300 C mods

[C4me]

A young man, probably 25-ish, picked up his new black "C" yesterday. He is the owner of a nice auto stereo/video shop. See it coming yet? Of course he'll do the adio/video thing, but he already had an appt with a muffler shop to have a new Flowmaster system installed . His shop is fairly near my house so I'll run up there in a week or so and look this thing over. I asked him if he thought it would sound bad on the hiway when it goes INTO 4 cyl mode and he replied that he didn't care 'cause he wouldn't be the one to hear it, only the other people on the hiway. Guess he's right on that one.

[rcktpwrd]

I personaly dislike the 'noise' FROM flowmasters...
but I am intrested to hear how it sounds
there are way better flowing and sounding mufflers out there...

[C4me]

Went to the guys shop today. The system they did took away the resonators (the ones in the back, and the mufflers (in the center of the car). If the names are reversed, OK by me. Anyway it looks like 3" pipes, forgot to ask him. We went for a ride and it is louder for sure, but not much more than stock at WOT. You hear 100% exhaust on his and on ours we hear intake and exhaust. BUT, it looks like he lost low end torque. Maybe not enough back pressure now. With TC off, nailed FROM a dead stop it will just barely squeek the tires. Even rolling I can get 5' of "squeek". But he isn't happy with it .... he wants it more loud! I'm afraid that at cruise speeds there would be a resonance with this system, let alone a louder one. And he may lose more low end. He said his muffler shop just installs and claim to know nothing about what the system does to power. ??? He hasn't done anything to the video or sound end yet. Hmmm

[rcktpwrd]

a free flowing exhaust shouldn't make the engine lose power, only gain power...
the computer may need a bit of relearing time to remap the fuel and timing curves because of the better exhaust flow... it should pick up after a couple hundred miles...

[DMAG]

I think the reduction of backpressure does have an effect on the low end.

[JJS]

Some info...

http://proficientperformance.com/tech_back_pressure.htm

[OBT]

I think the reduction of backpressure does have an effect on the low end.

It's a well documented fact that Harleys with straight pipes sound better and perform worse.

[FStephenMasek]

Yes, I agree, the engine needs some back pressure to produce torque. He wasted his money.

[Hersbird]

The Hemi Rams have shown the less backpressure the better. The fastest near stock Hemi Ram that ran 13.7 in the 1/4 mile on $100 in mods had the exhaust cut off completely before the cat, just dumped right after the y-pipe. Before the truck ran a 14.0 dumped right after the cat, but dropping the cat and blocking off the grill picked up another .3 sec. Some think they lose low end, but it's probably more of their butt-dyno misleading them. They probably gain on the top end which makes it feel like a loss on the low end. Also the computer needs time to adjust to changes so doing a mod and immediately looking for a gain may not always work, give it a few days and possibly reset the computer to learn only with the changes in place.

PS, that Ram is now running 13.1 on a 100hp N2O shot in 2nd and 3rd gear on the same $100 worth of mods above (plus a $800 N2O kit) and the stock 245 series tires.

[JJS]

The Hemi Rams have shown the less backpressure the better. The fastest near stock Hemi Ram that ran 13.7 in the 1/4 mile on $100 in mods had the exhaust cut off completely before the cat, just dumped right after the y-pipe. Before the truck ran a 14.0 dumped right after the cat, but dropping the cat and blocking off the grill picked up another .3 sec. Some think they lose low end, but it's probably more of their butt-dyno misleading them. They probably gain on the top end which makes it feel like a loss on the low end. Also the computer needs time to adjust to changes so doing a mod and immediately looking for a gain may not always work, give it a few days and possibly reset the computer to learn only with the changes in place.

PS, that Ram is now running 13.1 on a 100hp N2O shot in 2nd and 3rd gear on the same $100 worth of mods above (plus a $800 N2O kit) and the stock 245 series tires.

I have to make a couple observations on this...

Were the track runs done on the same day, same conditions (humidity, temp, wind direction, etc.), consistent launches? If not, a .3 sec 'gain' can be attributed to a number of things other than exhaust setup.

Also, many websites, forums, etc. do mention lost low end torque but some horsepower gains higher up...a 1/4 mile track run does not prove much in regards to low end torque since the high end would compensate over that distance. I would be more interested in 0-60 times or full track timeslips to see torque differences.

I am not arguing with you, I just want to pose some thoughts....

[C4me]

Same day, same street, maybe 10 min apart. His - no spin, mine spin. MY presumtion (OK?) is that his has lost low end. OR, I got one of those mythical "good" engines that somehow appear. :D

Seriously, I really doubt that he has gained anything except some sound. This car is noticeable enough!

[Hersbird]

0-60 is a poor measurment also, technically two cars could race to 60mph and the first car to hit 60 MPH could in theory still be behind the "slower" car. That Ram lays down some killer 60-foot times (almost 2 sec flat) which is a good indication of launch and low end. He is really a consistant racer and the runs were made in similar conditions on the same track. Bottom line 13.7 is wicked fast for a full size long bed Ram that looks bone stock but had a few tricks. One of the biggest gains over the stock 14.7 times was the removal of the cat. Here is a pic of the slip and the truck as it is run, at the bottom is a list of the mods to cut a full sec off an aready fast showroom truck (14.7 sec)
http://dtw.truckmoxie.com/showownerpic.ten?u=4650&n=125903&pos=1&album=8251

for comparision here is a slip before the removal of the cat and the remaing backpressure
http://dtw.truckmoxie.com/showownerpic.ten-u-4650-n-103687-pos-1-album-8251
both the 60 foot times, and 1/8 mile times were slower with the cat.

[Mike2thaC]

Alot of times when reading Motor Trend, they will have an article about a speed shop's performance version of a newer car. Most of the time the mods are usually intake, exhaust, pcm/ecm adjustments, and suspensions and brake upgrades. Alot of times these cars with freeer flowing exhausts will have slower than stock 0-60 times, but have slightly faster 1/4 mile times.

This seems to indicate that freeer flowing exhausts increase HP, while at the same time moving the powerband up INTO higher RPMs. Personally, I'd like to keep my low end torque, while just gaining a beefier exhaust note. I also think the 0-60 times are more important for street driving.

[C4me]

My opinion as well. In fact I'd prefer closer to stock sound and beef up the 0-60 times. A slightly less restrictive exhaust and a decent intake! Easy out means nothing if the air can't easily go in also. Improving one without the other tends to be counterproductive.