Guys, question for you...my setup is currently in that paradoxical state where more boost = less power because of too much backpressure and timing cuts (currently hitting 403 whp at 6800 RPM and 13 psi). I'm trying to open up the exhaust system a little bit, reduce the boost to maybe 12 psi, and advance the timing. What do you think the best solution is? Ideally, I'd like to shoot for about 415-420 whp at about 6600 RPM (with more advanced timing). I have a feeling a shop would recommend headers (conveniently with a nice labor charge), but could you achieve the goal with a less restrictive y-pipe? I'm not really considering cat-back systems because I'm not a huge fan of the sound.

Thanks.

 

So you are running the stock exhaust??

 

get a 2 1/2 inch dual exhaust on it and retune

 

What is the air temperature inside plenum............each 11F causes a 1% density/power decrease.

A proper intercooler should increase power by 6-10% even with its drop in plenum psi.

 

Pretty much man, just crawford HFCs.

I had a 2.5" dual on there for about a week, but I hated it man, had it taken off. It sounded horrendous. I'm so partial to the stock sound (or deeper). That's why I'm leaning toward headers or a y-pipe. Trying to preserve as much of the stock sound as I can. I know it's a little stubborn.

I'm just running the basic Vortech intercooler, no IAT sensor, but I know it's less than ideal, I have the stock bumper with that nasty blockage. This was another thing I've been floating though, the fan mod to direct more air toward the basic intercooler. There is a night and day difference between performance in 50 degree weather vs. 80 degree weather. I'm really looking at fixing the exhaust bottleneck first though, getting it to a "good enough" state.

All in all I'm actually happy with everything as it is, just trying to get it a little more stable/safe (the retarded timing worries me), and squeeze a tiny bit more power out of it in the process.

 

If arent willing to get headers and exhaust then u are really out of options. I dont see why u cant just advance more timing if u felt the timing was pulled way too much. How much timing are u at WOT is the real question.

 

wow 13 psi is a lot.

i would put headers and test pipes on it. and of course, an exhaust other than stock. i went with stillens TD exhaust and it keeps the stock note very well.

but ****, after you do all that, you're probably going to make too much HP/TQ for the stock rods.....

 

if you dont want to open up the exhaust . Get a bigger IC and water/meth injection to cool down the intake temps

 

get the Fujitsubo cat-back system. it sounds like a louder version of the stock. i don't know it they got the y-pipe option in this clip but here, enjoy>>> http://www.350z-tech.com/w/images/b/...Clip_Steel.mp3

 

^^You guys made a great point, I think the key here is to just open it up a tiny bit. If I gain more than 15 whp, my stock block may not last too long.

Can't provide any specifics on the timing at WOT (I didn't do it), all I know is that the timing was retarded as a precaution [I guess you were wondering because we can't know what I'd get from advanced timing without knowing the exact parameters it's set to now?]

I'm completely open to headers if that's what it takes to get the job done. I guess the question is whether I'll gain too much power/torque from them? That's why I was leaning toward the less restrictive y-pipe, something that will open it up just a little bit. With my luck I'd dump $1500 into something and then kaboom.

I did read up on the water/meth option on my350z, seems like a slippery slope though, like it may add too much complexity.

That Fujitsubo sounds bada$$ though. Never heard that one before.

 

Hmmmm . . . the problem is, if you keep the stock exhaust, you still have that bottleneck and restriction. Headers and hfc's are great but if you can't get those gases out through a bigger exhaust, you are still gonna have that backpressure. I'm sure the headers and hfc's help a little bit but it would run a lot more efficiently with a decent 2.5 inch exhaust. When I first got my Vortech, I had HKS. I loved it but I thought it might be too small. I then switched to the GReddy Evo TT with 2.75 inch piping and it was way too big. I lost too much backpressure and torque. Finally I got the Fast Intentions Intimidator which is 2.5 inch piping and it worked perfectly. I also have Fast Intentions hfc's but no headers. Bottom line, your best bet is probably to get a good 2.5 inch exhaust.

 

If it's just a matter of opening things up post-cats, I may have something in the works. My mechanic is gonna do a little R & D for me this week. It's either gonna be a sweet new mod or an epic failure.

 

Well, it is a matter of opening things up but you don't want to open it up too much. Unlike turbos, we still need some back pressure.

 

At 400 hp, i doubt your timing is that tame.

just post up your timing map from the UTEC and we can quickly tell ya how much room you have to play. if its only 13-14 degrees at the top, you can easily add another 5-6 degrees.

The Utec can log IAT, so you can defiantely monitor that.

Also, if you have big swings in performance, use the temp correction function. Its a little broad in its ranges, but still useful. Also, a bigger intercooler, like mentioned above, would be a smart upgrade before adding Crawford cats (only ones that consistently make power on the dyno). Apparently a 30x10x3.5 fits perfectly, as mentioned by others on My350z

 

open her up a bit with the Fast Intentions 2.5..you will still keep the stock tone but a little deeper..imo