Hey guys Im planing on getting the HKS Hi-Power exhaust for my 08 350Z. I wanted to know whats better, the test pipes or the hi flow converters. I herd that if im to run with the test pipes I would not have any back pressure and the car would need to be tuned, but why tune it for just an exhaust? Either way which is better to run on my car? Thanks.

 

cant help you all the way but i can tell you that i have the hks hi power exhaust on my 06. i have kinetix hi flow cats and i thought it sounded great and felt a bit more spring in its step. i too am putting on test pipes quite soon and do plan on getting it tuned as well. i have done much more to it and it needs to be tuned for sure this year.

so in my opinion it be a good thing to get it tuned after you do the exhaust. however you might want to hold off until you do a little bit more, such as say headers, plenum, intake or any other mechanical upgrade. things like that so everything can be on it and tuned all at once.

 

ibtl

 

You don't need back pressure in your exhaust. You also will not need to tune it after doing test pipes or high flow cats. Putting test pipes on will make your car pollute 100x more than with the cats but will only give you 5-8hp increase. Is 5hp worth polluting as much as 100 350z's on the road?

This article will help you with the back pressure: http://www.uucmotorwerks.com/html_pr...torquemyth.htm

Back pressure is an automotive myth right up there with the battery on concrete discharges it, tail gate down on a pick-up for better gas mileage etc...

 

i actually picked up almost 19hp on just test pipe with stock exhaust...and yes, it was dyno before and after

 

why is this in the exterior & interior thread??

 

i just notice that also

 

lol

 

Sounds good, so if I were to install it this weekend weather its hi flow cats or test pipes, I don't have to tune it like everyone says I do.

 

Seriously?

Do some research and find out for yourself.

S E A R C H!!@!@

EDIT: oh, and next time, post in the correct section, please!

 

Just because someone posts an internet article "debunking" a supposed myth doesn't mean it's true. The article in reference doesn't answer your question. Yes, the statement "more backpressure equals more torque" is, of course, wrong. However, the article's point is irrelevant to your question.

You will loose some low end torque if you switch to test pipes with no tune. You will, however, gain on the top end. The choice is yours...search if you think i'm kidding.

 

+1, this has been discussed many times. My advice is to browse the 100s of threads about the hks hi power exhaust and put some high flow cats on.

 

Lets see your dyno. Here are two threads I found saying otherwise here on my350z.com both with dynos...

https://my350z.com/forum/g35-g37/444...and-sound.html
https://my350z.com/forum/intake-exha...pipe-dyno.html


No the article doesn't directly answer the question but my posts does. He doesn't need back pressure. Simply google back pressure and read for your self. I spent a few years developing headers for quite a few models a way back. Many cars experienced some torque loss way down low at 2500 rpm. So just make sure you are not towing a trailer with your 350Z while trying to run the 1/4 mile cause that will be a problem. Otherwise where you use your power during hard acceleration 5000-6500 rpm the less back pressure you can get the better off you will be. The highest absolute hp is what wins races, not torque which is why a car with 350whp and 220ft/lbs is faster than a car with 340whp and 300ft/lbs of torque (all else being equal). Tuning the car will not do a lot to regain power at a low RPM level, there is almost no point either. At such a low RPM level the car will not accelerate fast regardless of the HP. A tune will help with higher hp, but you can gain hp from a tune on a fully stock car, so the tune doesn't give HP as a result of the exhaust alone.

The notion that, "I put intake headers exhaust on my car now I need to tune the ecu so it takes advantage of those parts" is wrong. The car will make power "untuned" with those parts. If you modify the ecu and have those parts yes you will get more power, but you are also modifying the parameters of the ecu outside of normal OEM conditions as well which is where part of that power is coming from. The ecu during open loop operation (WOT) runs on a fixed map and if it can get in air more efficiently thus allowing it to burn more gas (make more power) you will see gains. The "tune" people refer to changes the ignition timing, fuel delivery and other parameters during open loop only (not close loop generally) so the more aggressive timing and fuel numbers is where the power from the "tune" comes from. Not because somebody is magically taking advantage of your headers intake and exhaust. It's not the same as tuning with a turbo car which is a far more extreme example of tuning with a stand alone ecu.

Just as an FYI I was sponsored racing my Talon TSI by AEM and took their management certification course so I could dyno tune it myself. So I have a bit of experience in this area.

 

I had gotten confused, that is why I wrote on their "Wrong Location" I asked on here because this is a forum you can ask question and hopefully someone that has already done can help you.

 

Thanks for the information, I appreciate it.

 

sadly this was done over 2yrs ago and i do not have the dyno's to show but i have no reason to lie about this matter..i did have other my350z.com members(blasian and sumknguy) there that day with me...it was our test pipe install day...my baseline on an 06 was 238hp and after was 257hp...

btw, the test pipes i had was the turboxs

 

ok, just talk to blasian and he said i gained like 18horses

 

Yup, he's telling the truth but that was a long time ago and it was done on the same day.

 

Thanks for the info bro.

 

Ok, I believe you, thats a lot of HP from just test pipes so you can see why maybe I might be wondering about a claim like that. Much higher than what most people get I would have to say. Makes me wonder what other factor was contributing to you getting such a high number. Many of the stock dyno's I have seen were between 243-248hp, so maybe your low stock dyno number contributed to seeing such a huge gain.

In my experience a low stock dyno number is achieved on cars mainly when the engines are very cold and oil is not up to temp. Odd as this seems a cold engine with cold oil will produce a lower hp reading. This is why many times the 2nd or 3rd dyno a car does in a row the numbers go up a few hp each time.

I worked with a company producing a 3" exhaust system with 3.5" dp for a Caliber SRT4. The dyno numbers on the first three runs were very different, each run the numbers when up a few hp. After we slapped on the turbo back exhaust with high flow cat the increase was about 35hp from the base, but almost 45hp from the original dyno. So obviously you can see how dyno numbers from an exhaust system (especially on a turbo car) could be skewed widely, and generally are.

Here is a dyno from a guys car, as you can see his first dyno was lower by 3hp than the second. Pretty common..

https://my350z.com/forum/motorsports...o-numbers.html

Maybe that can explain some of the huge gain? Please know I am not attacking you or calling you out, very much the opposite. Just friendly conversation.