What makes the 40th ann 996 more powerful?

Is it tuning? Is it a bigger cam? More compression? Intake/exhaust? Are there parts available to give this extra hp to the rest of us?

https://rennlist.com/forums/996-foru...y-and-faq.html Scroll down to the FAQ section - it includes links to the X51 package (the stuff that makes it more powerful). From another X51 thread: The X51 kit is a engine upgrade to the standard M96 engine. It includes the cast aluminum GT3 intake manifold, larger headers, different cam shafts, modified cylinder heads, the third radiator and a re-programmed DME. The factory specs for the system are +25 hp and the 0-120mph time reduced by 1.0 seconds. I have driven both X51 and non-X51 back to back and find the X51 to have a more responsive throttle, noticably more power and no loss of low end torque. I woudl estimate it closer to +40 hp, but have not dyno'd my car yet. Retrofitting your car with X51 parts would probably be more trouble than an X51 swap into your car - but either way, you're going to spend a ton of money to get 40-50HP. This is one of those times when just selling the car and buying a more powerful 996 (or newer) probably makes more sense, at least financially.

good read http://www.911uk.com/viewtopic.php?t...er=asc&start=0

Marketing hype. A '99 with LSD will beat a 40AE around the track all day long.

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Your right foot and the extra BHP and LSD - help.

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If you compare power-weight ratio between a Mk.1 C2 and a C4S you need the 345hp of the X51 package to compensate the extra weight. And then still you have that extra weight...

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40th AE is not a C4S - it's a C2.

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Awwwwwww. Poor things have package envy...

mk1 C2s have, what, 50lbs on the mk2 C2? It certainly offsets some of the power difference but what else favors the mk1?

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I love the 40th AE by the way, for me it is the one to have if you are looking for a Mk.2; Too bad they did not stick the X51 as standard on the C4S, that would have been awsome. No envy here, in any way. I am totally happy with my car and wish all to be the same with their 911. Aircooled, watercooled, turbo, whatever. Enjoy is the key word!

You obviously haven't spent much time on a track.

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Nope, I haven't. But I don't need. Spending time on a track would not help me understand the emotion of your comment any better. Bringing up track capabilities has nothing to do with the OP's question. And, actually, driver ability has more to do with which car will do better on a track than does the difference in the engines. If you're going to comment, try adding value. So, perhaps inform the OP that there is some understanding that X51 engines may be down a few percentage points on low-end torque, but has more ooomph on the top end. He didn't mention track time, you did. So if you're going to bring up something off topic, at least make it meaningful, and somewhat relevant.

The more you talk the less it appears you know. The discussion was about performance and since a track is the only safe place to truly test the performance of a car I think it's quite relevant. I know a very good Rennlist racer that spent a large amount of money upgrading from a '99 to an '03 w/X51. He built the '03 out nearly identical to the '99 and after a year of testing and tweaking it was still a full second slower than the '99. So if you want to get the X51 for the marketing hype, have at it. I'm sure it will sound much cooler when you are telling your friends all about it.

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I'm sure you do know a guy... Anyway. Your "guy's" experience does not change the fact that driver ability hugely impacts their time around a track. Nice try, though. And, your comment about "your guy" assumes everything else about the cars were identical. We'll have to take your word for it again. But that doesn't change the reality of the situation. It's nice to add qualifiers on the back-end for a jackass comment on the front-end. Do better. Be better.

Your insults are as lame as your understanding of these cars. Try harder.

Back on topic. The answer is magic

I like unicorns too.

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An 03 isn't quite the same car as a 99... anyhow, in my 02 996 race car, I had a 3.6 "regular" engine for some time, then put in an x51 with no other changes to anything (same exhaust, weight, everything). As expected from 20+ hp, the car was faster with the x51 engine, especially on a big track like Cal Speedway.

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Well don't we all? Since we have to collect their semen to fill our magically fragile engines? I prefer the 5w40 unicorn semen..

Out of this list of x51 pack parts from Pistonheads quite a few aftermarket parts could be used to make up your own "x51" style "power kit" with bolt ons: Here is what is added/modified in the X51 kit: - new intake manifold with modified cross-section (material: sand cast aluminium ); - use an IPD plenum or even a IPD + GT3 throttle body - new intake pipe supports adapted to the form of the intake manifold; - out of luck with this one - need to stick with the standard - but the IPD would be an improvement - new exhaust manifolds with larger cross-section and optimized flow behaviour; - plenty of reputable exhaust manufacturers - new cylinder heads with optimized, CNC-milled inlet ducts; - nope - new camshafts with larger valve stroke on the inlet side and modified inlet and outlet timing; - nope - inlet valve springs adapted to the enlarged valve stroke; - nope - modified partition box in the oil pan; - genuine x51 pan or aftermarkets available - modified maps for the DME control module; - ECU tuning is available from various tuners (some better than other from what i've read) the PIWISII software does have a MAP for x51 but who knows what that would do - not recommended - new underside panel in the transmission area; - Would you need this? Guessing its because of the lowered suspension but genuine and aftermarket oil pan protectors are available - all cars (except C4S) get a third radiator - can be added with genuine or aftermarket parts So 6/10 options are available as bolt on options or get it rebuilt to a 3.8 or 4.0 if you intend to keep it.

Nice. Did you dyno them by chance? I'd be curious what the actual difference was. The '06 crate engine my race car with Fabspeed headers and no cats put down 20 more HP than the '99 Daily Driver I had with the original engine. I never determined if it was the mods or if the crate engine was just stronger due to design updates. And your right, the time gains from extra HP is very track dependent. I never put my 3.8 FSI in my '99 but at 2520# dry and a solid suspension, there isn't a production p-car that can keep up with it on small to medium tracks.

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Yes, I think it was mid 270's avg with the non x51, and almost 300 avg with x51. Different days, different dynes though, so who knows if there's any substance to that. (which is why I didn't bring it up initially).

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You forgot to include the very important shorter A/C tube that's necessary with an x51 manifold!

Looks to me like 5CHN3LL fully answered the OP's question right there in the first response. Also weighed in with a concise, informed and relevant observational opinion, which is appreciated. Now, we're just off somewhere else... All this entertainment for free!

Yes, thank you. I found a wrecked 40th ann that was being parted out. I am milling over the idea of buying the motor and transaxel as a spare for my track day car. I am aware that the 40th ann uses a limited slip diff. Is this a torsen type, or a clutch type? Alternately, it looks like I could refresh a "normal" set of heads and perhaps come up with cams/springs from the dealer. The list of aftermarket pieces was helpful.

Guards clutch type but with street grade material on the plates. Will not hold up to extended track use. But Guard can do a reasonably priced rebuild to make it track ready.

the engine and transmission would be great "battle spares" but yeah there are a lot of small things that get more difficult when you fit that intake manifold; like you can't fit a motorsports AOS for example. I can verify that the clutch-style LSD wears out very quickly; mine is totally open at this point. One of the nice things about X51 on track, beside the already mentioned oil pan baffles, is the dual oil scavenge pumps. The third radiator is not included on US models. I drove a 3.4 cabriolet and my 40th back-to-back at an autocross and was STUNNED how much weaker the 3.4 felt. The 3.4 works great in a lightweight '99 coupe though. The X51 is really only better at high RPMs and the usable mid-range torque is no better (if not worse) compared to the regular 3.6. Jake is usually pretty vocal about the power left on the table by the X51 package and how much better it could have been.

I could really feel the difference between a 3.4 vs a 3.6 when I was shopping for the car. I can't just imagine the difference with a x51....