Jump to content
Sign in to follow this  
enkrypt3d

Headers & Exhaust for more power?

Recommended Posts

Honestly man, are you just trolling?

 

Yes, the stock EGR pipe is used, the Thorleys are direct fit. Do you have a stock manifold and Thorley header in front of you to compare?

 

B

Share this post


Link to post
Share on other sites

Honestly man, are you just trolling?

 

Yes, the stock EGR pipe is used, the Thorleys are direct fit. Do you have a stock manifold and Thorley header in front of you to compare?

 

B

Really dude? I'm on here more than anyone and trying to answer countless unanswered threads here... what are you doing other than criticizing people for asking legit questions? Or just not answering any of them at all.

 

This site is full of thousands of threads that have tons of questions and no answers. I wonder why? Because there is no one here that's willing to help it seems. :wtf: (except for a small number of very friendly people)

 

So much for this forum being a close nit group of people... there's only a handful of folks here that are #1, willing to help and #2 know how to answer the questions... And yea before you say "just search", I do search and all I find are more threads of people asking the same questions with no answers or a thread that are 15 pages long. :headwall::rolleyes:

 

And no I don't have a shop with a professional collection of tools to fabricate anything I like at a moments notice. I live in LA proper. The pathy is my daily driver. So no I don't have the manifolds in front of me. They are on the truck. Excuse me for being a n00b.

Edited by enkrypt3d

Share this post


Link to post
Share on other sites

Wow, your criticism of precise1 IS way off, I have learned more from his advice and direction than any other person on this forum. I think he was asking if you had the parts in front of you to compare the two side by side so you could see how the parts fit. He was trying to HELP you to see how the egr attached. Yes I know some people here don't have a good answer to question, but MOST try to give they're best possible advice. Remember that this site is free to join, and to date, I have yet to see any other forums that can hold a candle to this one. First off I think you owe B an apology, second and more importantly you need to decide if you want our advice, OR don't ask for any. I challenge you to find a friendlier, cleaner and more honest site anywhere else. But that's just my own opinion. **¥^»£¿~

Share this post


Link to post
Share on other sites

This thread will die just like all the others.

 

Precise1 does reply but it's with a sense of reluctance rather than willingness to help. His posts exude a condescending tone (as per his last post calling me a troll)... I'm not apologizing to anyone.

Edited by enkrypt3d

Share this post


Link to post
Share on other sites

Thank you for your input Nissanland, I'm glad I could help.

 

 

Really dude? I'm on here more than anyone and trying to answer countless unanswered threads here... what are you doing other than criticizing people for asking legit questions? Or just not answering any of them at all.

 

This site is full of thousands of threads that have tons of questions and no answers. I wonder why? Because there is no one here that's willing to help it seems. :wtf: (except for a small number of very friendly people)

 

So much for this forum being a close nit group of people... there's only a handful of folks here that are #1, willing to help and #2 know how to answer the questions... And yea before you say "just search", I do search and all I find are more threads of people asking the same questions with no answers or a thread that are 15 pages long. :headwall::rolleyes:

 

And no I don't have a shop with a professional collection of tools to fabricate anything I like at a moments notice. I live in LA proper. The pathy is my daily driver. So no I don't have the manifolds in front of me. They are on the truck. Excuse me for being a n00b.

First off, I'm sorry you took that so wrong and ran with it. I wasn't trying to call you out (you would know when that happens) I was asking about your questions and approach....

Second, when you talk about timing belt and valve adustment (which is impossible) you make yourself hard to believe.

Third, almost everything you have asked is well docuented and archived. Most of us don't mind clearing up some confusion you might have, but don't want to type it for the 23rd time. Is this unreasonable?

 

No problem with the NooB part, everyone was at some point. The thing is to teach how to fish, not to feed them fish. Do you want to learn, or be fed?

If you don't have the manifolds in front of you, how did you deduce that the EGR port is in different places and wouldn't line up?

 

 

This thread will die just like all the others.

 

Precise1 does reply but it's with a sense of reluctance rather than willingness to help. His posts exude a condescending tone (as per his last post calling me a troll)... I'm not apologizing to anyone.

