Twin_Turbo
Der Maulwurf
- Joined
- Mar 5, 2008
- Messages
- 7,579
yes, npp exhaust uses vac servos like the aftermarket C4 system back then (exausteffects??) NPP is simply the RPO code Like ZR1,L98, LT1, Z06,Z51,HL9,J56...wah wah wah.....
Starting on the muffler fabrication.
- Thread starter 69427
- Start date
69427
The Artist formerly known as Turbo84
Made a bit more progress. Got the muffler buttoned up. Once I'm happy with the end result I'll weld the cover on.
(Here it is prior to the cover installation.)
Here's everything during the fitting process.
And the rear muffler replacements. I'm still trying to find some 3" 304 SS to make some new tips.
Fired it up today. All in all not bad. Not loud, very acceptable volume, but with a slightly "crisper" sound than the previous turbo mufflers. For reasons I can't quantify, there just seemed a very slight 5.0 sound that is common to many Mustangs. Not much, just a hint.
Doing all the weight numbers, the original mufflers weighed 12# each, while the replacement pipes weighed 4.5# each. The section I cut out to install the muffler was 3#, and the muffler itself was 14 pounds. Net effect of the parts movements is 7.5# off the left side, while adding 3.5# onto the right side, and taking 4# off the car.
Right now I'm trying to figure out what additional changes I could make before I weld the cover on. I have a slight rattle somewhere inside (I'll try the old stethoscope method) the muffler that needs attention. I suspect it might be related to an internal vane vibrating against the top cover. Once I'm happy with the internal dampening qualities I'll drill some access holes in the cover to be able to weld the top half of the vanes to the cover to (hopefully) eliminate the rattle noise.
(Here it is prior to the cover installation.)
Here's everything during the fitting process.
And the rear muffler replacements. I'm still trying to find some 3" 304 SS to make some new tips.
Fired it up today. All in all not bad. Not loud, very acceptable volume, but with a slightly "crisper" sound than the previous turbo mufflers. For reasons I can't quantify, there just seemed a very slight 5.0 sound that is common to many Mustangs. Not much, just a hint.
Doing all the weight numbers, the original mufflers weighed 12# each, while the replacement pipes weighed 4.5# each. The section I cut out to install the muffler was 3#, and the muffler itself was 14 pounds. Net effect of the parts movements is 7.5# off the left side, while adding 3.5# onto the right side, and taking 4# off the car.
Right now I'm trying to figure out what additional changes I could make before I weld the cover on. I have a slight rattle somewhere inside (I'll try the old stethoscope method) the muffler that needs attention. I suspect it might be related to an internal vane vibrating against the top cover. Once I'm happy with the internal dampening qualities I'll drill some access holes in the cover to be able to weld the top half of the vanes to the cover to (hopefully) eliminate the rattle noise.
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69427
The Artist formerly known as Turbo84
Muffler 2.0
I pulled the muffler off to see what the heck the rattle was. Didn't see anything loose or suspect, so I don't have an answer. While I had it out I decided to make a couple mods while I was at it. I welded in a bit more "screen area" to contain some more fiberglass in the periphery, and replaced the SS wool with fiberglass in the center area as I don't think I was getting enough crossflow in the area to warrant its use. Here's the second version:
I buttoned it back up and put it in the car. The rattle is gone (for whatever reason) and the exhaust note is pretty decent. I think I'll run this setup for a bit to see what it sounds like at the next track day/autocross. I still have to get some stainless to make the tips, and find some rubber/poly material to make the isolators at the hanger bracket points.
I pulled the muffler off to see what the heck the rattle was. Didn't see anything loose or suspect, so I don't have an answer. While I had it out I decided to make a couple mods while I was at it. I welded in a bit more "screen area" to contain some more fiberglass in the periphery, and replaced the SS wool with fiberglass in the center area as I don't think I was getting enough crossflow in the area to warrant its use. Here's the second version:
I buttoned it back up and put it in the car. The rattle is gone (for whatever reason) and the exhaust note is pretty decent. I think I'll run this setup for a bit to see what it sounds like at the next track day/autocross. I still have to get some stainless to make the tips, and find some rubber/poly material to make the isolators at the hanger bracket points.
MYBAD79
Moderator
looking good :thumbs:
you can get 304 ss from Jegs:
http://www.jegs.com/i/JEGS-Performance-Products/555/30911/10002/-1?parentProductId=752882
they have 180 degree bends as well, made by SW....
you can get 304 ss from Jegs:
http://www.jegs.com/i/JEGS-Performance-Products/555/30911/10002/-1?parentProductId=752882
they have 180 degree bends as well, made by SW....
Arthur Brown
Well-known member
wow, this is the first time I see a selfmade muffler. Any chance you can post a video ? Would love to hear what it sounds like.
69427
The Artist formerly known as Turbo84
I don't have a digital video camera, but if I get access to one sometime I'll post something. I haven't had the chance to do any high RPM or WOT runs to see where I'm at noise and backpressure-wise, so I don't know if I'll be doing some more tweaks to it yet.
