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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 6919
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Thu Mar 09, 2017 11:57 pm    Post subject: Reply with quote

Coming together now. thumbsup
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Wav
Silverstone


Joined: 30 Apr 2015
Posts: 133
Location: Herts


PostPosted: Sun Mar 26, 2017 9:03 am    Post subject: Reply with quote

Awesome work Harv, really liking this thread. An overall cost breakdown of the parts, machining and balancing would be great... if you don't mind sharing of course. This is something I plan to do in the future, hopefully not too soon though.

Keep up the excellent work,

Paul
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Harv
Suzuka


Joined: 18 Sep 2014
Posts: 1001



PostPosted: Thu Jun 15, 2017 1:41 am    Post subject: Reply with quote

Managed to get some more done on the build and into the real fun of assembly now.

Sorry for late response Wav, I've not done a cost breakdown as yet but suffice to say I'm doing this on a tight but reasonable budget not including my time I will try and get some figures added at the end. I suspect about 4k as I have been lucky with some bits and bought others a vastly reduced cost with the luxury of time as spares came up for sale and suppliers put up discount codes and offers.

Thanks to Dyno Mike for loan of the piston ring end gap tool and happy to say all ring end gaps are really exact, measurements taken at same depth in each bore Thumb

Lots more washing and cleaning of parts, gapped ring set kept with bores 1 thru 6 respectively and fitted to pistons.

Rods fitted to pistons 1 thru 3, gudgeon pins and clips fitted, rotated to same position and triple checked, assembly's inserted into cylinders for lefthand case, pay attention to which way up rods run and markings on piston crowns point towards flywheel.



Crank carrier built up with rods for cylinders 4 thru 6, new ims timing chain, guide, new tensioner arm, oil baffle housing, gaskets, cam chains. Check everything multiple times



Another new ims bearing fitted, had about 5k on old new one but think I nicked it's somehow on removal for cleaning as no longer felt buttery smooth, peace of mind for £8




Carrier lowered into lefthand case half checking it's seated properly, fit new bearings for rods, pre lube, fit rod caps new arp rod bolts torqued to spec (don't forget special grease). Temporarily bolt carrier assembly into left case half to keep things in place.



Next time, mating case halfs, fitting pistons 4 thru 6.

GT3 82mm plenum design finalised and should have prototype for checking here next week.





Trying to find a firm that can bend me up some decat pipes, drop me a PM if you know anyone or even have some to hand you don't want





Thumb

Last edited by Harv on Thu Jun 15, 2017 1:49 am; edited 1 time in total
 
  
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 6919
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Thu Jun 15, 2017 1:44 am    Post subject: Reply with quote

thumbsup
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911munKy
Spa-Francorchamps


Joined: 26 Nov 2014
Posts: 281



PostPosted: Thu Jun 15, 2017 2:23 am    Post subject: Reply with quote

Really interesting thread,
if you don't mind me asking are you and eng builder or mechanic by trade?
Great skills, I like to wield the spanners a bit but wouldn't attempt this sort of project.
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2000 C2 996
 
  
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Harv
Suzuka


Joined: 18 Sep 2014
Posts: 1001



PostPosted: Thu Jun 15, 2017 7:01 am    Post subject: Reply with quote

Thanks Thumb

I'm doing this build myself, mechanical engineer by trade or at least this is what I studied after leaving school when apprenticeships still existed though have spent years working in CAD to the oil & gas industry (sadly now as dead as the animals that gave us fossil fuels thanks to oil price and companies insatiable desire to constantly cut design costs in the last 10 years).

The m96 engine is a mechanical jewel and something like this is entirely within the capabilities of the home mechanic, just take your time.
 
  
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DynoMike
Suzuka


Joined: 25 May 2012
Posts: 1233
Location: The Cotswolds

2003 Porsche 996 Turbo

PostPosted: Thu Jun 15, 2017 8:07 pm    Post subject: Reply with quote

Nice one Harv! Looks like you are doing a very methodical and diligent job, just the way an engine should be built. I'm not sure if you are using a build paste but can recommend Graphogen, have used it for over 30 years. Great to put on shells, cams and followers etc in order to provide total protection whilst cranking for oil pressure. It costs quite a lot but is worth every penny. The only downside is that it makes your oil look black very quickly, but that will be flushed at the running in oil change. We don't use it on piston skirts though.

Good work, keep the forum up to date Thumb
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Jamesx19
Monza


Joined: 10 Jul 2015
Posts: 162
Location: Brighton


PostPosted: Sat Jun 17, 2017 2:33 pm    Post subject: Reply with quote

Great work Harv. And inspiring stuff.