 

The thread you created is Headers-exhaust for more power. How is that a specific tech thread compared to the others?

Third, haven't I posted many times (6-8?) in this thread alone (not to mention others of yours) with info, links, part numbers, etc? How is that reluctant?

Do you have any idea how many threads/posts I read through daily? Can you understand brevity or maximun efficiency?

Lastly, I like the line edited in. Shall I guess who wrote it? It wasn't you... ;)

 

B

Share this post


Link to post
Share on other sites

I don't pretend to know everything there is to know about my pathfinder... (not saying anyone is just to be clear) -

 

The *stealer*ship told me they did a valve adjustment just like they told me they replaced my UCA bushings (which they clearly did not do)...

 

And who did write that last line? :)

 

I saw the EGR line going into the manifold under the hood (where else would it be?)

 

It's pretty easy to see where it is... but again I don't have the tools and I'm not able to have my daily down for days (if I were to try this myself)... I was just eye balling it and wanted to make sure it would be fine since I have to smog my truck soon. Making mods to the truck before smog usually isn't the best idea...I've been down that road many times with my other car.

 

And again my complaint is not against you, it's just in general. There is tons of info here but finding it in an organized way is very time consuming. This is why we have countless unanswered posts b/c the assumption is "eh he'll search for it eventually". But I don't post unless I can't find it by searching first which is shocking I know. But if the info was better organized there'd be less noise and bloat covering up the valuable info here. /rant

 

Not to mention I'm on here all day reading and digesting information... the threads that I do find are 4+ years old and the info I need is spread across many threads with varying opinions on what the facts are as far as what to do, where to find parts, or what the best approach is... there are no turn key solutions for this truck unfortunately.

Edited by enkrypt3d

Share this post


Link to post
Share on other sites

Ok, fair enough. Yeah, the Stealership (in this case) lied to you in the worst way if they said they did a valve adjustment, and hopefully there wan't a charge for it!

 

Not you. Syntax, grammar and spelling. Gimme some credit... See your PMs.

 

Ok, so, the stock manifold looks a lot different, and I believe the Thorley headers raise a little higher, but you have to go by the bolt holes to get things lined up, hence the "do you have them in front of you" question. When you install the Thorleys, you want to get everything ready first, get them mostly lined up, thread in the EGR most of the way, install the headers and go from there.

 

Yes, you are right about all the info! Can you imagine all the time it has taken to orgainze what does exist this way? Pin threads, combine them, create directorys, move, merge, sort, direct threads, link, and discourage duplicates? That doesn't even include personal participation...

Honestly, I think the volunteer staff does a hell of a job, perfect/finished or not. :beer:

Sorry, a lot of things need to be sorted through too. You are welcome to make a compilation of them though... ;)

 

____________________________________________________________________________________________________________

 

So, back to the Thorley headers, they bolt right in, use stock EGR fittings and I thing can be bolted to stock exhaust, although that would be silly.

 

B

Share this post


Link to post
Share on other sites

I guess before this last mod to the DT headers some were having an issue with the placement of the EGR port making it difficult to fit to the headers. I recently installed the new production line and it lined up perfectly. I also ran the stock exhaust to the muffler shop. It was all very straightforward but some pretty tight spaces for hands and tools, especially the flange from header to downpipe. Be prepared to replace the exhaust studs too, you will most likely find some broken ones....

Share this post


Link to post
Share on other sites

Headers and exhaust seem to be a common thing to go after and this question has been asked multiple times. If you're having power issues, even if the maintenance has been done, it is really easy to overlook the most simple things.

 

Any rubber component on the engine will dry rot over time and cause a vacuum leak. Older engines use a lot more vacuum hoses than newer ones. Simply replacing all the rubber hoses can return lost power. Other than screwing with the function of various devices controlled by vacuum, another reason is if any of those get split open or crack, you will have unmetered air going past the MAF sensor and this results in a lean condition because the computer doesn't spray enough fuel. Also, check the most obvious one of all, the flex pipe between the air intake and the throttle body. I replaced mine recently because it split open and gained quite a bit of power back. Keep in mind that sometimes those cracks are not very easy to see. Squeeze it and feel it around to make sure there are no cracks.

