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post #1 of 13 (permalink) Old 07-08-2016, 06:14 PM Thread Starter
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DE intake mods help

My desired intake set-up is as pictured:



I'm using the stock airbox (I recently upgraded to the '06 rev-up box. I'm actually impressed with the change in throttle response and high RPM performance. The revs used to get sluggish around the 5000 rpm mark up to redline) And no, don't convince me otherwise. No need for a CAI or pop charger. I want street-able power.

Looking for an intake tube with a MAF sensor slot that will mate up to the stock airbox. An adapter will need to be made obviously. Also wanting to upgrade the throttle body. Might go with the MWP kit.

Now, where can I get a tube to fit my needs? And what is the best way to reprogram the ECU for the larger intake tube?

P.S. I am doing the Motordyne spacer and possibly the MREV2 as well. Headers and cams will be in the works so I need a way to reprogram it in succession.

Be kind. I'm a noob.
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post #2 of 13 (permalink) Old 07-08-2016, 11:56 PM
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I'll be kind since you are a noob. Replacing the OEM intake tube makes no sense, since it's made of a composite that won't absorb heat as quickly as a metal one. Yes, the chrome finish looks flashy, but will also transfer heat to the intake air charge, which in turn will be quickly by the intake sensor and transmitted to the ECM. The ECM will respond by pulling advance to prevent detonation and reduce horsepower. With the intake tube located on top of the engine, heat soak is all but assured to be quick with a metal intake tube.

Ne smart and recognize how good a job Nissan engineers did with the intake.
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post #3 of 13 (permalink) Old 07-09-2016, 12:22 AM Thread Starter
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Man, you like replying to my posts.

I know there is nothing wrong with the intake itself. My original plan was to install a Mishimoto silicone tube (black). But I ran into this picture and thought I would ask what it would take to increase the size of the intake tube to 3" or 3.5". Being "flashy" is irreverent to my quest.

I drove a 350z for 13 years without modding it.
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post #4 of 13 (permalink) Old 07-09-2016, 02:04 PM
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Originally Posted by ZEED View Post
Man, you like replying to my posts.

I know there is nothing wrong with the intake itself. My original plan was to install a Mishimoto silicone tube (black). But I ran into this picture and thought I would ask what it would take to increase the size of the intake tube to 3" or 3.5". Being "flashy" is irreverent to my quest.

I drove a 350z for 13 years without modding it.
Actually, I try to post on ANY of the rare posts on here. As far as mods go, even increasing the size of the intake tube won't help performance either.

My pre-order track model will be 14 years old this October. Never wanted to mod the VQ much, but suspension, a NISMO V2 body kit and upgraded sound system make me a happy Z owner.
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post #5 of 13 (permalink) Old 07-10-2016, 04:18 PM Thread Starter
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Not looking to make huge gains with the VQ35DE I'm trying to improve some of its short falls. Mainly on the intake. Considering I don't have a nearby tuner with a dyno I'm at the whim of internet forums. If I can bolt-on 20 HP I'll be a happy camper. Perhaps If i can find a Z tuner in Canada I can achieve some more. Ideally my goal is 1 HP per liter (350) in NA format if that's achievable
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post #6 of 13 (permalink) Old 07-11-2016, 02:48 AM
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I wont be mean but I will be real...

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Originally Posted by ZEED View Post
Not looking to make huge gains with the VQ35DE
Stop trying...you wont

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Originally Posted by ZEED View Post
Mainly on the intake.
Despite what (dare I say) most the community perceives...the intake is just about as efficient (without FI) as it can get...Remember that nissan had roughly 5 years to research, design, and develop the intake tract to squeeze as much power out of 3.5 liters...going back to the late 1990s and early 2000s, cost was a huge consideration for the death of the z32 and subsequently the rebirth of the z33. Nissan had to do as much as they could to get as much power out of this engine to compete with the retro mustang, genesis, S2000, etc...there was minimal room for slop.

start speculation\
Part of me thinks the most efficient method is the what the HR, VR and VG engines use (single intake per bank of cylinders)...but Nissan knew the DE engine wasnt the final engine to be found in a nissan z-type they had to incorporate some inefficiencies(passenger side running lean, cylinder 6 not getting enough flow, heavy material construction) to build off-of and improve for future sub-generations.
end speculation/

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Originally Posted by ZEED View Post
Considering I don't have a nearby tuner with a dyno I'm at the whim of internet forums.
Then you're s-o-l because that's what you'll need to squeeze non-FI power out of the engine as it comes from the factory...go look up what Sasha (from on-point dyno) with independent throttle bodies, an endless supply of Canadian dollars, a wind tunnel and a dyno...

