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YOUR RESEARCHI hope nobody had stock in aftermarket engine mounts
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My exhaust tips had been changed when the mounts were worn, so I had to lower the tips (and be careful jacking up for the new mounts until the tips were adjusted).
I hope nobody had stock in aftermarket engine mounts
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Fortunately the aluminum ant-seize paste I put on the exhaust clamps when I changed the tips did its job, so they were easy to loosen and adjust (unlike when I first remove the tips, where it took an act of god
I hope nobody had stock in aftermarket engine mounts
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Leading evidence: 'Adjust )' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'safest all around way' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Adjust (unlike' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Although they are not solid, they use rubber that provides some give but not as much as an OEM hydraulic fluid filled mounts.
I hope nobody had stock in aftermarket engine mounts
Fill oem" mounts
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Specifically 997.1 3.6 with "filled OEM" mounts from function first.
I hope nobody had stock in aftermarket engine mounts
Install oem mounts
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Raby on Facebook I installed the OEM mounts on my C4S and boy I am glad I did.
I hope nobody had stock in aftermarket engine mounts
Install oem mounts oday
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I hope nobody had stock in aftermarket engine mounts
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Fortunately the aluminum ant-seize paste I put on the exhaust clamps when I changed the tips did its job, so they were easy to loosen and adjust (unlike when I first remove the tips, where it took an act of god
I hope nobody had stock in aftermarket engine mounts
Adjust )
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My exhaust tips had been changed when the mounts were worn, so I had to lower the tips (and be careful jacking up for the new mounts until the tips were adjusted).
I hope nobody had stock in aftermarket engine mounts
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safest all around way
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I will say that running more octane than necessary is probably the safest all around way to approach this, since it takes a ton more of a mistake with this to equate to an issue than any of the other recipes.
I hope nobody had stock in aftermarket engine mounts
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Earlier in this thread Jake commented that he sees no difference in Porsche branded and OEM supplier branded (ie: Rein) stock type engine mounts.
I knew false knock was an effect but that 10-15 wtq difference in the 5700-6200 range (where the fun really happens) is substantial. This video should be cross-posted in every M9x subforum, at the very least.
I've only shared this data in my classes before I shot this very impromptu video last week. This is nothing new to us, I first saw this in 2008, and even before that.... I just never did a back to back till then. Once we did the back to back all the odd tuning and crappy plots shapes made sense. Looking at ignition angle and EGT simultaneously was alarming.
I'm sure the people that love these things will have an "issue" with these results, and will post their response videos. If they do that, well I'll throw in the ignition angle retardation, and exhaust gas temp data and a few other things that can't be disputed.
This is not an isolated experience, or manufacturer dependent- we see this with every brand of mount, some are worse than others but none are better than stock.
The next video will show me smashing these mounts with a tank, then melting the remnants with a flamethrower.
I was going to buy semi-solid mounts before you shared that in the M9x Engine Rebuild 101 Class class back in 2019.
That knowledge, and the difference in price, made installing new OEM mounts a no brainer.
Thanks for sharing your knowledge Jake!
No, never seen these traits with any stock mount, in any condition.
All it took was 4 laps at Road Atlanta on a hot August day to prove it. Then 7 miles on a mountain road proved it on the street.
"Modded to death" is my favorite term these days.
OMGoodness! I love this data. What poor thinking I went through when replacing my mounts to semi-solid. My thoughts were about power transfer loss due to mount stiffness. WRONG! Vibration sensors driving fuel and ignition circuits are very clearly affected. Guess I need to get rid of my '60's - '70's muscle car mentality... Super thanks for sharing!
Old cars care too.. When building engines for Formula Vees we kept running out of fuel the in the top end on the dyno. Come to find out the solid mounts on the dyno bell housing were causing the fuel in the carbs to behave in a manner that shut the needle valve off too soon, with an impact on float height. I had to soft mount the dyno when testing those engines. Instantly we dropped two main jet sizes, and made m ore power without running out of fuel. On the chassis dyno just last week one of my employees had the same thing happen to his 9,000 RPM Honda race engine running a pair of Weber DCOE carbs, all because vibration dampers weren't in place under the carbs.
Anything with a knock sensing system, and safety retard will see the negatives of false knock.
Everything matters. Every day is a school day here. I'm on the flow bench today, and I've already learned something that I didn't know at 0900 this morning.
I have asked people who sell screens for the test result data of air flow without then with their product. None have supplied the requested information.
Doesn't matter to me because I know my engine guy would hunt me down like I was a chicken stealing dog if I put a set set on! No Thank You! I'll take a hard pass...
They don't have it.
If they did have it, they would not know how to interpret it.
All they know is they look good, and they "keep the radiators clean". Both of those sell them.
By all means I want them to keep selling them. I wonder if they'd consider putting one of my brochures in each of the product shipments?
For those that are considering inlet grilles, I think it's important to understand that these cars were never engineered and designed with anything restricting or defusing airflow through the radiators and condensers. Inlet grilles will block larger objects (e.g. leaves), but the little stuff like dirt and road debris will still get through the grilles. And, in my experience, that's what gets clogged between the radiator and condenser. The big stuff can be easily vacuumed out with an extension tube.
