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Depends on the engine, the DE engine will see almost zero upgrades whatsoever from a cold air intake and in most cases they will actually lose horsepower. The rev up air box with a ZTube is pretty much the best intake unless you are going to step up to a 75 mm throttle body with a 3.5 or 4-in intake, those larger intakes will require you to get an up rev tune.
Exhaust mods however there are definitely gains to be made, the factory catalytic converters are restrictive so switching them out for high flow cats will usually pick up about 12 or so wheel horsepower, a true dual catback will pick up another 8 or so.
The intake was very well designed on the DE engine.
The HR engine on the other hand it's a little bit of a different story and going with a true dual cold air intake will usually pick up about 20 wheel horsepower. Exhaust gains are about the same on the HR and DE engine switching over to high flow cats and a true dual exhaust.
Depends on the engine, the DE engine will see almost zero upgrades whatsoever from a cold air intake and in most cases they will actually lose horsepower. The rev up air box with a ZTube is pretty much the best intake unless you are going to step up to a 75 mm throttle body with a 3.5 or 4-in intake, those larger intakes will require you to get an up rev tune.
Exhaust mods however there are definitely gains to be made, the factory catalytic converters are restrictive so switching them out for high flow cats will usually pick up about 12 or so wheel horsepower, a true dual catback will pick up another 8 or so.
The intake was very well designed on the DE engine.
The HR engine on the other hand it's a little bit of a different story and going with a true dual cold air intake will usually pick up about 20 wheel horsepower. Exhaust gains are about the same on the HR and DE engine switching over to high flow cats and a true dual exhaust.
What is a "true dual catback" and how is it different from high flow catalytic converters? Thank you Larry
So the stock exhaust system is 2 headers- 2 cats-single y pipe-single mid pipe-single muffler. They are all separate components that bolt together with flanges and reusable gaskets.
Basically it STARTS as dual but converges into a single exhaust at the y-pipe. Here is a photo of the stock setup on a coupe. Circled in yellow in the catalytic converters.
True dual exhaust replaces the y-pipe, the mid-pipe, and the muffler. Here is an example of an aftermarket, they typically use an X-pipe because you want to cross the streams of exhaust pulses or they tend to do bad things (drone/rasp, and no scavenging). So it DOES converge at a single point but you need to remember that exhaust isn't a solid steady stream of air, it's a rapid series of pulses as each piston clears it's air.
Here is a picture of a dual exhaust setup that replaces the y-pipe, mid-pipe and mufflers.
"Cat-back" just means everything downstream from the catalytic converters.
The cats are always sold as a separate component, not as part of an exhaust kit.
"Test pipes" replace the catalytic converter with a hollow pipe for less restriction but at the cost of noise and smell (cats installed the exhaust won't stink like gas).
Dang buddy.....as usual you have explained things that even a novice wanna be Motörhead like me can understand. That was GREAT. You have helped me better understand my car than any other person on the internet. I have asked a ton of questions over the years - some know it alls have been condescending in tone in reply but you have always explained things so that I could understand without acting like an A$$h@le.
I will be replacing my CATS soon because I have 270K miles on my 08 Journey Sedan and when the engine needs rebuilding I will know exactly what exhaust system I want and what it will look like thanks to you.
. When the time comes you will be the one that I contact for advice. I have found a very knowledgeable and honest mechanic who (like you) told me to hold off on the little bit of rattling noise coming from the timing chain tensioners/guides until it is time for a full rebuild. My problem is that I feel the bottom end is still in great shape as is the rest of the head area because no ticking, no extra noise, (besides what I BELIEVE to be the timing chain area issue) no oil burn, no leaks, great power, still 25 MPG @75 MPH. I am concerned that the tensioners/guides/timing chain can go South quick causing all the rest of the engine to go with it. It is a crap shoot. But I am going to listen to the people who know more than I do and not worry about it until it forces me to.
I have replaced all the wear parts you mentioned (All the engine sensors, crank cam MAP etc) along with the front and rear wheel bearings, struts, shocks, fuel pump assembly & plugs.
I have held off on the injectors and coil packs because they are still very efficient. I have used only OEM parts from Nissan/Infiniti The reason I have taken to replacing all these parts is because the ONLY part I have replaced is the starter in 270k miles . (Besides brakes, tires, plugs, shocks/struts & fluids) I do not know much about CV joints or the rear end on this car but there are no leaks anywhere and I have replaced the rear end gear oil every 30K. The fact the transmission is cooled inside the radiator via a HX is a concern but it has lasted 270K without a problem I will put a separate transmission cooler on it when rebuild time comes. I think I covered all the areas you mentioned to me to replace/inspect. If I have missed some - please let me know. Of course every fluid is being replaced/changed. Thank you Cleric for always taking time out of your day to help. Sincerely Larry
If you can, take a video of this suspected timing noise, post it to youtube, then put the link here.
And yeah when I'm typing stuff out I just imagine in my head "how would the car/computer explain the problem to you?" and it's just an emotionless string of words that convey just the facts.