I like your idea of not just a rebuild, but an upgrade. And for reasonable money considering the cost of parts and precision machining.

Have you needed to replace the valve guides as well? From a cylinder head flow point of view, is the restriction in the inlet or exhaust side do you think?
I imagine that lovely 3 angle job on the valve seats, together with the increase bore size deshrouding the inlet valve should make a sizable difference to head flow, and hence torque.

Will you change the cams as well? I can imagine this engine will have masses of mid range thump, rather than be a screamer!

Like the others have said, please keep going with the updates. Very interested.

Cheers
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Harv
Suzuka


Joined: 18 Sep 2014
Posts: 1001



PostPosted: Sat Jun 17, 2017 6:23 pm    Post subject: Reply with quote

Cheers,

I couldn't really justify taking this all to bits and then just refreshing it and generally mod my cars a bit when the time comes for something like this.

Regarding the heads no the guides didn't require replacement and had little wear for the mileage, so just the valves, seats and a little porting. I couldn't see anything to be gained in the inlets so only a little bit of clean up and then the exhaust had some smoothing. I don't think there's much on the table with these heads anyway they are not restrictive.

I don't plan on changing the cams either and not looking for all out peak HP just more usable midrange. I'm hoping the car gets is sparkle back, it's always felt lack lustre to me.

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sje00
Newbie


Joined: 08 Jun 2017
Posts: 17
Location: Herts


PostPosted: Wed Jun 21, 2017 11:07 pm    Post subject: Reply with quote

Wow! Awesome!

Would love to see the 3D printed part your looking to do!
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Marky911
Imola


Joined: 04 Jun 2009
Posts: 790



PostPosted: Wed Jun 21, 2017 11:20 pm    Post subject: Reply with quote

Still watching here. Mega impressive.
 
  
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Harv
Suzuka


Joined: 18 Sep 2014
Posts: 1001



PostPosted: Thu Jun 22, 2017 7:08 am    Post subject: Reply with quote

Still working away here.

Doing compression ratio check with the engine partially built (Engine on TDC for piston 1, old head gasket and head fitted) using the chamber fill method to get an acurate figure.

I have all the data to calc the CR but some of that data is manufacturer supplied, for example the piston data is -13.8cc which added to my heads would yield 63.8cc.

12:1 will be my absolute maximum limit and equally 10.5:1 would be too low so either a removal of material from Pistons or head maybe required to dial this in, there's the option also to add an additional shim into head the gaskets (stacking).

One thing I have struggled to find is the piston to head min clearance figure. At the top of the engines stroke you don't want the piston getting too close the the cylinder head face, a figure of around 0.037 - 0.040" seems acceptable (around the 1mm mark)

The printed plenum design is finalised and I have managed to get a consistent 3mm material wall thickness for the unit which should prove to be strong. The material is also good for 200degC though not expecting those kind of running temps even with heat soak. There will be some hand finishing required.
 
  
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Jamesx19
Monza


Joined: 10 Jul 2015
Posts: 162
Location: Brighton


PostPosted: Thu Jun 22, 2017 11:33 am    Post subject: Reply with quote

From your post, I'm assuming your doing a dry build with Plasticine on the pistons to get those measurements? Good squish will promote turbulence and a quicker burn of the mixture. Though 1mm sounds the minimum you would want to go considering heat and material expansion at 7,000 rpm?

Not in the same league, but I built a Fiat SOHC engine with that sort of tolerance. The pistons actually came above the block deck into the gasket space by 0.5mm as the gasket was 1.8mm compressed thickness. It only needed 28.5 degrees advance even at 7,500 rpm.

Do you know who did the design and development work on the Wossner pistons, they might have some data?

Don't forget the volume of the ring land to piston/cylinder walls. You've probably got that in hand anyway......

Cheers
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Jamesx19
Monza


Joined: 10 Jul 2015
Posts: 162
Location: Brighton


PostPosted: Thu Jun 22, 2017 11:53 am    Post subject: Reply with quote

Some back of an envelope maths....

Cylinder volume = 643.5 cc
Chamber vol = 50 cc
Piston is dommed? = -13.8 cc
Gasket volume at 1.8mm (nominal compressed) thickness = 14.13 cc
Ring land volume approx = 0.8 cc?