That's what I noticed also -- may more leaves and dirt in
between
the condenser and the radiator than there is on the condenser that is directly exposed to the air flow. It made me wonder whether the screens would even prevent them from getting leafy/dirty again because it kind of seems like the dirt between them works it way up from the bottom than from direct air flow.
Only for the mid- engined cars. I have not noted a difference in 911 variants since they only have the single mount on the gearbox and it is far away from the engine.
Some people like the handling of these stiff mounts.. Not me. I'm not giving up all the things I've noted for some better handling, and shifting. That's because I am an engine guy, and not a car guy.
That's according to the car, the engine, and the driver as well as the application. There's no blanket statements, what works for one doesn't work for another. That's why I don't build generic engines.
Jake, are the only mounts worth buying made by Porsche, or OEM Reins okay? I just replaced mine with a set of reins. They made it under 1000 track miles before they were shot. I have lifetime replacement on them from FCP, but should I just get Porsche parts?
The answer is using the mounts that match your VIN by part #.
It is THAT simple. I have never had an issue when doing this.
I have not seen any differences in genuine Porsche mounts Vs OEM replacements.
I've made this point on this forum a couple years ago that any kind of mesh is a restriction to airflow into the radiators but all the replies were that this is nonsense. Tried explaining that if you add up the surface area of the mesh, it is significant but since these meshes "look" like they are mostly make of nothing, what I wrote was ignored. Glad that finally people are listening to common sense.
You are seeing the mounts there also.. You could feel this in the car while on the dyno. After testing this back to back the very first time years ago I knew instantly what the gains were before I even looked at the first set of plots. It was clear from the vehicle behavior what was going on, and why.
I've also been stating this for years. People didn't listen then, and they still don't. They won't. They don't want to be told that the crap they unnecessarily add to their car is a detriment. They always complain that someone has a commercial interest in what is being said, or delivered in technical videos, or writings. Yeah, I do... Keep using them, and you'll earn a trip to my Morgue with no expenses paid.
The big thing these days are aftermarket front bumpers that lack the proper inlet air shrouds, and diverters around the radiators. These "turbo look" bumpers have huge inlets that stack all the inlet air into the corners of the bumper, but not through the radiators. One guy cracked 4 heads and a cylinder before he finally listened to me.
That said, I LOVE to modify EVERYTHING.. I am not stuck on keeping things the way the factory left them. I have built a 2.7L Boxster engine into a 4.4L and used the factory crankcase, so no way in hell would I say that what the factory does is ALWAYS best. At the end of the day the things they did do their homework on was the things related to engine management. If you mess with harmonics, and dampening, you will pay the price for this. The same goes for diffusing or limiting, or redirecting the charge air into the radiators.
Looks kill.
My guess would be no go given the findings (even though they are an OEM part). Although they are not solid, they use rubber that provides some give but not as much as an OEM hydraulic fluid filled mounts.
Even in the simplest terms if you look at grates/mesh, not only will it restrict airflow due to said surface area covered naturally, add in getting covered with leaves or something, air flow is restricted even further. For what cost, trying to save 15 mins to clean out some leaves from the inlets?
People want to buy something to prevent them from having to get their hands dirty.. Plus it looks cool.. Plus, all the cool kids are doing it.
Last week I drove a 996 with aftermarket shifter cables fitted. Within 15 minutes I turned around and took the car back, and assigned the rest of the test to my test driver. They pissed me off so badly that I changed cars and tested another one.
It's an interesting problem. It doesn't seem intuitive that hard mounting the engine to the chassis would cause a knock-like signal. I assume this is a sharp signal like tapping the block with a hammer would produce. I wonder what goes on here. I wonder what those stock mounts look like cross sectioned
The issue is the mount is not compliant enough, and the sensors confuse the additional shock loads with knock. It's false knock.
The stock mounts are able to absorb these frequencies and the stock sensors are tuned for them.
Yes, we have played around with adding spacers to the knock sensors, and desensitizing them in order to overcome this. It can be done, with a trade- off being risky when you actually do have a scenario that leads to the need for safety retardation to overcome detonation.
That is a hell of a lot of work/ risk/ hassle just to use a mount that never belonged in the car in the first place. We played with a lot of this in World Challenge and other pro series where these mounts did mean a lot to the rest of the car.
Install stock mounts and leave it alone. Period.
That's a good explanation. Is it fair to assume that the 964 or 993 cars that used the factory OEM RS mounts like these
https://www.pelicanparts.com/More_In...0&KeepHeader=Y
(rubber mount but with no hydraulic fluid) had their respective knock sensors tuned as well to work with those mounts?
Those cars used a much earlier and less sensitive knock sensing system. These are critical, and even the way the cylinder bridge is torqued on those engines will matter.
Assume nothing, and quantify everything is my rule, so before anything can be stated about the mounts on the earlier cars a back to back test would need to be done just like what we did in this video. You can't guess.
