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1991 Toyota MR2
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Discussion Starter · #41 ·
Just saw you fired it up on IG, came in to check for updates... NICE MAN! NICE
Sweet! I'll be uploading a YT video on it soon. I'll start linking those progress update videos. Hopefully one should come out soon... after I get over this covid business...
 

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1991 Toyota MR2
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Discussion Starter · #42 ·
Here's a link to the latest progress video:


Here's the current header design:

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Right now as it stands, it's 16-inch primaries and 1.75" diameter on both banks. It also has a 21-degree port exit angle. You can see FMW's video on that here. Comparing designs that the Lotus dudes have and what Marc at FMW has put out I believe this provides a "middle ground" between the two. I'm hoping these designs create a "deeper" tone compared to the baller FMW headers, but also not so much deeper that it sounds less like an F1 car, and with the extra primary length, potentially more (or less lol) power. Marc at FMW picked up I believe almost 10 ft/lbs of torque with his new cast headers. I know his design features the 21-degree port exit, 11.5" primaries, and I believe the primary size is a hair over 1 5/8". I'm curious as to how my design will hold up against his, seeing his gains with his new cast manifolds lead me to be optimistic about these ones. BUT, I believe another critical piece in all this is the Y-pipe, I will really have to try and make mine proper. I know that an unequal y-pipe can drastically change the sound and potentially power? I saw Alex Wilhelm mention to Marc that a longer primary (secondary?) length for each y-runner might be the cause of the increase in torque from his new header design due to his new design outlet sitting higher than the previous tubular design. If that's the case then I may end up making a similar setup to Alex's x-pipe design but instead of an x-pipe, a y-pipe (for sound) where the y-runners merge up and over the cross-member. Now that I think about it, that might fit better under the S54 axle compared to a 3-inch pipe.

With regards to sound, from what I can tell the notable "2GR MR2" exhaust tone is from the shorter, equal length header + equal length y-pipe combo (FMW + Alex Wilhelm). There's been a few designs I've seen with very long primary lengths (on MR2 2GRs and Evora/Exiges) that sound really good but are missing that FMW zing. If I can land it around the Porsche flat 6 pitch/deeper FMW, that would ideal.

For example the Supersprint headers, long primaries, not that iconic 2GR MR2 sound?

Here's the 2bular design, which seems to have a similar length to the old tubular FMW headers, hear how it sounds pretty similar? Although this header design has 1.75" primaries.

Here's an actual 2GR MR2 with a very long primary length. It sounds amazing, but it's missing that "F1" sound that the FMW headers give.

I know there are tons of other factors like cam timing, ignition timing, muffler design, etc that can change exhaust sound. I might have gone too deep into this exhaust stuff, but hey if it makes me comfortable with the design decisions I made then so be it. I just hope it sounds good LOL. Also, I hope this can spark some more exhaust discussion on the 2GR stuff, this motor really sounds amazing and I want to figure out how to make it sound more amazing.

A big thanks to the guys over at the FMW discord for helping me come to this design, those big brain dudes are epic.
 

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1991 Toyota MR2
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Discussion Starter · #44 ·
My bunk measurements have led me no where. Even with a new design, I was still running into the crossmember. Solution? 3D scan the motor and crossmember. This should fix most of my fitment issues...


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Discussion Starter · #45 ·
Progress, progress....
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"First" design with the 3D scan, so far so good. I just have to pull the primaries out just a liiiiitle bit as it's sitting too close to the axle than I like. Also, I have to tweak the collector angle. Other than that I think this rear bank design will be finalized. 20" length primaries! Longer than the ones before, hope it doesn't "beef" up the sound too much.

Although this Larini header car sounds amazing and those have pretty long primaries.



Will post more updates soon. Hope I can get to fabbing up these things soon, I'm running out of filament over here...
 

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Discussion Starter · #52 ·
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Got the collectors made. Rear bank is almost complete I just need to weld one last runner on, and the front bank is now being made. So.. close...
 

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Discussion Starter · #54 ·
The headers are finished, here's how the car sounds straight out the headers: 2GR MR2 Custom Headers Startup

I'm definitely curious as to how this compares to open header of the FMW headers, if anyone has a clip of their 2GR car open header I'd love to hear how it compares.

Latest update video:
 

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1991 Turbo
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Bet it makes doggo at least 3 mph faster. Watch out, squirrels!
 
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Discussion Starter · #60 ·
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This y-pipe is starting to look AWESOME. Super organic looking. Unfortunately I miscalculated some lengths on the front bank so the pic you see here will differ a little from the final design. It'll look pretty similar though. Absolutely LOVE how this looks.
 
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