 

What you really want is not even the DT short tube headers but equal length headers that ensure perfect exhaust scavenging at the collector. Unequal length short tube headers are just prettied up manifolds. Also, having extra components on the exhaust like muffler and catalytic converter are somewhat of a negation on the headers already. For these reasons, there isn't much of a gain changing out the exhaust with a slightly bigger aftermarket system but it does sound nice and look pretty under the hood. The gains are comparable to a regular cat back system.

 

My favorite part about changing the exhaust though is that I was able to replace all of the exhaust piping from the engine to the tail pipe with stainless steel tubes. No more rust there!

 

 

  • Like 1

Share this post


Link to post
Share on other sites

Not sure when the last mod was done, but before that (4 years), all you had to do was start the threads before bolting the header down. Not like the EGR tube is some impossibly stiff thing to deal with. :shrug:

 

B

Share this post


Link to post
Share on other sites

 

What you really want is not even the DT short tube headers but equal length headers that ensure perfect exhaust scavenging at the collector. Unequal length short tube headers are just prettied up manifolds. Also, having extra components on the exhaust like muffler and catalytic converter are somewhat of a negation on the headers already. For these reasons, there isn't much of a gain changing out the exhaust with a slightly bigger aftermarket system but it does sound nice and look pretty under the hood. The gains are comparable to a regular cat back system.

 

So what headers do you run? You have some sort of dyno info to support all this? Perfect scavenging for a N/A 3 liter V6 pushing 150hp? :blink:

Extra components are required here, some by law everywhere. What exactly is your set up?

 

B

Share this post


Link to post
Share on other sites

My current setup (also in my profile) is like this (and it does pass inspection here but not CA legal due to wrong cat):

  • Doug Thorley Headers (short tube)
  • 2.5" 304 SS piping
  • 49-state Magnaflow cat
  • Flowmaster 50 DF muffler

I agree, those extra components are required for the truck to be road legal in most states. Obviously you don't want to be driving around blowing out people's ear drums.

 

Perfect scavenging is possible on any engine no matter the size. It's really just a concept of physics. The more equal length and longer the pipes are before they meet at the collector, the better horsepower you get. Gain results may vary depending on other factors like boost. The muffler and catalytic converter cause turbulence and back-pressure inside the exhaust system and negate the scavenging effect somewhat but not entirely. That's just the reality. The quieter it gets, the more back pressure inside the system there is. It's not that big of a deal (if any at all) at low rpms but it becomes a drain once you're getting closer to the fun rpm. The exhaust isn't the only factor here. There are also different cam profiles that are used on a daily vs a race vehicle and different compression ratios. The factory cam profiles and maybe even the factory head is the real choke point of the engine, not so much the exhaust. You might see like a 15 hp gain on a N/A motor with stock cams just running open long tubes.

 

 

 

There are plenty of unequal length vs. equal length dyno charts online. For example on Subarus, the equal length headers remove the signature boxer sound but give more performance.

 

With all those things being said, good luck finding a high performance exhaust header for a Nissan truck. :lol:

 

You can make one yourself but you will need a tube bender and a welder and a lot of time and dedication.

 

I hope this answers all of the questions. There is a lot of confusing information out there.

 

Share this post


Link to post
Share on other sites

Coming back to this I forgot to mention that the pipe diameter going off the heads (primary tubes) also matters. The general rule of thumb is that the more power your engine makes, the larger the primary tubes should be. If the tubes are too small, the engine has to work harder to push the gasses out. If the tubes are too big then the scavenging effect starts to fade with lower rpms. They usually range from 1.500" to 2.125". Another thing that makes a difference is the shape and length of the collector.

 

Finally, coating matters. The coating of the primary tubes should ideally be ceramic. This makes a tiny positive difference in power but a huge difference in underhood tempereture and heat soak.

 

Edited by Tungsten

Share this post


Link to post
Share on other sites

You might see like a 15 hp gain on a N/A motor with stock cams just running open long tubes.

 

 

It is dyno proven that a 1998 Impreza 2.5RS gains exactly 15whp with an equal length header, high flow cat, and 2.5" exhaust.

Share this post


Link to post
Share on other sites

Yes, that is all fairly generic, standard info that can be looked up on the internet.

