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ELA
Suzuka


Joined: 30 Aug 2011
Posts: 1238
Location: Nurburgring Doorstep


PostPosted: Fri Sep 08, 2017 5:54 am    Post subject: Reply with quote

Sounds an absolute weapon that H, many thanks for taking the time to post all the gory details here.
I wonder why a remote filter was fitted, it's not as though the stock position is difficult to reach.
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Marky911
Suzuka


Joined: 04 Jun 2009
Posts: 1229



PostPosted: Fri Sep 08, 2017 8:04 am    Post subject: Reply with quote

As already said what an absolute beast. Gorgeous car.

I maybe be wrong but does the oil filter need to be relocated due to that airbox?

Stunning car. I miss my old one sooo much. nooo
 
  
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Roro
Long Beach


Joined: 01 Oct 2010
Posts: 6141



PostPosted: Sun Sep 24, 2017 6:21 am    Post subject: Reply with quote

Super read, nicely written and what a fantastic beast. Looking forward to the next instalment Thumb
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Dammit
Suzuka


Joined: 23 Sep 2016
Posts: 1125



PostPosted: Thu Jan 18, 2018 11:37 am    Post subject: Reply with quote

Could someone please tell me who built this car?
 
  
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NXI20
Paul Ricard


Joined: 02 Feb 2008
Posts: 3277
Location: South Bucks

2004 Porsche 996 GT3 Mk2

PostPosted: Thu Jan 18, 2018 11:40 am    Post subject: Reply with quote

Richard Chamberlain at

https://www.ctrdevelopments.com/
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Nick

2004 GT3 CS in Atlas Grey with too many mods to list!
1995 993 GT2 recreation in Polar Silver
2010 GT3 CS in Riviera Blue Smile
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Dammit
Suzuka


Joined: 23 Sep 2016
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PostPosted: Thu Jan 18, 2018 12:43 pm    Post subject: Reply with quote

Thanks!
 
  
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JarmoL
Newbie


Joined: 16 Oct 2011
Posts: 25



PostPosted: Sun Jan 21, 2018 7:18 pm    Post subject: Reply with quote

That is some fantastic build. I'd love to have engine like that in my car. Thumb

I wonder about longevity of these big displacement builds though. Can it ever be equal to stockish 3.6? Dont know

Any idea how many miles now on this particular build?
 
  
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NXI20
Paul Ricard


Joined: 02 Feb 2008
Posts: 3277
Location: South Bucks

2004 Porsche 996 GT3 Mk2

PostPosted: Sun Jan 21, 2018 7:26 pm    Post subject: Reply with quote

It’s got 4500 miles on it now. Just been taken out to have the valve clearances checked. Leakdown test results are decent so it’s going back in to be thrashed a bit more Wink
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2004 GT3 CS in Atlas Grey with too many mods to list!
1995 993 GT2 recreation in Polar Silver
2010 GT3 CS in Riviera Blue Smile
1978 Carrera SC Barn Find in Red (restoration project)
 
  
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DynoMike
Barcelona


Joined: 25 May 2012
Posts: 1345
Location: The Cotswolds

2003 Porsche 996 Turbo

PostPosted: Sun Jan 21, 2018 7:48 pm    Post subject: Reply with quote

NXI20 wrote:
It’s got 4500 miles on it now. Just been taken out to have the valve clearances checked. Leakdown test results are decent so it’s going back in to be thrashed a bit more Wink


So they have gone the mechanical cam route and ditched the hydraulics then, no wonder it goes so well.
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NXI20
Paul Ricard


Joined: 02 Feb 2008
Posts: 3277
Location: South Bucks

2004 Porsche 996 GT3 Mk2

PostPosted: Sun Jan 21, 2018 7:50 pm    Post subject: Reply with quote

Never going to rev to 9000 RPM on hydraulic lifters but I’m not convinced it’s worth the hassle of having to gap check the thing every 4500 miles.
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Nick

2004 GT3 CS in Atlas Grey with too many mods to list!
1995 993 GT2 recreation in Polar Silver
2010 GT3 CS in Riviera Blue Smile
1978 Carrera SC Barn Find in Red (restoration project)
 
  
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DynoMike
Barcelona


Joined: 25 May 2012
Posts: 1345
Location: The Cotswolds

2003 Porsche 996 Turbo

PostPosted: Sun Jan 21, 2018 8:15 pm    Post subject: Reply with quote

The motor should go well past that mileage before needing adjustment, Nick, some of the bikes are checked at 30000 miles, despite revving to 14000+ rpm. 4500 seems to be needlessly early, assuming that on the road, a motor can never be used as hard as on track.
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NXI20
Paul Ricard


