3.6 Conversion - Exhaust Considerations

[Cloggie]

https://www.cargraphic.de/en/?C=EUR

Or you can try these guys, I have their complete system including excellent cats, their active switching system, GT3 style muffler all custom made to my car for not a horrendous sum of money considering.

Call Thomas Schnaar.....he knows his stuff and in particular, he has an earlier 911 and a wife who hates droning sounds, so he worked during the development phase to ensure that there was no spouse related objections to driving around.

I love mine - on an ITB/Motec 3.4

D.

[rothaus]

Originally Posted by BrewsterBear

Hope that helps.

Thanks, looks like your muffler sits a little higher. I will modify the engine tin, that should give me another 20 - 30mm.

Thanks
Engelbert

[BrewsterBear]

Originally Posted by rothaus

Thanks, looks like your muffler sits a little higher. I will modify the engine tin, that should give me another 20 - 30mm.

Thanks
Engelbert

The rear tin required modifying on this to make it fit.

[Duc Hunter]

I am running the Rothsport headers and a valved GT3 muffler. Sounds great, valves do make a big difference. No drone, but it's not quiet. By comparison my 3.2 Carera has a full Fabspeed system, no cats, and only 1 of the 2 tips on it. That sounds great too, and is loud enough outside to sound great, but quiet enough inside to enjoy, drive everyday, and on long road trips. The GT3 setup I cannot take a phone call in, and on longer trips I always wear noise canceling headphones.

I would like to try packing the quiet side of the GT3 muffler with stainless steel to quiet that side down more. From pictures of opened GT3 mufflers it looks like you could pack the quiet chambers on each side, leave the rest alone and probably quiet the “daily” side down nicely. Remember the real GT3 has a muffler on each side before the rear muffler. My valves are hooked into the same vacuum line that activates the 3.6’s (964) intake valve. So at 5,500 RPM the intake and exhaust valves open automatically.

[BrewsterBear]

Originally Posted by Duc Hunter

I am running the Rothsport headers and a valved GT3 muffler. Sounds great, valves do make a big difference. No drone, but its not quite. By comparison my 3.2 Carera has a full Fabspeed system, no cats, and only 1 of the 2 tips on it. That sounds great too, and is loud enough outside to sound great, but quiet enough inside to enjoy, and drive everyday, and on long road trips. The GT3 setup, I cannot take a phone call in, and on longer trips I always wear noise canceling headphones.

I would like to try packing the quiet side of the GT3 muffler with stainless steel to quiet that side down more. From pictures of opened GT3 mufflers it looks like you could pack the quiet chambers on each side, leave the rest alone and probably quiet the “daily” side down nicely. Remember the real GT3 has a muffler on each side before the rear muffler. My valves are hooked into the same vacuum line that activates the 3.6’s (964) intake valve. So at 5,500 RPM the intake and exhaust valves open automatically.

I’ve also considered getting the quiet side packed. It’s bearable but the stereo would be pointless above 40mph. Please update the thread if you get it done. It may sway me to get mine split open.

I’ve also considered having the actuators for the valves driven off the same vacuum line for the Varioram control. Then they’d be closed below 4krpm but open up around 4200rpm with the trumpets opening and making things fun. I fitted a larger vacuum reservoir as part of the Varioram install so I’m sure I’ve got enough vac to do it.

The bigger torque means most ordinary street driving is up to 4k. On loud mode it drones around 3k and the noise is plenty lovely through the baffled side as is. At low revs it’s almost antisocial on loud. I have noticed a 10-15hp (seat of the pants dyno) difference between loud and quiet modes when up above 5500rpm though and the noise on loud up there is electric.

[Duc Hunter]

[QUOTE=BrewsterBear;12184752]
I’ve also considered having the actuators for the valves driven off the same vacuum line for the Varioram control. Then they’d be closed below 4krpm but open up around 4200rpm with the trumpets opening and making things fun.[QUOTE]

My understanding is that on the 964 motor’s the intake valve opens at 5,500 RPM. To me thats perfect, looking at the power curves. I am not sure where you got the 4,200 number, unless that’s not eh 993 motors.

