inspection the following day revealed total leak down cyl 1-3. strip down revealed bent exhaust valves 1-3. chunks of what looked like chain guide had become caught between the chain and exhaust sprocket. the rest of the engine looked great and i decided if i could find the source of the plastic, the engine was worth putting together again. i traced it back to the lower guide on the opposite head. turns out back in the UK it had work done to the vario cam on that side - wonder if the chain jammed against the guide during the work, breaking it off, and my enthusiastic driving caused it to migrate over.

anyway, the head went off and came back from rebuild, and we gathered all the parts. before i was able to put it together, my workshop was destroyed by fire. the boxster's engine sat on a stand and all the plastic bits and wiring were damaged. lights/visors,screen shroud were damaged on the car and it was written off, but purchased back from insurance.

we purchased a cheap damaged engine for parts, which was said to be a 3.2. this proved a useful source for all the plastic/rubber components, and also, we thought, the cams, as two original ones had sustained corrosion while in storage. it then became apparent from the cams the spare engine is a 2.7 - hence my question.

the car is not to be a race car, and speed limits are draconian here, anyway (and it is tiptronic), but we don't want to go too far backwards, either. my limited experience of interpreting cam specs suggests the 2.7 is a torquier cam down low which may suit the tiptronic very well, but as we all know, winding one of these out to redline is pretty intoxicating.

thoughts would be much appreciated

[dlud]

I don't have an answer but that is an amazing back-story!

[mb230sl]

i just hope that given the back story, we don't hit an errant kangaroo during its inaugural drive through the countryside!

i downloaded the 987 manual which i figured might be more relevant to the engine. the 986 manual only seems to cover the five chain engines. i don't recall such a resource being available when this project started nearly 2 years ago , and all for the princely sum of $20.

anyway the specs there suggest the following -

2.7 -

intake opens early/late; 21 before TDC/19 after TDC
intake closes early/late; 9 after BDC/49 after BDC
outlet opens ; 39 before BDC
outlet closes; 8 before TDC

3.2 -

intake opens early/late; 26 before TDC/14 after TDC
intake closes early/late; 20 after BDC/60 after BDC
outlet opens ; 39 before BDC
outlet closes; 6 before TDC

the calculator i've been using can't deal with inlet opening after TDC, so now i'm stuck.

i do notice the 3.2 has larger valves, that the 2.7 generates more hp per litre than the 3.2, and both have their torque band between 4700 and 6000.

all very interesting but it is a lot of work to swap cams over if the outcome is a flop.

[oldskool73]

"...speed limits are draconian here, anyway..."

...tell me about it, I've got a 2.5 and can't get above 3k in 2nd gear without breaking the law most places, 3rd maybe on the motorway

Also, despite the laid back image, cops are much more likely to book you here than they were when I lived in the UK. Coming back from Amsterdam at about 2am once on an empty motorway doing 150mph in a mates Golf R32, an unmarked car pulled up along side us, the driver motioned to us slow down, then he just turned his blue flashing lights on and sped off.. wouldn't happen here!

Sorry to veer off topic, no idea on the actual question I'm afraid!

[Smallblock454]

My question would be from which camshafts the data is, because for the 2.7 and 3.2 there are in total 4 sets of camshafts available (depending on model year and HP).

Also the camshaft adjusters are diferent.

[mb230sl]

Originally Posted by oldskool73

...tell me about it, I've got a 2.5 and can't get above 3k in 2nd gear without breaking the law most places, 3rd maybe on the motorway

sad but true. i am quite fortunate the speed demon left me when it did. if i were 17 in 2018, i'd be in big trouble!

[mb230sl]

Originally Posted by Smallblock454

My question would be from which camshafts the data is, because for the 2.7 and 3.2 there are in total 4 sets of camshafts available (depending on model year and HP).

Also the camshaft adjusters are diferent.

this is good info. you can break it down into three chain and five chain, which accounts for half of the options, and also accounts for the adjusters.

interestingly, according to the 987 book, belgium has its own version with torque and hp peaking lower - but doesn't mention a different cam, so must be in the "software".

[edc]

Originally Posted by mb230sl

this is good info. you can break it down into three chain and five chain, which accounts for half of the options, and also accounts for the adjusters.

interestingly, according to the 987 book, belgium has its own version with torque and hp peaking lower - but doesn't mention a different cam, so must be in the "software".

That will likely be due to tax and emissions regulations.

[Smallblock454]

2.7 220 HP and 3.2 252 HP do have electronic actuators for camshaft adjustment.
2,7 228 HP and 3.2 260 HP do have vane phasers for the camshaft adjustment.

Camshafts with electronic actuators for camshaft adjustment differ from camshafts with electronic actuators for camshaft adjustment in detail and are from my knowlegde incompatible if you only want to exchange the camshaft without the complete head.

228 and 260 HP engines only have single row imsbs. So they are 3 chain.

The belgium / netherlands 986 engine power is reduced by software.

[mb230sl]

Ok so the engine is a three chain 3.2 and the parts engine is a three chain 2.7.

The cams will physically fit, but what effect will it have? lower torque peak? On paper, the 2.7 cams might actually be more suitable for tiptronic street use, but thats based on prior research on the rover pushrod V8 - totally different animal.

Originally Posted by Smallblock454

2.7 220 HP and 3.2 252 HP do have electronic actuators for camshaft adjustment.
2,7 228 HP and 3.2 260 HP do have vane phasers for the camshaft adjustment.

Camshafts with electronic actuators for camshaft adjustment differ from camshafts with electronic actuators for camshaft adjustment in detail and are from my knowlegde incompatible if you only want to exchange the camshaft without the complete head.

228 and 260 HP engines only have single row imsbs. So they are 3 chain.

The belgium / netherlands 986 engine power is reduced by software.