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Originally Posted by ZEED View Post
If I can bolt-on 20 HP I'll be a happy camper.
keep your hopes low...especially if you can't dyno...

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Originally Posted by ZEED View Post
Ideally my goal is 1 HP per liter (350) in NA format if that's achievable
not achievable with out FI...especially if youre talking about whp...

'03 Z33
'71 S30
'04 Triton 5.4
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post #7 of 13 (permalink) Old 07-11-2016, 07:49 PM
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I know there is nothing wrong with the intake itself.
There is a hell of a lot wrong with the 350z intake
That plenum is just awful, restrictive, different flow to various cylinders, turning the intake through that sharp angle is horrible, etc
But the thing is, Nissan made it work for daily usage
There are a lot of factors making it work - notably the ECU
There is nothing simple you can do in isolation around that plenum to improve performance

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But I ran into this picture and thought I would ask what it would take to increase the size of the intake tube to 3" or 3.5".
A bigger pipe between the air box and throttle body won't help for 2 reasons
1) The air flow at full throttle is limited to the diameter of the throttle body - not the intake pipe - a bigger intake pipe will not make more power
2) When air flows from one diameter into a larger diameter velocity is lost
This is why gutting CAT's does not work really well - it becomes a bubble in the exhaust pipe
As a backyard hack it makes the car feel more responsive but if you dyno a gutted CAT versus replacing the CAT with straight pipe you will find the gutted CAT has less power


I hate the plenum so much I purchased a set of Jenvey ITB's to get rid of the plenum
They cost around $2,500 and I have not had the time or budget to install them yet
(I have 2 race cars soaking up time and money)


Last edited by MartinZ; 07-11-2016 at 09:57 PM.
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post #8 of 13 (permalink) Old 07-11-2016, 08:02 PM
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If I can bolt-on 20 HP I'll be a happy camper. Perhaps If i can find a Z tuner in Canada I can achieve some more. Ideally my goal is 1 HP per liter (350) in NA format if that's achievable

The Z has ~220kw which is 295hp
20hp would be a 6.8% increase
Unfortunately that ain't gonna happen my friend (not easily or cheaply)


People who convert the 350z for track/racing and keep the plenum typically have ~380hp
That's +28% from a $5k engine rebuild with:
  • Race cams
  • High compression pistons
  • Headers
  • No CAT's
  • No mufflers
  • Custom tune on the ECU +$1,000

For the street you could buy
  • exhaust headers $1,250
  • hi-flow CAT's $600
  • fitting above $1,000
  • custom tune on the ECU at a cost of $600 to $1,000
After spending $3,850 you would be lucky to get that 20hp you're seeking
But the car will sound great and it will feel a lot more responsive (due to improved area under the curve)

Last edited by MartinZ; 07-11-2016 at 09:55 PM.
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post #9 of 13 (permalink) Old 07-12-2016, 04:30 PM Thread Starter
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Being real is what I want. Thanks MartinZ for the excellent insight. To be honest I'm a driver, not a mechanic so tuning is beyond me for the most part because I don't live and breath it. I can learn.

I want to make due with my DE, I know the HR is a superior breather... but I prefer my '03 chassis more so than the '04.5 when it comes to spirited/track driving. Plus it's 363 lbs lighter then anything with a HR.

Anyways. From what I gather it is best to do what most have been saying: '06 airbox, stock pipe, and Motordyne spacer?

Lets get technical. The airbox intake hole and MAF housing are 70mm interior diameter. The TB is 70mm. (correct?) What is the plenum intake duct diameter, 70mm?

If I wanted to increase airflow to the plenum by boring out the TB, would I have to get the plenum duct bored out too? Could I keep the MAF and Airbox at 70mm and increase the pipe size?


I did see the On-point Dyno "Carbotron" plenum. That's what I would buy... but it seems the project fizzled away.
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post #10 of 13 (permalink) Old 07-12-2016, 09:51 PM
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The main reason the HR breathes better is because it has two throttle bodies
I don't like the HR valve train - too complex - too many moving parts

No point increasing the diameter of any one point,
the other/smaller diameters will restrict the flow and prevent you from realizing any gains

The plenum internals are larger than 70mm
Trick is to modify the flange and install a larger throttle body
Then the tubes, and airbox need larger diameter
You'll need a different MAF or at least recalibrate it in the ECU
The fuel and maf tables in the ECU will all need work
It's a lot of effort and cost
The Plenum is the limiting factor

The Cosworth plenum did not give any real performance benefit
The Kenetix V1 was a POS (V2 was ok but why buy from that manufacturer who ripped everybody off?)

There are plenty of TB threads




Last edited by MartinZ; 07-12-2016 at 09:57 PM.
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