Initially, I thought if any loss it would be low end, but thats not where I'm losing power. As far as the bends, the stock pipe has to 90 degree bends also, so I don't know.

It's either the gas, or, more probably, Nissan really did optimize everything to their current state of tune and aftermarket mods won't do anything as is. I think any aftermarket mods (other than ECU) that do make improvements will make very small ones at best. I'm really hoping an ECU can take advantage of the increased airflow.

 

any pics of the stock exhaust set up? I suppose I could crawl under my car, but I'm in my office right now. I don't recall the stock set up having bends in the exhaust as extreme as your two, but I only saw that pic once so I may be mistaken.

As for low vs high-end... if it is a back pressure problem, it would be more apparent at higher RPMs.

I hope you're right and its just the gas, though. Are you going to dyno again with good gas? We can get 100 octane around the corner from my house, I may run that and dyno stock if I can find some place around here to do it...

 

These new graveyards have me screwed up.

Here is a pic of my stock exhaust pre mod.

click here

I also thought that gains would be more noticable at high end too and low end would suffer. In the 1/4 though exhaust mods are very popular in bang for the buck.

A good L/T Header (illegal here) is usually good for like 25HP and about .3 in the 1/4! More than that with ORP.
(Long Tube with Off Road Pipe, No Cats.)

 

the bends of the stock system are hidden underneath the heatshield at the Y junction. I'm just gonna wait for an ECU upgrade to dyno again, unless someone local wants to go with me to the dyno, unbolt their exhaust, put it on my car in stages and retest with stock muffler and with stock y and see the differences to figure out where the loss is.

I would have liked to see gains, but since there isn't huge powerloss, I'm ok with it.

The backpressure problem I was referring to was too little pressure. Wouldn't that be a low-end type problem?

I noticed you want to dyno stock and with a y pipe. It will be interesting to see your results. Just do each mod separately between dynos. It would have been interesting to see which of my 3 mods caused the problem, or if its a combo of all 3.

 

Interesting info:
Just looked at the TS y pipe, and its 60mm into 80mm. Thats 2.36 into 3.15 in"

Mine is 2.5 into 2.5, so its pretty close in overall size.

McDuck, when you get yours bent, try to get smaller angles than 90 degrees, which I think you plan on anyway.

 

The consensus of this Dyno was that it was "searching for timing" it's from my 2002 Z28 shown at my website.

It later dynoed about 15HP higher.

Remember in another post I mentioned this Dyno read low, this car was in the low 12's.

Here is a pic of the exhaust, cut out completely bypasses the muffler lol, in my FireHawk it was electronic with a switch to open and close it. This Y-Pipe is not stock either.

Here is a shot of the top end, with headers slightly noticable.
These LS1 F-Bods were so easy to mod sigh....

Dyno Chart in Defibulation

FIPK w/ Headers

Yeah, I will do this as soon as possible and upload it, hopefully it will show some good results. It's a Dyno Jet II.

 

with a 2 1/2" pipes, I don't think pipe diameter is an issue, either. That pipe size is adequate even for a pretty strong V8. (i'm thinking late 60s muscle cars here)

Right now, my hold up will be finding a dyno locally to get my car measured before making any changes. Once I have that, I plan to model a Y-pipe after TS pipe. It will be interesting to see if there is any difference between that and 2003z's pipe arrangement. I like the sound of the Flowmasters, so the only difference between the two on the exhaust side would be pipe configuration.

 

dumb question here, i'm thinking about the amuse exhaust and their y-pipe, i know it is very expensive, but i'm also interested in the pounds i'll be saving from the stock (i figure adout 80lbs lighter), and their dyno claims to increase hp by 21, and tq. by about 10...my dumb question is, does the y-pipe replace the stock cat.? i've called 350z tuner regarding this question, but they did not know. thanks for your input,
Gerardo

 

Those numbers sound good. To an answer your question, cat back refers to everything *behind the cat* so it will weld up to your exsisting cats not replace them.

That is why I am considering putting some higher flowing cats in the same type I do my Y-Pipe.

Same area so save labor.

IOW, the Y will lead into your cats that are already in place.
Remove them and really watch that sucker scream down the track!

Disclaimer, it's been done but don't do this I am joking!

 

SO, with all said and done and dyno'd........im guessing the Y-pipe sentiment along with a flowmaster isnt such a good idea if urlooking to get faster. aside fromgetin louder.......would you recommend theCurrent Setup you are running(2003z) , or to mayb wait and see what comes.

im dying to get something done now, but no one has any solid votes of confidece on all this Y pipe buisness