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Upgrading AFM on rb20det

yogi000

By yogi000,
in Engines & Forced Induction

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yogi000 Mentor

yogi000

Posted
Posted

Hey Guys,

I've been looking around for the answer to my question with no luck, so make someone can help me.

I have an rb20det with 2530 turbs, gtr pump, adj cam gears, pfc, uprated injectors, exhaust and fmic, i'm just about to have the pfc tuned, but i'm not sure if i should change the AFM to a Z32? When does the stock one reach it limits??? Should i not bother with the z32?? I would say the car would be putting out 190rwkw once tuned.

Thanks in advance

George

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Roy Grand Master

Roy

Posted
Posted

Its probably a worthwhile upgrade doing the pipe from the filter to turbo, it seems to have merit.

But if the pipe is sucking shut, then in theory that means there must be a measurable pressure drop accross the filter which may be worth looking at.

Think of it this way, imagine air being sucked through an open ended 3" pipe, its never going to callapse is it. Now imagine putting something over the end of the pipe, there may now be a tendency for the pipe to want to collapse due to the negative pressure.

So equate that to your air filter...if its wanting to suck close then there is a measurable restriction somewhere before your turbo:)

Sydneykid Grand Master

Sydneykid

Posted
Posted
Its probably a worthwhile upgrade doing the pipe from the filter to turbo, it seems to have merit.

But if the pipe is sucking shut, then in theory that means there must be a measurable pressure drop accross the filter which may be worth looking at.

Think of it this way, imagine air being sucked through an open ended 3" pipe, its never going to callapse is it. Now imagine putting something over the end of the pipe, there may now be a tendency for the pipe to want to collapse due to the negative pressure.

So equate that to your air filter...if its wanting to suck close then there is a measurable restriction somewhere before your turbo:)

All true, but the inlet pipe itself is a restriction, I have seen one sucked in without any air filter at all. The convolutions, particularly around the bends are the main culprit. Since air flow is laminar (sticks to the outsides) having a smooth sided mandrel bend will reduce that restriction. As the rubber ages it gets softer where it flexes (when the motor twists on its mounts) and is more easily sucked closed. It shouldn't be high on your list of mods, but worth keeping in mind nonetheless. :D

quincy777 Community Regular

quincy777

Posted
Posted

Hey there, I have similar mods and just had my PFC tuned. My car got 172rwkw and my tuner said AFM was restricting things abit as it runs out of puff at 6250rpm.

It made sense to me with much more demand than standard and could see dip on curve, but I guess after reading here am I getting spun a load of crap or not??

thanks

i remeber martin donnon in HPI had a acticle about AFM, and he said it's only worthwhile to change the RB afm to Z32 once over 250rwkw
Sydneykid Grand Master

Sydneykid

Posted
Posted
Hey there, I have similar mods and just had my PFC tuned.  My car got 172rwkw and my tuner said AFM was restricting things abit as it runs out of puff at 6250rpm.

It made sense to me with much more demand than standard and could see dip on curve, but I guess after reading here am I getting spun a load of crap or not??

thanks

At 172 rwkw it's not a problem, at 80 mm diameter, it's prettty much bigger than all of the pipework. There are plenty of other cars with AFM restrictions, but not Skylines.:D

Gts-t Grand Master

Gts-t

Posted
Posted
Hey Guys,

I've been looking around for the answer to my question with no luck, so make someone can help me.

I have an rb20det with 2530 turbs, gtr pump, adj cam gears, pfc, uprated injectors, exhaust and fmic, i'm just about to have the pfc tuned, but i'm not sure if i should change the AFM to a Z32? When does the stock one reach it limits??? Should i not bother with the z32?? I would say the car would be putting out 190rwkw once tuned.

Thanks in advance

George

Hey george, i think u should be hoping for a little more than 190rwkw. Bbenny made about 220-230rwkw with the standard injectors and that turbo(hks2530) and a remapped ecu. So ulness u are only going to be running 1bar or so i think your estimate could be a little low. What does everyone else think, bbenny are you still around?

Be great to see your results and dyno graph posted george once the pfc is tuned. Oh and btw bbenny made this number with the standard AFM too :D

Roy Grand Master

Roy

Posted
Posted

Us RB20 punters have to be careful when looking at dyno results. A 20rwkw difference is huge between 210 and 190rwkws, but from what i have seen can be easily accounted for by different dynos.

Inlet pipe sucking closed with no filter:( they are a horrible looking bit of pipe.

I suppose the point i was trying to make was dont go throwing a nice alloy pipe at it if you have a horrible filter restricing flow which may have been contributing to the problem. Fixing a problem is not always fixing the cause...or it may be that i like to complicate things:)

yogi000 Mentor

yogi000

Posted
  • Author
Posted

Thanks for the help guys.

i'm not interested in top end much, i want the most responsive internal stock rb20. that was the exact same request i made to jim at CRD. I'll keep ya posted how it goes.

Also i did a compression test today, i had driven the car but it then started raining really hard and had to stop for an hour or so and the car cooled down. The results i got were 130psi on 5 cylinders and 128psi on the 6th. Are these results good, bad, ungly????? or because it was cooled down these aren't accurate?

Cheers

George

yogi000 Mentor

yogi000

Posted
  • Author
Posted

hey,

i've got my pfc in now and taken the car for a light run...i'm finding the afm to reaching 4.9V on stock 32 actuator boost(2530 turbo) on a hot day. Am i gonna have trouble with this when i up the boost and have it tuned and have it out on a cold night?....i'm sure the car isnt putting down any great numbers at the moment...should i take the risk and take it to the tuner with the stock afm?

any suggestions would be appreciated.

Cheers

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