I very seldom see the cars with my Aircooled engines, I test them on the test cell and ship them out.
Hence why I refer to them as "diffusers'. That's exactly what they do.
Even seen a turbo fan engine on a big *** airplane have an inlet screen?? They take the risk of sucking a pelican into the engine to avoid diffusion and restriction of inlet air.
Valid point. Watching from the window seat on an airplane you can see the turbulent air off one of the vertical winglets. Throw a ton "winglets" in front of a radiator and you get spastic irregular (and reduced) air flow into something designed for direct mass cooling, not going to end well.
Should have commented on this with my above post. Interesting the things I've learned working in aerospace that translate consistently to the automotive world. For good reason.
Is it possible that the USA engines have a more sensitive knock tune than the rest of the world due to petrol octane and or fuel quality variations?
I'm in Australia, I recently installed Rennline adjustable mounts, I put in the softest ones. Huge improvement in feel, less sway, better handling, more direct acceleration to the wheels, much less lag, honestly cannot feel any power loss or hesitation.I really like them, and this is changing out brand new OEM ones specific to the car.
GT3's have stiffer mounts, so I guess they're tuned differently, yes?
What about window weld OEM ones, have you tested these?
I spent quite a bit of time installing aftermarket shifter cables into my car. I probably drove about 25-30 minutes on the car before they were removed. Was not worth the noise.
But does the engine??
Worst thing ever.. They make the car sound like my 1944 Kubelwagen with straight cut gears.. Actually I think the Kubelwagen is quieter.
Safety retardation is there for a reason. If you have false knock then the ignition angle is reduced, and exhaust gas temps skyrocket. This has been noted with head castings that can require as much as .030" of material removal to mill the exhaust flange flat after deformation from exposure to these insane temperatures.
Of course, you won't read about that in a magazine.. You won't "research" that on Google, either...
Damn, i really liked these mounts, I've had them on for about 2 or 3 months with very spirited driving through the hills, about 2000km.
Do you think damage could have occurred in this period? Whats the tell tale signs of damage?
I'm running a cooler thermostat with a rebuilt 3.9L engine with Hartech parts about 10,000km's ago.
Strange, not one Porsche tech mentioned anything about mounts causing any issues, they encouraged me to fit them. And I've been to several well regarded techs.
EDIT; I had semi solid engine mounts in my previous car a 996 turbo for about 4 years, now sold, new owner has had the car for another 3 years, l keep in contact with him.
Never had an issue.
Keep them if you like them. Unless you have hundreds of cars to compare the performance against, you'd never know the negatives from the driver's seat. The engine does, but you likely won't.
Would a worn dual mass flywheel cause any power loss as a result of less than ideal dampening or harmonics? I'm curious to see if a clutch/flywheel replacement with OE would claw back any lost power from worn parts.
Appreciate the reply, Jake! I'm replacing my clutch/DMF alongside your dual row bearing, updated RMS, AOS, transmission mount, clutch+slave cylinders in the next few weeks. looking forward to how it drives after.
Any other items that would make sense to do while the transmission is separated?
When I installed my Numeric shifter cables, the added noise took me by surprise. It's like everyone had posted they loved them to convince themselves (and others) the price was worth it...
There's no conspiracy on the shifter cables, some people actually like the slightly increased NVH because it's a sports car and not a Camry. I have them in my Turbo and also enjoy the heavier and more connected feel.
Likewise, the reason people like aftermarket engine mounts is the instantly tighter and sportier feeling you get out of the rear end. You can't just smugly dismiss everyone with different preferences as being a bunch of tryhard morons wanting to seem cool, even if you happen to be the Smartest Guy on the Internet who's forgotten more than we forums peasants will ever know.
Yes but what�s the point of your comment we should sacrifice car longevity for the sake of poising???
if the smartest tech of the 996 world makes a point I�m going to listen so my car doesn�t end up in a salvage yard or at Flat6 anytime soon
I love the idea of a personalized 911 but it has to work so I can be poseur or a Schumacher if I want
Mike
Everyone likes sportier and tighter, but when there is
empirical evidence that it is bad for the engine, it seems like a no brainer to stick with stock.
This thread has inspired me to install the OEM motor mounts I bought about a year ago but never found the time to install. What's the best "how to" video out there for installing 996 motor mounts?
Wow great insights and knowledge. This is something I'd have never even considered, but reaffirms that I made the right call paying the extra $ to buy genuine replacements. Thanks for sharing, and thanks to Jake for making the video.
I already have the Function First mounts in my car. Like some of you this post makes me worry even though my mounts are supposed to be less stiff than a true semisolid mount.
Is there a way I can use my iCarsoft II data logging to see if my ignition is being pulled or knock sensors are being triggered before I go through the effort of buying OEM mounts and selling my FF ones? Thanks!