69427
The Artist formerly known as Turbo84
Got the system finished for now. I cut some tips out of 3" SS pipe with my chopsaw and put a couple of small weld beads on the pipes to hold them on. I also painted the pipes to help them blend in the background a bit better.
Now I need to get some track time to see how they sound at WOT (and get the bumpers bolted back on one of these days).
Now I need to get some track time to see how they sound at WOT (and get the bumpers bolted back on one of these days).
Mike, Looks good.
Got a question about the depth of the muffler. Did you say it was 4 inches thick? Is it lower than the frame side rails?
Got a question about the depth of the muffler. Did you say it was 4 inches thick? Is it lower than the frame side rails?
69427
The Artist formerly known as Turbo84
It's 2 1/2 inches thick, the same as the oval pipe height. (Post 14 shows how it's positioned.) I would have loved to have had 4 inches of available space for either additional ground clearance or just additional muffler plenum volume. (I had to go sideways to get some decent internal volume.)
The net affect is that it doesn't hang any lower than the exhaust pipes (which are below the frame rails), but it's still going to be ugly if I run off the track and catch it on something.
A somewhat related topic. I'm not happy about the additional height of the later rubber body mounts. I'm kicking around unbolting the body this summer and modifying the mounts (making them thinner) so I can drop the body a touch, and then raising the suspension the same amount so that I have a touch more ground clearance while still keeping the same wheel arch spacing.
I haven't tried this yet but the body mounts from a 55-57 Chevy are slightly thicker (~ 1/2" ) than the original aluminum mounts.
69427
The Artist formerly known as Turbo84
Muffler 3.0, system 2.0
After the Topeka track day a couple weeks ago I wanted to do some tweaks to the exhaust. I liked the sound at idle and WOT, but mid-RPM noise/volume was a bit too attention getting. So while I was out of town visiting relatives I kicked around a few ideas to try when I got back home. I was pondering a question Larry mentioned in an earlier post (regarding standing waves), and decided to try something to (attempt to) change the frequency/amplitude of any standing waves in the main passageway.
Version 2.0:
Version 3.0:
I used a piece of leftover sheet steel and welded it in the passageway. It's my hope that any standing waves in that area (between the floor and removable roof of the muffler) would be reduced in wavelength with an intermediate floor. I figured it was minimal weight to try this experiment.
While I had the exhaust apart I thought about doing a couple additional tweaks to quiet down the exhaust. Additional expansion volume and muffling material always seems to work, but I didn't have room for anything fancy, so I modified the Y pipe. Here it is during the change from a pure Y pipe to a crossover/expansion chamber/muffler.
I welded up some sheetmetal to enclose some the volume between the pipes. I then cut a bunch of holes in the pipes to permit the exhaust gas/pressure to flow into the volume, and then put some dampening fiberglass in the volume.
After sealing up the Y pipe here is what the muffling system on the car looks like.
The total muffler weight is located low and central in the car (somewhat improving the c/g and moment of inertia for the amusement of the geek in me).
I fired the engine up and it sounds darn nice. Some of the 1500-2500 RPM "attention getting volume" is gone, and I'm interested in getting it out on the road to see what WOT sounds like.
After the Topeka track day a couple weeks ago I wanted to do some tweaks to the exhaust. I liked the sound at idle and WOT, but mid-RPM noise/volume was a bit too attention getting. So while I was out of town visiting relatives I kicked around a few ideas to try when I got back home. I was pondering a question Larry mentioned in an earlier post (regarding standing waves), and decided to try something to (attempt to) change the frequency/amplitude of any standing waves in the main passageway.
Version 2.0:
Version 3.0:
I used a piece of leftover sheet steel and welded it in the passageway. It's my hope that any standing waves in that area (between the floor and removable roof of the muffler) would be reduced in wavelength with an intermediate floor. I figured it was minimal weight to try this experiment.
While I had the exhaust apart I thought about doing a couple additional tweaks to quiet down the exhaust. Additional expansion volume and muffling material always seems to work, but I didn't have room for anything fancy, so I modified the Y pipe. Here it is during the change from a pure Y pipe to a crossover/expansion chamber/muffler.
I welded up some sheetmetal to enclose some the volume between the pipes. I then cut a bunch of holes in the pipes to permit the exhaust gas/pressure to flow into the volume, and then put some dampening fiberglass in the volume.
After sealing up the Y pipe here is what the muffling system on the car looks like.
The total muffler weight is located low and central in the car (somewhat improving the c/g and moment of inertia for the amusement of the geek in me).
I fired the engine up and it sounds darn nice. Some of the 1500-2500 RPM "attention getting volume" is gone, and I'm interested in getting it out on the road to see what WOT sounds like.
MYBAD79
Moderator
that's impressive work :thumbs:
69427
The Artist formerly known as Turbo84
But am I gonna lose my low end torque? LOL
While I was visiting relatives last week I stopped in at my favorite junk/scrap yard. The owner was a friend of my dad, and he always treats me right. I found some 4" mandrel bent exhaust pipe for possible use in the next exhaust tweak.
