Port Matching -7's To Rb26 Manifolds

[snozzle]

hey all

im not sure if my manifolds have been port matched to the -7's i have installed so im thinking of removing them as i see its a common thing thats done on most twin setups.

is it worth taking them off to do this before my tune in 2 weeks? im hoping to run 1.3 bar through them

labour will be free but ofcourse ill have to use new gaskets so that will be the only cost

has anyone done back to back testing with and without port matched manifolds? would it be a waste of time for my 320kw goal?

thanks

oz

[R31Nismoid]

IMO, a waste of time/effort.

I don't run port matched items.

[waxracing]

I have been porting engines for years and I would say you need to match port things if you want them to flow as best as they can.

even if the turbos are bigger than the manifolds you will create an eddy as it goes into a bigger area and the tumbling effect shows up in reduced flow.

This shows up on the flow bench big time.

[R31Nismoid]

And as plenty have proven - what occurs on a flow bench isn't necessarily what actually occurs under boost/pressure/heat etc.

[waxracing]

And as plenty have proven - what occurs on a flow bench isn't necessarily what actually occurs under boost/pressure/heat etc.

And plenty has been proved on a flow bench as to what works as well.

If you dont want to port match its cool and up to you, its a free world after all.

[GTScotT]

From memory I read the autospeed article about changing the GTR turbos and thought the overall result was less than mediocre. They port matched the manifolds and ran -7s IIRC.

Most people on here acheive close to the numbers you want without touching the manifolds, thus I would simply follow suit.

I have always wondered though, which turbos come with the cut size T25 flange and which come with the full size T25.... I would IMAGINE the full size flange to be on something -10 size or possibly even the -5s. Can anyone confirm?

Running a full size T25 entry turbine housing on the stock manifolds would definitely warrant porting IMHO.

[BoostdR]

Port matching will aid "max" flow.

Leaving the manifolds std with smaller turbo's is not a bad idea as response can be effected by opening up the mani outlets.

If the std mani's aren't a great restriction at your power level ie: less than 2.5 x boost pressure. The effort may not be worth it.

If you would rather 10kw up top rather than the mid range then go for it. I would be aiming for average power(nice meaty mid range)

matt

[gtr fan]

if there already on the car just leave it.

If they weren't on the car you would just have the turbo flange on the manifold opened up to match the turbine housing flange.

You wouldn't go to the expense of port matching the manifold to the head unless you were getting pretty competitive with your car.

[STATUS]

IMO, a waste of time/effort.

I don't run port matched items.

exactly, it can even effect spool up time negatively.

[Moodles2]

I was thinking of port matching my standard manifold to match -9s, but everyone I've spoken to have said it's not worth it as response will be lost, but for -5s and bigger it's generally recommended to do the port matching

[bigmikespec]

I am surprised how anyone can look at the fitment of turbine housing to exhaust manifold flange, notice the overlap, and not attack it with a die grinder at least so the ports match! I would be amazed if measurable response was lost; and I would feel better knowing I fixed something that looks like s**t.

[snozzle]

thanks for all the responses guys, i have decided to leave them as is

cheers

[XRATED]

thanks for all the responses guys, i have decided to leave them as is

cheers

It's not worth the effort to pull the whole lot down again... 6 years ago I made 400rwkw on my 130k 26 with stock- unported manifolds.

J.

[Deano 1]

It's not worth the effort to pull the whole lot down again... 6 years ago I made 400rwkw on my 130k 26 with stock- unported manifolds.

J.

if you dont mind me asking, what turbos did u have bolted up at the time?

[bigmikespec]

It's not worth the effort to pull the whole lot down again... 6 years ago I made 400rwkw on my 130k 26 with stock- unported manifolds.

J.

Yes you are right Justin; should have add, if they are already off... do it... if not; next time!

[waxracing]

http://picasaweb.goo...134128251100338

It seems nissan thought it was a good idea, but then again what would they know

Edited January 20, 2011 by waxracing

[snozzle]

i dont understand why they arent that size to begin with.... damn nissan lol

[waxracing]

Tomei do it as well

http://www.tomei-p.co.jp/_2003web-catalogue/000_expreme/each-product/rb26_exhaust-manifold_en.htm

Dont they know it will give them lag

[NSNPWR]

Look at a 6BOOST maifold, particularly the flange...he has purposely left a lip around the flange and even gone as far as testing the shape of the exit at the flange, lip + oval shaped exit...his manifolds are second to none...

I think youre wasting your time match porting the flange, you then have the factory runners with all the bumps and casting lumps in them anyway. Just leave them, lot of work for little if any gain at all.

[gtr fan]

How would you loose performance? I'm not trying to be a smart ass, seriously am curious.

I have two sets of manifodls one standard and one ported. Shouldn't I use the ported ones?