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Physics. As the bore and or stroke (IE HP) increases, stresses increase linearly, compounded exponentially further by decreased mass of the static heat sink / vibration damper (block). Resulting in higher operating temperatures, less cooling / oiling capacity, and reduced service life.
Hartech in GB wrote a literal book on this, their conclusion is the 3.4 bore/stroke sits at the uppermost limit of what the wet sump M96 block can reliably output at the rev limit. All the further reduced M96 blocks are compromised, with the 3.8 being exceptionally so.
The problem isn’t so much the larger bores, as it is the smaller blocks. Because oiling and cooling remain essentially the same across all non Mezger M96/97 variants.
Are the cylinder sleeves thinner on the 3.6. than on the 3.4? If so, the above makes total sense. As I understand it, the problem is exacerbated by the fact that the block on the M96/M97 doesn't encase the cylinder sleeves (unlike most block/sleeve designs). This results in the sleeves having far more potential to go "out of round" under excessive heat conditions than in a typical block that surrounds and reinforces the cylinder sleeves.
I have nothing and no one to blame for my Porsche addiction but the wicked World Wide Web
I blame mine on the Catholic Church.
First modern Porsche I ever saw was when I was leaving CCD back in 2001 or so and a classmate got picked up in a shiny new speed yellow Boxster.
it was the first time I'd seen a car cooler than my dad's old 65 GTO and later 68 El Camino SS
Physics. As the bore and or stroke (IE HP) increases, stresses increase linearly, compounded exponentially further by decreased mass of the static heat sink / vibration damper (block). Resulting in higher operating temperatures, less cooling / oiling capacity, and reduced service life.
Hartech in GB wrote a literal book on this, their conclusion is the 3.4 bore/stroke sits at the uppermost limit of what the wet sump M96 block can reliably output at the rev limit. All the further reduced M96/97 blocks are compromised, with the 3.8 being exceptionally so.
The problem isn’t so much the increasingly larger bores, as it is the concomitantly smaller blocks. Essentially because oiling and cooling capacity remain essentially the same across all non Mezger M96/97 variants (so-called “powerkits” and nano-improvements throughout notwithstanding).
I get a kick out of you. Don't know if you really believe some of the crap you say or you are just having some "double-talk" fun.
Please don't let me stop you in any way. It's good entertainment. 😁
If you don’t have capacity to spare (IE Mezger’s GT1 964 block) then something’s gonna give
IE 3.4 was already a stretch. 3.8 was a bridge too far
Originally Posted by peterp
Are the cylinder sleeves thinner on the 3.6. than on the 3.4? If so, the above makes total sense. As I understand it, the problem is exacerbated by the fact that the block on the M96/M97 doesn't encase the cylinder sleeves (unlike most block/sleeve designs). This results in the sleeves having far more potential to go "out of round" under excessive heat conditions than in a typical block that surrounds and reinforces the cylinder sleeves.
Not enough information. More bore does not equal less metal. It could be a lot more metal if they built the sleeve thicker. If the larger 3.6 sleeve is the the same thickness as the 3.4 sleeve, then it will be marginally weaker. If the 3.6 sleeve is thinner than the 3.4 sleeve because they bored it out to achieve greater displacement, then it will be quite a bit weaker.
I suspect you are correct, and there is no debate that physics is physics (and unchangeable), just not enough information provided to make your case. I'd look up the sleeve info if I had time, but I don't (still curious though).
EDIT -- did a quick search and see that the bore size is the same at 96mm, the stroke was increased from 78 to 82.8 mm to get to 3.6L. Didn't see anything specifying sleeve thickness at a glance.
Do you have an example / photo of this? X51 did not receive a special intake box. Same as any other 996. Easiest visual is the intake manifold made out of aluminium. Besides this X51 package had better flowing headers, different heads, ECU mapping and changes to oiling system. The block was also the same as any other 996.
1. What makes the cylinders different in the 3.4 from the 3.6?
2. Do 3.4 owners change their oil more often than 3.6 owners?
3. Do 3.4 owners change their fuel injectors more often than 3.6 owners.
4. Do 3.4 owners use different gas than 3.6 owners?
Love your banter but you gotta stop talking so much smack.
Originally Posted by bdronsick
Physics. As the bore and or stroke (IE HP) increases, stresses increase linearly, compounded exponentially further by decreased mass of the static heat sink / vibration damper (block). Resulting in higher operating temperatures, less cooling / oiling capacity, and reduced service life.
Hartech in GB wrote a literal book on this, their conclusion is the 3.4 bore/stroke sits at the uppermost limit of what the wet sump M96 block can reliably output at the maximum power range. All the further reduced M96/97 blocks are compromised, with the 3.8 being exceptionally so.
The problem isn’t so much the increasingly larger bores, as it is the concomitantly smaller blocks. Essentially because oiling and cooling capacity remain essentially the same across all non Mezger M96/97 variants (so-called “powerkits” and nano-improvements throughout notwithstanding).
The 3.4 engines has a Ferrostan (iron) plating on the pistons, the 3.6 has a Ferroprint (Graphal-like plastic coating) on the pistons, the 3.4 has Lokasil 1 cylinders and 3.6 has Lokasil 2 cylinders,(difference in size/density of the silicone particles)..
Ferrostan was outlawed due to environmental reasons...
Last edited by Porschetech3; 10-19-2021 at 07:45 PM.
Is that a picture of the 997 X51 Airbox, or the 996 X51 Airbox? I've never seen a 996 X51 Box, but I know the 997 3.8 fits into the 996, but I was always curious if the 997 X51 fit into a 996....
Is that a picture of the 997 X51 Airbox, or the 996 X51 Airbox? I've never seen a 996 X51 Box, but I know the 997 3.8 fits into the 996, but I was always curious if the 997 X51 fit into a 996....
I must have drank the koolaid.
I thought I researched it, that the 996.2 X51 had that Carbon Fiber Air Box.
Apparently I was wrong.😱
After about a year owning my 996 I was hell bent on doing some modifications.
ECS Tuning offered these air boxes as an upgrade to stock air boxes. The kit even contained a template to cut right side air inlet. Then an entire kit came forsale on Ebay from somewhere in California complete with template. I passed at $1800, I think the new price was close to $3k.
I just looked back to try and find the part number to see if it started with 996 or 997, but couldn't find it.
About a year later, either here or on 6speed, someone listed one for around $1k, it sold instantly.
I’ve been on this forum fairly regularly since 2014, and the first I’ve seen of you here (at least noticed) is your “what makes the ‘99 so special” thread. So it seems to me like a sudden case of “expert-itis”... And, no you didn’t say bore scoring is “relatively unlikely in the 3.4 compared to the 3.6/3.8”... You said the 3.4 is “as likely to get struck by lightning as to get bore scoring”. That’s quite a bit different - especially to someone who doesn’t have any/much background with these engines... This is all fine as long as the statements in question are presented as opinions as opposed the facts.
Friend, what compelled you to write this post? If you own a 996.2 why do you care so much about his opinion about the original 996? Does it really matter that much to you? If so, why?
10-19-2021 | 06:22 PM
