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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Wed Jun 28, 2017 10:30 pm    Post subject: Reply with quote

Off-topic: one of my ex-girlfriends had a father who ran a couple of LMP style cars in partnership with a race-transmission specialist, they initially used the 3 litre Ford V6 but it kept throwing important parts of itself in improbable and inconvenient directions so they managed to argue that as the Metro 6R4 was a production car (albeit in rather small numbers) then the 6R4 engine counted as a production engine, so they could switch to that.

I had a few passenger laps in the car at Combe, it was astonishingly fast.

In terms of my engine, I suspect I am slightly under-resourced in terms of being able to support the test/fettle/test/fettle, iterative development model required to get ultimate performance from the M96.

Is this a situation in which a degree of educated guesswork can be deployed, with regards to cam profile, or is that lunacy to suggest?
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Wed Jun 28, 2017 11:08 pm    Post subject: Reply with quote

https://www.fvd.net/us-en/100105290/996-sport-camshafts-34l-4pc-set.html

Description

Inlet Cams:
Cam lift (Valve Lift) I/E (mm) = 10.7 mm
Duration°/Peak Timing = 280°/127-102°
Valve Timing °CRA (IO-IC-EO-EC) = 13-87 38-62
Valve Lift at TDC I/E (mm) = 0.4-3.2mm

Outlet Cams:
Cam lift (Valve Lift) I/E (mm) = 10.7 mm
Duration°/Peak Timing = 272°/113°
Valve Timing °CRA (IO-IC-EO-EC) = 69-23
Valve Lift at TDC I/E (mm) = 1.5mm

More reading around the 'web seems to suggest that the FVD cams will be from Schrick, going to the Schrick website the latest catalogue available is for 2014, but then the car is from 1998 so that should not present a problem (as long as they still make everything).



And the figures certainly marry up for the first two camshafts.

Last edited by Dammit on Thu Jun 29, 2017 8:56 am; edited 2 times in total
 
  
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DynoMike
Barcelona


Joined: 25 May 2012
Posts: 1252
Location: The Cotswolds

2003 Porsche 996 Turbo

PostPosted: Thu Jun 29, 2017 8:43 am    Post subject: Reply with quote

poppopbangbang wrote:


I've just finished mapping a 3.8L HB F1 motor which is a 300CC increase on the standard motor achieved in a similar way to 3.7L conversions on the M96 engine. Peak power on this motor moved down by 700RPM over a good standard motor (peak at 11.9K vs 12.6K) but it made more power everywhere than any other HB before it and comfortably exceeded the best 3.5L motors peak figures by a long way.



Now that's a proper engine! HB is a beautiful motor, getting it to 3.8 will only make it better. You did well to only drop peak power speed by 700 rpm, good work ppbb. The area under the torque curve must be immense, is it for hillclimb use or still circuit race? How much meat was left between the cylinders and were they plated?

You certainly get to work on some interesting projects Wink
_________________
2003 996 Turbo
Previous toy 1974 Mini 1000
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 450



PostPosted: Thu Jun 29, 2017 10:18 am    Post subject: Reply with quote

DynoMike wrote:
poppopbangbang wrote:


I've just finished mapping a 3.8L HB F1 motor which is a 300CC increase on the standard motor achieved in a similar way to 3.7L conversions on the M96 engine. Peak power on this motor moved down by 700RPM over a good standard motor (peak at 11.9K vs 12.6K) but it made more power everywhere than any other HB before it and comfortably exceeded the best 3.5L motors peak figures by a long way.



Now that's a proper engine! HB is a beautiful motor, getting it to 3.8 will only make it better. You did well to only drop peak power speed by 700 rpm, good work ppbb. The area under the torque curve must be immense, is it for hillclimb use or still circuit race? How much meat was left between the cylinders and were they plated?

You certainly get to work on some interesting projects Wink


It had been converted to stand off injectors (similar to an EC) running with 10bar fuel pressure so I think this helped it hang in a little longer than it would have on standard under slide injectors, it became VERY sensitive to injection timing at higher RPMs as you would expect.

It's for circuit racing so it will be very interesting to see how it does but the power it's making coupled with how light the chassis of the car it's going into is should mean it can hold it's own against some much more modern stuff!
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Wed Jul 05, 2017 9:01 am    Post subject: Reply with quote

Cats: my car is the 1998 which I believe means I have a pre-cat Lambda on each bank, what does this mean with regards to choosing between 100 cell (which I have on the Volvo, and passes emissions there) and the 200 cell (which Cargraphic states is "OBD2 compliant", intimating that the 100 cell (motorsport) cats are not) option?"

i.e. if I get the 100 cell X pipe:



Will I have a CEL on the dash and an inability to pass MOT's?
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Wed Jul 05, 2017 4:11 pm    Post subject: Reply with quote

Answering my own question the cat on the Volvo is actually a 200 cell unit (my memory is failing as I age, clearly!) so that's what I'll get for the 996.
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 450



PostPosted: Fri Jul 07, 2017 12:28 pm    Post subject: Reply with quote

If it's anything like my 99 you can bin the Cats completely and it won't show a CEL. Single lambda per bank engines won't as they only have pre-cat Lambdas, not post cat for efficency monitoring so the engine controller has no idea as to if the cats are there, working or missing.

