Newfound BALLS for the Bull

[Qshiplvr]

Yesterday I took the ’99 SHO into the local performance exhaust shop called FMS Performance. I asked the owner, Mike if he could sell me Dynomax Ultraflow mufflers like I had on my ’73 440 Charger Rallye. He said, he’d have to order them, then asked me why I wanted THOSE particular mufflers (this was back in 1997 when I bought them) since their construction was sub-par and straight through design was similar to the much better constructed Magnaflow mufflers (he had a cut out model on display). I agreed that muffler design/construction had come a long way since 1997 and deferred to his experience (considerable) to swap out the stock mufflers and weld in Magnaflow 11235s reattaching the stock tips. Well, when I came back to pick up the car, I couldn’t tell that it had been worked on. The tip positions looked EXACTLY stock. He said: “You’ll like ‘em now!” Yumpin’ Yimminie! He was right! The Magnaflows make it seem like puberty hit the SHO and it went from wheezing Tenor to a nice strong Baritone at full throttle. Now that the car can actually EXHALE, it scoots better too! He said he could give me a little more by going 2.5” pipe all the way back from the third cat. I insisted that I had to be able to pass visual CA **** smog inspection, and he said that would do it. WOW! I can’t believe it is the same car! All I did was swap out the stock mufflers and it’s like I fell in love all over again! I’m thinking for the extra $200 to do the rest of the piping would be money well spent. The muffler swap cost me $300. Mike is SO experienced; he has a waiting list 2 weeks long to get on his rack. Guess I’m gonna have to go back to the end of the line and wait my turn again.

 

[glockcoma]

I had flowmasters 40 series on my 97, I got compliments all the time on the sound. I can't count how many times people asked me at a streetlight if I swapped a 5.0 in it lol.

 

[Qshiplvr]

Mike, the shop owner said Flowmasters are the number one selling brand of muffler that he sells. I debated (with myself) about the Flowmaster choice, and I likened putting Flowmasters on the SHO with engaging the CAPS LOCK on your keyboard, then ripping it off so that you type IN CAPS ALL THE TIME. I opted for the less loud option so I could hit CAPS LOCK occasionally. It is more stealthy that way. Granted the more I unrestrict the exhaust, the less subtle I will become, so I need to walk a fine line. The Magnaflows are a great start.

 

[GEN 3 SHO FAN]

According to some very old posts here and on V8SHO.com, swapping mufflers can add 10 hp to the car (maybe 15 if added to others mods). It's the feeling you have ? Maybe your experienced mechanic gave you an added hp number for this change in exhaust. Do you feel some change in low end torque, some spoke about that ?

Thanks to share.

 

[Qshiplvr]

I have not noticed any low end torque improvement. Since our AX4N transmissions almost feel like a granny gear or towing first gear, it is geared so low, I do not try to launch hard off the line. I usually take it very slow (most times too slow for anyone behind me, which ****** them off), let the transmission shift into second, then really hold the throttle down to drag out 2nd. By the time it shifts at 7,000 rpm, I have an ear-to-ear grin and I am going way over the speed limit on city streets. Since I did not do any dyno measurement to establish a baseline, any guess would be meaningless. All I know is that it is a LOT more fun to drive now, between stops and commute to work. After all, isn't that what enjoying our SHOs is all about?

 

[stephen newberg]

There have actually been a number of times that fairly serious people have played with the exhaust and used a dyno, and there really is not much there to be gained. The main advantage of shifting mufflers is to help the sound go to what you personally like, rather than increase HP.

pax, smn

 

[98SF19]

I likened putting Flowmasters on the SHO with engaging the CAPS LOCK on your keyboard, then ripping it off so that you type IN CAPS ALL THE TIME

I think the FULL TIME CAPS would be running no mufflers at all. There's a video on Youtube of some farm boys doing a burnout in their ****-less Gen 3. It's loud as heck, so be sure to turn your volume down. Sounds very nice on the vid but I've never heard that setup in person. Maybe the Flowmaster analogy would be using a larger monitor with everything proportionally bigger?

I've always heard that opening up the exhaust gives a slight increase at high end (but robs low end), and inversely, that having an operating IMRC helps down low (when secondaries are closed). Of course, the advantage of the latter is nullified if IMRC does not open secondaries @ 3500. In this case, mashing the gas is tantamount to William Wallace going into into battle, shouting at the top of his lungs, but walking instead of running.

 

[stephen newberg]

I suggest just wiring open the secondaries. This is another thing that a lot of work over the years has been done on, and it seems to be a simple and effective fix that causes no harm. Some people have gone so far as to actually remove the butterflies completely and fill the axle holes. Everything still works the same with them gone.

pax, smn

 

[98SF19]

Everything still works the same with them gone

I think with them gone, you'll get better high end, at the expense of low end (which sucks on the Gen 3 anyway).
Maybe somebody with them removed can chime in . . .

