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The Official "RX8 in DSP" Thread

Old Jun 1, 2019 | 08:00 PM
  #1101  
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I just measured our passenger side and it came out to ~3 1/4", maybe a touch more, for the same measurement, with the washer in place, so seems like we're good to go.

Thanks for posting Tom!!
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Old Jun 1, 2019 | 09:43 PM
  #1102  
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It’d be helpful to know what this dimension is for reference:

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Old Jun 4, 2019 | 04:17 PM
  #1103  
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Thank you Tom. I certainly appreciate someone contributing some useful information and input in addressing the situation.

In supporting contribution, I measured roughly 3” height for my installed RX8P engine mounts. Based on this measurement and then careful study of how the mounts are configured I decide to go full bespoke in not only reconfiguring them some but also full hardware conversion for max weight reduction.



Originally Posted by TomD_Cincy
Driver (left) side


Passenger (right) side



As I mentioned previously, my car is a 2009 and the mounts have about 100K miles on them. It's an R3, but if I remember correctly the motor mounts are not any different. Engine is all stock.

After looking at these on my PC screen, I'm not very happy with how the passenger side turned out. Let em know if you guys need a better picture and I can re-measure that side tomorrow.

This was my second attempt at posting this, so hopefully it goes thru this time and there aren't two posts.

Last edited by TeamRX8; Jun 5, 2019 at 07:55 AM.
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Old Jun 7, 2019 | 11:15 PM
  #1104  
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I was surprised how much the aluminum version of the RX8P engine mount weighs; 1.6 lbs. each.



Thought I read somewhere that the OE mounts are 1.80 lbs each. Don’t think I’ve ever seen the weight of the standard stainless steel RX8P mount, but would expect them to be over 2 lbs. each.

In addition to correcting the height issue on mine, also reconfigured them down to 1.3 lbs each. Wouldn’t have bothered otherwise, but since I was already hassling with height correction it wasn’t any more work to dump in some sugar and make lemonade



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Old Jun 8, 2019 | 06:49 AM
  #1105  
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This is from rx8p's website. I suspect it's probably close to the oem weight.
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Old Jun 8, 2019 | 03:41 PM
  #1106  
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Didn’t realize they had those listed on a separate webpage and wasn’t sure if they still sold them. Regardless, there is the actual weight with washers and nut; 724g = 1 lb 9.6 oz = 1.6 lbs
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Old Jun 9, 2019 | 06:12 AM
  #1107  
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You guys would lose your mind if you weighed the engine mounts and brackets on the SM car. Each one is close to 10lbs
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Old Jun 9, 2019 | 10:27 AM
  #1108  
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Originally Posted by John V
You guys would lose your mind if you weighed the engine mounts and brackets on the SM car. Each one is close to 10lbs
Mild steel I assume?

I'm surprised how much weight you removed from the front of the car. The Renesis is about 240lb with accessories, I imagine the mzr is north of that + the mounts.
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Old Jun 9, 2019 | 12:11 PM
  #1109  
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The MZR is a little lighter than the Renesis when fully dressed. Not by much, 15lbs maybe? I have it in my notes somewhere on the other computer. The rest of the weight loss was nip and tuck stuff. I only run one oil cooler vs. two on the Renesis, the radiator is smaller and the engine holds less water. The fan (one versus two on the Renesis) is lighter. It lost a lot of weight in wiring and miscellaneous brackets and stuff. The MZR is pretty simple to run versus the Renesis. I lost a lot of weight with the swap to the FD transmission. Like 30lbs, mostly off the nose.

The engine brackets are fabricated mild steel, and they are thick, because they had to be cantilevered somewhat. The mounts themselves are Good-win racing UHMW mounts with steel bodies. They are not light. I know Mark has fun designing and building stuff but I came to realize with the BMW that trying to save ounces here and there just isn't worth it.

Next year I'll may re-do the engine mounts to get a few pounds off of them, but there is so much other low-hanging fruit to make the car faster and lighter that it may not be worth the trouble. I'm running a full tank because of fueling issues, my seats and brackets are crazy heavy, brakes are stock heavy stuff...
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Old Jun 9, 2019 | 01:10 PM
  #1110  
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Originally Posted by John V
You guys would lose your mind if you weighed the engine mounts and brackets on the SM car. Each one is close to 10lbs

Like I said, if it wasn’t for the fact that they were already being addressed for the other issue ...

Not to mention an NA Renesis can’t produce impressive amounts of torque by fuel type and boost setting. This is a DSP thread after all and not relative to a non-Renesis engine swap in SM. Which my DSP setup strategy is also based on achieving minimum possible weight. Whether it’s worth it or not just depends. Definitely not the critical component; just one of many, but we’ll see ...

And I also don’t have much else to post since I spending way too much time fabricating an IGN-1A ignition coil mount with minimal fabrication equipment It is a 3 birds with one stone deal though, all-in-one custom ignition mount, engine oil filler/vent tube, and UIM support.

Some of this stuff is slower going than anticipate for that reason. I finally have the energy and determination to see it through though ...

.

Last edited by TeamRX8; Jun 9, 2019 at 01:16 PM.
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Old Jun 9, 2019 | 08:27 PM
  #1111  
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That's fair.

