R32 GTR Front Pipe Question

[TXSquirrel]

My R32 GTR currently has Reimax 60mm front pipe (was told 65mm when I bought it), but the Tomei dumps I recently had installed have 68mm exit.  Is it worth spending a few hundred getting a 70mm front pipe to match the dumps?  Will I loose low end torque with a bigger front pipe?

Also the Reimax front pipe has 80mm exit, but previous owner had a 76mm straight pipe installed.  Is it worth upgrading to a 80mm straight pipe?  The cat back section is also 80mm Reimax with 115mm tip.

Inputs appreciated!

[r32-25t]

Bigger is always better when it come to turbo exhuasts, 

[Dose Pipe Sutututu]

You will never lose low end going bigger, should watch that episode of Engineering Explained 

It's a myth 

[TXSquirrel]

Just watched it, very good info.  So going big decreases back pressure, but too big will also decreases velocity and decreases scavenging effect.

How about equal length?  There are half a dozen choices out there, some equal length some not.  For an NA engine equal length is likely important, but I'm not sure about turbo...

Should I also spend another few hundred for a 80mm straight pipe to replace my 76mm?

[GTSBoy]

There's no such thing as "scavenging effect" in the 2x dump pipes on a GTR.  The exhaust pressure pulses are extremely softened by the turbines.  They do not arrive at the downstream merge as pulses with energy to drive scavenging from the other pipe.

[Dose Pipe Sutututu]

This is why twins are gay.

Single turbo, full divided housing, full divided manifold, equal length manifold is the only way to harness the scavenging effects. Less heat due to less restrictions, less piping, less blown 2nd turbo (because it doesn't' exist).

But back on topic, just go massive

[Juan_2_3]

No large power benefits to equal length more so the sound. The sound above 5000rpm with a equal length sounds HEAPS better than non-equal. Turbo engine you just want to get rid of the gases as quick as possible, bigger the better.

[TXSquirrel]

Is there a brand preference?  Because the price range is really wide, almost 3x difference between highest and lowest. 

Mine's ¥72,986, HKS ¥54,481, HPI ¥45,678, Greddy ¥27,210.  All stainless steel except Greddy, which I think is mild steel but painted.

https://www.rhdjapan.com/mine-s-front-pipe-pro-stainless-steel-bnr32-bcnr33-bnr34.html

https://www.rhdjapan.com/hks-stainless-front-pipe-bnr32-bcnr33-bnr34.html

https://www.rhdjapan.com/hpi-single-front-pipe-bnr32-bcnr33.html

https://www.rhdjapan.com/trust-greddy-mx-front-pipe-bnr32.html

[r32-25t]

I’ve got the Midori ones that go from 76mm to 90mm

[burn4005]

+1 equal length pipe sounds glorious.

[TXSquirrel]

Yeah I saw the Midori front pipe too, but it is one of the few that is not equal length.  (and most titanium ones are not equal length)

I end up buying Greddy, which is cheaper but still equal length and weights slightly less than others because it is not stainless steel.  Where I live I do not need stainless steel anyways.  I also bought Tomei's titanium straight pipe.  Will see if anything improves after I have them installed and dyno'd during the next couple months.

[sneakey pete]

Greddy are not equal length...

[TXSquirrel]

Really?  Google Translate says it is 

http://www.trust-power.com/products/exhausts/greddy-mxフロントパイプ/

Product features

It is a front pipe pursuing smoothing of piping and optimization of pipe diameter. 
By improving exhaust efficiency, exhaust gas resistance immediately after turbocharger is greatly reduced, and efficient supercharging is promoted. 
For RB 26 DETT, it is designed to increase the exhaust efficiency by using exhaust pulsation by equalizing the length from the turbocharger to the collecting section.

[l0ckym]

where did you buy it from?

[Robzilla32]

In the pic, the pipes do not look to be of equal length.

[UWISSH!]

I think that’s just a general statement saying that going to an aftermarket front pipe is going to improve gas flow and efficiency.
Not one bit of that to me says equal length pipes

[UWISSH!]

http://cartoys.com.au/product/greddy-trust-nissan-skyline-r32-gtr-mx-front-pipe-rb26dett/

They are most certainly not equal length

[Piggaz]

Need a single. Don’t have to worry about equal length wanker junk. More power everywhere, better transient, just put one on it. Waste of money. 

[TXSquirrel]

I will measure it once I receive it to see how big is the length difference.  I will weight it too.

I didn't get HPI because they dent their pipe to make it fit (says so on their Japanese website and it shows on their product picture) instead of designing to make it fit.  HKS has 85mm exit, and my cat back section is 80mm, I didn't want to create another step down.  Midori is a true non equal length (at least Greddy tries to fake it).  https://www.rhdjapan.com/midori-seibi-center-front-pipe-sus-80mm-bnr32.html  Mine's is just very expensive and is made to order so will take a long time.

I bought mine from FRSport.com, they price-matched another webste so I paid $314.40 USD shipped.

[sneakey pete]

Don't worry it'll work, and as said above equal length is more about sound than anything.
I do find that a good twin scroll single manifold makes a similar sound so i'm happy either way.