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Old 02-21-2015, 11:19 PM   #1
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3.4 996 Engine upgrade

Hi currently in the process of installing a 3.4 996 engine into my 2.5 its a rebuilt motor, new bearings, piston rings, chains, guides etc.
Ive a few questions hopefully someone can answer

1, As the engine will need breaking in, will it run with the 2.5 map to do this before my remapping guy reflashes the ecu with the 3.4 map and runs it on the rollers.

2, I'm going to use the 5 speed gearbox with an aasco lightweight flywheel to start, with the options of switching to a 6 speed at a later date, So what up-rated clutches are available for the 5 speed one with a spring loaded disc, part numbers would be great.

Thanks

Last edited by whitecliffs; 02-21-2015 at 11:22 PM.
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Old 02-22-2015, 07:35 AM   #2
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Are you looking for a AASCO lwfw? I have a new and used one for sale for the 3.4l
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Old 02-22-2015, 08:00 AM   #3
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A couple suggestions. I'm running A 3.6 LN Boxster motor and 5-Spd for 2 years. Still in the 5 speed because the change to a 6 speed requires many changes, Suspension supports, bearing carriers, axles, rear transmission mounts, calipers, rotors,

1. Find a 2003 or 2004, 5 spd they are a little better built, and also allow the 2003 2004 axles.
2. The 2003 and 2004 axles are heavier than the previous generation. They have a 10 MM through hole in the CV joint instead of 8MM. Although the thread on the 10MM shouldered bolt used on the 03 and 04 is still 8MM threads, it is not difficult to retap the holes in the flanges for a 10 MM bolt, and use a straight 10 MMx45 bolt. I opted for 3/8"-24 X1-3/4" 18/8 Socket Head Cap screw. This also stopped my shearing off axle bolts.
3. Porsche did not make a 23 spline 23.8MM spline dia. clutch disc that is sprung. You need to go after market, Clutch Masters or Spec. Look under Boxster on Pelican they sell one 88-1861-000-017-M410 Sach sprung clutch disc for ASSCO plate.
4. Buy a heavier sprung pressure plate also I'm using a Spec level 2.

My 3.6 sleeved motor ran on the 2.7 L program. Before I was done running it in I had Softronics modify the program. I want to run the motor before I started changing other operating parameters.
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Old 02-22-2015, 08:24 AM   #4
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Quote:
Originally Posted by Trendy996 View Post
Are you looking for a AASCO lwfw? I have a new and used one for sale for the 3.4l
Thanks for the offer but i already have one

Quote:
Originally Posted by jsceash View Post
A couple suggestions. I'm running A 3.6 LN Boxster motor and 5-Spd for 2 years. Still in the 5 speed because the change to a 6 speed requires many changes, Suspension supports, bearing carriers, axles, rear transmission mounts, calipers, rotors,

1. Find a 2003 or 2004, 5 spd they are a little better built, and also allow the 2003 2004 axles.
2. The 2003 and 2004 axles are heavier than the previous generation. They have a 10 MM through hole in the CV joint instead of 8MM. Although the thread on the 10MM shouldered bolt used on the 03 and 04 is still 8MM threads, it is not difficult to retap the holes in the flanges for a 10 MM bolt, and use a straight 10 MMx45 bolt. I opted for 3/8"-24 X1-3/4" 18/8 Socket Head Cap screw. This also stopped my shearing off axle bolts.
3. Porsche did not make a 23 spline 23.8MM spline dia. clutch disc that is sprung. You need to go after market, Clutch Masters or Spec. Look under Boxster on Pelican they sell one 88-1861-000-017-M410 Sach sprung clutch disc for ASSCO plate.
4. Buy a heavier sprung pressure plate also I'm using a Spec level 2.

My 3.6 sleeved motor ran on the 2.7 L program. Before I was done running it in I had Softronics modify the program. I want to run the motor before I started changing other operating parameters.
Cheers for the info on the gearbox will bare it in mind, have found a few Audi clutch part numbers that cross reference with the Porsche one but will have a look at the Pelican one
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Old 02-23-2015, 10:04 AM   #5
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I would just use a SPEC clutch kit, and specify that you want a sprung disc.
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Old 02-23-2015, 12:08 PM   #6
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Whitecliffs ,
Interesting project you are doing. 2.5 to 3.4 will be a significant performance upgrade!
The clutch+flywheel - the conventional wisdom is that substituting a conventional flywheel(SMF) for the DMF will lead to dire consequences because of the lack of dynamic balance. I am confused by such warnings because the LWFW mod is often mentioned without any comparable admission that it eventually caused mechanical problems . I do not mean just an uneven idle. These dark and mysterious unbalanced forces are allegedly an assurance of doom for the crankshaft/bearings. If the M96 engine was an inherently unbalanced 90 degree V6 ,I understand.But a flat 6? O.k. it isn't quite perfect but short of a rotary/Wankel or 12cyl. ,it is about as good as we'll get Yet no posts about the actual damage caused by LWFW/SMF substitutions?
By contrast, a worn DMF seems more likely to cause exactly the damage the LWFW or SMF is rumored to cause.
So how did you reconcile the two conflicting points of view ?
This may help?
"The final issue is that if the clutch/DMF assembly wears and runs out of balance it can cause severe engine damage by overloading the crankshaft main bearings. This problem is especially prevalent on the 986, 987, 996 & 997 2.5, 2.7, 3.2, 3.4, 3.6 & 3.8 models, For these reasons Ninemeister highly recommend replacing the Porsche DMF at the same time as a clutch replacement and will only warranty a clutch package when fitted with a new DMF. "
I mention this because I am sure you don't want to inadvertently damage your new and expensive 3.4.