Here is the Porsche supercup solution to motor mounts. Did these cars have problems with false knock sensing? The mounts look pretty Beefy. are they solid? Looks like they might be.
yes, apparently. do they have knock sensors? how do they prevent false knock with the full race motor mounts like zbomb has and are installed on the super cup cars?
Yes the Mezger engines have knock sensors. The Turbo cars don't seem to be bothered by the semi-solid (urethane) motor mounts, they don't like solid mounts (aluminum) - solid mounts on a street car are dumb anyway.
It is amazing how people always pat themselves on the back after completing an engine mount change. You hear comments such as "I notice an immediate improvement"..... "I can feel the difference right away"....... all they did were mind-f**king themselves.
I don't think this is an accurate assessment. The original OEM mounts sag
considerably
over time. Whether you replace worn mounts with OEM or aftermarket, it is very likely that you will feel a difference simply because worn out OEM mounts are nowhere close to their original spec. Replacement OEM mounts will restore it to how it was when new, and aftermarket can make it feel a lot stiffer than it was when new, so a difference in driving difference is the norm and expected. I've seen occasional RL posts where they didn't feel a change, but even then there was a large difference in exhaust height (if not, then the originals weren't worn).
The only thing that wasn't broadly known was that the stiffer aftermarket mounts actually reduce power a bit because it triggers the knock sensors, but even then (from Jake's prior comment), you won't likely feel the power degradation despite the fact that it is consistently measurable on a dyno.
I can feel the difference in power when the ignition timing is altered due to false knock, both on the dyno and on the street. I would likely never know the power was falling off if I didn't already know it from seeing a graph beforehand, or having my extensive prior experience with this.
New mounts tighten everything up,, and that is good for everything except the engine. The car handles and shifts better, but I don't care about the car- I care about the engine. I especially care about my engine going back into the car.
Here's an example of what high EGT (exhaust gas temps) can do when coupled to aftermarket headers that are too large at the port entry. The excess heat from the retarded ignition timing has all sorts of negatives that go along with it. This car had non- factory engine mounts, tranny mount, and some "well known" headers that are built from the "bigger is better" perspective.
The retarded timing that is pulled away to help reduce detonation rapidly increases EGT, couple that to the larger than rehires primary entry diameter and shape, and you see where the elevated EGTs actually melted the port all the way to the edge oof the primary header tube. Using any component that causes a reduction in ignition angle will elevate EGT, especially at WOT, so as you can see, this is about more than a reduction in power. No, I am not making this up, I have seen the same things with aircooled engines when I botch ignition timing on the engine dyno, even on old stuff with carburetors and no knock sensing. too much timing kills power and creates pre- ignition, not enough timing allows the combustion to occur while the exhaust event is still underway, and the valve is not seated. In these cases the flame acts like a cutting torch, and you warp exhaust flanges, have exhaust leaks that can't be cured, and ultimately will crack heads through the secondary air injection passages (especially M96.24 and M96.03 engines).
You quickly learn to tune for EGT, yet modern tuners typically have no idea what the hell it even is.. Then you end up with this. Since they don't have experience tuning older stuff, they don't know how to find the sweet spot of too much timing, and not enough timing. Since most of them don't have a thorough understanding of how the engine operates, they don't know what their changes to the tune will do to the physical things inside the engine.
These heads are now junk, they are 997.1 3.8 Carrera S heads, and while I could repair them, I will not. They have seen too much trauma. These will now be training aids in my hands on classes.
No compromise here.
No, I don't make this stuff up.. I share just enough of what I see and experience here and on Facebook. We see the wildest of the wild, and the most hacked up, and butchered up stuff out there. After everyone has exhausted all "other options" then they finally give in, and make the call they should have made first~
Jake please elaborate doesn’t certain aftermarket exhaust or all aftermarket do damage I have fabspeed 200 xpipe cells going on with muffler delete should I stop the process or are these ok
Thanks for sharing. I'm an originality guy, so I'm never really tempted to change anything (only exception is the rare occasion where a factory part has a known weakness). It's easy to get tempted, because some of the aftermarket stuff looks like it is much better built than the factory parts -- and some of them are much better built -- but "better built" doesn't matter if something doesn't fit with the engineering in the rest of the car. Your post helps shed a lot of light on that.
Another myth is the oil-impregnated air filter letting more air-intake. It is more porous for sure, but using oil to trap dirt. The only way to allow more air flow is more filter surface area which the paper elements achieve that by having more pleats. And another way is not to use air filter at all like the F1 cars which they rebuild their engine after every race.
If he posted the number, when someone had a problem it would be "But Jake said this was the spec.... "
Never mind that no two engines are alike and you might be +/- 500 rpm or 5 degrees of timing ,, different temps etc..
The trash talk would commence, Then the keyboard commando's show up to party.
The symptom has been described, the tools are available to use on your own to grab your own data..
I've seen the same issue on a Corvette, Takes significant changes in engine management to tune around the issue.
LS7's are twitchy too once you circumvent the millions GM spent developing them.
Same principle as running a lightweight aluminum single mass flywheel on many engines..
Race track benefits with proper tuning and acceptance of the limitations.
