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-   -   Engine Leash - Introduction (https://www.gencoupe.com/3-8-v6-discussion-2013-up/558953-engine-leash-introduction.html)

titan2782 08-01-2016 10:19 AM

Engine Leash - Introduction
 
Introducing the Engine Leash! What is it? To start, if you're not familiar with solid engine mounts or torque dampers, then let me explain the problem first.

The Problem
When fitting engines and transmissions into a car, be it FWD, RWD, AWD, mid or rear engine, it doesn't matter, they all need some way to connect to the frame and/or body of the vehicle not only so it stays in place, but to provide rigid support.

What happens is that you have a moving piece of metal that vibrates, twists and makes noise. When you connect that noise/vibration to a solid frame and/or body of the vehicle, those vibrations have to go somewhere, right? Right! They go into the car. This makes it uncomfortable for the driver and passengers. Another issue is that when you step on the throttle, the engine will twist opposite of the crankshaft. This movement can be felt in the car as well.

Manufacturers are quite smart, of course, and add a cushion between the engine and the frame/body. They use various strategies, but basically it comes out to a rubber insert that will absorb the vibrations from the engine. The inserts are also soft enough that when the engine twists, it will cushion that too so the passenger doesn't notice.

These rubber inserts are what go out when you hear someone talk about needing to replace their motor mounts. But what else happens with these rubber inserts? Well, motor flex!

What is motor flex?
Maybe not the correct term, but your engine and transmission have a certain geometry that it is expecting in order to work. When the motor flexes or twists too far outside of this geometry, you risk breaking things.

The biggest problem is over time the rubber inserts on the motor mounts will wear out and you get more and more flex. This will cause problems with high performance shifting since the engine twists so much you can no longer engage the gear selector. It's possible to break wires and vacuum lines and it's also possible to break driveshafts.

Performance wise, you give up quite a bit as well. Off the line response is dampened due to energy being used to twist the engine instead of putting that energy into the crankshaft. This makes the car feel less responsive.

Solid Mounts
There are many options to solve this problem. Solid mounts, filling the stock mounts with polyurethane, engine brackets, torque dampers, etc. They all do the same thing, they stiffen up the motor and keep it from twisting under acceleration. You get that responsive feel back and since the geometry doesn't change, your shifting is more accurate and crisp.

The down side? VIBRATION! Anyone who has ever installed any of the options listed above will tell you that you significantly increase the vibration in the cab. I installed solid mounts in my SRT4 (upper, lower and trans) and the first drive around the block I was already reconsidering. If you daily drive your car, it will bother you.

So that's the trade off. To be fair, over time the solid mounts will wear in a bit and the vibration will be reduced, but it will never go away.

Genesis Coupe
Don't care about vibrations? Want all the performance you can get? Too bad, there are no options for us. There were some torque damper options for the 2.0T, but they seem to have gone away. Basically the only options for us are to pull the engine mounts and poly-fill them. I had considered that, but then I got an idea.

The solution
I wanted to build a bracket, but I didn't want the additional vibration. Not only that, I couldn't find a good mounting point other than the manifold. I didn't want to put additional stress on a potentially weak point of the car.

Waiting for my insomnia to go away so I could finally sleep, I was hit with an idea, why not use a steel cable? Brilliant! The goal was to get the benefits of solid mounts without the problems of solid mounts (i.e. vibration).

Introducing the engine leash!

http://i.imgur.com/WTvArx6h.jpg

It's a stupid simple concept and I built it for only a few bucks. The bracket mounts to the strut tower brace and the other side mounts to the hoist bracket used for pull the engine out of the car.

By using a cable, you get the benefit of solid mounts by keeping the engine from twisting but since the cable absorbs the vibrations, you don't feel them in the car at all. By using an eye hook, you can adjust how tight the cable is based on your preference. If you want more comfort, keep it slightly loose. if you want instant feel, then make it tighter.

Here is a video of the impact it has on twist. please note that you will still see some twisting of the motor with the leash on. This is how I have it setup. I do not have it super tight so it still has some flex for normal daily driving comfort.



These mounts have 36k on them with a lot of hard WOT pulls and 2 track days. If your car has 70k, you'll have far more movement than I do.

