Internal M96 Tips/Tricks/Mods

I've had a little down-time to reflect and the thought came to me that a Technical Thread on internal Mods/Tip/Tricks might be due...There really hasn't been one that I can recall , although I have made a few "posts" I can't even go back and find my posts that are buried in other threads that have drifted a bit off-topic and went down some Technical Rabbit Hole... I don't want to cause any Newby's any nightmares, so if you're just interested in the best cup-holders, or which wheels look the best on your car, you want to scroll on by this thread... Back in the late 70's 80's I was heavily involved in IHRA Super Stock Racing ( set a couple World Records) in my spare time...Super Stock Class was extremely competitive and highly regulated with "rules against common well known modifications" for unfair advantages.. So competitors like me would seek any and all less obvious Tricks/Tips/Mods to gain 2-3hp in as many places as possible...plus places/things that can add strength/durability/dependability...all within the restrictive rules.... One such place on the 2.5 2.7 3.2 Boxsters and 996.1 3.4 engines to get "Free HP " is the bottom of the cylinders between cylinders ..As the Piston come down on the Power Stroke , any air pressure under the Piston is taking Power away, so letting the air pressure escape more freely gives a few extra Free HP especially at high RPM... Porsche realized this Free HP left on the table and on the 3.6 engines in 2002 cutaway a large channel between the cylinders...This can be replicated on the 3.4 engine .... 2.5 2.7 3.4 early m96 late 3.6 3.8 m96 Spending a little time here with a Die Grinder can net some Free HP !! I have quite a few more Tips/Tricks/Mods to come !!! Will post when I have time/inclination ...Feel free to share your Own

So it looks like bank 2 of the 3.4 does have holes there for installing the wristpins. Do you think having the holes on one bank and not the other is detrimental in any way?

Quotes source post: 20100856

Yes I think Bank 2 is making bit more HP at high RPM than Bank 1 and not a "perfect" balance.. .

The very idea of this thread is FIRE! Can't wait to follow along.

I am going to enjoy this thread , nothing wrong with learning !