Joined: 02 Feb 2008
Posts: 3277
Location: South Bucks

2004 Porsche 996 GT3 Mk2

PostPosted: Mon Jan 22, 2018 7:03 am    Post subject: Reply with quote

I believe that's what the engine builder recommended - probably erring on the side of caution (not a bad thing given what could happen if they do go out of spec!). Of course, the GT3 valves / springs are considerably heavier than the ones in a bike so I'd guess that's also a factor. Even on the standard engine, the springs are very close to being coil-bound on full lift.
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2004 GT3 CS in Atlas Grey with too many mods to list!
1995 993 GT2 recreation in Polar Silver
2010 GT3 CS in Riviera Blue Smile
1978 Carrera SC Barn Find in Red (restoration project)
 
  
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Cheburator
Trainee


Joined: 15 Aug 2014
Posts: 90



PostPosted: Wed Jan 24, 2018 11:52 am    Post subject: Reply with quote

NXI20 wrote:
I believe that's what the engine builder recommended - probably erring on the side of caution (not a bad thing given what could happen if they do go out of spec!). Of course, the GT3 valves / springs are considerably heavier than the ones in a bike so I'd guess that's also a factor. Even on the standard engine, the springs are very close to being coil-bound on full lift.


Next time I race with Richard I would ask about that. Sounds wrong - the S54B32 as found in the BMW M3 of 15yrs ago has a tappet adjustment interval of 30k miles on the Street cars. In stock form it revs to 8000rpm, while in race trim it revs to 9000rpm...
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Slippydiff
Monza


Joined: 22 Nov 2007
Posts: 156



PostPosted: Wed Jan 24, 2018 6:23 pm    Post subject: Reply with quote

Cheburator wrote:
NXI20 wrote:
I believe that's what the engine builder recommended - probably erring on the side of caution (not a bad thing given what could happen if they do go out of spec!). Of course, the GT3 valves / springs are considerably heavier than the ones in a bike so I'd guess that's also a factor. Even on the standard engine, the springs are very close to being coil-bound on full lift.


Next time I race with Richard I would ask about that. Sounds wrong - the S54B32 as found in the BMW M3 of 15yrs ago has a tappet adjustment interval of 30k miles on the Street cars. In stock form it revs to 8000rpm, while in race trim it revs to 9000rpm...


I believe Richard was being cautious in this recommendation. That the clearances needed adjusting wasn’t cast in stone, but merely his recommendation to keep an eye on things such as maximum revs used, cylinder leakage, and the valve clearances.
But another Porsche indy who’s run 996 GT3 R race cars (and yes it is relevant in this instance) was also adamant the clearances on this engine should be checked and adjusted if necessary.
Bearing in mind the build cost, the above suggestions sound pragmatic.
As for your example of the BMW M3 engine, I think the specific output/maximum rpm of an engine has little to do with it’s valvetrain durability and longevity.
I’m sure Mike will confirm that valve train wear has far more to do with cam lift and duration, with as Nick has said the weight of the components within the valve train, those being the valves, retaining collars and rockers etc also being a major factor.
(but the above are only my thoughts, and thus they’re not gospel...) Smile
 
  
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DynoMike
Barcelona


Joined: 25 May 2012
Posts: 1345
Location: The Cotswolds

2003 Porsche 996 Turbo

PostPosted: Wed Jan 24, 2018 8:37 pm    Post subject: Reply with quote

Slippydiff wrote:
Cheburator wrote:
NXI20 wrote:
I believe that's what the engine builder recommended - probably erring on the side of caution (not a bad thing given what could happen if they do go out of spec!). Of course, the GT3 valves / springs are considerably heavier than the ones in a bike so I'd guess that's also a factor. Even on the standard engine, the springs are very close to being coil-bound on full lift.


Next time I race with Richard I would ask about that. Sounds wrong - the S54B32 as found in the BMW M3 of 15yrs ago has a tappet adjustment interval of 30k miles on the Street cars. In stock form it revs to 8000rpm, while in race trim it revs to 9000rpm...


