Thoughts about going 4" exhaust? Improved equal length header design?
 

I have an opportunity to have a full Titanium exhaust be made for the Maxima. He has 4" piping on hand as that's what he primarily uses. Should I go 4" or stay 3"?

I'm planning on doing some power adders later this year, and get in the 420- 440hp range. Currently I'm at 380hp. Would the 4" help any?

I'm not concerned about fitment, as I think there is plenty of room to work with..even over the axle. I may even talk to him about Ti equal length headers...first things first though.

Thanks in advance for your input.

i think it's an overkill

stick with 3"

Remember how a few years ago, everyone thought 3" was overkill? Now 3" is the new standard, even on NA 5th gens...

i think you should try it just for awesomeness factor.

Yolo.

Go ahead and try it and be a pioneer!! I'd personally stick with a 3" if you at 380 and want more power just turn boost up you will have no problem making 420-440 on a 3" exhaust. Are you stock block??? Be careful if so.

The only cars I seen 4" exhausts on were like 800WHP supras and BIG V8 turbos making like 800+HP MONSTER POWER. I think its overkill but I could be wrong. Do it.......if it works, heck, maybe I'll go 4" too!!!

seeing how a cutout even at 380hp would result in gains a 4inch exhaust should too. Can you reach your goals with a 3inch yes but a 4inch would be soooooooo cool

I'd stick with 3inch ....

Oh yea and be careful entering the 400hp club if your on stock motor.

stick with the 3" unless you you want as much hp as your supra *wink wink*

Do it for Johnny!!

I'd do 4in just cause theres no1 else around with it lol. Is there anyway he can make another set for my turbo 5.5?

If you can fit it but how the ef will you over the rear beam?

Its overkill. For 400+ three inch will be just fine. Of course 4in wouldnt hurt there really is limited space down there, especially going above the rear axle and geing lowered. My custom 3in is a tight fit, and werent your complaining about banging of the cattman? I get some banging going over certain sized bumps with my custom 3in from times to times. Then your goin to have to find a muffler available in 4in that you like as well.

4" please.

I don't think you guys read what he posted.

Another thing to add, now there are some NA guys on this board that are experimenting with 4" intakes and showing gains I believe (with tuning).


Anyway, it's official. I made a payment today to cover the cost of materials to have the full titanium exhaust system made.

nice, i was just saying yesterday that id like to try a 3.5' exhaust.


i'm running 4" intake and it had huge gains.


but, with my car on the dyno, and opening up a cutout, i only gained 5whp. so im pretty sure the 3' cattman catback, its not restricting much power. the headers themselves are the restriction imo.

I had a unequal length 3' ypipe with larger collectors too and it made more power over stock cattman y pipe.


What i want is a better performance header option. n/a that would pickup some serious power.

dude.... :drool1:

Since I have multiple Maximas, I decided to have two systems built. One 3" and one 4". I'm hoping the whole system will be under 15lbs once complete (Cattman's system weighs 42lbs for reference)

After some discussion, the shop convinced me it would be beneficial if I didn't ship my 3" system to use as a go-by, but rather purchase a Maxima for $500 and design it from scratch. The shop is based out of Texas. Not to mention, the Cattman's 3" system would need some tweaking as fitment is **** at the gastank. After the project, the Maxima, will be re-sold or scrapped for $300.

It will have v-band flanges for ease of installation/shipping.

Having a Max there got me thinking...like some of you guys have been saying, now might be the time to have them develop bigger and better headers...maybe even a custom one-off manifold with internal velocity stacks and setup for a larger TB...hmmmm

In general, if equal length headers were designed from scratch, what improvements can be made over what's out there already (OBX, Cattman, etc)?

If looking for nothing but top end power, how would you change/design the headers compared to what's out there and available to us today?

If looking for an equal bump in power throughout the entire powerband, how would you change/design the headers compared to what's out there and available to us today?

Longer primaries and a bigger collector.