How to avoid cracks in metal parts :::: It is well known that all solid metal has internal stress trapped inside it....especially casted metal ... When metal is molten/liquid it has no stress, but as it cools, it can never cool evenly, it always cools slower on the inside than the outside no matter how carefully it is cooled......This traps stress inside the metal... Along with the stress that is inherently trapped in the metal, outside forces can add more stress, like bending/heating/cooling/fatigue ect... Stress flows inside the metal atomically like water and can flow freely in objects shapes that are circular or arched, but will concentrate in corners and sharp edges... The concentration of the stress on 90* corners or sharp edges will make the area much more likely to crack ...Placing a Radii on 90* corners and sharp edges will spread the stress out over a larger area and lessen the likelihood of cracking... The 5 chain m96 engines are known to have cracking problems in the heads that originates from the sharp edge at the top of the spark plug hole.....From the edge of the Spark Plug hole the crack will usually follow one of three paths...either to the Exhaust valve guide or to the bolt hole, or to the expansion plug shown on the picture below...... Radiusing the top edge of the Spark Plug hole can stop the crack from forming... I know it has been said many times that overheating and water pump failure is the main cause of cracking but I have seen quite a few 5 chain heads crack with the original water pumps still on them and still good.. There are many many other sharp corners on the M96 just like all engines that can be strengthened by de-burring/radiusing/ and polishing.. I know most reading this will not be inside your engine, but if you happen to find yourself in there with some spare time, turn on your favorite music / or movie get an air grinder/Dremel ect, with sandpaper rolls and get rid of all the sharp edges you can... If you think the Top Engine Builders/Racers don't do this on their own engines I think you would be mistaken..It is a few hours well spent...( I have done my share) Cracks start at spark plug hole and can take one of three paths a few General Guidlines for Radiusing from our friend AI because I'm am too lazy to type it out myself... In racing engines, radii on sharp edges are used for several important reasons: Improved Airflow and Performance: Radiusing sharp edges, particularly in areas affecting airflow like intake ports and valve seats, helps reduce turbulence and improve the smooth flow of air or the air/fuel mixture. This can lead to increased power output. For instance, smoothing out valve seats can increase airflow, potentially leading to a 30 horsepower difference compared to sharp edges. Creating a radius in the intake port eliminates turbulence introduced by a sharp edge, allowing for more accurate flow characteristic evaluation. For high-velocity airflow like in the intake system, a radius at transitional points (low speed to high speed) is essential. Increased Part Longevity and Durability: Sharp edges can be stress concentration points, increasing the likelihood of cracking and failure under high loads or stresses. Radiusing these edges helps distribute the stress more evenly across the material, reducing the risk of fatigue failures. This is particularly important for critical components like connecting rods, which are subjected to significant stress during high-RPM operation. Safety: Rounding off sharp edges reduces the risk of injury during handling and assembly, both in the production environment and in the field. Where are radii applied in race engines? Intake and Exhaust Ports: Smoothing and radiusing port edges, especially at the intake and exhaust seats, optimizes airflow. Valve Seats: Radiusing valve seats improves airflow into the combustion chamber and can improve throttle response and horsepower. Connecting Rods: Sharp edges on connecting rods should be deburred and radiused to prevent fatigue failures. Abrasive work on connecting rods should be done carefully, ensuring that marks are parallel to the rod beam. Engine Block: Sharp edges inside and outside the block should be deburred and radiused to prevent cracks and improve handling safety. Pistons: Piston skirt and top edges should be lightly radiused for better durability and to prevent damage during assembly. General Guidelines for Radiusing: Sharp corners should be rounded with a radius between 25% and 60% of the nominal wall thickness, especially for load-bearing parts. A minimum inner corner radius of 0.5 mm is recommended. For external corners, the radius should ideally be equal to the inner radius plus the wall thickness to maintain uniform wall thickness. Sharp outer edges and rib edges should have a minimum radius of 0.125 mm.

Very helpful, I will remember this when I try to rebuild my engine! Thanks!

Quotes source post: 20103289

Dirty hands is good exercise !!

Quotes source post: 20100797

Thanks for doing this. Most of this stuff is a mile over my head but I enjoy trying to comprehend.

Really enjoying these @Porschetech3 - these feel almost like they should be mini blog posts or something. Please keep them coming

I really enjoy reading and learning about these mods, tips and tricks from Porschetech3 even if I don't get dirty working on my 996. I am more confident in the company of other Porsche enthusiasts and also with my Indy or Porsche service advisor. TYVM! /X3

I have posted about this before but is buried deep in one of the many oil pressure threads....I thought it would be good to post again here.. I have identified all the ways to improve the oil delivery , oil return, and oil control on the M96/7,Here is a couple more ways to improve but can only be done during a rebuild or a disassembly/reassembly... There are 4 6mm oil return holes i( two in each Bank ) n the IMS area below the shaft , this area is also connected to the heads on each end because of the timing chains have to have a fairly large channel for the chains, and chain guides.... So oil can go from one head to the other after passing underneath the Intermediate Shaft...( shown in Green Circles) Increasing the size of the drain holes from 6mm to 13mm will give 4x more drain back oil flow from this area and will Gravity fall into the center of the Sump... Another way to improve the oil drain back and oil control is by keeping oil from finding places to hide....Shown below ( Purple rectangles) are two large cavities where oil can hide when doing hard cornering ...These cavities do nothing, their outer walls are used in form other channels/pathways . Porsche could have filled them in during casting but it would have added considerable more weight so was left just a couple voids... Filling in these two cavities will force the oil that would normally go in there and hide to take another route to be drained back via the 4 enlarges holes i just mentioned above or to flow out to he Scavenge pumps to be pumped back down to the Sump... Either way is better than hideing in the cavities doing nothing.. These types of Tips, Tricks,Mods are not for DIY'ers or average rebuilders...These are for the Pro's who are used to these types of modifications... Filling in these cavities should be done with a high temp Epoxy, or for a "lightweight fill" use the high temp Epoxy with Cork Nodules as a filler ... The cavity prep is important, the outer surface needs the oxidation cleaned off and roughed to bare aluminum with an abrasive sandpaper roll and half dozen divots in the surface for grip... I know most reading this will not be doing these type of Tips, Tricks, Mods, but may find it interesting what CAN be done and is being done in few select instances... More to come !!! I keep remembering more but it takes time to get pictures or drawings gathered up so it can be easily understood without extremely lengthy details that may get Technical and boring for most ..I will post as I can ..

