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Old 03-20-2018, 03:35 PM   #1
mb230sl
Registered User
 
Join Date: Mar 2018
Location: australia
Posts: 8
2.7 & 3.2 cam characteristics/swap

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
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