CAI or catback exhaust?
10-09-2013, 02:55 AM
#6
I've always done CAI first on all my cars. I guess (as mentioned) it's cheaper and easiest first mod. Not only that, but it just seems like the best first step in getting the car to breath the way you want it! I.E., intake, headers, exh..etc., etc...
10-09-2013, 05:38 AM
#8
Member
Join Date: Jul 2012
Location: Ottawa, Canada
Posts: 159
personally i had an 00 max and i started with the CAI intake and it messed up the low end power on my car and really altered the driving feel. the suction sound is cool tho
i just got an 02 6sp and i put an SRS dual tip catback on first this time and its great. it wont alter the powerband and it makes the tone of the exhaust much deeper. if you still want it louder after that point you can slap a CAI on right after and it'l definitely be roaring
Id go catback first. plus the aftermarket muffler really improves the look of the car as a whole whereas an intake is invisible
i just got an 02 6sp and i put an SRS dual tip catback on first this time and its great. it wont alter the powerband and it makes the tone of the exhaust much deeper. if you still want it louder after that point you can slap a CAI on right after and it'l definitely be roaring
Id go catback first. plus the aftermarket muffler really improves the look of the car as a whole whereas an intake is invisible
10-09-2013, 11:03 AM
#15
JWT/Stillen, proven gains. Not CAI's, but IMO, CAI's are overrated, especially on the A32 & 33.
JWT/Stillen = best performance for the $$, and best construction too. Save for headers for real gains before you do anything to the exhaust.
Also, as we've learned on here over the past decade or so, y-pipes are close to the same price as headers, and headers give better gains than a y-pipe even on an A32 VQ30, so that in and of itself would make me wait for headers before I went with anything exhaust related.
JWT/Stillen = best performance for the $$, and best construction too. Save for headers for real gains before you do anything to the exhaust.
Also, as we've learned on here over the past decade or so, y-pipes are close to the same price as headers, and headers give better gains than a y-pipe even on an A32 VQ30, so that in and of itself would make me wait for headers before I went with anything exhaust related.
10-09-2013, 11:35 AM
#16
Good point, you'd be better off picking up this "supercharger" instead
http://www.ebay.com/itm/Nissan-Elect...0f8527&vxp=mtr
10-09-2013, 12:22 PM
#17
Good point, you'd be better off picking up this "supercharger" instead
http://www.ebay.com/itm/Nissan-Elect...0f8527&vxp=mtr
http://www.ebay.com/itm/Nissan-Elect...0f8527&vxp=mtr
10-09-2013, 01:54 PM
#19
Seriously though, if you don't have a ypipe already, start there. Best bang for the buck performance mod.
and see post #12
http://forums.maxima.org/4th-generat...hread-yet.html
and see post #12
http://forums.maxima.org/4th-generat...hread-yet.html
10-09-2013, 02:12 PM
#20
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
Intake first, exhaust is way more tricky, especially if you want it done right and see actual gains from it.
I second what NMex said above on the CAI being overrated, and anyway unless you drill a hole in your car none of these will be a true CAI anyway. Just get a Stillen hi-flow/JWT pop-charger or make your own SRI of that style.
I took ideas from both Stillen/Jwt as well as a CAI and made a hybrid SRI. I put a venturi tube type chamber inside (aircraft/jet engine style), and made it longer than the Stillen high-flow by about 2" which adds just a bit more HP up top, plus it sits at the very edge of the hood that way (bit colder), I wrapped it up too, to make it even colder, it works. Make sure you leave the helmholtz in place when you do this, it helps.
Correct me if I'm wrong, but IIRC the following rules apply to intakes:
Shorter intake tract = more low-end torque gained/hp lost up top
Longer intake tract = lost low-end torque/hp gain up top.
The reason people don't like the Injen CAI and such is because not only does it have a very long design (proven to lose a ton of low-end torque) but also pulls in hot air from behind the radiator. What I did was played around with mine until I got what I really wanted, and BTW having it be a straight design without turns helps that torque (look at Stillen/JWT design).