Personally I'd decat it and just put the originals back on for MOT each year if required.
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Fri Jul 07, 2017 1:06 pm    Post subject: Reply with quote

'98, so I presume exactly the same as yours.
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 450



PostPosted: Fri Jul 07, 2017 11:29 pm    Post subject: Reply with quote

Dammit wrote:
'98, so I presume exactly the same as yours.


Is yours cable or DBW? Mine is DBW but with regards cats it will be the same if it is only single lambda per bank the engine controller has no way of knowing what the cat efficiency is!

Having said that mind didn't even show the CEL when it had no Lambdas at all so pre OBD2 it appears to be a total free for all Grin
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Sat Jul 08, 2017 3:37 am    Post subject: Reply with quote

Ah- yes, mine is cable throttle.
 
  
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ELA
Suzuka


Joined: 30 Aug 2011
Posts: 1075
Location: Nurburgring Doorstep


PostPosted: Sat Jul 08, 2017 7:34 am    Post subject: Reply with quote

Dammit wrote:
Cats: my car is the 1998 which I believe means I have a pre-cat Lambda on each bank, what does this mean with regards to choosing between 100 cell (which I have on the Volvo, and passes emissions there) and the 200 cell (which Cargraphic states is "OBD2 compliant", intimating that the 100 cell (motorsport) cats are not) option?"

i.e. if I get the 100 cell X pipe:



Will I have a CEL on the dash and an inability to pass MOT's?


Hi Dammit, I have the exact same set-up as your good self (early 3.4, same lambda config...). Having spoke to many exhaust designers and engine specialists, my opinion is around 150cell cats would be the optimum. Now as cats are standardised, you'll know you can only buy 400, 200, 100.
The 100cell cats can throw an Eng light. This could be simply avoided by fitting spacers so that effectively the lambda is tricked. The back pressure for optimum performance, is as already mentioned around 150cell. So I went with 200. Your choice at the end of the day, but the difference between them in performance terms, will be pretty much negligible.

Great thread and good to know we have so many knowledgeable contributors here. I never realised Mike was a dab hand in this area Wink
_________________
1275kg 997GT3RS with:
Kessels 458bhp 3.8l & vgs-MS ECU
Akrapovic titanium exhaust
Cup 9:35 diff, Airbox, PAS, front lip
BBS 19's
H&R Suspension
Carbon wings/doors/bonnet/door cards
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Sat Jul 15, 2017 4:38 pm    Post subject: Reply with quote

The subject of the exhaust is still on my mind.

The X51 manifold is said to have larger ports to match the X51 head - however I suspect that a bit of gasket matching on any manifold will open the ports to the correct size.

PPBB has recently posted on Facebook about the Chinese (Direnza) manifolds which he's happy to run, they're "homages" to the FVD ones, and they're a very attractive price. PPBB uses his as a sacrificial skid plate, so low cost/high utility is key, therefore I'm wondering if his priorities and mine may not align - basically, does quality scale in a linear fashion with cost, and should I therefore get the Cargraphic long tube headers rather than the Direnza manifolds?

I've already got the Cargraphic sports exhaust so will leave that but the cat-section needs to be looked at. Topgear appear to have a 200 cell X-pipe alternative to the Cargraphic 200 cell x-pipe, has anyone fitted one/either of these and can comment?
 
  
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poppopbangbang
Nürburgring


Joined: 25 May 2015
Posts: 450



PostPosted: Sat Jul 15, 2017 11:52 pm    Post subject: Reply with quote

Dammit wrote:


PPBB has recently posted on Facebook about the Chinese (Direnza) manifolds which he's happy to run,


Posted from the Pitlane Hand As soon as I'm back after this weekend I'll reply properly - I've got your PM too by the way Smile
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Mon Jul 17, 2017 1:46 pm    Post subject: Reply with quote

Great, thanks- hope you are having a good time.

In other news- throttle bodies: an I correct in thinking that the 996.1 GT3 has a cable operated throttle? If so, is there enough similarity between that throttle/plenum and the M96 versions for me to use the 82mm GT3 in place of mine?
 
  
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thecarfixer
Trainee


Joined: 03 Nov 2016
Posts: 73



PostPosted: Mon Jul 17, 2017 10:14 pm    Post subject: Reply with quote

Dammit wrote:
Great, thanks- hope you are having a good time.

In other news- throttle bodies: an I correct in thinking that the 996.1 GT3 has a cable operated throttle? If so, is there enough similarity between that throttle/plenum and the M96 versions for me to use the 82mm GT3 in place of mine?


No, eGas.
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Sun Jul 23, 2017 1:41 pm    Post subject: Reply with quote

Maybe some regional differences? Mr Streather states that the 996.1 has a cable throttle:
 



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thecarfixer
Trainee


Joined: 03 Nov 2016
Posts: 73



PostPosted: Mon Jul 24, 2017 8:08 am    Post subject: Reply with quote

Dammit wrote:
Maybe some regional differences? Mr Streather states that the 996.1 has a cable throttle:


Doing some research, yeah it does. Good luck finding one though, and it appears to be in unit with the plenum when investigating parts lists and photographs, so wouldn't actually fit.
 
  
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Dammit
Spa-Francorchamps


Joined: 23 Sep 2016
Posts: 366



PostPosted: Mon Jul 24, 2017 9:47 am    Post subject: Reply with quote

That's a *****. What other options exist, short of the Jenvey ITB kit and all the hassle that that would entail?
 
  
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