Maybe make this a sticky thread, people always have soo many questions about HP gains and sound involving exhuast. Maybe we should make a sticky thread that is more informative the the FAQ about the maxima's exhuast. I have never gotten a definite answer on several questions. Like if its worth getting a random tech cat. w/my Y pipe. I mean maximadriver.com says that the "gains are either 1hp or nil, and most likely nil", when random tech claims like 15hp (w/a catback system of coruse), but then others say that with a Y pipe this can make like 5hp, others say its a butt dyno deal and its HP you can feel but not see on paper...my real question...if I put this on in addition to my Y, how many HP will I really be gaining? does anyone know?

 

I think it would be worth it to collect everybody's dyno numbers and what mods they have. With the amount of people here I would think we could build a good database of "If I add this what does it give me?" type things. This should be made sticky people post your mods and the dyno #'s achieved with them. I'll start:

VG auto
mods:
2 1/4 cat-back exhaust

128hp
153lb/ft torque

 

15hp from a catayltic converter? gimme a break.

BUT the Ypipe has been dyno proven, and i think its one of the best hp exhaust mods...

as far as free flow exhaust goes,.. if you get a mandrel bent bpipe with a free flow muffler, you'll see some gains but nothing NEAR the advertised HP.

i've never seen any product make the claims the company claims..

 

Someone correct me if I'm wrong here, but this is what seems to be the consensus.....

y-pipe: Best single hp mod (besides forced induction)

anything behind the y-pipe: about 1 or 2 hp each part (if that) unless you have forced induction (including NOS)

Yeah?

 

Justin Gadladge dynoed a gain of 2hp and 16lb/ft of torque when he added the RT cat. So there is a gain. And it's supposed to quiet the sound of the Y-pipe a little, too.

 

www.geocities.com/jgadlage/dyno.html

 

how old was your previous cat?

 

I had about 45,000 miles on the cat until I accidentally lowered it onto a screwdriver. DOH! =)

That's when I replaced it with the RT 3" cat.

 

Sorry, but a RT cat isn't gonna increase torque by 10% on a 3.0 liter. I don't even think isn't possible to gain 16fwtq and only gain 2fwhp since hp is a recording of torque over time. To gain 16fwtq and only 2 fwhp would technically mean that the gain in torque would hit very hard and very fast down low and then it would fall VERY quickly. This particular relationship of torque vs hp in this application is almost like what you'd see in a big diesel motor. I really doubt it's feasible for a high revving 3.0 to show this kind of gain between torque and hp.

I've got the RT cat and looking thru the RT cat looked NO different than looking thru the stock cat. The only reason I did the RT is that it does quite some drone and it appears that the RT cat does a better job of "lighting off" on startup vs the stock cat with a y-pipe. If I gained anything, I didn't feel it.

I felt a very nice gain with the y-pipe.

My b-pipe (with a straight extension) dropped my et a consistent .1 and gained me 1.5mph. My car felt a bit stronger in the mid range.

My intake gave a little power when stock, but with the deletion of the resonators and addition of the y-pipe my car felt a bit quicker.

My UDP feels like I've got some extra torque and initial acceleration after each gear change. Also, I've got no clutch chatter anymore and clutch engagement is slower and steering is heavier.

With the RT cat, I felt nothing.

My car makes a little more torque than most 4th gens with the same mods, but I doubt it could be related to the RT cat.



Dave

 

UDP doesn't sound too bad, hmm i wonder if its worth getting for an automatic.

 

Oh, it was a 7hp gain, not 2.

 

Ok, I know I'm going to sound like a total nerd for asking, but I just want to get a better idea of what you mean here. Basically, the way I think of it, is that torque is that 'off-the-line' power, and horsepower is the already in motion 'push' you feel. But, is what you are saying then that technically horsepower is just the time derivative of torque?

 

In simplist terms, hp just a measure of torque over time. Consider these two engines, a C5 LS1 motor putting out 350hp@6000rpms and 350ft/lbs of torque at 4000rpms and then a turbo diesel I6 making 230hp@3200rpms and 450ft/lbs of torque at 1800rpms. As you can see, the turbo diesel makes a ton of torque compared to the LS1, but the diesel lacks the ability to rev any higher than 3200rpms to make power. This powerband means power comes right off idle, but the power is short lived and acceleration is weak after 40mph. The LS1 on the otherhand, has a much flatter torque curve and a higher powerband which is great for both off the line acceleration and topend acceleration. The torque holds of for longer, therefore hp is increased.

The Pontiac GTP is a great example of having a ton of torque and low hp (compared to torque). This is why you see pullied GTPs running in the 13s, but only trapping out at 94-95mph. What this is showing is that the GTP is very strong from 0-80 (torque), but falls down on the topend. What is happening is the torque comes on hard 1800rpms, but falls off fast after 3200rpms which makes for an odd shaped torque curve. These odd power curves is why a NA Maxima can give a pullied GTP a run for it's money after 70mph. Most of the GTP guys know this too.


Dave