As for exhaust, it's way more complicated. I started with Y-pipe + hi-flo CAT right after intake. Felt the gains from the Ypipe but nothing that great (I have a cali spec). Then recently got a shop to make a custom 2.5 cat-back and you can definitely feel the power now and you can feel how well it's breathing. One thing to add about headers is that yes, while they do give the best gains they will also be LOUD AS HELL which is why I still don't have headers and decided to just stick with Y-pipe and also going to punch that damn front pre-cat.
My .02, good luck and have fun with it!
I second what NMex said above on the CAI being overrated, and anyway unless you drill a hole in your car none of these will be a true CAI anyway. Just get a Stillen hi-flow/JWT pop-charger or make your own SRI of that style.
I took ideas from both Stillen/Jwt as well as a CAI and made a hybrid SRI. I put a venturi tube type chamber inside (aircraft/jet engine style), and made it longer than the Stillen high-flow by about 2" which adds just a bit more HP up top, plus it sits at the very edge of the hood that way (bit colder), I wrapped it up too, to make it even colder, it works. Make sure you leave the helmholtz in place when you do this, it helps.
Correct me if I'm wrong, but IIRC the following rules apply to intakes:
Shorter intake tract = more low-end torque gained/hp lost up top
Longer intake tract = lost low-end torque/hp gain up top.
The reason people don't like the Injen CAI and such is because not only does it have a very long design (proven to lose a ton of low-end torque) but also pulls in hot air from behind the radiator. What I did was played around with mine until I got what I really wanted, and BTW having it be a straight design without turns helps that torque (look at Stillen/JWT design).
As for exhaust, it's way more complicated. I started with Y-pipe + hi-flo CAT right after intake. Felt the gains from the Ypipe but nothing that great (I have a cali spec). Then recently got a shop to make a custom 2.5 cat-back and you can definitely feel the power now and you can feel how well it's breathing. One thing to add about headers is that yes, while they do give the best gains they will also be LOUD AS HELL which is why I still don't have headers and decided to just stick with Y-pipe and also going to punch that damn front pre-cat.
My .02, good luck and have fun with it!
10-09-2013, 02:24 PM
#21
The reason people don't like the Injen CAI and such is because not only does it have a very long design (proven to lose a ton of low-end torque) but also pulls in hot air from behind the radiator. What I did was played around with mine until I got what I really wanted, and BTW having it be a straight design without turns helps that torque (look at Stillen/JWT design).
As for exhaust, it's way more complicated. I started with Y-pipe + hi-flo CAT right after intake. Felt the gains from the Ypipe but nothing that great (I have a cali spec). Then recently got a shop to make a custom 2.5 cat-back and you can definitely feel the power now and you can feel how well it's breathing. One thing to add about headers is that yes, while they do give the best gains they will also be LOUD AS HELL which is why I still don't have headers and decided to just stick with Y-pipe and also going to punch that damn front pre-cat.
My .02, good luck and have fun with it!
My .02, good luck and have fun with it!
10-09-2013, 02:27 PM
#22
10-09-2013, 02:39 PM
#23
You'd be surprised. Being in CA, we don't get a lot of rain or heavy rains. A friend of mine hydrolocked his engine with an Injen intake driving through the rain and puddles. Imagine how the odds increase in states with much more rain.
10-09-2013, 02:44 PM
#24
Wow man, that's shocking. I'm now not so pleased with my recent purchase.
Anyone want an Injen for a 5.5?
10-09-2013, 02:47 PM
#25
http://www.autoanything.com/air-filt...FWLHtAodghYAQA
10-09-2013, 03:00 PM
#26
The fact that Injen and other companies sell hydro shields should speak volumes...
http://www.autoanything.com/air-filt...FWLHtAodghYAQA
http://www.autoanything.com/air-filt...FWLHtAodghYAQA
10-09-2013, 03:10 PM
#27
Small disclaimer, most of my testing has been done on a 5.5 gen, but I still think the concept applies and should be noted.
And even then, it has been proven that ambient temps aren't much lower than underood temps in normal driving. Granted in heavy traffic that is different, but, who needs extra power in traffic?
