Porsche 996 X51 - Page 2 - 911/Carrera GT - PistonHeads UK

Hi, Does anyone know much about the X51 996 3.4 and/or 3.6 I am very interested to learn more Thanks Simon

On the 997, X51 adds this massive carbon airbox. I will shamelessly admit it gives me a chubby. I will add a post from me elsewhere on this forum. Also look past it - if you can - to the Massive alloy inlet and plenum thingie. Without both you have just apple pie without the custard. So I believe the 3.4 X51 had the least mods. There was an early pre GT3 car which was basically a 3.4 X51. Then they must have decided to switch to the different engine in the GT3. I think - guess - the X51 option on the 3.4 wasn't generally available because I have never seen any for sale except the pre GT3 car which I think is still for sale, and looks expensive to Me. Then came the X51 3.6 996.2 but again it is a rare option. I only see this on the 50 anniversary 996. So I believe there are differences to the inlet, cams and the exhaust manifolds for performance or better power at higher revs. Also there were some extra mods to the oil coiling internally. I read somewhere that this extra oil cooling inside the engine prevented bore scouring but this was debunked elsewhere. @Dammit has done a lot of work and diggin to find ways to find extra horsepower from these engines. I think the best and most well known tuner is Jack Raby in the USA. On the 997 3.8 X51 Porsche took the mods to another level. It was around an 8000 quid option and added almost 30bhp I think so not to be sniffed at. I think it came with a higher rev limit also. So the bigger airbox clearly and chunkier alloy inlet plenum and pipes / manifolds to allow more airflow, Then I'd probably guess cams, maybe heads / valves and oil cooling stuff like the 996. Maybe even a centre rad too. Its the traditional approach to NA engine modifications. Higher revs, more cam duration, maybe also more cam lift and maybe bigger valves. Throw in these engines have variable valve tech and you can try to keep the gains at the high rev range from taking away at the lower end of the revs which you would typically see when you go down this road on any other engine. There is this X51 997.1 24 grand But its Cat S https://www.ebay.co.uk/itm/126384456651

I've got an X51 996.2 3.6 and found a good thread on the 911uk page which seems to detail out the differences. From what i gather mine has got different heads, exhaust cams/ springs, cast inlet manifold instead of plastic with some sort of balanced extended runners between that and the heads, baffled sump, secondary oil scavenge pump, GT3 triple radiator set up. It also got a vacuum amplifier (unsure exactly of the benefit!), which can be seen with the extra take off on the induction hose between the airbox and the throttle body, like a tiptronic car. The Gen 1 996 x51 had different pistons and also inlet cams too. As this X51 kit went through the generations they seem to drop off how involved the kit was i.e. 997 didnt get different cams at all (but did get that nice carbon airbox!) or the extra lubrication changes etc. The car goes very well and has a lot of other cool options on it like the LSD, M030 handling pack (i've replaced with other stuff now), lots of interior carbon, factory aero kit etc.

Thanks for the information chaps. The 997 x51 is a thing of beauty but its the 996 X51 that I am most interested in learning about. I wanted to find out about the differences between the 3.4 (Gen 1 996) and the 3.6 (Gen 2 996 ) cars including the 40th anniversary (Gen 2 996) that I think had the 3.6 X51 engine but did not have the dual scavenge pump on the drivers side (UK rhd).

I thought the dual scavenge pump came with all X51 996.2?

Mike Oxlong said: Thanks for the information chaps. The 997 x51 is a thing of beauty but its the 996 X51 that I am most interested in learning about. I wanted to find out about the differences between the 3.4 (Gen 1 996) and the 3.6 (Gen 2 996 ) cars including the 40th anniversary (Gen 2 996) that I think had the 3.6 X51 engine but did not have the dual scavenge pump on the drivers side (UK rhd). The 40th anni cars didnt get the GT3 triple radiator set up with their standard fit X51 pack. Unsure on the dual scavenge pump but that is interesting, i've never had a proper look for it (mine isnt a 40th anni car) but you might be right in that gen 2's didnt get them, i'll try remember to take a look next time its up in the air!

https://www.autotrader.co.uk/car-details/202402297...