I got a bunch of 3" mandrel bent elbows from that same yard a few months ago, and I'm thinking of eventually just duplicating the present exhaust configuration (2.5" and 3.5" pipes) with 3 and 4 inch pipes. Depending on what my EGT probe shows for temps at the muffler I was also kicking around duplicating the muffler in aluminum for a couple less pounds of system weight.
While I was visiting relatives last week I stopped in at my favorite junk/scrap yard. The owner was a friend of my dad, and he always treats me right. I found some 4" mandrel bent exhaust pipe for possible use in the next exhaust tweak.
I got a bunch of 3" mandrel bent elbows from that same yard a few months ago, and I'm thinking of eventually just duplicating the present exhaust configuration (2.5" and 3.5" pipes) with 3 and 4 inch pipes. Depending on what my EGT probe shows for temps at the muffler I was also kicking around duplicating the muffler in aluminum for a couple less pounds of system weight.
69427
The Artist formerly known as Turbo84
Thanks Karsten!
(Hey, the '79 seat was comfortable at the track the other week, so I'm planning on welding up another set of brackets to put the passenger seat in. The driver seat and bracket was 15 pounds lighter than the stock '69 setup, so I'm looking forward to taking some more weight out of the car.)
MYBAD79
Moderator
i still have the seat track for the passenger seat , let me know if you want it
69427
The Artist formerly known as Turbo84
Thanks Karsten. IIRC I ran into some compatibility issues with the later tracks and early C3s, and that prompted me to weld up some lighter custom brackets (which also allowed me to position the seat a touch lower). I guess either keep that one in storage or offer it up to someone who may need one of those brackets.
Thanks again.
Mike
69427
The Artist formerly known as Turbo84
Spent a test and tune evening at Gingerman last week. Got there early to do some minor adjustments, but ended up having a good time. The engine ran great, and the brakes were consistent the whole evening. I've got stainless steel shims between the caliper pistons and the pads to reduce the heat travel as I don't have additional air funneled to the rotors at the moment other than the deletion of the splash shields.
Things were going good until I noticed a gradual increase in exhaust noise. Between sessions I checked the muffler and noticed that the cover (to allow internal modifications) was coming loose. I put some cotton in my ears, but even with the helmet on the noise eventually got too stinking loud and I shut things down for the evening. I pulled the muffler off this evening, and it's obvious I overestimated the clamping power of the rivets I used to hold the cover on.
I decided that while the exhaust system is apart I'd just upgrade the whole system. I've been running 2 1/2 inch pipes off the headers since shortly after I bought the car (the car had 2 inch pipes on it originally), and have been spending most of my time working on reducing the vehicle weight and improving the suspension. I'm close to running out of ideas on the suspension and weight changes, so this looks like a good time to do the exhaust. I've got a lot of 3" mandrel bends and straight tubing on the shelf, and this is also a good time to try building the new muffler in aluminum. The lighter muffler should hopefully more than offset the weight of the bigger pipes.
Things were going good until I noticed a gradual increase in exhaust noise. Between sessions I checked the muffler and noticed that the cover (to allow internal modifications) was coming loose. I put some cotton in my ears, but even with the helmet on the noise eventually got too stinking loud and I shut things down for the evening. I pulled the muffler off this evening, and it's obvious I overestimated the clamping power of the rivets I used to hold the cover on.
I decided that while the exhaust system is apart I'd just upgrade the whole system. I've been running 2 1/2 inch pipes off the headers since shortly after I bought the car (the car had 2 inch pipes on it originally), and have been spending most of my time working on reducing the vehicle weight and improving the suspension. I'm close to running out of ideas on the suspension and weight changes, so this looks like a good time to do the exhaust. I've got a lot of 3" mandrel bends and straight tubing on the shelf, and this is also a good time to try building the new muffler in aluminum. The lighter muffler should hopefully more than offset the weight of the bigger pipes.
mrvette
Phantom of the Opera
Aluminum?? won't that melt under full blast freeway runs of maybe 80 mph for a few summertime miles.....??
69427
The Artist formerly known as Turbo84
Aluminum?? won't that melt under full blast freeway runs of maybe 80 mph for a few summertime miles.....??
Well, I don't do full blast stuff on public roads, but I think I'll be okay on track days. Aluminum melts at 1200+ degrees, and I'm betting the EGT at the muffler won't be above 8-900 degrees. Plus, aluminum is a pretty good thermal conductor and there's going to be plenty of airflow going across a lot of surface area.
mrvette
Phantom of the Opera
Aluminum?? won't that melt under full blast freeway runs of maybe 80 mph for a few summertime miles.....??
Well, I don't do full blast stuff on public roads, but I think I'll be okay on track days. Aluminum melts at 1200+ degrees, and I'm betting the EGT at the muffler won't be above 8-900 degrees. Plus, aluminum is a pretty good thermal conductor and there's going to be plenty of airflow going across a lot of surface area.
Yeh, but don't aluminum distort and get funky under that constant heat stress/cycle application?? brittle??