Chevy engine suck. So, was it Ford FE blocks or Chrysler? I'm an ex FE man myself.

Quotes source post: 20119025

TurboCharged Alky-Injected 2.0 Liter Cosworth YB/T-88 EAO OHC

Water Pump Screens I posted about this internal Mod back in 2019 when I had a water pump fail and missing pieces of the impeller blades that could not be accounted for ...I back-flushed the engine with a high pressure washer but still could not recover all the small pieces of the blades .... So it got me to thinking ( I know a dangerous thing for me to do ) and I decided I wanted some screens to catch any blades that can break off the impeller and catch them in a good location so that they can be removed from the engine when a Water Pump Fails... Here is a pic of one of the two screens I fashioned and fit in the case to catch any impeller blade debris... The screens fit snug and are sized to be big enough not to impede the coolant flow but small enough to catch broken impeller blades so they can't get lodged in the head passages and cause local hot spots in the heads that have been theorized to be a contributor to head cracking... Scavenge Pump Screens I also made some similar screens to fit at the inlet of the Scavenge Pumps in each head them from debris...A piece of valve spring or timing chain roller if it gets pulled into the Scavenge Pump will lock the Pump . When the Pump locks up the best thing that could happen is the Pump Drive breaks and you notice a fluctuation in the oil pressure especially on turns and find/fix the broken Pump.....But if the Pump Drive doesn't break first, it can break the timing chain or cause the IMS gears to slip on the Shaft.... this can/will lead to Pistons hitting the valves and catastrophic failure... ( sorry not pic of the Scavenge Pump Screens ATM ) These are not common occurrences but can and do happen... Chamfering Oil Holes in Crank Chamfering the oil holes in the crank is a good practice ...The sharper the edge the more it SHEARS the oil and hinders the flow...chamfering helps the flow also strengthens the crank due to cracks always start at sharp edges.... It doesn't take very long to chamfer the oil holes a very much worth the time.. Stock M96 oil holes A better chamfered oil hole Knife Edged Crank All stock production Cranks have counterweights with flat faced leading edges.....These flat faced leading edges are not Aerodynamic ....By shaping these leading edges into a Knife Edge the Crank will spin much easier at high RPM through the thick oil-laden air/oil vapors and make/save HorsePower......it also lightens the Crank which also helps... Knife-Edging a Crank takes a LOT of time and effort and has to be done carefully and evenly then a more expensive balancing job has to be done...You don't want to make the knife-edge too "sharp" as that will weaken the Crank, it needs to a bit rounded like the leading edge a Air Plane Wing... Stock M96 Crank with Flat Faced Counterweights Example of a Knife-Edged Crank Back in my younger days even my daily driven street car had a Knife-Edged Crank that I had spent tons of Man-hours on ...