Oh.... now you find a 996 on Autotrader....

https://www.40jahre911.com/the-story-of-the-40-jah... details under...The Engine section re X51 and yes includes baffled sump and extra pump.

The X51 on the 3.4 is amongst the most comprehensive powerkit

Filibuster said: The X51 on the 3.4 is amongst the most comprehensive powerkit This what I had thought. I also think that the USA 40th anniversary MAY not have the extra scavenge pump/"tea towel" rail

Mike Oxlong said: Filibuster said: The X51 on the 3.4 is amongst the most comprehensive powerkit This what I had thought. Or 3.4 is the most s t of all when standard.

Filibuster said: The X51 on the 3.4 is amongst the most comprehensive powerkit Very interesting ... I wonder why the X51 was never offered as an evolution on the 981 GT4 ?? Instead it was used in the 718 GT4 Clubsport rather than the then new 4.0l for racing ...

ChrisW. said: Very interesting ... I wonder why the X51 was never offered as an evolution on the 981 GT4 ?? Instead it was used in the 718 GT4 Clubsport rather than the then new 4.0l for racing ... Not sure I understand the relevance of this or am I a bit thick ?

It's relevant to the great information provided in reply to your question on the various X51 specifications vs. I then compared this to the 4.0l and wondered why P didn't use the X51 version of the 981 engine in the 718. I agree it's irrelevant to your original question ... do you wish to bring this back on topic ?

ChrisW. said: Very interesting ... I wonder why the X51 was never offered as an evolution on the 981 GT4 ?? Instead it was used in the 718 GT4 Clubsport rather than the then new 4.0l for racing ... Perhaps cost (and gearbox integrity) Chris ? For all it's undoubted benefits, the X51 conversions are very much of the "Need to wring its neck to feel the full benefit" nature.

