3.6 Conversion - Exhaust Considerations

[ahendy]

I have an 87 Carrera w/ a 993 3.6 swap. It came to me with the Instant-G "Happy Crab" / Magnaflow muffler bolted to stock 993 headers w/heat exchangers, and while it sounds neat, it's far too loud and full of drone for day to day driving. I don't want stock-quiet, but it needs to be tolerable (and wife approved!)

I've seen several threads about this, but many are quite old so I thought I'd start again and get people's thoughts on today's options.

Based on what I've read, I have a few options..

1. Change nothing, cap one side of my Magnaflow, and maybe throw some CC inserts in there.

I haven't tried capping one side, but I have tried CC inserts and while they make a substantial difference it's not significant enough for me to consider this "solved"

2. Triad on stock headers

Unfortunately Dave passed away this year so this is no longer an option (unless someone wants to sell me one!) — seems everyone that owns a Triad agrees that it's the best possible option. RIP Dave.

3. Fabspeed headers + muffler

I've seen reports stating that the Fabspeed headers w/ heat + muffler setup is tame, performant, and sounds great. It's expensive though, and I wouldn't want to drop the money on it without knowing that I'll like it.

Seems they've changed their lineup at some point, and the one that seems like it would fit my car is now called the "Fabspeed RSR Header and Muffler kit"... has anyone used this successfully?

4. Move oil tank and use stock 993 exhaust

Not interested in doing this at this time.

Any other thoughts or options? Tolerable noise is my priority here, and while I do care about performance I am willing to take a performance hit for more tolerable noise.

[blucille]

I have an m&k muffler that will bolt to stock 993 exchangers (bischoff flanges). Sounds great. I swapped to a full new system and couldn’t retain the m&k. Single out, no drone. Sounds great. I’d be interested in selling it at some point.

[ahendy]

Originally Posted by blucille

I have an m&k muffler that will bolt to stock 993 exchangers (bischoff flanges). Sounds great. I swapped to a full new system and couldn’t retain the m&k. Single out, no drone. Sounds great. I’d be interested in selling it at some point.

Interesting.. I had some concerns that M&K options may be too loud. Any chance you have any videos of it?

Definitely would be interested in buying it from you if it seems like it could be a good solution..

Curious, what did you switch to?

[plexiform]

I went with B&B on my 3.6 from a 93 964. Nice sound and not too loud. The only thing I would change is to make the tips exit more centered than out the corners of the rear.

[ahendy]

Has anyone used this setup: https://patrickmotorsports.com/products/exhfpor140036pms

Quite pricey but would be interested to hear it (and hear about it!) if anyone's tried it out..

[ahendy]

Originally Posted by plexiform

I went with B&B on my 3.6 from a 93 964. Nice sound and not too loud. The only thing I would change is to make the tips exit more centered than out the corners of the rear.

Are you using the B&B headers as well?

Could you shoot a video showing how it sounds?

[ahendy]

Curious if anyone has used SSI headers/heat exchangers on their 3.6L conversion?

By the looks of it, this may be a good solution as I could just bolt up a Dansk 2 in/1 out muffler and get stock quiet.. but everywhere selling the SSIs claims "requires modifications" to mount up to a 3.6L. Unclear what those modifications are but it seems something about cam tensioner clearance?

[RarlyL8]

SSI will choke a 3.6L engine which pretty much defeats the purpose of the transplant. I would at bare minimum retain the OE exchangers. Properly sized headers and muffler would be a significant improvement.
We still make a muffler with the correct inlets if keeping the OE Bischoff exchangers. Have done all of the typical tailpipe configurations; single out, dual out, GT3, S, R, or Rally.

[Bill Verburg]

Originally Posted by ahendy

Curious if anyone has used SSI headers/heat exchangers on their 3.6L conversion?

By the looks of it, this may be a good solution as I could just bolt up a Dansk 2 in/1 out muffler and get stock quiet.. but everywhere selling the SSIs claims "requires modifications" to mount up to a 3.6L. Unclear what those modifications are but it seems something about cam tensioner clearance?

The original SSI have 35mm ID pipes , too small for a 3.6 at higher revs, Eisenman has 38mm ID versions of SSI which is closer to what you want.

factory 993 is 39mm I.D.

Most of use use 1.75" OD(1.625" ID which is 41.25mm ID)

[-Levi-]

I had the same issues with my prior exhaust setup. the best solution ofter a few years of looking was to use the factory GT3 muffler with electronic cutouts. I can be pretty loud or tone it down a bit, adding cats would probably bring the volume down a bit more as well. its absolutely louder than stock, but you can be reasonable or loud depending on a flip of a switch.