The Helmholtz only helps with smoothing the curve a bit, but peak power is found without it. I have proven this as has another member. I can post dynos if needed. This was seen on both the VQ30 and VQ35
We used to think that.
http://forums.maxima.org/5th-generat...i-rethink.html
http://forums.maxima.org/7939656-post37.html
Even though the post is from a scam artist, I believe the concept still applies. Also, even though the pictures are gone, I have the actual DRF's.
Also, I have also proven test pipes do add power in the midrange and up top. A test pipe coupled with removal of the Helmholtz netted a lot more power.
Intake first, exhaust is way more tricky, especially if you want it done right and see actual gains from it.
I second what NMex said above on the CAI being overrated, and anyway unless you drill a hole in your car none of these will be a true CAI anyway. Just get a Stillen hi-flow/JWT pop-charger or make your own SRI of that style.
I second what NMex said above on the CAI being overrated, and anyway unless you drill a hole in your car none of these will be a true CAI anyway. Just get a Stillen hi-flow/JWT pop-charger or make your own SRI of that style.
Originally Posted by D.Stillwell
I took ideas from both Stillen/Jwt as well as a CAI and made a hybrid SRI. I put a venturi tube type chamber inside (aircraft/jet engine style), and made it longer than the Stillen high-flow by about 2" which adds just a bit more HP up top, plus it sits at the very edge of the hood that way (bit colder), I wrapped it up too, to make it even colder, it works. Make sure you leave the helmholtz in place when you do this, it helps.
Originally Posted by D.Stillwell
Correct me if I'm wrong, but IIRC the following rules apply to intakes:
Shorter intake tract = more low-end torque gained/hp lost up top
Longer intake tract = lost low-end torque/hp gain up top.
Shorter intake tract = more low-end torque gained/hp lost up top
Longer intake tract = lost low-end torque/hp gain up top.
http://forums.maxima.org/5th-generat...i-rethink.html
http://forums.maxima.org/7939656-post37.html
Even though the post is from a scam artist, I believe the concept still applies. Also, even though the pictures are gone, I have the actual DRF's.
Also, I have also proven test pipes do add power in the midrange and up top. A test pipe coupled with removal of the Helmholtz netted a lot more power.
10-09-2013, 03:20 PM
#28
I just chatted with a rep and received a very vague response to the water and heat questions. The response I did get was on the ground clearance - 1.5 to 2 inches of the ground. I can see how water could be an issue.
http://a.cdnbrm.com/images/info/injen/RD1940.pdf
http://a.cdnbrm.com/images/info/injen/RD1940.pdf
10-09-2013, 06:45 PM
#31
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
Nmex, great info!
You are right on point with the ambient temps not being much lower than under-hood while driving, air flows into the grill and flows right over top of the engine and exits at the top of the hood and over the windshield...
I've seen the threads about the helmholtz and smoothing out the curve. But did not know that peak power is found w/o it. Can you share those dynos please if not a hassle? I would love to see the gains w/o helmholtz, mine is only a few min away from being removed at any given time you know.
Looks like I actually made a decent intake after all. I tried copying the inner design from a jet aircraft intake. Mine runs all the way to the edge of the engine, so it is longer and 100% straight, and it has a test pipe/mid pipe before the MAF but mine is like a venturi chamber and runs thru the helmholtz so that max pressure builds right before the TB.
I love the .org, where a thread by a newbie asking what he should do first turns into a full blown technical discussion on intake/exhaust.
You are right on point with the ambient temps not being much lower than under-hood while driving, air flows into the grill and flows right over top of the engine and exits at the top of the hood and over the windshield...
I've seen the threads about the helmholtz and smoothing out the curve. But did not know that peak power is found w/o it. Can you share those dynos please if not a hassle? I would love to see the gains w/o helmholtz, mine is only a few min away from being removed at any given time you know.
Looks like I actually made a decent intake after all. I tried copying the inner design from a jet aircraft intake. Mine runs all the way to the edge of the engine, so it is longer and 100% straight, and it has a test pipe/mid pipe before the MAF but mine is like a venturi chamber and runs thru the helmholtz so that max pressure builds right before the TB.
I love the .org, where a thread by a newbie asking what he should do first turns into a full blown technical discussion on intake/exhaust.
