Straight piped for power
 

Hey guys, currently I'm running non resonated test pipes , Topspeer 2.5 inch dual cat back, and my own shirt tails with those hemlotz resonators in them. Leo you think I am loosing any significant power ?? My car is a 2014 Nismo 370z btw

Why would you lose power?

No pressure in the bsck anymore

I removed th mufflers

Just changing the mufflers isn't gonna lose or gain you any power

Exactly! Why the hell
Do people keep insisting I am loosing power and torque from taking off my mufflers from my cat back

Do you know what your A/F is? With the muffler gone. You might be lean.

Agree.

I have no idea, but if I am, a tune would correct it? Btw what wre consequences of running lean

Don't worry about running lean. I put a custom dual with top speed axle backs and my Z screams. I even picked up 2-3mpg too. I'm at 22.5 on daily and 28 hwy. Go for it and you will be happy. There is a bit of drone tho.

They are insisting that you are losing low down torque due to the loss of back pressure from having no restrictions, such as cats, and a larger pipe diameter, which would increase flow. A tune would correct the A/F and bring some of that lost power back.

As for consequences, if you were really lean it could cause detonation and damage your engine. I doubt that's happening though. The ECU will compensate as much as it can.

When the ECU is in closed loop. It can adjust the A/F pretty close to where it needs to be, unless it is too far to the one side. Then you need a tune. At WOT, think you will need a tune to correct the A/F. As for engine damage. Agree, detonation, burnt exhaust valves, turn the tops of the pistons into silly putty, burn the ends of the spark plugs off, etc. Don't ask me how I know. :facepalm:

wow, so exactly how much power (hp and torque) am I really loosing from being straight piped on my nismo? even with a tune will I never have as good power output as with mufflers?

Hard to guess on power loss. The only way to know for sure is to dyno before and after. You lost a couple ponies, and some torque on top. How much, don't know. With a tune. You might be more then what you had before the mods. Don't know because you have no base line.

Probably not losing any power down low -- test pipes and exhaust delete are common mods that haven't shown losses to the best of my knowledge -- and you almost certainly gained a good bit up top.

Now, how the ECU has adjusted to these changes (especially without a tune to deal with the missing cats...) isn't clear.

Do you have a CEL (SES) light on?

Loosing your stock exhaust for a better flowing one does help considerably. My best 1/4 mile time was a 13.3 with the stock exhaust and a 13.4 with my dual. Difference being is the 13.3 was in October with cooler weather vs May with high humidity and higher temperatures. I'm hoping to run a 13 flat here in a few weeks with cooler weather heading here. Will post up times in a few weeks

:worthless:

Put up a video too! This sounds like it's a monster.

i agree with the OP. straight pipes does feel like you're missing some TQ on the bottom.

on top however it feels like it pulls harder than when i have my mufflers on.

running full 2.5" Fast Intentions non-res TP and non-res CBE with custom short tails to match up with the FI system. with FI tips of course :tiphat:

been running mine since march, with a small exception of putting the mufflers back on for inspection.

have not been on a dyno nor re-tuned. everything runs great but the butt dyno does report a slight delay/tw loss on the bottom. WOT feels great so i dont see a AFR issue.

i mean i do have my own personal uprev i guess i could fire up the laptop i test it out lol

http://www.the370z.com/intake-exhaus...s-exhaust.html

I'm a little confused on this one like the OP, currently I'm running only aam short tails and k&n drop ins with z1 post maf tubes. From what I understand the short tails causes a loss in back pressure which takes away some low end torque, which honestly my butt dyno didn't notice lol but I did notice a small gain up top because it revs easier. My plan is to pick up the AAM s line midpipe to go along with the short tails. Now they claim that is pretty much an increase in 20whp and torque, but from reading this thread it seems like I would lose power? Isn't the AAM s line and short tails combo pretty much a straight pipe catback I guess? Thanks fellas

Nope, to my amazement no check engine light lol. Only the windshield washer fluid from the INjen 😂😂

with my regular set-up my only backpressure was my mufflers and it was a monster.....still is ;)

i was tuned at AAM with my original set-up (in sig still) at 324whp and 258wtq.

i feel that now without the mufflers is the only reason i feel the slight loss in tq. and again it's butt dyno and it may be my ears playing tricks on me.

i say this since now with it being so loud so quick my brain may be telling me i should be going faster than i am based on pure sound......if that makes sense?

i have ran the 1/4 in back to back weekends with and without mufflers recently and saw no real differnce in my ET's and other numbers soooo idk.

