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Port And Polish Gtr Plenum

Kaido_RR

By Kaido_RR,
in Engines & Forced Induction

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Kaido_RR Grand Master

Kaido_RR

Posted
Posted

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

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Styline GTR Rising Star

Styline GTR

Posted
Posted

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!

Al Grand Master

Al

Posted
Posted

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.

iwantagtr Rising Star

iwantagtr

Posted
Posted

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.

shanef Grand Master

shanef

Posted
Posted
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

Al Grand Master

Al

Posted
Posted
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.

GODZ1LA Explorer

GODZ1LA

Posted
Posted

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

rev210 Grand Master

rev210

Posted
Posted

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.

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