For the street with no tuning checks? We all pick our poison.
Like using HP Tuners ? Tuning for knock control is not something new or particularly exotic. I don't really understand your significant engine management statement as ECU tuning for the LS is WIDELY supported and the knock control tables can be configured for a particular application.
To clarify, I tune my own car and have had no issues similar to those that he's describing, hence my response. I wasn't asking for how much timing he's running. I was asking for how much is getting pulled, correlated to RPM, compared between runs. I don't understand the secrecy, especially if your goal is to alert your clientele ('running aftermarket mounts are bad and here are the data to corroborate that').
Any amount of timing that is pulled from safety retardation due to false knock is too much. One degree of timing retard that is not necessary is notable when looking at EGT closely. I have seen 2 degrees of timing retard equate to a 50*F elevation in EGT @WOT. Once EGT hits 1250F, things change fast. I have seen valve jobs killed with a 1350F EGT in a matter of just a few minutes. The last one was so bad that when the cylinder head was removed you could easily see light around 1/3 of the valve, where the seat had drooped from under it. This helps to loosen valve seats, especially in M96.03 engines that already have issues with dropped seats.
The primary O2s have a job of loosely monitoring EGT and reporting back to the DME, but they are located too far from the exhaust valves to really indicate anything. I fit engines with test headers that have an EGT probe in every primary located 3" from the exhaust flange, and I gather this data stand alone. I don't give a damn what the DME is reporting, I want to see my data and tell the ECU what to do, not allow it to do things for me that I don't like, just because it was programmed to keep the catalytic converters happy, so they'd live for 10 years.
The issue with threads like this is people end up listening to respond, rather than listening to learn. It would be a lot more productive if the information was one direction only, just like it is when people pay me to come sit in my classroom. That is when they actually learn.
99.6% of the people watching the video that explains what I experienced directly will never be my "clientele". Typically the ones that don't watch it, and bolt things onto the engine that end up with negative impacts on the engine will become my clientele because they experienced a failure.
This video was one from direct experience that probably cost me more future business than it created. Why? Well, because
people don't need me until something blows up, fails, or becomes injured beyond simple repair.
Further, this won't benefit my clientele because any car that arrives here with aftermarket mounts, will not leave with them fitted. That's also not because I want to sell them a set of factory mounts, either.
I was running the 964/993 RS mounts for a few months but swapped back to OEM last week. When I get back into the office, I'll share some plots of some data logged via Torque Pro app. I was comparing MAF vs RPM, and also overlayed calculated MAF for various volumetric efficiencies. I found MAF dropped noticeably relative to VE above 5000 rpm. Leads me to believe that's due to timing being retarded. Haven't had the chance to log more data and update the plots with OEM mounts.
Jake, If you were working on a racing engine with the chassis utilizing solid mounts, would you tune the knock algorithm to filter out the noise associated with the mounts and other various non-street car modifications ?
I would base the route on whether engine longevity, and power was more important than handling to the driver.
I would do everything possible up front to refrain from using the aftermarket mounts, even if it was a full competition car. If they still wanted to use them, I'd explain what would happen in the future, and why. We'd have a full agreement that no whining would occur when something popped.
That said, we have tried to tune around the issue, but I have had much better, and more consistent luck using rubber faced washers to fit under the knock sensors to try to isolate them from the false knock. How many washers are used seems to be the key. We have to watch the timing and adjust them as necessary, but of course you have to collect your own empirical data from the same car and same engine with stock mounts to try and replicate later. Seems crazy, right? It is. I have also used additional systems, like a JS Safeguard to monitor knock that really existed.
In some cases we have turned the safety retard off completely, and then ensured that the engine had adequate octane to overcome the chances of knock occurring. For maximum power, this has always worked best, and even though it is risky, I would rather take this risk as deal with the ECU doing things to the timing (unknowingly) that could be even more risky. I want to tell the engine what I want oil to do, based on what it tells me that it likes, I don't want corrections to be made otherwise.
Awesome ! Thanks for the detailed response and the over-octane method and killing the knock control completely makes a ton of sense I had not considered.
This also doesn't come without some potential issues.. If you go too high on octane you can end up having the same EGT issues that you do with less octane, and retarded timing. The slower burning fuel needs more advance to burn completely IF you have more octane than the engine combination and operating environment dictates. By this point you are probably using leaded fuel anyway, which also throws another dynamic into things.
This is where you need stand alone EGT logging, or old school EGT thermocouples to see what the EGT is at the end of a WOT hard pull to max RPM. Adjust octane as necessary to reach an EGT maximum of 1200 F for max power that will live. Enrichment also impacts EGT, and both rich, and lean conditions can run it too high. The worst combination is too much octane, too rich of a mixture, and too little ignition advance. That skyrockets EGT.
I will say that running more octane than necessary is probably the safest all around way to approach this, since it takes a ton more of a mistake with this to equate to an issue than any of the other recipes.
