Jump to content
SAU Community

Recommended Posts

Hi,

I current have my gtr plenum off the car atm, and was wondering is it worth port and polishing it? I'm not talking about sending it off to some machine shop to get it done, im just talking about attack it with some sand paper and my free time?

And if it is what is the best material to use and is there anything i should look out for do?

Cheers Michael

Link to comment
https://www.sau.com.au/forums/topic/211304-port-and-polish-gtr-plenum/
Share on other sites

Hi,

I current have my gtr plenum off the car atm, and was wondering is it worth port and polishing it? I'm not talking about sending it off to some machine shop to get it done, im just talking about attack it with some sand paper and my free time?

And if it is what is the best material to use and is there anything i should look out for do?

Cheers Michael

Well it really is up to you!

PPL only do it if they wanna make there engine bay look good i guess!!! No Performance Gain out of it!! To much hard work i say!! Not like we look at the engine bay whilst were driving along and other ppl seeing the work you have done when its under the hood whilst driving!

Waste of time unless you want it a show car!!! Spare ya hands bro from sanding and give your car a hand polish for a bit of shine, cause you will get more looks from that instead of a New looking Plenum hidden underneath the bonnet!

Think he is talking about internally porting and polishing the plenum.

To answer the question: Don't do it. Waste of time and may even go backwards.

It is well known that polishing intake runners is not a good move. As the fuel spray/mist hits the polished surface, it form droplets, which may cause idling issues, etc. The course surface of the inlet runner causes minor turbulence which helps the fuel remain as an "even" mist, as it enters the combustion chamber.

PS: Nothing wrong with having a clean and well presented engine bay.

I'm with AL I went and spoke to an engine reconditioning shop in syd and they told me the same news as what AL described. Then I asked a skyline specialist and got the same answer from him. I wouldn't bother doining it.

Think he is talking about internally porting and polishing the plenum.

To answer the question: Don't do it. Waste of time and may even go backwards.

It is well known that polishing intake runners is not a good move. As the fuel spray/mist hits the polished surface, it form droplets, which may cause idling issues, etc. The course surface of the inlet runner causes minor turbulence which helps the fuel remain as an "even" mist, as it enters the combustion chamber.

PS: Nothing wrong with having a clean and well presented engine bay.

thats all well and good for the ports in the head, but the fuel never touches the ports/runners of the intake manifold

also there are gains to be had from matching the manifold to the head on the inlet side

thats all well and good for the ports in the head, but the fuel never touches the ports/runners of the intake manifold

also there are gains to be had from matching the manifold to the head on the inlet side

Ah true.

But polishing is still useless as it will have no measurable gains. Porting the plenum runners to gasket size will be beneficial only if the head was ported to the same size.

doing anything to the stock plenum is pointless as the rear two runners (more so the very rear) restricts the output (due to lack of flow, pressure and volume) at higher than normal pressure

i had a 18-20% gain with a greddy plenum (less knock too) and still retained the six throttle arangement.

about to trial a hypertune with a single throttle on a mates car

The rear runners actually get a little too much air, making the rear leaner.

Port matching is always worth it. Don't know how bad gtr plenum to head factory matching is but, if it's anything like the exhaust then it's going to help.

Polishing the matched area isn't really necessary, if you just sand it neatly that should be fine and save time too.

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


  • Similar Content

  • Latest Posts

    • So stock ECU does not like anything above 10 psi?  That Nistune one is just for "try" if it will be any different, I know it need to be tune for that. I know but YOU may know about these problem but i/we dont. They few little Skylines here let alone people who know anything about tham so that is why iam asking here  
    • So now we have a radiator with no attachments whatsoever. It lifts up with a particularly tight spot between the drivers side air box mount and the lower radiator outlet, but if you've got this far you will sort that too. This is the lower mounts with the rad out so you can see where the rubber bushes go, it is a straight shot upwards Done! Assembly is the reverse of disassembly, with blood less likely to be shed.
    • Right, onto the second last trick. The Air Con condenser is mounted to the front of the radiator and stays in the car when the radiator is removed. There are 2x 10mm headed self tappers holding the top of the condenser to the radiator, remove those The bottom of the condenser is attached to the radiator with clips. You need to lift the condenser out of those clips and clear (up, then forward). f**ked if  could work out how to do that last bit with the front bumper on. I hope you can, and you share the trick.  Bumper removal probably deserves its own thread one day once I've recovered the will to live, but basically you need to remove the wheels, front inner guard liners (clips and 10mm headed bolts), the self tapper between the guard and the bumper at the rearmost point of the bumper (same as an R32 that bit), any remaining clips at the top/front of the grill, an absolute bastard design with a plate that holds the top of the bumper above the headlight each side (only 1 bolt which is tricky to get to, but the plate catches 2 places on the bumper and must be removed....carefully!) and push clips between the bumper and guard under the headlight. If you've done all that you will be faced with wiring for the fog lights on both sides and in ADM Q50 RS at least, 4 nasty tight plugs on the driver's side for the ADAS stuff. So, the clips at the bottom look like this on drivers side (looking from the front) And on the passenger side (also from the front), you can see this one is already out Clearance on both of these are super tight; the condenser needs to move up but the upper rad support mount prevents that, and the radiator can't move down far because it is (rubber) mounted. Once you achieve the impossible and drop the condenser off those mounts so it does not stop the rad moving, you are good to go
    • OK, next the shroud needs to come off and there are a couple of tricks. Firstly, there is a loom from near the passenger side headlight to the fans, coolant temp sensor etc and there is no plug to undo.  In my case I was OK to leave the shroud on top of the engine so I just undid the passenger side fan plug and about 10 of the clips which gave enough free wire to put it aside. The fan plugs were super tight, the trick I used was a small falt screwdriver to push down on the release tab, then a larger flat screwdriver to lever the plug out of the fan unit....be careful with how much force you apply! If you need to remove the shroud altogether for some reason you will have to deal with all the plugs (tight) and clips (brittle)....good luck. I removed all of the clips and replaced them with cable ties that I will just cut next time. Also, in the Red Sport / 400R at least, the intake heat exchanger reservoir hose is bolted to the shroud in 2 places with 10mm headed bolts; so remove them (the hose stays in the car; no need to undo it at the t fittings down at the radiator lower mount. Once you've dealt with the HX hose and the wiring loom, there are 3x 10mm headed self tappers holding the top of the shroud to the radiator; remove those.   The shroud then lifts out of the bottom mounts where it sits on the radiator, up and onto the engine out of the way. Simples
    • Ok, disregard my “rate them” comment, sorry for my unrealistic input
×
×
  • Create New...