I installed the offset lower bushings and re-did my alignment tonight. I got right at 0.9 degrees more negative up front. I don't think the car needs -4.4 front camber but that's the max I can get now.
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Old Jun 10, 2019 | 06:12 AM
  #1112  
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Originally Posted by John V
The MZR is a little lighter than the Renesis when fully dressed. Not by much, 15lbs maybe? I have it in my notes somewhere on the other computer. The rest of the weight loss was nip and tuck stuff. I only run one oil cooler vs. two on the Renesis, the radiator is smaller and the engine holds less water. The fan (one versus two on the Renesis) is lighter. It lost a lot of weight in wiring and miscellaneous brackets and stuff. The MZR is pretty simple to run versus the Renesis. I lost a lot of weight with the swap to the FD transmission. Like 30lbs, mostly off the nose.

The engine brackets are fabricated mild steel, and they are thick, because they had to be cantilevered somewhat. The mounts themselves are Good-win racing UHMW mounts with steel bodies. They are not light. I know Mark has fun designing and building stuff but I came to realize with the BMW that trying to save ounces here and there just isn't worth it.

Next year I'll may re-do the engine mounts to get a few pounds off of them, but there is so much other low-hanging fruit to make the car faster and lighter that it may not be worth the trouble. I'm running a full tank because of fueling issues, my seats and brackets are crazy heavy, brakes are stock heavy stuff...
A fully dressed Renesis is like 230/240 though, isn't it? Holy **** the mzr is wicked light.
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Old Jun 10, 2019 | 07:18 AM
  #1113  
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Originally Posted by Abendschein
A fully dressed Renesis is like 230/240 though, isn't it? Holy **** the mzr is wicked light.
Looking back on my notes, the long block 2.5 with no accessories was 190lbs on my scale (one Longacre chassis scale pad). The renesis that came with my car was 205 on the same scale, stripped of manifolds and accessories (so same level of dress as the MZR). Not a huge difference. Neither had fluids in them.
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Old Jun 10, 2019 | 08:02 AM
  #1114  
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Originally Posted by John V
Looking back on my notes, the long block 2.5 with no accessories was 190lbs on my scale (one Longacre chassis scale pad). The renesis that came with my car was 205 on the same scale, stripped of manifolds and accessories (so same level of dress as the MZR). Not a huge difference. Neither had fluids in them.
That's impressive. I know the lower and upper intake don't add much, but damn.

The car also runs like 7+ quarts of oil with the dual cooler setup too. Dropping 2 quarts of oil is about 15lbs or so. I can see it now.
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Old Jun 10, 2019 | 09:05 AM
  #1115  
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2 gallons of oil might weigh 15 lbs

Is it asking too much for you to limit the discussion here to DSP? There are dedicated threads for both STX and his SM build for those discussions.
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Old Jun 10, 2019 | 09:19 AM
  #1116  
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Sorry, I was thinking all of the lines and hardware, not just the fluid.
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Old Jun 10, 2019 | 09:47 AM
  #1117  
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Pretty sure he covered most of that in the specific thread about it.

https://www.rx8club.com/rx-8-racing-...rx-8-a-267751/


otherwise I apologize for having to state it bluntly since it seemed like the more subtle approach of my previous reply was insufficient to convey the message.
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Old Jun 10, 2019 | 10:47 AM
  #1118  
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Should be to the surprise of no-one that the 3.5" exhaust version is crazy loud. I'm thinking though what I'm going to do to quiet everything down, but it might be trying a different muffler than the burns, or figuring out a Y to run a second muffler.
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Old Jun 10, 2019 | 11:18 AM
  #1119  
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Originally Posted by mrazny
Should be to the surprise of no-one that the 3.5" exhaust version is crazy loud. I'm thinking though what I'm going to do to quiet everything down, but it might be trying a different muffler than the burns, or figuring out a Y to run a second muffler.
Why on earth are you running a 3.5" exhaust?!
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Old Jun 10, 2019 | 11:21 AM
  #1120  
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I asked him this same question yesterday (once my ears stopped bleeding).
The answer boiled down to "Because SpeedSource told him to."

Last edited by NotAPreppie; Jun 10, 2019 at 11:32 AM.
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Old Jun 10, 2019 | 12:28 PM
  #1121  
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Originally Posted by NotAPreppie
I asked him this same question yesterday (once my ears stopped bleeding).
The answer boiled down to "Because SpeedSource told him to."
I'd clarify that Speedsource offered that there are torque gains at 3.5", and that they got below 100dB. However, they said "with a good Borla XR1", no direct experience with a Burns. the 7 day "solution" might be a Vortex Cone turn-down, and if it did jack-**** park it.

Probably need to start with a switch to a Borla.
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Old Jun 10, 2019 | 12:52 PM
  #1122  
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Originally Posted by mrazny
I'd clarify that Speedsource offered that there are torque gains at 3.5", and that they got below 100dB. However, they said "with a good Borla XR1", no direct experience with a Burns. the 7 day "solution" might be a Vortex Cone turn-down, and if it did jack-**** park it.

Probably need to start with a switch to a Borla.
Most Burns stuff is really low internal volume (i.e. it's small). You need a lot of muffler volume to meaningfully reduce dB.
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Old Jun 10, 2019 | 01:18 PM
  #1123  
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Corvette Application - Spiral Turbo Baffles
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Old Jun 10, 2019 | 01:25 PM
  #1124  
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Originally Posted by John V
Most Burns stuff is really low internal volume (i.e. it's small). You need a lot of muffler volume to meaningfully reduce dB.
The one I went with was the 6.5" total OD, but in general different muffler is the main step, and/or a 30" stretch or two of what Mark posted.
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Old Jun 10, 2019 | 01:46 PM
  #1125  
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Originally Posted by John V
Most Burns stuff is really low internal volume (i.e. it's small). You need a lot of muffler volume to meaningfully reduce dB.
I used that style quite successfully, the key is the packing material, which you won’t get from Burns.
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