anyone running performance cams in their 996? i want to get some opinions on their experiences if so.

 

I would be interested in this too... The X-51 cams have a different part number, so they could be an upgrade. I think 3rd party ones may be cheaper though.

 

3.4 & 3.6l cams are not interchangeable, just for information only. 3.6l X51 cams cost €2665,- at Porsche Germany, Schrick's similar ones are approx. 1750,- , also in Germany.
Autofarm charges £1600,- +VAT for that Schrick set.

Just the cams will not do miracles, you'll need a complete head job for maximum gain. A full X51 set ( cams, heads, intake & exhaust manifolds ) add 25 hp, according to the factory. My own guessimate is that there might be even more to gain with extensive head machining. We'll be back to that later...

BTW, if someone is interested, I have a full set of unused and NEW 3.6l X51 cams, which I'm willing to sell for half of that factory price...

 

What makes the cams not interchangeable? I was under the impression that the engines were virtually identical other than the longer stroke of the crank?

Cat cams (google them if you aren't familiar) would probably do you a set and they are well priced and gaining a real reputation for making good power with driveability, so may be worth a look.

I have seen flow curves for the heads and it does look like a set of cams would do *some* good as the full flow is not utilised with the factory cams. There is also little 'meat' to port the inlets from what I have seen and the standard inlet geometry would be hard to improve. At the risk of damaging your heads, I wouldn't actually touch them. Also, the metal *can* be soft on M96 heads and machining the face/ chambers can be risky.

If I was to drop my engine then I would look at higher CR pistons and cams if I was to stay with the standard capacity but 3.4 -> 3.7 would be best. These engines liek compression by all accounts and I like squish and torque.

I have also looked into the X51 aluminium inlet manifold as I wonder whether the standard, plastic one may be restrictive especially since you can't port match it?

Pete, what are your thoughts? Are you upgrading an engine?

 

3.6l has VariocamPlus, which includes a cam position wheel in the middle of the cam. EDIT: Of course in addition to this the cam lobes are totally different. It's hard to explain how, so see this animation: http://vids.myspace.com/index.cfm?fu...ideoID=7065336 Std Variocam lobes are "traditional" ones.

Googled, cams only for 996 GT3 Race and 911 2V heads, so nothing for M96.0x engines. German regrinder dbilas is another alternative though.

I can comment after I've seen - and touched - a dismantled head. EDIT: Jake Raby claims just with his heads ( = cams/valves etc ) 1XX hp/l.

At least plenum volumes and runner shapes are completely different. X51 parts ( plenum / runners / in & ex ports / exhaust ) are machined to match at the factory. EDIT: I think plenum/runners could be machined ( careful sanding & polishing ) to match manifolds, which can be matched to heads etc.

I might be, I'm still weighing my options: a complete swap or a rebuild to 3.x l. In rebuild the cost effectiviness of X51 heads vs. machining of originals is still unclear. Also I still haven't decided whether to use LN Engineering or Autofarm services for displacement increase...

 

Pete, cheers for that - All understood.

Autofarm have been building my car for me, see this thread here:

http://www.pistonheads.com/gassing/t... 3.4&mid=73213 Trackday build/ rebuild on my 996 Carrera 3.4&mid=73213

So, I would use them for any work. For the power increase you get though, the 3.7 (or even 3.9 with the 3.6 crank) is very, very expensive, especially if you are yet to blow your engine so don't 'need' one.

I have been toying with the idea of rebuilding an early Boxster S 3.2 engine as that is virtually identical and i could sell my good 3.4 for good money and buy the 3.2S for much less, effectively saving a couple of grand. Or, for the same money, running all steel internals.

Cams would be nice, but i don't see much point without high CR pistons as I have been told that I wouldn't want to skim the 3.4 head face much to get the CR up - at which point, i might as well rebuild the whole engine.

Cat Cams will do them if you ask, so that shouldn't be much problem and we have some good value regrinders over here, if that is possible, which it sounds like it is.

330bhp would be nice (10% increase) but that may be achievable, just, with bolt ons (full exhaust including headers, upgraded induction including maybe plenum) and a re-map/ stand alone ECU (with a rev limiter increase). I have been looking at the Emerald ECU over here as it is good value and very well respected in performance circles. I am still concerned about longevity though, so a rebuild including liners would see most sensible. I wouldn't want to spend a load of money only to have the engine pop after a few miles.

 

Pete, I don't have enough posts to PM... Can you email me?

domwright9 at hotmail com

 

I currently has 43000 miles and we have found some small brown specs in the oil filter, thanks to the members who told us it was related to the rail guides. I also read that it's possible to detect a possible IMS fututre failure by using the durametric tool and read the camshaft position deviations between cam 1 and camshaft 2.

 

What model of 996 do you have?

The Durametric is a good tool to help pinpoint problems. Cam deviations is one of it's great features. You should also consider a bore scope to detect for bore scoring and manometer for cylinder vacuum problem and/or a failing AOS.