Not bigger, just longer? and for which scenario? top end power or overall power?

Sorry for not being specific.

For top end I would like longer primaries. Larger diameter primaries may be a good idea also but length comes to mind first.

Gotcha. Thanks for clarifying.

What about 3.5?

I keep coming back to this question, but didn't have anything to add. Now I have a few ideas.... First, if they're made from titanium, local welders may not be able to add bungs ? (dunno welding) so any bank-based O2 sensor bungs need to be there and of course a wideband sensor after both banks are merged. Bungs on each cylinder for EGT would be good for a few people. 4th gens would still need the post-cat sensor location. (just stating the obvious)

For a top-end project, the flanges and exhaust tubes should be port-matched to the heads. Any turbulence at that point messes up flow. Where the three tubes merge, a longer 3-way merge would reduce turbulence at the point. Bring each bank's tube back to a tapered collector so that there are gradual changes in diameter into the collector. Any cutout should be a sweeping exit from the collector, not a T off it. Avoid sharp changes in tubing diameter.

Maximum power? Wow.. I would like longer individual tubes from the flanges before merging the 3 together. Ideally the pipes after the merges could go directly into a tapered collector which could exit underneath the car before the rear wheel well using oval tubing and no muffler. Equal-length is not possible here. Even more insane - front and rear long tubes merged into one tube each and exit, through oval tubing, just behind the driver's door (NHRA reg.) on each side of the car. I want those.

Enlarged header tubes are unknown to me, but the mags show that a larger down-tube can pick up some power. Diameter would vary based on the engine and how much exhaust flow the engine produces, and how the ports are configured.

These are just my wish-list thoughts (probably have more coming), but if your builder has better ideas about fitting long-tube header pipes, please share. :)

I would want them to look like this-ish:
Attachment 31715

but equal length

only problem is somewhere between 18-23inch long primaries is the best for the vq30/35, which means the rear header collector would have to point towards the front of the car and the ypipe would have to wrap around kinda like cattmans

I like what I see here. Hum... it looks like the two sections would merge into a 3" or 4" pipe without too much work. Is there any definite reason why they should be equal length after the 3-to-1 merge? And where did you find these shiny pipes, and what car are they built for? :eek:

Dibs on that maxima being used for the prototypes

Wouldn't it be easier to design a true dual exhaust with two 2.5" pipes? You still have mored diameter than one 3" and have an x-pipe or h-pipe.

There was an article I had somewhere linked years ago that tried to scientifically show how backpressure is always bad. Plus all the highest dynonumbers were achieved with open exhaust cut outs, that would go to show that the less restriction, the better.

I think from a practical standpoint 4" might be tough to fit. My 3" scrapes over all kind of bumps already.

SG Motorsports had an awesome longtube header setup for their 350z before they closed doors...I believe it was over 30whp gains vs the stock manifolds. I wonder how close a FWD setup could get with the limitations of the transverse setup...

Cool build Wizard, like the others mentioned, my main concern would be the aggravation of fitting/hearing the piping bang around the rear suspension (if it could fit)...

Have fun!

3000gt.

equal length helps even out the pulses and it will definitely sound better.

Not much of an update except that the 3" Ti tubing and muffler have arrived. Still waiting on v-band flanges.

We also started discussing the possibility of making improved headers and a better intake manifold.

Oh Shiet!!!!:run::run:

They're making great progress and all almost done...

Teaser pic

Attachment 31188

wouldn't a mandrel bender have been easier

^^ not for ti, that's how proper ti 2 stroke expansion chamber exhausts are made


I was gonna say go for it, you have the funds and connections to be a pioneer :)

as for headers... Shorter length headers are the way to make more top end. Jus look at shorty vs unequal vs long tube for mustang or gm v8 in google. Longer ones are good for low and especially mid like the oovi long runner for low rpm and shorter path when vias activates.

Ebay shorties are too short and everything else we got is jus enough length without being a long tube. What i'd want to see is an improved shorty design