Jump to content
SAU Community

Rb25de Vct Performance Modifications

Brentmcd12

By Brentmcd12,
in Engines & Forced Induction

 Share

Recommended Posts

Eug Grand Master

Eug

Posted
Posted
cant the time VCT enables/disables be altered without an aftermarket computer (other than afc4) if so how? cheers

never heard of the AFC4 (apexi item?).

you can enable it and disable it, by unplugging the solenoid. that's how you determine the most optimal rpm point for it to engage, by doing two dyno runs one with and one without.

i'm pretty sure you will need an aftermarket something to control when the vct/vvt/nvcs (whatever you want to call it) is activated/deactivated, whether it be a full replacement ecu or a little piggyback controller.

stock; the vct turns on just above idle rpm and turns off around ~5000rpm'ish. don't quote me exactly on that though.

the power fc guys require the fc datalogit (laptop program) to be able to access the function.

i know that doesn't exactly answer your questions, but hopefully it'll provide a little grounds for discussion.

SKiT_R31 Experienced

SKiT_R31

Posted
Posted (edited)
never heard of the AFC4 (apexi item?).

you can enable it and disable it, by unplugging the solenoid. that's how you determine the most optimal rpm point for it to engage, by doing two dyno runs one with and one without.

i'm pretty sure you will need an aftermarket something to control when the vct/vvt/nvcs (whatever you want to call it) is activated/deactivated, whether it be a full replacement ecu or a little piggyback controller.

stock; the vct turns on just above idle rpm and turns off around ~5000rpm'ish. don't quote me exactly on that though.

the power fc guys require the fc datalogit (laptop program) to be able to access the function.

i know that doesn't exactly answer your questions, but hopefully it'll provide a little grounds for discussion.

Cheers, Yeah meant the AFC Neo, Apexi Air Flow Convertor 'neo', it calls itself number 4 (upgraded from a SAFC2 because i thaught it had VCT altering functions)

Yeah i understand what your saying about how to decide when to activate the VCT, i just now need to figure out how to make it automatically engage at that point.

Ill properly talk to my tuner about it when i get the car ready, just waiting on damn extractors, and loom

Edited by SKiT_R31
Brentmcd12 Enthusiast

Brentmcd12

Posted
  • Author
Posted

is 6200 the rev limiter for the 25de ??? coz thats when mine bounces back.. i thought it was 7500 ??

the engine needs wayy more torque is crap at speeds goin from 5th to 4th just to speed up and usuing 3rd to hold power... anything under 3000rpm is terrible

Eug Grand Master

Eug

Posted
Posted

mine sees 7000 regularly at QR, it tends to taper off around 6800ish anyway

4500-6500 is usually about the thick of it for me, very thick and chunky through there.

i agree, could do with abit of torque, but at the end of the day it's a 2500cc motor. you'll need cubes for torque.

the rb is a fairly revvy motor, and i personally think that's what makes it fun.

with regards to 'under 3000rpm is terrible'

- the high gearing and ratios have something to do with it, especially when you are just cruising around

- i have no dramas getting a decent progressive punch 1st and 2nd on the motorkhana and skidpan.

Brentmcd12 Enthusiast

Brentmcd12

Posted
  • Author
Posted

ah k well maybey because mine is in a R31 the tacho reading might be wrong.. yeah true with the gearing but similar stuff at 100kays... 5th to 3rd.. again..

im doin RB30DE very soon...

wat i was going to ask is...

what series head do i have its a 93 RB25DE the afm has 4 wires if that helps is that S1 or S2 ? yes it has VCT...

i want to buy camshafts of Nengun i belive its cheaper than just jap... which ones are good for midrange power ? keeping in mind it will be for RB30DE..

SKiT_R31 Experienced

SKiT_R31

Posted
Posted (edited)

My limiter with a stock 25DE ecu, was at exactly 6800rpm, now have a Mines ECU with no limiter... - goign to get somthing like a jaycar and set it at ~ 7000-7200rpm (or whever power drops off, dont want to take it much further than that though, it is a 30 block after all)

are you goign to fully balence it, maybe get a new harmonic balencer? dont forget 30e's have bad harmonic issues in mid 7k rev range

being 93 i would have said S1, but 4 AFM wires!?

Edited by SKiT_R31

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • The Bogan
      NC MX5

      By The Bogan · Posted

      Yeah, it's getting like that, my daughter is coming over on Thursday to help me remove the bonnet so I can install the Carbuilders underbonnet stuff,  I might get her to give me a hand and remove the hardtop, maybe, because on really hot days the detachable hardtop helps the aircon keep the interior cool, the heat just punches straight through to rag top I also don't have enough hair for the "wind in the hair" experience, so there is that....LOL
    • joshuaho96
      Cas issue

      By joshuaho96 · Posted

      Could be falling edge/rising edge is set wrong. Are you getting sync errors?
    • joshuaho96
      Jacks that fit under GTR lips that can reach the subframe?

      By joshuaho96 · Posted

      On BMWs what I do because I'm more confident that I can't instantly crush the pinch welds and do thousands of USD in chassis damage is use a set of rubber jacking pads designed to protect the chassis/plastic adapter and raise a corner of the car, place the aforementioned 2x12 inch wooden planks under a tire, drop the car, then this normally gives me enough clearance to get to the front central jack point. If you don't need it to be a ramp it only needs to be 1-1.5 feet long. On my R33 I do not trust the pinch welds to tolerate any of this so I drive up on the ramps. Before then when I had to get a new floor jack that no longer cleared the front lip I removed it to get enough clearance to put the jack under it. Once you're on the ramps once you simply never let the car down to the ground. It lives on the ramps or on jack stands.
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      Nah. You need 2x taps for anything that you cannot pass the tap all the way through. And even then, there's a point in response to the above which I will come back to. The 2x taps are 1x tapered for starting, and 1x plug tap for working to the bottom of blind holes. That block's port is effectively a blind hole from the perspective of the tap. The tapered tap/tapered thread response. You don't ever leave a female hole tapered. They are supposed to be parallel, hence the wide section of a tapered tap being parallel, the existince of plug taps, etc. The male is tapered so that it will eventually get too fat for the female thread, and yes, there is some risk if the tapped length of the female hole doesn't offer enough threads, that it will not lock up very nicely. But you can always buzz off the extra length on the male thread, and the tape is very good at adding bulk to the joint.
    • Duncan
      Mistakes were made, my R34 Story

      By Duncan · Posted

      Nice....looking forward to that update
×
×
  • Create New...