Boosted motor mounts

[jeepmor]

Baseline - 14FRS 6MT HKS Supercharger, HKS base tune from their tablet like device. Reported per HKS website to be a 255 whp tune.

I swapped out the OEM motor mounts for some Torque Solution models. The huge hysteresis (flex/slop in and out of throttle) is pretty much gone. But the parking lot speed NVH is pretty harsh. At speed NVH is acceptable and I like the firm in/out of throttle feedback. The engine noise is significantly more as well due to it transferring into the entire car. It's so racecar sounding it's hard not to like, until, parking lot speeds.


I see STI, group N mounts and Cusco as remaining options for less NVH. I gather Cusco is like the Torque Solutions due to the similar/same design.


Looking for feedback from STI or group N engine mount owners on NVH. And any other options if I missed some.

Tried a search or two but didn't turn up much. Really curious of N type is about the same and I need to peel back to STI.

Also see possible compatibility with WRX/STI subi mounts. Might be looking at the same thing as BRZ STI type mounts, not sure. Trying to sort that out. That may be a good match since the hp levels are very close if the 15% engine to wheel loss applies, that puts me at 293 crank hp, and the STI is 300 or so. Especially with the FA20D WRX STI motor if I have my blocks and all that right. The lower compression turbo motor mounts from the same/similar block might be the ones, but sorting out the exact details is proving I haven't done my homework.

[Ohio Enthusiast]

From my reading, the order is OEM < STI Group N < Perrin < Cusco < solid. Reducing drivetrain lash goes hand-in-hand with increased NVH.

Note on Perrin mounts - they had some bad rep due to early failure, presumably due to being to close to the headers. They now sell a redesigned mount, but there is little info on the new version.

[RedReplicant]

As a data point, I have Cusco mounts on my SC'd car and Perrin poly bushing ones on my other car. The Cusco mounts have significantly less NVH.

[Ohio Enthusiast]

Originally Posted by RedReplicant

As a data point, I have Cusco mounts on my SC'd car and Perrin poly bushing ones on my other car. The Cusco mounts have significantly less NVH.

That's interesting, my impression was always that Cusco have high NVH. Are your Perrin the first revision or the second?

[RedReplicant]

Originally Posted by Ohio Enthusiast

That's interesting, my impression was always that Cusco have high NVH. Are your Perrin the first revision or the second?

They are the newer poly bushing ones

[jeepmor]

Looking at the Cuscos, I think the Torque Solutions model is stiffer with poly bushings. Cusco looks like the normal rubber bushings in a special shape.

[Brz-123]

In the UK forums there was a discussion and the conclusion was that STi or TRD mounts were the best compromise. TRD is cheaper here than STi. Also it was recommended to do gearbox mount at the same time assuming yours is a manual.

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[jeepmor]

Thanks for all the input, I still have the torque solutions models in the car and am shopping for the N group. Torque solution are fine at traffic speeds and provide the response I was after between power and lift off.

Any help finding N group. Any comments from someone who has them?

I'm finding 41020A and 41020B for RH and LH sides, but no confirmation of it being the N group. I looked up 2020 Subi STI mounts against the listed 14 BRZ mounts from nearest dealers subaru part site, the numbers are the same. Hmm, that doesn't seem right. Looks like I'm going to Subaru on Monday.

[jrhudson]

I have the STI mounts and i feel like almost no difference but i'm on a built motor with a turbo so might be different.

These are the part numbers for them. i saw bought mine at rallysportdirect
Left side ST41022AS010
Right side - ST41022AS000

[Decep]

The sti mounts are nice. They aren't night and day but do reduce a bit of slop. There's a lot of slop from the transmission mounts too if you haven't done those yet. The STI motor mounts, whiteline transmission insert and perrin rear shifter mounts is as far as i'll go on a street car. NVH isn't bad unless it's a cold start. When it warms up it's tamed quite a bit.

[jeepmor]

Thanks for the installed user feedback. Very helpful. And thanks for part numbers, I was getting confused as to where to turn next. Didn't get to the dealer yesterday, spent the afternoon getting new tires instead.


I have a Whiteline trans mount bushing, and also had rear cross member whiteline bits installed at the same time the Torque Solution motor mounts went in. But I can still tell the big player for NVH is the motor mounts.

[jeepmor]

Tried to find softer poly bushings for the torque solution models. They use 75 durometer bushings, wanted to try lower spec like 65 range to see if I could cut down on NVH a bit. They don't offer any other options, I did send an email or two to find out.

The more I dig, the more I think the N group is the OEM FRS/BRZ mount. I say this since rallysportdirects images of the Ngroup STI mounts match the part numbers on my OEM mounts I took off. Can anyone confirm or deny this? I checked my old mounts and the images for the part on Rally Sport direct. Same part number is in the casting. Blast it anyway, looks like I won't be spending money buying new OEM mounts. Unless I'm missing something, that's a disappointing discovery.

The casting ID on the mount leg matches my OEM mount. I don't see the ST label on my OEM steel plate bits like shown here. Maybe that snubber part when they meet under high torque is a thicker form to take up the torque load sooner, not sure, can't see it. But the same number on the mount proper tells me even if they are different, it's only that snubber ear cover, not the material in the mount itself. Damn.


https://www.rallysportdirect.com/par...ount-left-side