How much power increase when doing full exhaust?
10-27-2010, 03:02 PM
#1
How much power increase when doing full exhaust?
I was wanting to get headers because my precats are starting to get clogged but I think I want to go full exhaust all at once (Cattman headers, y-pipe, fastcat, and 3" exhaust) I will be getting my tax return in January and this is what I have my eye on. For anyone running this setup did you notice a significant increase in power? BTW how much hp do you gain from a full exhaust? I read that the headers alone give up to 26hp
10-27-2010, 06:31 PM
#7
I did the full setup all at once. Honestly, I didn't notice as much in gains as I expected... but, I believe I'm running super rich because of my mods, so I'm getting my tune on for christmas 
(VAFCII, Wideband) Oh, and I don't have an intake, so I'm getting that too. Then hopefully I see that 35-40 or so hp that I'm supposed to see.
My point is... if you want the full gains, you usually need to tune your AFR as well. Full exhaust (esp. headers) will make our cars run pig rich... some more than others.
(VAFCII, Wideband) Oh, and I don't have an intake, so I'm getting that too. Then hopefully I see that 35-40 or so hp that I'm supposed to see. My point is... if you want the full gains, you usually need to tune your AFR as well. Full exhaust (esp. headers) will make our cars run pig rich... some more than others.
10-31-2010, 01:21 AM
#9
I did the full setup all at once. Honestly, I didn't notice as much in gains as I expected... but, I believe I'm running super rich because of my mods, so I'm getting my tune on for christmas (VAFCII, Wideband) Oh, and I don't have an intake, so I'm getting that too. Then hopefully I see that 35-40 or so hp that I'm supposed to see.
My point is... if you want the full gains, you usually need to tune your AFR as well. Full exhaust (esp. headers) will make our cars run pig rich... some more than others.
(VAFCII, Wideband) Oh, and I don't have an intake, so I'm getting that too. Then hopefully I see that 35-40 or so hp that I'm supposed to see. My point is... if you want the full gains, you usually need to tune your AFR as well. Full exhaust (esp. headers) will make our cars run pig rich... some more than others.
11-25-2010, 11:45 AM
#10
Junior Member
Join Date: Oct 2007
Posts: 69
That Oem intake is restrictive, I made 8whp peak w/that overly restrictive Injen Intake which made about 12-14 whp over the Oem (under the curve) in the midrange. The midrange was awesome with this Injen but over 6K it's a bit too long (39") to move air as fast as the engine needs it.... Make yourself a SRI or switch to a JWT popcharger and you see the difference.....
11-25-2010, 11:49 AM
#11
Short ram intake.
OP: I'll say this...I did a few power-adder mods to my car before getting headers. Intake, exhaust, and NWP block plate, specifically. Of the four mods, I/H/E/BOP, the headers were the only "holy ****" mod as far as actually being able to feel the gains.
Coupled that with a test pipe a few months later, and I picked up a ton of midrange torque.
OP: I'll say this...I did a few power-adder mods to my car before getting headers. Intake, exhaust, and NWP block plate, specifically. Of the four mods, I/H/E/BOP, the headers were the only "holy ****" mod as far as actually being able to feel the gains.
Coupled that with a test pipe a few months later, and I picked up a ton of midrange torque.
11-26-2010, 12:18 PM
#12
SRI stands for (Short Ram Intake).....these intakes seem to work better with the VQ35 IMO, longer intakes can't flow as fast as the shorter intake.....Maybe using a 3.5"-4.0" intake tube would work I'm not sure, but I do know Injen's Intake becomes restrictive at higher rpm's cause the systems way too long! The normal theory as usual in engine breathing dynamics short for power/ long for torque!
11-26-2010, 12:49 PM
#13
Knowing my limitations on engineering considerations like this, I'm content enough to accept the way it works, without understanding why it works.
Last edited by Rochester; 11-26-2010 at 12:53 PM.
11-26-2010, 02:51 PM
#14
Found this some time ago and it may be of some help on understanding it. Makes sense to me
source: http://auto.howstuffworks.com/question517.htm
When the intake valve is open on the engine, air is being sucked into the engine, so the air in the intake runner is moving rapidly toward the cylinder. When the intake valve closes suddenly, this air slams to a stop and stacks up on itself, forming an area of high pressure. This high-pressure wave makes its way up the intake runner away from the cylinder. When it reaches the end of the intake runner, where the runner connects to the intake manifold, the pressure wave bounces back down the intake runner.
If the intake runner is just the right length, that pressure wave will arrive back at the intake valve just as it opens for the next cycle. This extra pressure helps cram more air-fuel mix into the cylinder -- effectively acting like a turbocharger.
If the intake runner is just the right length, that pressure wave will arrive back at the intake valve just as it opens for the next cycle. This extra pressure helps cram more air-fuel mix into the cylinder -- effectively acting like a turbocharger.
11-27-2010, 08:52 AM
#16
torque steer will be an issue lol....but definitely well worth it. i have yet to set down and tune, but its plenty quick with the additions ive made. I would have to say with the 3 inch installed first it was a big difference. and then doing the headers it was another notable/pleasant difference. should have the wideband and utec installed by the 8th of next month sooooo...let you know how it goes from there. but pull the trigger you wont be disappointed.
11-28-2010, 10:11 AM
#24
Bandwagon Lover
Join Date: Feb 2002
Posts: 1,023
I had no torque steer with Eibachs, Illuminas, and FSTB.
A consideration when talking Injen CAI (LRI) is that the stock Maxima can boil the tires from a start as it is. Taking away some low-range power in that aspect won't hurt 1/4-mile times that much. Regardless, I found a GAB to be better than the Injen.
A consideration when talking Injen CAI (LRI) is that the stock Maxima can boil the tires from a start as it is. Taking away some low-range power in that aspect won't hurt 1/4-mile times that much. Regardless, I found a GAB to be better than the Injen.
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