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Rb25 Afm's On A Gtr

Brezza

By Brezza,
in Engines & Forced Induction

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Brezza Proficient

Brezza

Posted
Posted

Hey everyone,

i was just doing some searching on whether i could replace my stock GTR afms for some green label RB20/25 ones.

i have read some posts saying that it is possible, but i was wondering whether there is anyone that is using 2 green label AFM's on their GTR and what issues they experienced with it. for me it seems to be the much cheaper option than forking out for a pair of z32's. i am not chasing huge power.

my mods are

2860-5's

Nistune ECU

660cc injectors

Walbro fuel pump

3in exhaust with a 3.5in muffler

3in highflow cat

rebuild engine with forged internals

recond head done while engine out for rebuild

stock r34 GTR intercooler

stock AFM's

i had it last dynoed and got 320rwkw @ 18psi

i know that the turbos have much more room for more power. but i would be limited to the stock intercooler and 3in exhaust

but i would like to just be able to bump the boost up to 20psi and see if i could get close to 350rwkw without maxing out my AFM's

so to me paying $400 for a second hand set of z32's and getting some piping and filters for the bigger AFM's is not worth the extra 30rwkw. so if i could pick up some green label AFM's for cheaper i would be much happier, and my wallet would be a little fuller.

Cheers,

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https://www.sau.com.au/forums/topic/326962-rb25-afms-on-a-gtr/
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GTScotT Grand Master

GTScotT

Posted
Posted

It is doable, you will require a retune just as if you had installed Z32s or nismo AFMs.

Guaranteed it is covered more than enough on the forum, it would be almost the exact same deal as installing Z32s. You will need a new suction pipe to fit the 80mm AFMs as the stocks are 65mm and you will need the plugs for them also.

AFAIK you will also need to change your air filters.

Thats EVERYTHING you need to know.

Nee-san Grand Master

Nee-san

Posted
Posted
Hey everyone,

i was just doing some searching on whether i could replace my stock GTR afms for some green label RB20/25 ones.

i have read some posts saying that it is possible, but i was wondering whether there is anyone that is using 2 green label AFM's on their GTR and what issues they experienced with it. for me it seems to be the much cheaper option than forking out for a pair of z32's. i am not chasing huge power.

my mods are

2860-5's

Nistune ECU

660cc injectors

Walbro fuel pump

3in exhaust with a 3.5in muffler

3in highflow cat

rebuild engine with forged internals

recond head done while engine out for rebuild

stock r34 GTR intercooler

stock AFM's

i had it last dynoed and got 320rwkw @ 18psi

i know that the turbos have much more room for more power. but i would be limited to the stock intercooler and 3in exhaust

but i would like to just be able to bump the boost up to 20psi and see if i could get close to 350rwkw without maxing out my AFM's

so to me paying $400 for a second hand set of z32's and getting some piping and filters for the bigger AFM's is not worth the extra 30rwkw. so if i could pick up some green label AFM's for cheaper i would be much happier, and my wallet would be a little fuller.

Cheers,

$400 for 30Kw is a very good deal, once you do all the basic stuff like ECU and Exhaust, getting a whack of power like that get's a whole lot more expensive then $400...

My 2c :D

doo doo Proficient

doo doo

Posted
Posted

Pluses I found for using 2 RB25 AFM's- they fit on the stock inlet piping (with a little stretching, and I needed to add an elbow to get the top one around the power steering res) and they plug straight into the standard plugs.

GTScotT Grand Master

GTScotT

Posted
Posted
Pluses I found for using 2 RB25 AFM's- they fit on the stock inlet piping (with a little stretching, and I needed to add an elbow to get the top one around the power steering res) and they plug straight into the standard plugs.

Well there you go!

Although, they are the same size as a Z32 and have been said NOT to fit.

Brezza Proficient

Brezza

Posted
  • Author
Posted

cheer's guys,

i am aware that i'll need to get a retune for the bigger AFM's, that's not an issue. i'll speak to my tuner and ask whether he is able to do it.

another tuner i spoke to about this told me he wouldnt do it, because he wont tune on second hand AFM's he only uses brand new z32's because he said that its very hard to get the tune right on GTR's because there are 2 AFM's and they could be reading differently?

all i am after is a little more scope so with a slight bit more boost i have some reading from the AFM's that isnt at full.

will post back once i get it done with the results

STATUS Grand Master

STATUS

Posted
Posted
cheer's guys,

i am aware that i'll need to get a retune for the bigger AFM's, that's not an issue. i'll speak to my tuner and ask whether he is able to do it.

another tuner i spoke to about this told me he wouldnt do it, because he wont tune on second hand AFM's he only uses brand new z32's because he said that its very hard to get the tune right on GTR's because there are 2 AFM's and they could be reading differently?

all i am after is a little more scope so with a slight bit more boost i have some reading from the AFM's that isnt at full.

will post back once i get it done with the results

If thats the case, just get nismo or mines afm's, direct fit and same power handling as they are essentially std units recalibrated to near z32 specs. The smaller body of the nismo /mines items allow nicer low and mid tuning.

doo doo Proficient

doo doo

Posted
Posted
Well there you go!

Although, they are the same size as a Z32 and have been said NOT to fit.

And yes you need to change your air filter setup as the afm's (either ones) are physically bigger. The inlet pipes are quite stretchy, will stretch to accomadate 3'' piping. Keeping the same plug for the rb25's was the factor that decided it for me at the time. If I was going to keep running afm's (I now run motec) I would seriously consider the nismo option though expensive, they are brand new, have the required resolution for the sort of power you're after with a streetable twin turbo setup and fit without modification (apart from tuning of course).

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