I mean, if this approach is what you'd prefer, that's your prerogative; as someone who presents regularly (albeit in a different field (software automation)), I welcome feedback/bidirectional communication. It seems like you're attaching your ego to the information that you're providing and that's unfortunate.
That's a bit of a stretch. Why share any information then? If he's going to present his findings, more information is better. If his goal was to teach/help people better understand how these engines/software function, actual numbers that correlate various metrics would be the way to go, in my opinion.
100% agreement there.
In my opinion, you don't have a clue.
This man has devoted the last two decades to helping and teaching people about these engines. He has trained thousands through the organization he founded called The Knowledge Gruppe. I've personally had the honor of working with him to produce educational media for professionals and DIYers alike. We've spent countless hours over the last three years giving out free information about the inner workings of the Porsche engine on YouTube and other platforms.
If he chooses to refrain from giving out specific information, then he probably has good reason to do so; therefore...
Suck it up, buttercup.
There's a class for that.. The M9X High Performance Engine Class, 201. I first held this class in 2013, and this sort of information is what is shared in the class. 6 hours of a 40 hour (4 day ) class is dedicated to this type of tuning information.
Yeah, there's a lot of ego involved with dedicating 29 years of life to understanding engines, and earning your way to the top of the food chain from direct experience, blowing things up, and picking the pieces up and doing it again.. Some people don't like that, and I don't care. What you perceive as ego should be perceived as confidence, if you put the judgment stick aside, there's a ton of difference with the two.
I have had limited exposure to the function first mounts. I have a 997 coming up that came to us with these mounts fitted, and I will do a comparative when the R44@ 4.4L engine goes back into that car.
I did test another 997 two weeks ago that used the Rennline mounts Vs stock replacements, and did not see as big of a difference in that car as I had seen in the past. These results do carry over, but both the 997 and 897 ECUs seem to do a better job of not pulling as much timing as the 996.
These comparatives have always gone on here, this isn't new. I usually have to waste time to gather data to prove to the customer why their beloved "*** shakers" need to be removed and replaced.
That would probably just make me tell more people no.. I've done too many R- Series this year. I'm cutting way back on what I produce personally in 2022-23.
Thanks, I appreciate you going through the effort to report back on the effect of the function first mounts on the 997. Would definitely like to see the 4.4 on the dyno regardless
Warning, NOOB. OK, I just read this interesting thread. I recently acquire a 2006 997 C2S Cabriolet Tiptronic with 78k miles. I just took a look at the mounts and the date indicates they are original.
How do I know whether they need to be changed? Is there some kind of test I can perform?
Some people look at how their tailpipes are hanging. Some get excess vibration at idle. Not sure there is any definitive test but at nearly 80k miles it wouldn't hurt to replace them with new stock mounts.
Post a pic of the rear of the car. We can generally tell by the tail pipe sag. May want to start a new thread. Either way they r old rubber so just plan on doing it.
As others have noted at 78k miles I would do it just as a preventative measure. Tailpipe sag is an easy indicator, and end of the day it's a simple job that doesn't cost much to replace with fresh OEM mounts.
No, eyeballing the tailpipe is not definitive on whether the engines mounts needs replacing. You just can't base on the exhaust plumbings, which is routed throughout the various engine bay, to decide whether the mounts need to be replaced. A better way is to rev the engine from idle to about 4000 rpm and eyeball to see if the exhaust pipe sways back and forth excessively. Having said that, I would replace them if they have been in the car for over 50K miles.
Ok...Ok...How about this: If certain people who are known to you sign a waiver stating they will not bug you incessantly for a 4.4 after viewing the drive video and that if they try to share the video with anyone else it automatically melts down their computer and all it's internals would you send it out? Huh...would you...?
So what do think about time, like how many years? Mine only has 30k on it. Was in storage from I bought it out of storage with 9500 on it 3 years ago. I put The solution in it right away from a registered installer along with a new water pump. Needed to replace the starter motor last year. Everything runs great ( I started getting a puff of white smoke on cold startup! just this week) but thinking about UAOS and mounts preemptively. I just found a cracked front axle boot that I need to replace.
Nobody said that it was definitive, only that it's a visual potential indicator. Rev'ing the engine to look for movement works also, but again, a visual indicator. It's cheap and simple, why count pennies on an OEM mount?
Mine has 34k on it, bought with 23k in 2017. Replaced in 2020 just for something to do. As above, it's easy/cheap and only provides benefit to a 20 year old car. You paid up for the solution and a water pump, drop in new mounts. Smallest hit in your pocket outside of an oil change.
Not new tech,, but with a solid motor plate and > 900HP NA the game is "more extreme" We did it with the GM ECm ,, but eventually it got a motec.. BTW this was a full "tube in tub" car so extremely rigid. Mainly I was pointing out this problem is not unique to Porsche..
After talking to Mr. Raby on Facebook I installed the OEM mounts on my C4S and boy I am glad I did. Mine were shot, and after installing the car feels completely different, not like a tractor. I also gained a little bit of gas mileage in the process, which i thought was interesting.
I used the FCP Euro video as a good reference point to do the install. It took me about 45 minutes to do it.