If I open mine up and pack it I will report back on pelican. Mine is a stainless 997 GT3 unit, so opening it up will be easier than the Ti ones.

[Cloggie]

Further to my post on CarGraphic - with which I have zero affiliation other than as a customer.

Here is my exhaust, Eisenmann 42mm exchangers, rest is CarGraphic.

They modified the Eisenmann's to fit (shortened slightly), dual 400 cell cats, exhaust path switching (normal and about 60% straight through muffler bypass) and their own in house fabricated banana muffler with GT style centre exhaust (my request).

I am programming the Motec to only actuate the bypasses when over 4000 rpm and 75% throttle. They are zero pressure valves so they are normally shut, so startup will be quiet.

They run a large factory in England that apparently does a lot of race work, so they can custom make anything.

Anyway...here are the pics






D.

[rothaus]

I got the GT3 muffler together with the B&B 964 headers with heat installed on my 71.

I modified the rear section of the engine tin to make more space for the muffler. I used the SC engine console and cross bar. Made a custom support for the muffler. For the heat cross over pipe I use one from a 3.2 and modified it a bid. I also had to modify the bottom section of the rear bumper. I made a heat shield above the right side of the header and wrapped the oil line with heat screen insulation.

Here are some pictures of the system.













Here is what it sounds like



Cheers
Engelbert

[Bill Verburg]

This was mentioned earlier but IMO a big issue is the way the 3.6 is mounted in the car

Method 1 using the 3.6 console, cross bar and engine tin










requires that the rear be spaced down 1+" This causes any std. exhaust to hang low giving a droopy drawer look to the rear,
using a GT3 exhaust in the set up it is easy enough to place the muffler up where you want it and then 2 short pipes to connect to the headers are also easy enough to handle

i had some custom pipes welded up decades a go that did the same job connecting B&B headers to a Flowmaster muffler it looked great.

When i needed to replace the system the fabricator had died and there was no one else nearby to do the work, So back to an off the shelf setup.

I bough a Fabspeed RSR system w/ some minor tweaks to the application done by Fabspeed, back to the droopy drawer look.


method 2 using a 3.2 console, crossbar and Sheridan f/g



the Sheridan f/g is custom made for the 3.6 in an early chassis w/ the 3.2 parts

This eliminates the spacer and the engine sits the same as a garden variety 3.2 Any off the shelf exhaust will fit as designed.

I still highly recommend the Fabspeed for fit , quality and sound they even provide for heat

You will definitely want to drop the engine to switch from method 1 to 2

[Duc Hunter]

Originally Posted by Bill Verburg

method 2 using a 3.2 console, crossbar and Sheridan f/g

This eliminates the spacer and the engine sits the same as a garden variety 3.2 Any off the shelf exhaust will fit as designed.

I still highly recommend the Fabspeed for fit , quality and sound they even provide for heat

You will definitely want to drop the engine to switch from method 1 to 2

I did this. I found someone who had amber FG tins designed to mate teh 3.6 to the 75 body. My engine still needs some spacers. The tins are parallel to the body, and if I remove the spacers in the back the tins are angles so the rear is close to the body, and obviously the front is in the same place. I did not do this conversion. I have heard there is a spacer for the tranny mount....maybe mine is missing to drop it down? My car originally was mounted using method 1.

[wildcat077]

I have the Fabspeed RSR system in my 89 with a 95 3.6 , i was a direct bolt on.I also installed the Rennline stainless engine mount/ crossbar as i had welded the original one twice.
The Fabspeed exaust was a perfect fit with no modifications whatsoever , although there is a drone between 2-3 thousand rpms.I purchased some Car Chemistry inserts which reduce the sound and droning but i find it chokes the exaust note too much.I use the ones with two baffles and they fit perfectly between the muffler and tailpipe.They’re easy to remove/ install so i leave them out in the city and install them if i go on longer drives.I would like to install one of MK’s complete system one of these days …

[Bill Verburg]

Originally Posted by Duc Hunter

I did this. I found someone who had amber FG tins designed to mate teh 3.6 to the 75 body. My engine still needs some spacers. The tins are parallel to the body, and if I remove the spacers in the back the tins are angles so the rear is close to the body, and obviously the front is in the same place. I did not do this conversion. I have heard there is a spacer for the tranny mount....maybe mine is missing to drop it down? My car originally was mounted using method 1.