Results
The biggest thing I noticed is loss of traction. Up to this point, I've had great traction with the wider tires, but now I can break them loose no problem. I was cruising at 70mph and some WRX wanted to play, so I downshifted and punched it. The TC light started flickering at me.

At the track and on the fwy when doing WOT pulls, I'd constantly have a problem going from 3rd to 4th and would get locked out due to engine movement. I don't normally launch my car, but hard 1st-2nd pulls were pretty difficult as well. Not any more! Every shift is exactly where I want it to be. 1st-2nd gear pulls are pretty damn fun and you notice the difference in launching. If you're a 1/4 person I'd bet you improve your 60ft times with this.

Throttle blips are so much better too. If you do heel-toe then this will help that. Sometimes when blipping the throttle it doesn't respond quick enough, it feels like it was asleep and it had to wake up so rev matching isn't always successful. Now it's not an issue, blips are instant and happen as expected.

Responsiveness of the car in general, weather it's giving it throttle or downshifting, it feels so much better.

Problems?
So far I've put about 500 miles on this thing and the only "issue" I've had is that if you have the radio off, and you listen hard, you can hear the steel cable vibrating.

For Sale?
At this point in time I am gauging interest in this. I only have an option for models with the strut tower brace, but if I can find the brackets by itself for the brace, I'll offer a solution for other models.

If I were to start making and selling these, they'd probably go for ~$70-$80. Of course I'd paint the bracket.

So if I were to offer this, would anyone be interested at that price point? I'm also curious on your thoughts about this idea.

Dfwlly 08-01-2016 11:30 AM

Any benefit on an AT? I'll let you take my money, sir!

DubbuD 08-01-2016 11:33 AM

I'd be interested, unfortunately I don't have a strut tower brace though. :P

titan2782 08-01-2016 11:36 AM

Quote:

Originally Posted by Dfwlly (Post 4282257)
Any benefit on an AT? I'll let you take my money, sir!

As long as you have an engine :)

Quote:

Originally Posted by DubbuD (Post 4282265)
I'd be interested, unfortunately I don't have a strut tower brace though. :P

So far I've had great feedback so I will start looking into getting brackets to support models without the brace.

TKJode 08-01-2016 01:49 PM

Nice write up - I've broken or warped every torque damper I ever installed on my last car, so there's that too lol. I did megan 70A polyurethane mounts for the Gen and the cabin vibration at low RPM is definitely enough to cause trim to buzz, but definitely better than solid mounts (I still have all my teeth!) :)

I used to get some odd driveline axial infighting with the engine & DMF with the stock mounts - mainly trying to take off aggressively at lower speeds - like a weird surging and the mounts alleviated a lot of that - afterwards only the DMF was handling driveline damping, no feedback between that and the engine.

Thumb5 08-01-2016 01:54 PM

You would think the engine hoist hooks would be strong but they aren't really. Seen a few get bent by mongrels using cherry pickers so maybe worth keeping an eye on the hook over time.

Red Raspberry 08-01-2016 02:14 PM

Quote:

Originally Posted by DubbuD (Post 4282265)
I'd be interested, unfortunately I don't have a strut tower brace though. :P

The 2L doesn't have a hook in the right place like the 3.8L.

ApexEight 08-01-2016 02:35 PM

1 Attachment(s)
Interesting idea! Subbed.

titan2782 08-01-2016 03:02 PM

I should add in that this was meant for the BK2 V6 with a strut brace. But I am looking at making one for the BK2 V6 without a struct brace. This may very well work for BK1 V6, but I don't have one to be certain.

As for the 2.0T I don't have one and as red said, the bracket is not in the same spot, so I'd have to engineer a different setup. However, feel free to follow my idea with the cable, but you also have the damper options.

As far as the bracket being strong enough, I made the assumption that because it's used to lift the engine weight, it should be strong enough. Having said that, the force is applied side to side and not up and down so my assumption could be invalid. I did look at the brace and that way it's bent/shaped, I believe it'll be fine, BUT, I am keeping an eye on it for sure.