You Tube
My mounts were shot when I had them replaced last year although I didn't notice any increased mileage afterwards. However, two weeks ago I had coil packs/plugs and fuel injectors replaced and my car has never driving as smoothly as it does now, and I can see my average mpg gauge drifting higher with every drive. UAOS was installed as well though I don't know if that could be having any impact on the quality of the drive.
I have new oem units on the way. I am glad Jake posted this when he did, but less glad that the car always finds a way to take my money!
My car currently has semisolid mounts and just about every tech who has ever driven the car complains about them, but they never mentioned the potential harm they could cause. It will be nice to have a smooth running engine since I do a lot of long road trips in it.
Please post your thoughts on going back to factory mounts when you get them installed. I'm in the same situation and wouldn't mind hearing what other people thought the feel of going back to stock is like.
Thanks for posting the video -- very helpful. I bought my OEM mounts at least a year ago, never had time to install, but hopefully will get to this weekend or next.
The only thing that I found was that I did the passenger side first and didn't have the engine jacked up enough, so when I got the nut off the engine settled a little. I jacked it up more and everything went together perfectly. Only do 1 at a time and make sure they match up (ie the little square on the mount goes into the little square on the car).
You can’t warn about things you don’t know.
Most techs/shops don’t have a dyno readily available to test mods.
Plus most people wouldn’t think an engine mount would affect the engine.
Really only someone who focuses on the engine(the same one hundreds of times) would even consider testing before/versus after.
Why not just have any technician rebuild your engine?
Because you should really want someone who focuses only on getting the best out of the M9x, not someone who wants to sell you a brake job, or tires, or transmission flush, or tires, or alignment, or…
Same thing goes for transmission rebuilds…pick someone who specializes in transmissions.
Installed my OEM mounts oday. Thanks again for the video and advice, particularly about the little square. You really have to have the engine jacked up enough to be sure the new mount is seated in the square by making sure you can no longer rotate the mount. My exhaust tips had been changed when the mounts were worn, so I had to lower the tips (and be careful jacking up for the new mounts until the tips were adjusted). Fortunately the aluminum ant-seize paste I put on the exhaust clamps when I changed the tips did its job, so they were easy to loosen and adjust (unlike when I first remove the tips, where it took an act of god
to get the clamps loose).
I'm pretty sure mine were original (2000, 78k miles). They were stretched more than half an inch. The new mounts make a big difference in how the car drives. Over bumps it is a lot more composed instead of wanting to track with the divots in the road. Smoother, better shifting, and feels significantly better in corners. It almost looks like the rear end sits a little higher, but I doubt that is the case.
I changed my original mounts out for semi-solids back in 2018 and saw an immediate improvement of a different type. My original mounts were so bad that I could set up a weird rear end vibration if pushed the car at speed. After a heavy acceleration from, let's say 60-80, a vibration would set up like a wheel out of balance. It would dissipate over a short time at the new speed. When I changed the mounts, it went away. I was happy! Needless to say, with this data, they've been changed back to the original mounts. And I'll be even happier!
I used to repeat this information when people would post "what mounts should I get?" but got tired of doing it after a while. Some people simply don't want to hear it.
What's interesting about this topic is the elevated Exhaust Gas Temperatures (EGT) that may result and the damage it may do. It would be an interesting topic to explore further.
Is this concept applicable to RoW cars as well or is this primarily a USA thing?
Have genuine 964RS mounts in my RoW C2 - have never had an issue with them but the data is compelling...
It's interesting as the 964 has knock sensors as well - not that it's much to go by. As well as the RoW tune being different. THe RoW cars don't have the emissions regulations the US cars do as well.
Guess I could do some PIWIS logging swap them out and log again and see the differences. Although someone in this thread said they had done that already?
The Knock Sensor is a simple Piezo Sensor ( Piezoelectric Sensor)/voltage generator that produces a voltage when vibrated or it hears a knock sound..
The ones for Automotive engines are tuned and filtered for specific applications...There are several ones that are tuned for different engines and each can be filtered to filter out unwanted EMI noise or vibrations that are inherent of the application.
When the Piezo hears a knock sound or vibration it produces a voltage signal. The knock or noise it is tuned and filtered for is the pinging/knocking sound of Detonation that is almost exactly like the sound /vibration from hitting the engine with a metal wrench or extension ect..
I was the Top Troubleshooter in the SouthEast for a decade in the 80's when FoMoCo was developing the EEC Control Systems with the help of Toshiba,INtell, and finally Motorola ,, in the EEC-I through EEC-VII which is still in use today......In fact the KOER self test ( Key On Engine Run), the Tech would strike the engine with a wrench or extension during the self-test to pass the Test and make sure the knock Sensor was working.....If the Tech didn't strike the engine, or the Knock Sensor didn't produce a signal, you would get a code for "Knock Sensor faulty"....
When the knock/vibration is heard by the Piezo Sensor and voltage is produced, the timing is retarted by 3 degrees each step untill the knock/vibration is no longer heard...