Interesting

Using Method 1 the thing that forces the spacers is that the 3.6 tin even modified is so tall that when it contacts the chassis the engine can't go higher.

look at the 2 pics above of 2 different 993 engines you can see how high the 993 tin is compared to the Sheridan f/g designed for the swap. W/ 964 there is the additional problem of the f/i stack height which is greater than that of a 993 engine, This may be another different reason for spacers. Way back when I first had a 964 in there and that was the genesis of the method 1 install.
964

[Bill Verburg]

Originally Posted by wildcat077

I have the Fabspeed RSR system in my 89 with a 95 3.6 , i was a direct bolt on.I also installed the Rennline stainless engine mount/ crossbar as i had welded the original one twice.
The Fabspeed exaust was a perfect fit with no modifications whatsoever , although there is a drone between 2-3 thousand rpms.I purchased some Car Chemistry inserts which reduce the sound and droning but i find it chokes the exaust note too much.I use the ones with two baffles and they fit perfectly between the muffler and tailpipe.They’re easy to remove/ install so i leave them out in the city and install them if i go on longer drives.I would like to install one of MK’s complete system one of these days …

also interesting, Don't know if I got lucky or if Joe just put together a special system for me( we do go way back together) but there is absolutely no drone, it sounds great but also not too loud, I can actually hear the engine fan again after 20 yrs of just exhaust roar.\

did you use the aluminum 993 console w/ the Rennline cross bar? I hadn't thought of that, I just assumed it wouldn't work, also did you use the Sheridan f/g tin?

The main tweak to the Fabspeed was 1" extensions of the exit pipes to match my bumper cutouts.

I've also seen several different muffler setups on these and it looks like the 2024 version may be different from the 2022 version I used.

[Bill Verburg]

Got the engine out and started the f/g and console install, shorter studs are needed for the 3.2 console vs the 3.6 version
new plug wires while in there, it never ends

[rothaus]

Here is a picture of the engine bay after the conversion.



Cheers
Engelbert

[Bill Verburg]

Originally Posted by rothaus

Here is a picture of the engine bay after the conversion.



Cheers
Engelbert

Love what you have done there!

[Bill Verburg]

Engine is back in, the 993 nvr fits like a glove w/o any spacers

need to redo the heat though, that's a bummer

[wildcat077]

Originally Posted by Bill Verburg

also interesting, Don't know if I got lucky or if Joe just put together a special system for me( we do go way back together) but there is absolutely no drone, it sounds great but also not too loud, I can actually hear the engine fan again after 20 yrs of just exhaust roar.\

did you use the aluminum 993 console w/ the Rennline cross bar? I hadn't thought of that, I just assumed it wouldn't work, also did you use the Sheridan f/g tin?

The main tweak to the Fabspeed was 1" extensions of the exit pipes to match my bumper cutouts.

I've also seen several different muffler setups on these and it looks like the 2024 version may be different from the 2022 version I used.

Hi Bill,

I made my own engine tin by modifying a 911 unit , at the time Patrick and Timmins were asking $1200 for a 3.6 modified tin.As far as the 993 console goes, i don't recall using it ... the Rennline crossbar is definitely a good upgrade over the OEM 911 unit as it's a lot beefier and it looks good as well.I mounted my coils on the crossbar if i remember right.My car is in storage at this time so i can't confirm other details, but i do have the annoying drone at 2-3 K rpms.The good thig about the RSR exaust with the narrow tailpipes is my Car Chemistry inserts fit right in between the muffler and tailpipe, just before the bend and they will never blow out.

[Bill Verburg]

finally figured out how to post on U-tube
993 engine in "76 Carrera 3.0 chassis w/ Fabspeed RSR exhaust

[SalazarS2K]

I’m using 993HE with MK dual in/out muffler. Still have the spacers on for my 3.6 conversion, but happy with the muffler spacing. No drone in the muffler setup and I have silencers to tone down the overall sound and probably choking a few horses.




Here is a sound clip: https://youtube.com/shorts/74VXTy0xh_4?si=Oy_SAo9BOKtFnguw