ATM said: On the 997, X51 adds this massive carbon airbox. I will shamelessly admit it gives me a chubby. Too much information. ATM said: I will add a post from me elsewhere on this forum. Also look past it - if you can - to the Massive alloy inlet and plenum thingie. Without both you have just apple pie without the custard. Apple pie without custard is fine, as long as there's lashings of double cream on it. ATM said: So I believe the 3.4 X51 had the least mods. Not so much, there's no doubt the power output of standard 3.4 engine was well optimised during its development, but Porsche was then being run by the beancounters rather than engineers, so any extra power was going to be hard won. The X51 was an attempt to build an engine for the upcoming Mk1 996 GT3 on the cheap, primarily as an answer to the naysayers who said Porsche had stopped making "proper sportscars" with the introduction of the watercooled 996. ATM said: There was an early pre GT3 car which was basically a 3.4 X51. Then they must have decided to switch to the different engine in the GT3. I think - guess - the X51 option on the 3.4 wasn't generally available because I have never seen any for sale except the pre GT3 car which I think is still for sale, and looks expensive to Me. The X51 3.4 M96 engine was generally available, but it was a ludicrously expensive (£8k) option for the 20hp gain it provided. There have been 996.1 X51 engined cars owned by contributors to both 911UK and Rennlist forums IIRC. 30 X51 engined 996.1 prototypes were built as I understand it. “The first GT3 was revealed in 1999, once again a limited run to qualify the race credentials of the latest 911, the 996. However, the GT3 was significantly different from its RS forebears : It was not lightened, though its chassis underwent considerable modification, and for the first time, it did not use the 911 production engine. Porsche knew that the new fluid cooled M96 engine of the 996 which effectively had a wet sump (although its marketing people talked (BS) about an ‘integrated dry sump’) would experience oil starvation at lateral cornering forces exceeding 0.7g. This would convey entirely the wrong image of Porsche said then engineering director Horst Marchart who commissioned engine builder Herbert Ampferer to create a suitable race engine. Rather than try to reinvent the wheel, Ampferer saw the GT3 engine as an extension of the competition motor that Porsche was developing for GT1. He took the aluminium block of the 964/993 and grafted a water cooled 24-valve head on to it, the capacity increased from the GT1’s 3.2 to 3.6 litres. This would be an expensive unit to build, but by making it the basis of the yet to be introduced 996 Turbo, its costs could be amortised over thousands rather than hundreds of units. Often referred to as the ‘Mezger’ engine, the name is something of a misnomer as although the bottom end dated from that era, indeed some blocks even had ‘964/993’ stamped on them, Hans Mezger who retired in 1993 had nothing to do with this engine. Indeed in his memoirs he observes that if Porsche had heeded his advice, Zuffenhausen would never have designed the M96 the way it did and thereby avoided the need to design a separate engine”. Ouch !! ATM said: Then came the X51 3.6 996.2 but again it is a rare option. I only see this on the 50 anniversary 996. So I believe there are differences to the inlet, cams and the exhaust manifolds for performance or better power at higher revs. Also there were some extra mods to the oil coiling internally. I read somewhere that this extra oil cooling inside the engine prevented bore scoring but this was debunked elsewhere. 40th Anniversary. The bores and pistons were the same as all the other M96.2 engines, so the same issues afflicted them. Scottos on here has a 996.2 with the 3.6 X51 powerkit : https://www.pistonheads.com/gassing/topic.asp?h=0&... ATM said: @Dammit has done a lot of work and diggin to find ways to find extra horsepower from these engines. I think the best and most well known tuner is Jack Raby in the USA. Jake : https://flat6innovations.com/ Hartech and their development partner are in the process of developing both the M96 and M97 engines to produce higher power outputs ATM said: On the 997 3.8 X51 Porsche took the mods to another level. It was around an 8000 quid option and added almost 30bhp I think so not to be sniffed at. I think it came with a higher rev limit also. So the bigger airbox clearly and chunkier alloy inlet plenum and pipes / manifolds to allow more airflow, Then I'd probably guess cams, maybe heads / valves and oil cooling stuff like the 996. Maybe even a centre rad too. The 996.1 X51 kit was £8k back in 2000. No upgraded cams on the 3.8 997.1 X51 kit as I understand it. The kit produced 381hp, so a 26hp increase over the stock 3.8 S engine, as opposed to the 25hp increase the 996.2 X51 powerkit provided, and the 20hp increase the 996.1 X51 powerkit provided. Meanwhile the 997.2 managed a 23hp increase. I drove an X51 equipped 997.1 a few years ago, it didn't feel anything like as torquey as the stock 3.8S engine low down, nor in the mid-range, and it didn't have the top end verve of any Mezger. It seemed a pretty pointless exercise to me.

Slippydiff said: ChrisW. said: Very interesting ... I wonder why the X51 was never offered as an evolution on the 981 GT4 ?? Instead it was used in the 718 GT4 Clubsport rather than the then new 4.0l for racing ... Perhaps cost (and gearbox integrity) Chris ? For all it's undoubted benefits, the X51 conversions are very much of the "Need to wring its neck to feel the full benefit" nature. I thought the GT4 RS has some crazy induction system. So perhaps getting enough air in due to the shape of the car is a problem. Also cooling the mid engine layout is problematic. Rear engine 911 type config gets a lot of air flow from under the car and this helps cooling. In mid engine config the engine is tight up against a solid bullhead behind the driver. This doesn't get any air flow. This is why higher BHP modified Caymans from the 987 era always struggle to keep their cool.