 

[stephen newberg]

No, removing the butterflies, from a lot of testing, does pretty much nothing. Or wiring them open. You can do some looking around for data on this here and on V8SHO.com. The alteration in the torque curve you are mentioning seems to come from opening the exhaust up, but its pretty minor, according to the dyno curves. What you get from the secondaries opening is a sound effect rather than an HP one, though eventually without them open I guess you would starve the motor. The point is, you can just put them open all the time if your IMRC is causing problems and there is no resulting problem or loss.

pax, smn

 

[Qshiplvr]

I took the SHO back to FMS Performance on Wednesday. Mike, who installed the Magnaflow mufflers, offered to replace the 2.25" pipe from the third cat back with 2.5" diameter pipes. The car has a much deeper growl, and I enjoy the drive EVEN MORE, in addition to sawzalling off the mousetrap, I think the SHO can finally breathe!

 

[GEN 3 SHO FAN]

I retreived the last part of the saxocone only last summer (first part is U shaped and a second part with an intake silencer in it). The two seems somewhat restrictive for a V8. I can feel (and heard) a difference without the second part too.

Did you have to replace your mufflers to handle the 2.5 pipes ?

I looked to some dyno sheets and it's appears that a less restrictive exhaust can have benefit not only at the high rpm end but in medium range too. I will try to re-found this V8SHO page.

 

[Qshiplvr]

If I had planned ahead, I would have told the muffler shop to just replace all exhaust from third cat back with 2.5" including the mufflers. But, alas, I did not. So he made the 2.5" mate with the 2.25" Magnaflows, so no, I did not purchase new mufflers. Poor planning on my part, but oh well, it is what it is.

 

[GEN 3 SHO FAN]

I looked to some dyno sheets and it's appears that a less restrictive exhaust can have benefit not only at the high rpm end but maybe in medium range too. I will try to re-found this V8SHO page.

I searched on V8SHO to find the link but I wasn't able to find it. Sadly, that miss some order in there. :S I found it on my personnal SHO bible, amen !

This link says the low end may suffers from opening the exhaust but without any proof (ending update).
http://v8sho.com/SHO/exhaust.html

Tim Wright wrote this on an old link, maybe the the low end loss comment is coming from a confusion with his explanation :

"Extrude Hone Exhaust Manifold
It was tried and the ample exhaust manifold made less HP when hogged out. The cavernous castings indicate either more displacement or rpm may have been planned at one time."

http://v8sho.com/SHO/perfdeadend.htm

But this comment itsn't about the exhaust line, it's about exhaust manifolds. I never rode something proving a loss on low rpm or see a dyno sheet below 4000 rpm proving that. The dyno sheet seem imprecises below that RPM...

Cannot speak about TQ but if you look on the board of this other link, we can see that we can have a good hp gain with exhaust modif (with a removed intake silencer) the lower the rpm is... Let see (difference between 3rd and 4th column) :
6600 rpm : 1 hp
6400 rpm : 2 hp
6200 rpm : 2,4 hp
6000 rpm : 2,8 hp
5800 rpm : 2,4 hp
5600 rpm : 3,3 hp
5400 rpm : 4,1 hp
5200 rpm : 3,4 hp
5000 rpm : 5 hp
4900 rpm : 5,4 hp
4800 rpm : 7,4 hp
4700 rpm : 26 hp (!) (maybe imprecise data, but a logical curve can give a progressive hp gain with lower rpms like 9-10 hp at 4600)

Also on bottom part :
"Performance mufflers (purple line) help hp and torque mostly at low rpm as they help scavenge the cylinders better. Their contribution also levels off from 5500 to 6000 rpm because the upstream exhaust system is achieving full capacity becoming the controlling restriction."

from Tim Wright dyno sheets :
http://v8sho.com/SHO/wheelhpimprovement.htm

The first board on this link seems to confirm this in indicating that a removed intake silencer added to modified mufflers can give a great upgrade to the car like 33 hp... (216 hp to 249 hp at 6000 rpm)
http://v8sho.com/SHO/speeddreams.htm

The fact is we can have benefits from aftermarket mufflers at lower rpms, at least in medium range and maybe at low rpm too.

 

[stephen newberg]

I suspect most of the gain is from the change to intake air capacity. With the stock set up the engine is air starved at high loads.

The numbers for the exhaust changes tend to confirm this, and yes, I am pretty sure that last 4700 rpm number is not valid.

pax, smn