Engine vibration Damping Since my last post included Crank Knife-Edging it reminded me about balancing/vibrations that always need to be factored... ICE Engines produce vibrations,, all of them...Some worse than others.. The ICE process converts chemical energy into thermal energy, thermal energy into reciprocating energy, reciprocating energy into rotating energy, rotating energy into kinetic energy......Quite a lot of energy transformations right ?? ( important to note that not all, infact the majority, of chemical energy/heat energy is lost though the exhaust and the cooling system ) With each change/transformation of energy there are forces created that if not counteracted will result in vibrations...Some of the forces can be successfully counteracted and some cannot...... The basic vibrations are called Primary and Secondary....and then we have the Harmonic Vibrations... Primary and Secondary vibrations are inherent in all engines of 1 cyl 2 cyl 3 cyl ,4 cyl, and 5 cyl......an In-line 6 cyl is the min number of cylinders to achieve an inherently perfectly balanced Primary and Secondary design .... v10 v8 v6 v4 v2 no matter if they are 90* or 60* or 180* ( flat) are inherently imbalanced ..only the v12 ( 2 in-line 6cyl's) is inherently perfectly balanced On the inherently imbalanced designs some have good Primary and bad Secondary, and some have good Secondary and bad Primary and some have bad Primary and bad Secondary , but all can be minimized by crankshaft counter weighting and/or balance shafts.. Now we come to Harmonic Vibrations Every object has a frequency at which it vibrates/resonates at...(when the natural frequency equals the forced frequency)....like taping a tuning-fork.....or when an Opra Singer hits the High C note it will shatter glass.........If you hold a Crankshaft in the air and hit it with a hammer, it will ring like bell...That is its natural frequency ... When the left over vibrations of the engine that cannot be 100% counteracted (or the twisting vibrations of the Crankshaft that cannot be counteracted and must be "dampened") reach the same frequency of the natural frequency of the crankshaft, then the vibrations are "amplified".... The Dual Mass Flywheel ( DMF) was designed to damped/absorb the twisting vibrations of the Crankshaft.... Trust me, Porsche LOVES to save weight and would not have used such a heavy part unless it was justified....That would be utterly "stupid" Also on the M97/01 3.8 "S" engine Porsche used a "Vibration Damper" on the front of the Crankshaft in conjuction with the DMF .. This Vibration Damper ( part # 99710224101 )will also fit on the 3.4 and 3.6 engines to help absorb Harmonic Vibrations... 997.1 3.8 "S" vibration Damper What Harmonic Vibrations can do

Dumb question� but this vibration damper will still allow for the crankshaft to be locked correctly?

Quotes source post: 20172477

Yes, has the same U4, U5, U6 position holes plus the UT hole position.. A little back-ground into why I am well versed in Harmonic Vibrations, Back some 30 years ago I set my sights on setting an IHRA World Record.... Subject Engine ::: 2.0 liter 122 Cubic Inch 4 cylinder in-line SOHC production engine Production HP 96hp :: Target HP 500hp Using the stock production Iron Block, Iron Head, and Forged Iron Crankshaft, all other Parts I designed and built my self or commissioned Custom Parts, like Rods, Pistons, Cams ect... In 4 years of development the engine went through 3 stages...Stage 1 150hp, Stage 2 325hp , and Stage 3 over 500hp In Stage 1 Trim I won many many Class Races and Track Points Championships at Lassiter Mountain Raceway, Holiday Beach Raceway, and Green Valley Raceway in Super Stock Class.. In Stage 2 Trim the winning continued but adding the King of the Mountain Race.. In Stage 3 Trim it got a new Tubular Lightweight Chassis along with International attention with a feature article in Super Stock Magazine... Stage 1 : Natural Aspiration ,Knife Edged Crank, TRW 11-1 Pistons, Stock Rods, Holley 2300 Carburetion, Crane p-312 Cam, Hooker Exhaust ...150hp 7k RPM rev limit Stage 2 ; Blow-Through Turbochager Garret T3-60 ,Knife Edged Crank, TRW 9-1 Pistons ,Stock Rods , Holley 2300 Carburetion, Stock Cam, Stock Cast Iron Exhaust ..325hp 8k RPM rev limit Stage 3 :: Turbocharged Alky Injected Induction, T4/B35 Garret ,Edgars Vetting Mechanical Injection, Knife Edged Crank, Aries 11-1 Pistons, Aluminum Super Rods, Crane P322 Cam, AK MiIler Turbo Exhaust Manifold....over 500hp 12k RPM rev limit As i mentioned earlier the in-line 4 cyl has pretty good Primary balance, but a terrible Secondary balance, and this shows up at 12k RPM in the 4th Order Harmonics ..... I did the Knife Edged Crank and polished the complete crank all counterweights to a mirror polish and had it professionally balance by Bill Hamner ( Bill was the Crew Chief for the Woods Bros NASCAR Team in the 60's). he was a good friend of mine as well as his Sons... At 12k RPM the M10 Flywheel Bolts snapped off !!! ...I had to clean up the end of the Crank and Flywheel face and I enlarged the Bolts to 1/2" fine thread grade 12 and Loctited them in ....at 12k RPM they snapped again !!! ......This time I drilled 1/2: dial pins in between each 1/2" Fine thread Grade 12 Bolt plus Safety Wired the Bolt Heads,, and installed a high dollar "Fluid Damper" on the front of the crankshaft...... FINALLY was able to keep the Flywheel on the engine and get back to the business of Racing the new Stage 3 set-up.....and boy was it fast ....I could tell a few stories about that ...but going through this Hell of the Flywheel snapping the Bolts at 12k RPM taught me to respect those Harmonic Vibrations...