In the case of the Doug Thorley headers which is what we are speaking of...

 


What you really want is not even the DT short tube headers but equal length headers that ensure perfect exhaust scavenging at the collector. Unequal length short tube headers are just prettied up manifolds. Also, having extra components on the exhaust like muffler and catalytic converter are somewhat of a negation on the headers already. For these reasons, there isn't much of a gain changing out the exhaust with a slightly bigger aftermarket system but it does sound nice and look pretty under the hood. The gains are comparable to a regular cat back system.

You still haven't justified this statement, which is patently false. Even the video you posted talked about torque gains from short tube headers and midrange/upper end HP gains from long tube headers. Between that and the ground clearance issues mentioned, it seems that unless you just race around on the freeway, the short tubes would be the more desirable.

Thank you for providing the real information in the video though.

 


I agree, those extra components are required for the truck to be road legal in most states. Obviously you don't want to be driving around blowing out people's ear drums.

 


With all those things being said, good luck finding a high performance exhaust header for a Nissan truck. :lol:

 

There is a lot of confusing information out there.

 

And then there is that whole polution thing...

 

They are still made for the TBI versions.

http://dougthorleyheaders.com/products/searchType/vehicleSearch/year/1988/make/NISSAN_SLASH_DATSUN/model/PATHFINDER/sfID1/9/sfID2/40/sfID3/31/productID/906

 

Yep, that is what we are trying to fix here.

 

B

Share this post


Link to post
Share on other sites

The whole point of that was to show that just popping on an exhaust system from manufacturer X may not guarantee any results. There is a lot of ground to cover when changing out a system. Everything from noise levels to emissions to heat output and what you can do about those things.

 

Short tube headers perform identical to exhaust manifolds because more modern exhaust manifolds are designed to also function as performance headers at low rpm. If there is any gain going from manifolds to short tubes, it will be very marginal. You may see a little bit more just replacing old exhaust components with slightly bigger better quality ones. Similar to a cat-back but with a few more parts.

 

See link: http://www.carcraft.com/techarticles/ls1_engine_header_test/evaluation_dyno_numbers.html

Share this post


Link to post
Share on other sites

 

Short tube headers perform identical to exhaust manifolds because more modern exhaust manifolds are designed to also function as performance headers at low rpm. If there is any gain going from manifolds to short tubes, it will be very marginal.

How is it that you talk about "modern exhaust manifolds" when you are talking about a design from the late 1980's? :scratchhead: It certainly has nothing to do with Pathfinders, the subject here, and posting a link detailing a high performance V* from a sports car that comes tuned from the factoryis silly at best.

 

Once again, your claim of 'very marginal gain' in the Pathfinder application is purely your speculation.

I suggest you contact the people at Doug Thorley headers and advise them of their errors. I'm sure they would appreciate your advice that they stop making their 'prettied up manifolds' and will act on it immediately! :rofl:

 

B

Share this post


Link to post
Share on other sites

I agree that Doug Thorley makes fine headers. However, Nissan knew what they were doing in the 1980's because they actually won races. Their exhaust manifold design for the VG30E/i was also re-used on the VG33E and that should say something. The manifolds are not the problem but the rest of the exhaust can be a little restricted.

 

It doesn't matter if you have short tube headers, long tube headers, or exhaust manifolds. The difference between them will be very small just due to the fact that you are running stock cams with stock heads (that have casting flashes in them) and there is a muffler and a catalytic converter in the way. Suppose you have a "high flow" exhaust setup. The difference between short tubes and long tubes may be like 5-7 hp all else being equal. The difference between short tubes and manifolds if you are lucky (and Nissan didn't design the most efficient manifold possible) will be like 2 hp. Actually removing the restrictions down-stream is more important. If you were to compare the exhausts just opened up after the Y-pipe (and not road legal) you would see a bigger jump between long tubes and short tubes and manifold. Still, you won't feel it in anything over second gear because of the garbage truck style gearing these trucks have.

 

I am basing these assumptions on countless hours of research and experimenting and obtaining information from actual high performance engine builders. This isn't something I'm just pulling out of nowhere. If you spend some time on this, you will see what I mean.

