maximob

OK...Maybe this is a stupid question, but

Does Cat-back mean Catalitic converter in the back?

Can you improve exhaust flow and leave the catalitic converter in place?

04BlackMaxx

I think it means the pipes are bent in the shape of a cat's back.

ramberg

iTrader: (29)

Maybe this will help.

It wasn't easy to improve on the popular GReddy SP system. But through customer feedback from over 10 years of use and testing, GReddy redesigned the SP as a full stainless steel cat-back exhaust system that is similarly priced to the original SP system. The new SP2 features a 304 stainless steel muffler canister with extra strong 430 SS end caps that feature a deep, high polish. Large, high volume mufflers provide maximum flow with a deep, pleasing tone and are especially effective when used on vehicles with aftermarket turbocharger systems. The unique outer curled oval tip (115 x 110mm dia.) is embossed with the famous GReddy logo. Employing state-of-the-art robotic seam welding, the single wall canisters feature increased rigidity for maximum durability and life. With over 35 types of internal perforated tubes, each SP2 application is specifically tuned for the best combination of sound and performance. The new SP2 also features thick walled (1.5mm), polished 304 stainless steel mandrel bent piping for better resonance and vibration control and enhanced corrosion resistance and durability. New lightweight, flared and stamped stainless steel flanges are also used to provide improved sealing characteristics. The GReddy SP2 Exhaust System will initially be available for over 50 popular Japanese vehicles with more to come as they are developed.

blackpaladin67

This engine has 3 catalitic converters one each under right and left exhaust manifold bank and then one later on before the primary resonator. So cat back mean to change the resonator and all the bit back from the last cat.

BadBlackMaxSL

iTrader: (1)

Ramberg,
Your words are so elegant, you should write greeting cards for Hallmark with pictures of hot chicks on Maximas.

maxmale

are you sure

maximob

thank you, thank you, thank you...that helps alot.

OK, so we change the pipes from the cat back. Will we get a noticable improvement leaving the cat in place? Or is the catalitic converter too restrictive?

blackpaladin67

I think that you can safely dump the last cat and then replace the resonator with a much smaller one and then also the two rear mufflers .If you are going to do that may as well dump your OEM Y pipe an replace that.You also replace all the pipe work as it's like flat as a pancake in places.

See what people like ramberg & others have done , he has the whole lot done and can give you suggestions on brands of mufflers and y pipes.

I have too but my system is a little differnent as i have an Australian spec one.
Things to note:
Replace the Resonator with a much smaller one and do not get talked into ditching it all together as the droning noise that will result will drive you nuts.
Ditch the 3rd cat you don't really need it you have two others.
No point going more then 2 1/2 " pipe work as you need the back pressure

Cat forward



Catback minus the 3rd cat and with superflow very small resonator.



Sort of what the underneath of your car looks like ( Your resonator is about a foot longer then mine was which is like HUGE) and well it's exactly what mine looks like.

ramberg

iTrader: (29)

I will not take credit for this. I took it off the Greddy website. I did search for the answer to his question. Warren

ramberg

iTrader: (29)

[QUOTE=maximob]

I have the CE y-pipe and Greddy SP-2 Cat-Back System. I like it and you do get some extra power from it. Cattman has a system also. There are treads on these, you have to search for them. It also depends on the look that you want. Warren

04BlackMaxx

Thats a really detailed toy, I really want a 6th gen model dammit.

DeusExMaxima

iTrader: (1)

Regarding whether or not a cat back makes a difference, check out this pic of my stock exhaust which I removed to trial fit the Cattman exhaust which is coming out shortly. The copper colored pipe is the stock pipe. I think a picture speaks a thousand words.

darrinps

I might be wrong, but I think that the mufflers in our Maximas is of a high flow design, and with two of them I just don't think that calling them "Restrictive" is correct.

The pipes and cats yes, but the mufflers I really don't think so.

chernmax

iTrader: (15)

I think the US version only has the resonator, B-pipe than mufflers, never saw a num# 3 cat on my US car???

boone

iTrader: (1)

I believe the #3 cat is part of the stock y-pipe.

05MAXSE

It was on my car.

DeusExMaxima

iTrader: (1)

#3 cat IS part of the stock y-pipe, for sure.

blackpaladin67

My factory ones were made by Carlson and were supposed to be resonably free flowing , when they exhaust guys cut it open they were of the opinion that it was pretty good but,the aftermarket ones are better breathing , however you are penalised with a lot louder sound with the aftermarket one, getting used to it now.

