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-   -   Engine mount inserts ... don't ! (http://986forum.com/forums/showthread.php?t=59484)

10/10ths 01-01-2021 01:09 PM
No codes....
 
....you will just lose power.

The stiffer motor mounts trigger the knock sensors and the engine management will retard ignition timing to prevent what it thinks is detonation.

I’ve seen dyno tests to prove it.

I promise you that every Porsche out there with inserts or polyurethane bushings in their motor mounts now own slower cars.

So if you want more noise/vibration/harshness AND a slower car, by all means, send your hard earned money to the aftermarket purveyors who feast on all of the uninformed new Porsche owners who are now buying these old cars because they have depreciated to the point where they are cheaper than new Corollas.

You have been warned.

Just don’t do it.

Cheers.

78F350 01-01-2021 01:29 PM
Quote:
Originally Posted by 10/10ths (Post 628489)
... I’ve seen dyno tests to prove it.

I promise you that every Porsche out there with inserts or polyurethane bushings in their motor mounts now own slower cars. ...
If that's the case - and I'm not arguing, I'm enjoying driving my slower car fast.

Are any of the dyno comparisons documented and available? I enjoy reviewing details and statistics to to learn and arrive at my own conclusion.

GLImages 01-02-2021 03:34 AM
Quote:
Originally Posted by 10/10ths (Post 628489)
....you will just lose power.



The stiffer motor mounts trigger the knock sensors and the engine management will retard ignition timing to prevent what it thinks is detonation.



I’ve seen dyno tests to prove it.



I promise you that every Porsche out there with inserts or polyurethane bushings in their motor mounts now own slower cars.



So if you want more noise/vibration/harshness AND a slower car, by all means, send your hard earned money to the aftermarket purveyors who feast on all of the uninformed new Porsche owners who are now buying these old cars because they have depreciated to the point where they are cheaper than new Corollas.



You have been warned.



Just don’t do it.



Cheers.
If you can see the effects on a dyno, I would think you would be able to see this in durametric. Should be easy to test I think. Can you see what the cams are doing live with a durametric? I don't have one, so not sure. If so the ecm should be pulling timing when detecting knock right? Drive around with durametric running, what does the timing do?

Question, do porsches of this year show 'pending' codes? My other cars do, but are newer canbus cars. I would think there would be at least a 'pending' code if it detects any knock at all, then sets a full blown code once it hits the requirements (whatever those are, detection during a certain # of drive cycles, etc).

edc 01-02-2021 03:42 PM
I'd be imlpressed if somebody has done back to back Dyno runs on the same car showing before and after a change of engine mount and has posted the plots for consumption!

djw8282 01-03-2021 01:41 PM
Quote:
Originally Posted by 10/10ths (Post 628489)
....you will just lose power.

The stiffer motor mounts trigger the knock sensors and the engine management will retard ignition timing to prevent what it thinks is detonation.

I’ve seen dyno tests to prove it.

I promise you that every Porsche out there with inserts or polyurethane bushings in their motor mounts now own slower cars.

So if you want more noise/vibration/harshness AND a slower car, by all means, send your hard earned money to the aftermarket purveyors who feast on all of the uninformed new Porsche owners who are now buying these old cars because they have depreciated to the point where they are cheaper than new Corollas.

You have been warned.

Just don’t do it.

Cheers.

Hey 10/10ths.

I will be pulling my Powerflex engine mount. The vibration is too harsh coming from this area. Question for you. When you say lost of power from engine mounts, are you saying Transmission mounts as well?? I have Rennline trans mounts and I'm not sure if I want to pull those as well.

By the way I have a Durametric. I didn't see any underlying codes. Maybe someone can direct me what to look for if theres a knock sensor issue. Thanks.

JFP in PA 01-03-2021 05:09 PM
You wouldn’t get a code, the timing would be retarded by the DME when it senses the vibrations the mounts transferred to the chassis, assuming it was actually pre ignition, but as soon as the vibration stopped, the timing would return to normal. You would need to catch the timing in real time.

djw8282 01-03-2021 05:43 PM
Hey JFP,

So when you say real time do you mean while driving? Anyway to monitor it with the Durametric while driving? What about the transmission mounts? Do they aid in retarding the timing? Any insight is much appreciated. Just trying to decide if I will keep the transmission mounts. I'm definitely taking the front mount out.

maytag 01-03-2021 06:17 PM
Yes, the durametric will allow you to monitor any systems while driving. I understand that there's also a utility to record a session, though I've never used that feature.