 

If you want to do it the cheapest and best way possible, save your money and skip the headers. Look for any exhaust leaks and broken hangers and fix them. Consider taking the heat shields off the manifolds and then taking off the gap guards from the inner fenders. This puts a lot less heat and stress on the studs and makes them last longer. Get either a Gibson cat-back exhaust or a Borla cat-back exhaust or even just make one yourself with a Flowmaster 60 Delta Flow muffler. Then get a Magnaflow high flow Direct-Fit bolt on CARB compliant catalytic converter. Put those on and enjoy the small added throttle response. The only drawback is it will be slightly louder than factory. Maybe except for Gibson which is really quiet for an aftermarket muffler. This will help scavenge exhaust better from the factory manifolds because you are helping with the main restrictions downstream. If you have to use crush bent tube, which I'm not a fan of, make sure the tube diameter is bigger to accomodate for the crush bends. Mandrel bent/CNC bent pipe is always the best way to go.

 

Now if you want more power, consider either swapping to a VG33E or building a VG34E which is a VG33E that's bored and uses some parts bin stuff. If you go the VG34E route, then you can build a larger diameter exhaust and look into getting a set (or making a set) of long tube headers.

 

Share this post


Link to post
Share on other sites

Did some searching around and found this: http://www.nissanpathfinders.net/forum/topic/35773-what-to-expect-out-of-a-vg33-and-vg34/

 

That's pretty much it for power gains!

 

Also the only guys that have had some reasonable gains with the Thorley short tubes and high flow exhaust alone are those who run the supercharged VG33ER. I am suspecting that this is due to an increase in the size of the down pipes rather than actually scavenging better.

 

Edited by Tungsten

Share this post


Link to post
Share on other sites

Again, that link has nothing to do with VG30E and short tube heders. Please try to stay focused on the topic and not parrot theory.

 

The manifolds are not the problem but the rest of the exhaust can be a little restricted.

 

It doesn't matter if you have short tube headers, long tube headers, or exhaust manifolds. The difference between them will be very small just due to the fact that you are running stock cams with stock heads (that have casting flashes in them) and there is a muffler and a catalytic converter in the way. Suppose you have a "high flow" exhaust setup. The difference between short tubes and long tubes may be like 5-7 hp all else being equal. The difference between short tubes and manifolds if you are lucky (and Nissan didn't design the most efficient manifold possible) will be like 2 hp.

 

I am basing these assumptions

 

Do you realize what the difference between headers and a manifold is? Can you explain it in one normal sentence?

 

Yes, these are your assumptions and should be recognised as such. Yes, your basic comprehension is along the right lines but as usual, the numbers you come up with and assertions you state as fact are unsupported or incorrect.

Some things just don't change...

 

B

Share this post


Link to post
Share on other sites

Not sure when the last mod was done, but before that (4 years), all you had to do was start the threads before bolting the header down. Not like the EGR tube is some impossibly stiff thing to deal with. :shrug:

 

B

i was quoting Doug Thorley directly, the manufacturer. The reason for the new production line (once more quoting DT) was the bung location and mods to relieve some stress points or something similar. I am sure someone with your awesome talents would never have an issue with anything because you are soooo great.

Share this post


Link to post
Share on other sites

Tense much? :rolleyes:

 

If DT decided to modify/change it, I'm sure it was for good reason. There have been a few cases of cracking with their headers but that seems to be few and far between.

I'm just going by about a decade people installing the headers pre-mod, and my personal experience.

Yes, the EGR tube is easy to slightly bend if so desired, and another trick is to loosen the top tube mount as well to get maximum positioning flexability.

 

B

Share this post


Link to post
Share on other sites

Aren't you the one who asked for the information in the first place? :scratchhead:

 

B

Share this post


Link to post
Share on other sites

its pretty clear to me why this forum is dead.... because you always try to make people feel stupid with your condescending remarks....sure there is some useful info there but I think everyone could do without the snarkiness.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

Welcome to NPORA Forums

 

Please register to gain full access to the forum.

Make sure you read the Forum Guidelines and don't forget to post a new intro in the New People Start Here! section, to say hi too everyone.

 

-NPORA

×
×
  • Create New...