Red Raspberry 08-01-2016 03:38 PM

There are two bolt holes on the intake manifold a bracket can be attached to, then the cable out to the strut tower on the 2L.

The lifting bracket may be strong when lifting up but I don't know how long it will last when being pulled on at 90*.

Tumba 08-01-2016 05:15 PM

7 Attachment(s)
This looks great! I'm definitely interested. Does anyone smarter than me have any thoughts about how our drivetrain will handle the additional torque? I'm mostly worried about my differential bolts breaking. If it's causing his wheels to break loose then then rate at which torque is applied has increased correct?

titan2782 08-01-2016 05:35 PM

Quote:

Originally Posted by Red Raspberry (Post 4282625)
There are two bolt holes on the intake manifold a bracket can be attached to, then the cable out to the strut tower on the 2L.

The lifting bracket may be strong when lifting up but I don't know how long it will last when being pulled on at 90*.

That was my point, but so far it's been fine. I just checked it and it's still in the same shape it was in before. I think with the line taught, it will be ok. If I had slack in it and it snapped tight then it would probably bend it over time, but that bracket is pretty think and it has an elbow in it that makes it pretty rigid. We'll see. I'm

Quote:

Originally Posted by Tumba (Post 4282705)
This looks great! I'm definitely interested. Does anyone smarter than me have any thoughts about how our drivetrain will handle the additional torque? I'm mostly worried about my differential bolts breaking. If it's causing his wheels to break loose then then rate at which torque is applied has increased correct?

So far so good, but strengthening 1 area will always expose weakness in another. Hopefully it's only the tires. But, when I upgrade the tires again, it'll just put stress on the next weakest area.

ApexEight 08-01-2016 05:51 PM

1 Attachment(s)
Have you ever considered doing the additional differential mount mod or have you already done that? I feel like it would also really help with this same issue that your leash is tackling

titan2782 08-01-2016 09:58 PM

Quote:

Originally Posted by ApexEight (Post 4282793)
Have you ever considered doing the additional differential mount mod or have you already done that? I feel like it would also really help with this same issue that your leash is tackling

i have a trans mount. have not done the diff mount yet, but considering it just to say I've done it.

2NR4LYF 08-06-2016 12:01 PM

Pics on engine?

andbudzi 08-06-2016 12:35 PM

Quote:

Originally Posted by 2NR4LYF (Post 4287610)
Pics on engine?

Yes, pics on the engine please.
I have luxon stratbar so might not work for me.

Sent from my SAMSUNG-SM-G900A using Tapatalk

Lumi1828 08-06-2016 03:38 PM

Thats some damn good innovation you got there. Was looking into buying motor mounts for my car, but after i installed my trans mount i realized the extra vibrations from motor mounts were not for me... (way worse compared to my MK5 GTI) so i started looking for alternative methods and come to found you already made a solution! Might be looking into something like this in the near future! let us know how the bracket holds up!

andbudzi 08-06-2016 03:54 PM

Quote:

Originally Posted by Lumi1828 (Post 4287690)
Thats some damn good innovation you got there. Was looking into buying motor mounts for my car, but after i installed my trans mount i realized the extra vibrations from motor mounts were not for me... (way worse compared to my MK5 GTI) so i started looking for alternative methods and come to found you already made a solution! Might be looking into something like this in the near future! let us know how the bracket holds up!

Did trans mount gave you significant vibration?

Sent from my SAMSUNG-SM-G900A using Tapatalk

superchode 08-06-2016 03:57 PM

6 Attachment(s)
Interesting..... So u r seeing shifting improvement? And how the he'll do you heel toe with the oem pedals hahah? Every time I try I feel like I am going to blow my knee out cuz I gotz to move my heel so dam far. Maybe I need reel wide shoes?? Or better pedals ;)

Lumi1828 08-06-2016 04:05 PM

Quote:

Originally Posted by andbudzi (Post 4287730)
Did trans mount gave you significant vibration?

Sent from my SAMSUNG-SM-G900A using Tapatalk

Slightly, yes. But nothing i cant deal with especially being brand new, i know its going to fade a little bit when they are broken in.

The Pros outweigh the cons with increased vibration i must say.


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