The oem ones however were built like to last a life time ...the whole lot including the resonator also weighed like 30kg and the replacements now about 10kg , so it's also a good diet for ya car...

blackpaladin67

Not often we catch ya nappin ...mate LOL....

chernmax

iTrader: (15)

OK, found it, correct...

Pimp_mobile

Stoopid n00b question:

Will adding an exhaust system like this help or hurt your fuel economy? Also, what will it sound like? I don't want my car to sound like one of those souped up lawn-mower Honda's. I am looking for something deep and powerful sounding ( like my brothers 98 Mustang GT )

Thanks.

blackpaladin67

I have found it to be only slightly more consumptive, say .3 liters per hunded Kms.. But that may well be as a result of the beautiful sound it now make , which causes me to put my foot down more to hear more ..LOL...

DeusExMaxima

iTrader: (1)

I have a video/audio of me revving up the car during a test fit of the new Cattman exhaust that is coming out shortly. It will be available with and without a resonator depending on your taste in loudness. Search the archives for it. It sounds great to me. also note that it is a bit louder than the production version as it was only tack welded in place for fitment.

russgriz

When? WHEN?!? Can't anyone give us some idea when? I'm not asking for an exact day, hour, minute, second. I have already decided that I would rather go with the Cattman than the Greddy, but patience is wearing thin. If I knew what month it might be available and a price range within a $100 it might be easier to be patient. Thanks in advance to anyone with particulars!

BadBlackMaxSL

iTrader: (1)

On the area where there is a flattening of the pipe, does this really cause a restriction in airflow? Isn't the area/volume of the pipe when its round the same as the area/volume of the pipe when its oval/flattened? If you look at a drinking straw, the cross section is round and if you flatten it its now an oval. The same amount of a chocolate milkshake (my favorite) will flow through at the same rate, right?

The Area of a circle is found by the formula A=Pi(r)squared.
If we assume, for easy math, that our exhaust is 3 inches in diameter, radius = 1.5 inches. So A=3.14(1.5)(1.5) A=7.065 inches.

Now on the flattened pipe we (I) have had to make some measurement assumptions based on the picture, so....
the formula for an elipse (oval) is A=Pi(R1)(R2) Now, I am thinking that the height if the pipe is now 2.2 inches and the width is now 4 inches. So A=3.14(1.1)(2) A=6.908

Now I know 7.065 doesn't equal 6.908 but its pretty damn close just using my eye and guessing the size.

I think I have too much time on my hands to think about such things. Is anyone here an engineer that could look at this problem a little more closely and give us their opinion?

blackpaladin67

Has a lot to do with back pressure , not too much and not too little ..

Like the exhaust specialist said , He could put like a 4" pipe work on my car and it would look hot , but I would have no back pressure and it would actually lose hp..

straumi

I actually called them yesterday to find out when. I've got a CE ypipe coming and would like to pair it with their exhaust...they said they were still working on it.

darrinps

I see what you are saying, but by the looks of the pipe, it doesn't appear that the width has changed much at all, so the flattened are just cuts the circle down by...mmmm...looks like 30 to 40 percent or so.

Given that, the calculation would be 3.14 * 1.5 * .975 (average) = 4.59

That would restrict it quite a bit. What we need is for someone to crawl under their car and measure the thing!

darrinps

Here some more math...

I've read that you need around 2.2 CFM of flow/HP. So, if we want say a 300 HP engine, then we would need....2.2* 300 = 660 CFM of flow.

Now, how big of a pipe do you need to flow that amount from a normally aspirated engine?

Well I think (and I might be wrong here folks), that is around 115 CFM per square inch.

So now let's do the math....

We want 660 CFM of flow. The surface area of a cross section of a pipe is calculated as 3.14 * radius * radius so...

660 = 3.14 * radius * radius * 115

1.828 = r*r

That would yield a 2.7" pipe.

RHMax

Other than the sections by flattened y-pipe, stock resonator entry, and before the rear y-split, the rest of the piping is about 2.5". Replacing some or all those spots may reduce low end tq, couldn't it?

darrinps

Without a test, I couldn't say for sure but my guess would be no, unless you go too big and kill exhaust velocity at low RPMs that is.

darrinps

I'm not a guru in this but are you sure that is what the guy said?