ChrisW. said: It's relevant to the great information provided in reply to your question on the various X51 specifications vs. I then compared this to the 4.0l and wondered why P didn't use the X51 version of the 981 engine in the 718. I agree it's irrelevant to your original question ... do you wish to bring this back on topic ? Ok Chris. I understand now. so it's the X51 nomenclature not being used on 981 and 982 Porsches you find strange. Probably "Marketing" didn't deem it relevant enough

Thanks Or it's the gearbox / cooling / cost / ... or the fact that P wanted something new that could be used for the last of the fossil fuelled cars other than the GT's / real Turbos ... And using the standard non-"turbo" .. turbo block bored out to 4 litres and naturally aspirated was an inexpensive way of achieving this ? And the 718GT4 and Spyder clearly did not fall into the GT's / real Turbos category ..... 'says it all really. For me this has turned into a really interesting thread, thankyou !!

Beats the "what colour stitching should I spec" threads we see now

ATM said: I thought the GT4 RS has some crazy induction system. So perhaps getting enough air in due to the shape of the car is a problem. Also cooling the mid engine layout is problematic. Rear engine 911 type config gets a lot of air flow from under the car and this helps cooling. In mid engine config the engine is tight up against a solid bullhead behind the driver. This doesn't get any air flow. This is why higher BHP modified Caymans from the 987 era always struggle to keep their cool. I think you'll find the 911's bulkhead is fairly solid and that it too is located "right in front of the engine" and worse still, the 911 engine has a hot gearbox and clutch in front of it. 10 years old, horsepower figure is overstated to the tune of probably 20hp, but with additional centre radiator, there's no issue keeping a 987 Cayman or Boxster sufficiently cool for it to remain reliable : https://www.motortrend.com/features/1411-2009-pors... I considered doing the same conversion to my Cayman R, but came to the conclusion it didn't really need an additional 90-100hp ...

Mike, I've had a look at my car tonight and don't believe the 996.2 has the dual scavenge pump, there's no rail on the right hand side, running along the head like the pictures and diagrams I've seen would suggest.

scottos said: Mike, I've had a look at my car tonight and don't believe the 996.2 has the dual scavenge pump, there's no rail on the right hand side, running along the head like the pictures and diagrams I've seen would suggest. Thanks Scott. I read on an American forum that it was suggested the 40 year Anniversary in the USA wasn't fitted with the dual scavenge pump may be it wasn't fitted to any World wide/ Anyone else got a 996 X51 engined car either 3.4 or 3.6 to check /confirm. I appreciate I am sad but find all this really interesting Just thinking about this ...The Dual Scavenge pump in question 996.107.980.00 was fitted to the Gen 1 3.4 886 X51. It was then remanufactured by one of the French pump manufacturers as 996.107.980.01 and it is reported that the pump was designed to run the wrong way so blew instead of sucked. Interestingly the original pump was designed by Concentric pumps in the UK and manufactured in the UK too. So maybe no Gen 2 996 were fitted with these pumps Edited by Mike Oxlong on Sunday 14th April 11:34 Edited by Mike Oxlong on Sunday 14th April 11:35

Mike Oxlong said: Thanks Scott. I read on an American forum that it was suggested the 40 year Anniversary in the USA wasn't fitted with the dual scavenge pump may be it wasn't fitted to any World wide/ Anyone else got a 996 X51 engined car either 3.4 or 3.6 to check /confirm. I appreciate I am sad but find all this really interesting Just thinking about this ...The Dual Scavenge pump in question 996.107.980.00 was fitted to the Gen 1 3.4 886 X51. It was then remanufactured by one of the French pump manufacturers as 996.107.980.01 and it is reported that the pump was designed to run the wrong way so blew instead of sucked. Interestingly the original pump was designed by Concentric pumps in the UK and manufactured in the UK too. So maybe no Gen 2 996 were fitted with these pumps Edited by Mike Oxlong on Sunday 14th April 11:34 Edited by Mike Oxlong on Sunday 14th April 11:35 I have a 2000 996 3.4 x51 which has the scavenge pump