How would I post a video ??

like this lol

haha I was gonna ask you for a video of your car, good looks it sounds insaneee. Anyone know any good tuners that do uprev in Jersey? Probably going to be a while before I tune it tho, still have a lot of modding to be done. Envy, big difference in how the car ran before and after a tune? I know with my Talon heavily modded, it ran lean and like **** before a tune.

Dude! You hit the nail on the head! that's rxsctly what I predicted. When I was stock muffler I felt slow since it didn't sound like I was going fast. With mufflers on I felt way fast since I heard the engine revving, and now I'm straight piped I still feel fast but when I rip it , it feels like my car is going to go to the moon, But it's not any faster than before.

I was just open mid pipes for like s week . I felt no difference at ALL. and when I crafted my own short tails with helmholtz, I must note that now is when I feel the loss.

where in jersey are you?

R/T tuning is in the Philly area. they are well known for 370Z tuning and have a fall special right now.

and where i went AAM Competition is in the Baltimore area.

as for the before and after on the tune. YES lol

i put my full exhaust on (with mufflers) and my intakes so i was due for a tune.

pre-tune i baselined at 309whp/250wtq
post tune was 324whp/258wtq

plus i had them bump up my redline, remove speed limiter, raise my transmission line pressure, etc...

it made a difference for sure. went out the next day while still in the area to Capitol Raceways and ran my PB 1/4 mile ET of 12.89 @ 111mph.

North Jersey in Wayne, so not toooo far from Philly. I plan on getting the aam s line midpipe, then after that maybe nst pullies. Still researching on the FI long tube headers, and not sure if I am going to be going with test pipes of hfc. I think the car will be too loud with those options, especially with my short tails and midpipe setup lol. Any advice or recommendations on mods bro?

Thanks for all the info I appreciate it.

i ran FI non-res TP and non res CBE with the carbon fiber mufflers for arounf 30k miles and loved it. that is pretty much the loudest set-up you can buy from them considering the LTH give a little more depth to the sound but performance wise there's not a major difference between the LTH and TPs since the real power come from the cat deletion.

AAM makes some good exhaust pieces as well. i've heard good things about them and plus ive been to AAM's shop and its a nice operation.

NST pullies i know not much about them besides a issue they had with a group buy i believe a while back.

i will suggest after the exhaust mods are done to just finish off the breather mods with a set of intakes as well. then tune.

intake choices are really up to you and there are many lol

With the short tails, I know a lot of people find it too loud and don't like it. I think it's a deep low growl while normal driving, then spirited it sounds good. You don't even hear the tails while cruising on the highway.
With the midpipes though I have no clue how much louder they get besides a couple of crap quality YouTube videos lol. Lets say I go with the tails, midpipe, and hfc but resonated. Would the hfc's make the car scream even though they are resonated? I don't know anyone on the forum running this current setup, not many people have the midpipe with tails. Sorry for all the questions man.

and my bad OP! I just realized I jacked the hell out of your thread haha can't help it, love learning about this sh**!

anything under like 2500 RPMs for me and it's pretty quiet even with striahgt pipes but just has this mean sound then once morep edal is applied it's just a monster.

as for the short tails, mid pipe, and HFC question i feel that it'll be pretty loud.
the only restriction you will have is the small catted section and the resonators on the S line midpipe. also are you getting just HFC or the ones like FI also offers that are resonated HFCs? i say you said resonated but not sure if you were reffering to them just having some sound restriction due to the cat cells

Yea def interested in the FI hfc's, always hear great things about them. Guess I'll just have to see where the car is when I get the s line midpipe done, along with short tails and the drop ins with tubes hopefully I'll be at 300 whp.

you should hit 300whp with that setup and probably over 300whp with a tune.

remember i baselined pre-tune at 309whp with just my exhaust/intakes.

Thanks bro I appreciate all the help. After the exhaust mods I'll start working on the suspension!

:tiphat: anytime.