Recent discussions reminded me of a few more Internal m96 Tips/Tricks/Mods.... Water Pump Screens On water pumps with the plastic blades, when the bearings in the pumps fail, the plastic blades will break off ....This has been hypothesized to cause hot spots in the heads and lead to head cracking/intermix on the M96/7 engines,if those blades get stuck in the wrong place.. One very popular preventative measure is to replace the water pump every 3-4 years . This method greatly reduces the chances of having a water pump failure , but doesn't eliminate it entirely, and thus doesn't entirely eliminate the chance of plastic blades getting where they shouldn't be .. An alternative method I chose 6 years ago ( just an FYI, not for everyone ) is to install "catch screens" at the outlets of the water pump to catch the broken blades so they can't infiltrate the cooling system, and be easily all collected and removed when replacing the water pump...Thus eliminating all chances of the broken blades causing hot spots/head cracks/intermix... Another alternative to catch screens As another alternative to Catch Screens for avoiding broken water pump blades/hot spots/head cracks/intermix, that is actually a favorite of mine, is to use water pumps with metal blades...Yes , i know that the metal blades can damage the case, and that many many engines have been scraped due to the damage caused by the metal blades digging into the case.... But I have designed a method of repairing the case with a Stainless Steel Molded Shim-Gasket that gives a new surface to the case without welding and expensive machining and can be done in situ without removing and disassembling the engine.....I have one such engine that was was saved from the scrap pile that has been running for year as "proof-of-concept " ...I hear Jake has a whole pile of cases that were replaced due to the damage from the metal blades...I'm sure there are plenty more out there .. Catch Screens on Scavenge Pumps Catch Screens are also used to protect oil pumps..There is a Catch Screen on all oil pump pick-up tubes, even on the M96/7, but there is no Catch Screen protection on the Scavenge pumps on the m96/7 engines.. ( there is one on the 997.1 vacuum pump/scavenge pump tandum device)...It is rare but, Yes I have seen quite a few catastrophic failures from just a small piece of debris about 3-4mm that came from a cam/lifter bucket/spring/ or timing chain , that if it gets sucked up by the Scavenge Pump can lock the pump, then either break the pump drive, or drive gear, or timing chain, or slip the egears in the IM Shaft. This will cause the valves to hit the pistons and can break the cylinder walls or rods ect.. When this type of catastrophic failure occurs, only very careful Forensic Analysis can find the root cause of the failure being just a 3-4 mm piece of debris and that a simple Catch Screen could have prevented it ... If it were a perfect world , and engines were always perfectly clean, we would not need any Filters or Catch Screens...But unfortunately we need Filters and Catch Screens to increase protection and are good internal Tips/Tricks/Mods...