Maybe what he said instead is that you could lose low end torque?

Also, I don't think it is too little backpressure, but the reduction in low RPM exhaust velocity that kills it.

RHMax

From what I remember, back in my ricerocket days, it also mess up the shifting of auto trans with reduced "back pressure" with mods from header on. Don't know first hand or details since I didn't believe in auto back then, and if my wife could/would drive stick, need less to say...

darrinps

OK, I crawled under the car yesterday and measured the circumference around the necked down area (didn't do the Y-pipe one...figure it is about the same).

It was just under 7" around.

Now if I remember my math right, that would be a radius of...

7 = 3.14159 * r + 2r

1.36 = r


So the area would be

area = 3.14159 * r * r / 2

area = 2.9

Now the flow should be about (115 * 2.9) = 334

For 225 WHP we need about (2.2 * 225) = 495

So, either my math is wrong (VERY well could be) of the neck down areas of our exhaust are hurting our HP.

Now the question (assuming my math is right) is why are these neck down areas there to begin with? It doesn't look like the one in the rear was needd for manufacturing.

Anyone hazard to guess why it is there?

DeusExMaxima

iTrader: (1)

I discussed this a bit in the exhaust thread I started for teh development of the Cattman exhaust system. Brian and I dropped the stock exhaust to examine it. We bounced ideas back and forth as to why Nissan crimped the pipes so much. The initial appearance is to clear the chassis. However, I dont believe thats what it is. Nissan regulates the output of the VQ35 motors to where they vary in hp output from 240 to 298. It is very easy to do my crimping the exhaust but make it appear to be for the purpose of clearing the chassis. When I was at the Stillen open house, they were installing exhausts in the G and Z cars. I saw the stock exhaust for those cars and they had the appearance of aftermarket because I did not see any crimps in those pipes. Anyway, thats my guess, I beleive I am right. I also beleive a properly designed cat back exhaust coupled with a y pipe should get about 20 hp because of the obvious severe restrictions. Also, aftermarket Gs and Zs dont gain much from cat backs because the exhaust for those cars are already decent.

blackpaladin67

I have recently had the opportunity to be able to drive my car hard in a number of different ways at a local Advanced driving school track down the road from my house and have noted the following since my upgrades to my full exhaust.

1. The tourque steer issue has simply vanished ?? ( would pull hard right in the non mod form) It now just tracks straight and goes..
2. I have a really strange sound very similar to a turbo exhaust dump when the gear change occures (quite interesting and resulting in everbody present asking to look at my motor and check if i had a turbo fitted)
3.Best time to 0-100kph was 6.12 seconds which I am tickled pink with.
4.I need to do something about the suspension set up , tower brace and new tighter Bars me thinks..

I will post some pictures when the send them too me ..

RHMax

Yes pics please! About torque steer, I also notice the same w/ my car. Don't know about the exhaust dump sound, but the 0-100km time is real good. FSTB and RSB will help quite a bit in handling. Again, waiting for pics

maximob

Just eggs me on more....I look forward to experiencing the extra power. The y-pipe is a definite add on. I'm undecided on the cat-back system. Curious to know the difference in sound between resonator and no resonator. As far as mufflers go, I like the shiny greddy, but I also like dual tips. I also don't know yet which muffler gives better flow.

I had an idea for an intake. I like that the CAI keeps an even temp on the air, but we've had bad floods here in Miami and I'd be afraid of sucking up some water. I'm thinking of a high flow intake like the Berk or Stillen under the hood, then cutting a crescent out of a basketball and painting it to use as a heat shield. It's flexible enough seal the filter from the engine without requiring modification to the inner body.

What do you think?

chernmax

iTrader: (15)

I love the sound and feel of the CE Y-pipe and GReddy SPII, the sound is throaty and a lot deeper than stock, not like a V-8, but more like a Formular-1 race car I have been told. As for CAI, check out the thread about the NISMO CAI, looks and installs like an Injen, however has a bypass filter in case you decide to take you car jet-skiing in Miami, also has been reported to have some respectable HP gains. Regardless, nothing wrong with a little A$$ Bling on a Max...

wrestler760189

i bought some resonator exhaust tip will it change the sound or in prove it? from a non resonator exhaust tips? help any one?