Sent from my SM-G970U using Tapatalk

djw8282 01-03-2021 06:24 PM
I've used the Durametric for other issues, but I'm not sure which feature to select for the knock.

My main concern is the transmission mounts. I want to know if they have an effect on the knock as well.

maytag 01-03-2021 07:04 PM
Well to be honest, I don't think that you can monitor the knock sensor directly. I think you'll be looking for the DME's RESPONSE to knock.

I'd watch for things like ignition angle, for instance.

JFP may know more.

I've used mine mainly for watching the o2 sensors and the fuel trims. (And cam deviation, etc).

To be honest though, I seriously, SERIOUSLY doubt that you're going to be able to demonstrate that the knock sensor is being triggered by the engine mount. I just don't believe it is, so I don't know how you'll demonstrate that it is.

Sent from my SM-G970U using Tapatalk

djw8282 01-03-2021 07:07 PM
I gotcha Maytag. I'm not sure what to think to be honest.

Radman 01-04-2021 04:56 AM
Are we talking the inserts or the replacement bushings they offer? My understanding is the replacement bushing largely feels like stock, maybe a little more stiff, but that the inserts drastically increase the stiffness. Is this correct?

JFP in PA 01-04-2021 05:50 AM
Quote:
Originally Posted by djw8282 (Post 628566)
Hey JFP,

So when you say real time do you mean while driving? Anyway to monitor it with the Durametric while driving? What about the transmission mounts? Do they aid in retarding the timing? Any insight is much appreciated. Just trying to decide if I will keep the transmission mounts. I'm definitely taking the front mount out.
In the Durametric system, you can see the amount of ignition timing; if vibrations triggered the knock sensors, the timing amount would suddenly step down until the vibrations fall off, then the timing would come back up in a step like function. You can set the Durametric system up to record the timing and take the car for a run.

Solid or near solid engine mounts can trigger this phenomenon, transmission mounts less so because they are further away from the sensors.

djw8282 01-04-2021 02:31 PM
Thanks JFP,

That answer my questions. I will most likely set the semi-solid trans mounts to the softest setting and take out the front engine mount. Thanks

My question is this, why do race cars have more aggressive mounts? Does it detract performance as well?

Thanks.

JFP in PA 01-04-2021 03:02 PM
Race cars typically either remove the knock sensor or disable them as they serve no purpose on a race car; and quite often run an aftermarket computer as well. And race cars run either very hard or totally solid mounts as softer mounts actually consume some HP that would other wise be transmitted to the rear wheels. Racing is a totally 10 tenths world, were small differences add up to winning or losing.

Competition cars and street cars are two totally different worlds, and neither one tends to do well in the other's environment.

djw8282 01-04-2021 03:09 PM
Gotcha, thanks for the detailed explanation.

djw8282 01-04-2021 04:57 PM
Oh just want to piggy back off of what JFP said about softer mounts consume HP. That's why I changed my mounts so I can put the power down to the ground better. Honestly I'm not sure if I can feel a difference.

10/10ths 01-05-2021 05:22 AM
And...
 
....just to tie a ribbon on this, a street car makes a lousy race car and a race car makes a lousy street car.

A lot of these aftermarket parts that people think will improve their street cars actually make things much, much worse on the street in the real world.

Now I’m done.

JayG 01-05-2021 05:36 AM
Quote:
Originally Posted by 10/10ths (Post 628639)
....just to tie a ribbon on this, a street car makes a lousy race car and a race car makes a lousy street car.

A lot of these aftermarket parts that people think will improve their street cars actually make things much, much worse on the street in the real world.

Now I’m done.
yup! Applies to aero as well. What you think looks good can reduce performance

djw8282 01-05-2021 12:45 PM
Quote:
Originally Posted by 10/10ths (Post 628639)
....just to tie a ribbon on this, a street car makes a lousy race car and a race car makes a lousy street car.

A lot of these aftermarket parts that people think will improve their street cars actually make things much, much worse on the street in the real world.

Now I’m done.
You live and learn..


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