These Sensors and Filters are carefully designed for each Application specifically ..
This has created many problems for guys doing engine swaps, and swapping engine mounts., so I wouldn't advise it without doing before and after engine Timing Logs...
Because to produce maximum power you want the fuel burn to end by ~23 degrees ATDC ( After Top Dead Center) to give the maximum "push" on the connecting rod........ .so when the Piezo Sensor is picking up a vibration that it is not actual Detonation, and the timing is retarded by 3 degrees each step , so the timing can retard a lot and the fuel will still be burning when the exhaust valve opens, this will cause the EGT ( Exhaust Gas Temperatures) to rise more then normal...( and produce less power)
A lot of unfavorable conditions will start to emerge when the ignition timing is retarded more than is needed to keep from detonating, depending on the severity of the late ignition timing, but the exhaust valves will get hotter, as will the pistons, the coolant, the oil will be thinner, the headers will be hotter, and of course the power will be less...
It applies to any car with Piezo Knock Sensors.....
On Cup cars the Sensor and Filters are tuned for that application...
But if you change things, its best to do before and after Timing Logs to make sure it is compatible...
This is cool info! In the spirit of learning and asking questions I'll stir the pot a little on the topic
1. When getting an aftermarket or a custom tune, can the knocking sensitivity be "tuned out" to an extent, like it is in cup cars so this becomes a non-issue?
2. I'd be curious under what specific conditions would the knocking and timing change occur? Is this under any driving conditions or more present when when really pushing the car, like on a dyno or on track conditions?
3. Arguably, there has been hundreds or probably more like thousands of various versions of aftermarket motor mounts sold and have been in use for a very long time, many years in a lot of cases. Potentially, those or at least some of those drivers should be able to tell the loss of power taking place or maybe they can't if it's really nominal? I say this as I have not seen any reports of people going back to stock mounts because the car lost power. I know ignorance is bliss but if the reduction in power is significant, the forums would be lighting up with reports.
4. The increase in exhaust gasses is very interesting! What would the prolonged exposure to this condition look like? Can we expect some sort of damage to the valves, heads, exhaust ports and headers over time, especially if someone ran aftermarket mounts for several years?
Just a few questions that I had. By no means am I saying the findings from flat six are wrong but more curious how they really present themselves in the real world and off the dyno. I imagine that by a large margin, the reason for getting the stiffer mounts is to tighten up the feel and handling of the car by doing away with the secondary motion of the engine, for which the OEM mounts allow. Myself included, but many folks have reported tighter rear end handling characteristics and better shifting, which I think is the main reason for getting these mounts. Modern P cars have active mounts that can be softer and stiffer based on mode or driving condition which is a great approach. One can only assume that Porsche has tuned those cars to compensate for that, similarly to the cup cars - I don't know much about the modern engines but that's my guess. At the end of the day, modifying cars is a balancing act. You might get something on one end and lose something on another. You need to find a balance in it and ideally not cause any damage to the car as a result of those mods.
Posted this before but may be interesting to some folks following along with really good info on how the sensors work and the calibration strategies used.
You Tube
I can't detect a power loss with my GT3, but the handling improvement was night and day. I'm running the RSS semi-solid mounts. I probably have about 30K on these mounts.
The Video from HP Acadamy is as usual from them very good and accurate info and is a great over-view of the how Knock Sensors work and the tuning strategies for ECU tuning,. This of course has already been done on the Porsche DME 5.2.2 or 7.8 DME's by the Porsche Engineers who were responsible for the calibrations and also the EPA certifications of the calibrations...
The HP Academy video does touch on the issue were are talking about here near the end of the video at about 32 min in, but only for a short instance ,when discussing/ tuning the "threshold" of the signal...The threshold is the "other noise/vibration" that is inherent in the signal that is NOT cause by actual detonation....in other words, he is tuning out the noise/vibrations caused by engine mounting systems ect...On this Nissan ( or whatever it is ) if he were to change the engine mounting system,( even going from sold mounts back to rubber/isolated mounts) the " threshold value" would change .... and would need to be re-optimized ..
Other issues that will be included in the "threshold value" beside the engine mounting system is the EMI noise ( Electro Magnetic Interference ) that is generated in every application from things like the alternator, the ignition coils, the injectors , and change-over valves -solenoids/coils.....all these produce EMI noise that is also in the Knock Signal along with any mechanical noise such as piston slap, lifter noise, ..all these are combined and is refereed to as the "threshold value" ...which means all the noise the Knock Sensor is hearing that is NOT actual Detonation....
Bottom line :::: Engines are noisy and vibrate , do all M96 engines produce the same noise and vibration ? NO ..........Do all M96 engines have the same "threshold value settings" ? Yes :; if the same DME calibration it is the same settings......... Is your engine/set-up very near the threshold values ? Who knows ....
I have not heard of issues with the Mezger engine, it's already super noisy. The dme is a newer version as well. I datalogged mine extensively with RSS poly mounts and did not find any evidence of timing pulling.