I believe Richard was being cautious in this recommendation. That the clearances needed adjusting wasn’t cast in stone, but merely his recommendation to keep an eye on things such as maximum revs used, cylinder leakage, and the valve clearances.
But another Porsche indy who’s run 996 GT3 R race cars (and yes it is relevant in this instance) was also adamant the clearances on this engine should be checked and adjusted if necessary.
Bearing in mind the build cost, the above suggestions sound pragmatic.
As for your example of the BMW M3 engine, I think the specific output/maximum rpm of an engine has little to do with it’s valvetrain durability and longevity.
I’m sure Mike will confirm that valve train wear has far more to do with cam lift and duration, with as Nick has said the weight of the components within the valve train, those being the valves, retaining collars and rockers etc also being a major factor.
(but the above are only my thoughts, and thus they’re not gospel...) Smile


Hi Slippy. There are many factors which need to be borne in mind here, principally the design of the ramps at either end of the cam flanks. These serve the purpose of preparing the valve for lift by decreasing the tappet clearance just prior to the actual lift profile becoming active.

Of more interest is the closing flank of the lobe and its attendant 'closing ramp', which dictates the velocity at which the valve is re-seated. If this engine runs titanium valves and beryllium-copper valve seats (possible?), they need to have a bespoke closing ramp to avoid pounding the seats out. A well designed ramp will gently seat the valve, without adding excess duration to the profile. As an analogy, it is akin to feathering the brakes just before a dead stop is reached after some hard braking, thus avoiding the dreaded kick-back due to an instantaneous velocity change.

If the engine still runs steel valves and standard seats, the mileage at which they should be checked depends largely on the duty cycle of the engine (the amount of time it spends at WOT, basically), which on a road engine is in single figure percentages. A cup car will likely experience a 45% duty cycle, so typically 8-9 times the road car's. This was why I suggested it should run longer than 100 hours between checks, but Richard was probably wanting to get them checked in order to get a feel for the valve train when running under road conditions, rather than race conditions.

The mass of the components should always be factored into the profile design, along with a properly designed valve spring. When properly matched, the inspection intervals should be relatively light.

One odd phenomenon can take place with engines that see sporadic use; the clearances can increase due to carbon lifting off the backs of the valve heads , (as a result of moisture being present in the atmosphere), which then drops onto the valve seats, increasing the tappet clearance. Generally, clearances tend to close up rather than increase, but this is one exception to that 'rule'.

I would imagine that if Richard finds that there is no change at a all in the clearances, along with minimal cylinder leakage, he will be happy for the motor to go for a longer period before inspecting them again. I get where he is coming from, I built a hillclimb motor in 2010, which due to the short run times, I had no idea of the point at which it needed checking. Fast forward to 2017, the motor came in for a freshen up, all the valve clearances were as the day it left the workshop, despite having its neck wrung at 9300 rpm for the last 5 years at least. That engine should now run happily for the next 7 seasons or so, but the valve train was a total unknown when it was built, in terms of longevity.
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Cheburator
Trainee


Joined: 15 Aug 2014
Posts: 90



PostPosted: Thu Jan 25, 2018 4:08 pm    Post subject: Reply with quote

Slippydiff wrote:


As for your example of the BMW M3 engine, I think the specific output/maximum rpm of an engine has little to do with it’s valvetrain durability and longevity.
(but the above are only my thoughts, and thus they’re not gospel...) Smile


The reason I used the M3 is that physically the dimensions of the valve train components are very similar to the ones found in the GT3. It is simple physics after all. The only major difference is that the M3 uses rockers while the Mezger doesn't. As to what causes valve train wear/problems - well aware of the causes/problems, given that I tend to build my own historic watercooled race engines with somewhat modified valve trains Mr. Green
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Geo
Newbie


Joined: 29 Oct 2012
Posts: 5



PostPosted: Fri Feb 16, 2018 9:08 am    Post subject: Reply with quote

What a machine! Quality engineering and good taste in spades!

Thanks SlippyDiff for the write up, I really enjoyed reading it!

Interested what sort of spring rates these JRZ's run with.... Very Happy
 
  
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NXI20
Paul Ricard


Joined: 02 Feb 2008
Posts: 3277
Location: South Bucks

2004 Porsche 996 GT3 Mk2

PostPosted: Fri Feb 16, 2018 9:24 am    Post subject: Reply with quote

Proprietary info Hand
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Nick

2004 GT3 CS in Atlas Grey with too many mods to list!
1995 993 GT2 recreation in Polar Silver
2010 GT3 CS in Riviera Blue Smile
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