[Bill Verburg]

Originally Posted by -Levi-

I had the same issues with my prior exhaust setup. the best solution ofter a few years of looking was to use the factory GT3 muffler with electronic cutouts. I can be pretty loud or tone it down a bit, adding cats would probably bring the volume down a bit more as well. its absolutely louder than stock, but you can be reasonable or loud depending on a flip of a switch.

Nice job!



w/ 3.6 tp's you need to take account of how the engine is mounted in the car

there are 2 methods
1) using the 3.6 tin and 3.6 cross bar and 3.6 engine console to bolt to, this method requires ~1.25? spacers that lower the rear of the motor and exhaust, this will need to be compensated for, a stock 911 type exhaust will give you a droopy drawer look to the exhaust, Best method I've found is to find a good fabricator to make pipes that allow the muffler to be raised.

2) use a 3.2 crossbar and 3.2 console and smaller than stock crank pulley and aftermarket f/g for tin. This allows the motor to sit more normally and use a stock exhaust setup, properly sized of course.

[ahendy]

All great info - thanks folks!

Still would love to hear the B&B setup that Patrick Motorsports sells specifically for 3.6 conversions in a G body. Anyone have any examples they can share?

[Bill Verburg]

which method are you using to mount the engine in the chassis?
1) using the 3.6 tin and 3.6 cross bar and 3.6 engine console to bolt to, this method requires ~1.25? spacers that lower the rear of the motor and exhaust, this will need to be compensated for, a stock 911 type exhaust will give you a droopy drawer look to the exhaust, Best method I've found is to find a good fabricator to make pipes that allow the muffler to be raised.

2) use a 3.2 crossbar and 3.2 console and smaller than stock crank pulley and aftermarket f/g for tin. This allows the motor to sit more normally and use a stock exhaust setup, properly sized of course.

I ask because the exhaust is nice and high here


My custom welded up exhaust bit the dust after 25yrs of service

Reolacedit w/ A Fabspeed RSR, which sounds great byw and is very liveable , I can actually here the engine cooling fan again.

I'm not sold on the appearance w/ the 3.6 being so low the exhaust is more visible than I care for

before


after

[PeteKz]

I definitely like the "before" setup better.

[Bill Verburg]

Originally Posted by PeteKz

I definitely like the "before" setup better.

Me too, but the skilled welder is nla

so I've been looking into getting the engine to sit higher, currently w/ the RS console and cross bar and tin it uses 1.25" spacer to lower the rear, using the 3.2 console cross bar and custom f/g surround could alleviate that

the issue is it's like searching for hens teeth to find some pics of the latter setup, hence my question for Levi

The sound quality and level of the RSR is outstanding, i would like to keep it

Plan B is a Ti Gt3 muffler sitting in the garage, but that will hang too low too w/o raising the engine

[-Levi-]

I am using the 3.6 carrier with spacers

[-Levi-]

Bill, here are some better pictures that may show what you were referring to

[Bill Verburg]

Originally Posted by -Levi-

Bill, here are some better pictures that may show what you were referring to


...

thanks for that info.

I think I now understand how you got it tucked up so high.





inlets are at the bottom and the connector have more rise

looks like I need to keep searching for a good pipe bender/welder to change the inlets to the bottom and outlets to the top.

[ahendy]

Curious if anyone else has thoughts on this? Still struggling with it a bit.

M&K is very backed up and I don't expect I'd be able to get anything out of them for quite a while. Also still not convinced that it's the answer anyway for quiet.

[Bill Verburg]

Originally Posted by ahendy

Curious if anyone else has thoughts on this? Still struggling with it a bit.

M&K is very backed up and I don't expect I'd be able to get anything out of them for quite a while. Also still not convinced that it's the answer anyway for quiet.

The absolute best street sounding 3.6 exhaust, this side of a real 993 dual can setup, that i have ever heard is Fabspeed RSR, I can actually hear the cooling fan again as the engine revs and all the high frequency clatter and resonance is gone, Just a real nice basso rumble especially w/ RS cams

The appearance isn't what i would want but the sound makes up for it.

The spacers used to drop the rear of a 3.6 in many t/p's is the culprit, there are ways around it one that looks much better is to have new header to muffler inlets made up that go to the lower ports on the muffler instead of the upper ports, then move the stock outlets from the lower ports to the uppers, this actually looks pretty good, Tho I can't seem to find the pics just now,

another way to go is to use custo f/g tin replacements w/ 3.2 bar and mount console w/ a 993 single sheave pulley( the stock 964/993 3 sheave is too wide to fit), no spacers needed an the exhaust fits as designed.