Charles is there a DYI to create the screen? For laymen�s not techs 😅

This post is not about an M96 engine Tip Trick or Mod, but it is about debunking an Internet Myth that the 997 oil pump bypass valve is an " upgrade" to the 996 ...IT IS NOT !!! Any improvement in oil pressure after installing the 997 by-pass valve in the 996 is from fresh oil, higher viscosity, or a placebo effect..... I was involved in the creation of this valve and its purpose was to stop a squealing/screeching noise in early 2005 997/987 engines with a slightly different oil pump housing... Originally they used the same 996 by-pass valve in the new 997/987 oil pump housings, and we ground a champher on the end to stop the noise in early production 997/987 engines....Then the Factory started putting the champher on ALL by-pass valves and added a new part number and this part number supperceeds the 996 part number because this champher causes no harm, ( but doesn't help oil pressure either, just stops a noise in 997/987 engines).. The spring has not changed and ALL 996/986/997/987 engines use the same spring....If your is shorter than a new one, then yours has gotten weak, and this WILL effect oil pressure... So, don't get all excited over changing the by-pass valve...but by all means replace a tired old spring with a fresh one .!!!!!

Good to see you back Skip sharing your knowledge!

Thanks Glen, That post was viewed a lot but not Liked very much. I guess the new group of 996 people want to hold on to their "perceived upgrades" ....lol

I'm bringing a couple of posts over here from another thread because they really belong here.. It is about some testing I did a good while back and found a frugal way to upgrade the oil pump drive ... One thing to mention is the Factory oil pump drive fails at 54 Ft/lbs of torque,. That is a LOT considering the engine only makes about 250 ft/lbs, so the oil pump drive can handle about 1/5th the engines ability to twist things....lol...If your oil pump is consuming that much power something is definatly wrong with it , and it is fixing to lock up. But many feel that an upgrade is in order, so here is my testing and a frugal way to make your own 8mm 50mm long high strength drive shaft... I tested the stock oil pump drive shaft to failure torque, the stock oil pump drive shaft fails at 54ft/lbs torque. I tested several to make sure the first one wasn't faulty. I made my own drive shaft from an 8mm Mac Tools Allen wrench and tested it to failure 153ft/lbs !!! Almost 3 times as much. So I make all mine out of Mac 8mm Allen wrenches now. I have 3 cars, a 99 coupe, 99 cab, and an 02 986, plus I made a few for some friends, Quite simply you just cut to length. I have not tested the LN drive shaft, but I'm sure it is much better than stock also. If someone wants to send me one to test, I'll be happy to see what it takes to snap it into. Three stock oil pump drives all three stock oil pump drives failed at 54ft/lbs simple but effective test rig Tool steel oil pump drive made from Mac 8mm Allen tested 153ft/lbs Just an update on the oil pump drive shaft hardness. I tested the factory drive shaft and it measured from 32-37 Rockwell C varying at different points. then tested the one I made from a Bondhus Protanium hex key , it tested 54 Rockwell C,. So the stock drive shaft not only is more brittle, and fails at 1/3 the torque, but also is less hard too !

At work we use hex material sourced from an L-wrench instead of stock hex steel. It was trial and error as we attempted to find stock that could harden to RC59+. The material has a higher tensile strength and can harden with a torch to a much higher RC value.

Quotes source post: 20491921

Where do you work ?? For sure the US made Tool Steel like is used by Bondhus or the Big Three US Tool Companies is much better than any China sourced Hex Steel Stock..... The "Protanium " Tool Steel from Bondhus is very very good ....