Last edited by Gelbster; 02-23-2015 at 12:10 PM.
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Old 02-23-2015, 01:16 PM   #7
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The issue is not only a question of balance but also of harmonics. Without the DMFW there is no harmonic dampening in the system.
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Old 02-23-2015, 01:34 PM   #8
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Unless the entire rotating assembly and the light weight flywheel are balanced as an assembly, bad things can result

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Old 02-23-2015, 02:41 PM   #9
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JFP
Thank you.
A picture is worth a thousand words(certainly any 1000 of mine!)
As they say in England 'nuf said.
JFP wrote: "Unless the entire rotating assembly and the light weight flywheel are balanced as an assembly, bad things can result"

Last edited by Gelbster; 02-23-2015 at 04:16 PM.
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Old 02-23-2015, 03:19 PM   #10
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Ive seen the story behind that picture it came from a 3.6 that had done 12,000 track miles, ive been running a lightweight flywheel on my 2.5 for the last 10,000 miles with no issues, ive seen some of the horror stories and just like the IMS and bore scoring any faults seems to get a lot of negative comments.
Ive also seen a few good comment regarding the flywheel and in the UK we have a guy who's done over 30,000 mile with a lightweight flywheel without any issues.
Like most fun things in life, they all come with some element of risk
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Old 02-23-2015, 04:15 PM   #11
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That pic was my engine. You are correct some do and some don't, blow up that is. Hopefully they did some balancing and weight matching on your rebuild and that should help. Getting the new LWFY, clutch and PP balanced as a unit will help too.
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Old 02-24-2015, 01:25 AM   #12
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That is some spectacular photo and enough to scare the living day lights
out of some people.
That's a fair point Gelbster about the duel mass flywheel.

Last edited by whitecliffs; 02-24-2015 at 01:28 AM.
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Old 02-24-2015, 07:31 AM   #13
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You will be happy with a stock flywheel. Check out my signature. I am more than happy with my results.
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Old 02-24-2015, 09:11 AM   #14
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You will be happy with a stock flywheel. Check out my signature. I am more than happy with my results.
What exhaust back box are you using, i've got the ebay headers no cat's and a Janspeed backbox, but was wondering if the u-bends to the backbox would be to small and maybe a custom backbox with larger u-bends would be more beneficial
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Old 02-24-2015, 09:42 AM   #15
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I have some swedish muffler on it now. I have tried many different aftermarket mufflers. I just went for the best made with the sound I wanted. A stock S muffler is just fine also with that motor. I would invest in some high flow cats.
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Old 02-24-2015, 10:45 AM   #16
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It seems to me the guys with the 2.5 motors do OK with the LWFW but you jump the cubs with a much larger motor and people seem to get in trouble especially if everything is not perfectly balanced as a unit.

I am no expert but I believe Jack Raby is and I have heard him say more than once never use a LWFW on an M-96 motor. Proceed at your own risk and be careful. If you blow one of these motors the replacement is NOT CHEEP.

Just some thoughts.
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Old 02-24-2015, 12:00 PM   #17
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My LWFW and Spec sprung clutch went in at 142K. I'm at 172K now. 2000 BoxS, 3.2L.
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Old 02-24-2015, 12:36 PM   #18
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j.fro, I am not saying I am necessarily right .........I am just passing on information for people to include in there thought process when making a decision. Again, I am not an expert and I tried to pass on information from someone I believed was
truly knowledgeable. Thanks
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Old 02-24-2015, 12:57 PM   #19
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LWFW, Spec sprung clutch ...and supercharger kit on 2000 S. 20K miles so far with.
Don't jinx this for me!!!
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Old 02-24-2015, 01:04 PM   #20
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You LWFW guys - did you get some trick balancing of the whole c/s,bearing carrier,rods & pistons ?
I do not understand why this works well without at least a harmonic balancer on the c/s pulley. Unless you reason that the M96 is really a heavily counter-weighted 3 cylinder engine and does not need much harmonic balancing?? Because it sure isn't getting any dynamic balancing with a LWFW.
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