10-09-2013, 08:25 PM
#34
Bought a PR style CAI off ebay for $35. Filter is **** so I bought a Amsoil dry cone filter for $65. An actual CAI that got air from outside the engine bay unlike the sh1tty HAI (hot air intake) Injen that costs about $200+
10-10-2013, 06:33 AM
#36
Irish44j had a PRCAI, drill hole in the fender deal and he tested ambient vs IAT's, and saw about the same as a normal underhood intake.
Intakes on these engines comes with added size, as in a larger MAF diameter coupled with a MAF scaling device.
Test pipe + Helmholtz delete.
On a 4th gen:
On a 5.5 gen:
Helmholtz.
No Hemlholtz
Helmholtz vs no Helmholtz closed airbox
Helmholtz vs no Helmholtz open airbox (GAB)
The 4 above were my early dyno days, so the lockup torque convertor was doing its thing, that's the reason for the RPM switchback loop since the X axis is RPM.
Intakes on these engines comes with added size, as in a larger MAF diameter coupled with a MAF scaling device.
Test pipe + Helmholtz delete.
On a 4th gen:
On a 5.5 gen:
Helmholtz.
No Hemlholtz
Helmholtz vs no Helmholtz closed airbox
Helmholtz vs no Helmholtz open airbox (GAB)
The 4 above were my early dyno days, so the lockup torque convertor was doing its thing, that's the reason for the RPM switchback loop since the X axis is RPM.
Last edited by NmexMAX; 10-10-2013 at 07:03 AM.
10-10-2013, 03:03 PM
#37
Irish44j had a PRCAI, drill hole in the fender deal and he tested ambient vs IAT's, and saw about the same as a normal underhood intake.
Intakes on these engines comes with added size, as in a larger MAF diameter coupled with a MAF scaling device.
Test pipe + Helmholtz delete.
On a 4th gen:
On a 5.5 gen:
Helmholtz.
No Hemlholtz
Helmholtz vs no Helmholtz closed airbox
Helmholtz vs no Helmholtz open airbox (GAB)
The 4 above were my early dyno days, so the lockup torque convertor was doing its thing, that's the reason for the RPM switchback loop since the X axis is RPM.
Intakes on these engines comes with added size, as in a larger MAF diameter coupled with a MAF scaling device.
Test pipe + Helmholtz delete.
On a 4th gen:
On a 5.5 gen:
Helmholtz.
No Hemlholtz
Helmholtz vs no Helmholtz closed airbox
Helmholtz vs no Helmholtz open airbox (GAB)
The 4 above were my early dyno days, so the lockup torque convertor was doing its thing, that's the reason for the RPM switchback loop since the X axis is RPM.
whats helmholz?
10-10-2013, 03:33 PM
#38
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
^^^ 
BTW, thanks Nmex. Awesome info and dynos and all, now I have more work and testing to do.
Hard to believe that it makes such a huge difference, then again not really. Stock intake isn't designed for performance, no sir it's not.
What's not surprising is the closed vs. open airbox, I've done a bunch of tests myself and definitely can back up the fact that closed airbox is the worst for performance and opening it up in any way does wonders for airflow.
Anyone want to buy an OEM Helmholtz resonator? I also have stock airbox and all that stuff too, any takers?
BTW, thanks Nmex. Awesome info and dynos and all, now I have more work and testing to do.
Hard to believe that it makes such a huge difference, then again not really. Stock intake isn't designed for performance, no sir it's not.
What's not surprising is the closed vs. open airbox, I've done a bunch of tests myself and definitely can back up the fact that closed airbox is the worst for performance and opening it up in any way does wonders for airflow.
Anyone want to buy an OEM Helmholtz resonator? I also have stock airbox and all that stuff too, any takers?
10-10-2013, 03:37 PM
#39
This is the GAB mod, small free modification done to the 5th gen airbox. I was also of the opinion that TP's were just for rasp, but I was a believer after that dyno. The helmholtz resonator deal is pretty old stuff, though if onlt the curve could be amplified using it, I'd rather use it. Being that it's far more consistent and not as "camel humpy" as a straight pipe. Though I'm sure the pipe length and acoustics could be tuned to reach the hemlholtz type curve on an amplified scale if the resonance tuning was good.