Static Compression ratio = 13.6 : 1

Variables are gasket thickness and volume and piston dommed or dished. ie intruder or not?
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DynoMike
Suzuka


Joined: 25 May 2012
Posts: 1233
Location: The Cotswolds

2003 Porsche 996 Turbo

PostPosted: Thu Jun 22, 2017 1:41 pm    Post subject: Reply with quote

Harv, best to use a squish of 1.2-1.3 mm to allow for any carbon build up in the cylinder. If you have the squish too tight, the carbon will start to impact the head, which is not a good idea. In fact, on a large cylinder capacity, we have found more power by increasing not decreasing squish.

Measuring the volumes the way you are doing it is not accurate. It is very difficult to ensure all air is out of the chamber, it does some very strange things as fluid is added! Our preference is to use a plexiglass plate to measure the head volume, where the trapped air can be observed clinging for dear life to the surfaces.

To measure the piston crown and deck volume, move the piston down from TDC, lightly smear a little grease in the bore to seal the ring end gap, then return the piston to TDC again. We then make spacer rings of known volume (calculated from diameter and depth), with the same plexiglass plate greased on top to measure the nett volume. The simple calculation reveals your total intruder/dish volume volumes.

Head gasket wise, measure the compressed thickness and diameter to calculate the HG volume. This is okay as long as the gasket is circular, for those with cutouts, plexiglass with clamps to a surface plate works well.

A very quick calc from your figures above gives; 3900/6 = 650cc per cylinder. 650+63.8 total volume (if that's what you measured?)/ 63.8 gives 11.18:1

To find a theoretical compression volume from a known or desired CR, divide the swept volume by the CR-1. Example, for 12:1 desired CR, take 650/11 (12-1) = 59.09 unswept volume required. Feeding this back in gives 650+59.09= 709.09/59.09 which gives 12:1.

Shout if you need any help Martin.
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Harv
Suzuka


Joined: 18 Sep 2014
Posts: 1001



PostPosted: Thu Jun 22, 2017 2:10 pm    Post subject: Reply with quote

Thanks for you're replies.

As you can see, many ways of skinning a cat!

The pistons are not domed but have pockets and the manufacturer quotes the cc of them as - 13.8 but effectively this add's cc's to our total chamber volume.

Thanks Mike for the detail on measuring the cc of the piston crowns installed, I like that suggestion as I have done the heads with valves and plugs installed.

The cylinder heads gaskets for the 3.8 997 are 0.7mm compressed so quite thin.

I need to measure piston crown protrustion above the liners yet but believe its around 0.15mm

More once I have proper data Thumb
 
  
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jimk04
Newbie


Joined: 10 Dec 2013
Posts: 33



PostPosted: Sat Jun 24, 2017 3:34 pm    Post subject: Reply with quote

Great work. I have a 3.4 that I was intending to build to 3.7 to go in my boxster. I see the picture of the under drive pulley.... I'm the guy that made those....or at least had them made!

Would be interested in buying a 3d plenum if you arwant thinking of making more.
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Track focused 986S
 
  
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Jamesx19
Monza


Joined: 10 Jul 2015
Posts: 162
Location: Brighton


PostPosted: Sat Jun 24, 2017 7:10 pm    Post subject: Reply with quote

Not to hijack anything, but .... my worry would be that the under drive pulley would exacerbate the low speed running cooling issues. Especially water flow to number 6 cylinder. Is this unfounded? I appreciate things are different in a track only car, so the question relates really to running this pulley on a road car.
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DynoMike
Suzuka


Joined: 25 May 2012
Posts: 1233
Location: The Cotswolds

2003 Porsche 996 Turbo

PostPosted: Sat Jun 24, 2017 8:23 pm    Post subject: Reply with quote

Jamesx19 wrote:
Not to hijack anything, but .... my worry would be that the under drive pulley would exacerbate the low speed running cooling issues. Especially water flow to number 6 cylinder. Is this unfounded? I appreciate things are different in a track only car, so the question relates really to running this pulley on a road car.


Yeah
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jimk04
Newbie


Joined: 10 Dec 2013
Posts: 33



PostPosted: Sat Jun 24, 2017 11:39 pm    Post subject: Reply with quote

I believe that the pulleys do not adversely effect the cooling.
Many racers in the US use them in much higher ambient temperatures than us. Supposedly they help with cavitation at higher engine speeds.

With regards to street driving. ..there seems to be a good amount of folk use these with seemingly no ill effects.. I have no hard data for any of this but likewise have heard no bad news against the use of them.

I have heard plenty of advice against lwfw though. Particularly on larger displacement engines. But if all balanced then that is the best approach. .....I use a lwfw on my 3.3.2 986. Stock engine.
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