Jump to content
SAU Community

HKS2535 on RB25DET results...round 1

SeriesIIGTST
 Share

Recommended Posts

Steve Grand Master

Steve

Posted
Posted
rev210, I'm interested where the turbo finds another 20hp worth of air to flow. I don't doubt that it happened, but doesn't it mean a standard turbo at 10psi is now pushed higher into its flow range? Just wondering how safe cams on a stock turbo being pushed to its limits really is :). I was considering cams on with the RB30DET on a stock turbo, but decided against it till after a turbo upgrade.

Except you don't have the pull the motor down to change cams. We're not running pushrods with cams in the block you know. Cams can be easily changed with the head on

It will happen. Any improvement to flow characteristics (it seems esp on the ehxuast side), will mean more power at lower boost.

If a turbo is pushing 10psi boost, but against a heavy resistance, once you remove the resistance, you get more flow at the same boost.

Boost pressure only comes about because of resistance, so the higher the resistance, the higher the pressure will be with the same volume of flow - and vice versa.

Just like upgrading an exhaust I suppose.

Please feel to flame away if I am off the mark here, but its my understanding.

  • Replies 56
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Ustasa Enthusiast

Ustasa

Posted
Posted

The most disappointing thing I find on the dyno is a car that comes in like a burger with the lot – except for the camshafts!

220rwkw RB20DET’s with 300rwkw turbo’s that only need a decent pair of cams to turn them into the short stroke screamers that they are or 280rwkw RB25DET’s that could hammer out 330+rwkw with just the right set of cams.

Blocks, cranks, pistons and rods are your power support structure that has to hold under the strain. But it’s your head/turbo that delivers the power.

Most of you guys would be amazed what a set of decent after market cams (yes exhaust AND inlet!) can do for your engine in terms of mid range and peak power. With the factory setting up their cams for best emissions and down low response then it makes the upgrade even more noticeable.

Gradenko Mentor

Gradenko

Posted
Posted
If a turbo is pushing 10psi boost, but against a heavy resistance, once you remove the resistance, you get more flow at the same boost.

Understood. What my question was getting at - will the stock turbo with its higher shaft speed to match the increased flow, not be at greater risk of failure than before? My understanding is that flow rate is propotional to shaft speed, and increase in engine power always corresponds to an increase in shaft speed.

Another way of putting it: reducing intake resistance should mean the turbo has to work harder and increase shaft speed to maintain the same flow resistance (or boost pressure) as before.

Am I way off track?

Sydneykid Grand Master

Sydneykid

Posted
Posted
If a turbo is pushing 10psi boost, but against a heavy resistance, once you remove the resistance, you get more flow at the same boost.

Or the same airflow at lower boost.

reducing intake resistance should mean the turbo has to work harder and increase shaft speed to maintain the same flow resistance (or boost pressure) as before.

Look at it the other way, same air flow = same power but at lower boost. This means less resistance to shaft rotation = lower load on the turbo.

will the stock turbo with its higher shaft speed to match the increased flow, not be at greater risk of failure than before

Not if you net off the lower torque loading on the shaft.

Maybe some examples....

Option 1 = 200 rwkw at 1 bar with standard cams

Option 2 = 220 rwkw at 1 bar with aftermarket cams

Option 3 = 200 rwkw at 0.8 bar with aftermarket cams

Option 4 = 215 rwkw at 0.9 bar with aftermarket cams

Maybe Option 4 is less turbo damaging than Option 1, but there is little doubt that Option 3 is.

Heat is also very relevant here, if we are talking about a standard ceramic turbine equiped turbo. Depending on the efficiency of the turbo and its ability to heat the inlet air and/or the intercooler efficiency, we may well find that Option 4 is still less turbo damaging than Option 1.

Interesting thread this one, hope I added to it a bit

benm Grand Master

benm

Posted
Posted
Well I'm convinced! My next mod will be cams :)
hahaah, I think I need to be banned from these SAU Forums, every thread I read is costing me about $1000 in mods. I'm in debt for the next 4yrs and that doesn't even include my mod list :thumbsup:
whatsisname Grand Master

whatsisname

Posted
Posted

Sk, will do mate. It won't be for a little while though, but as soon as funds are healthy, in go the cams!

I'm hearing you Ben. I could almost buy a GT-R for the cost of my mods/tuning alone (~30k)! That's every little mod I've done though, including non-performance items like stereo etc.

  • 3 weeks later...
SeriesIIGTST Mentor

SeriesIIGTST

Posted
  • Author
Posted

Robo's

Yeah I think so, turns out it was my knock sensor - one wire was loose and sending intermittant signals to the ECU, which would retard my timing and cause a big hole, particularly when the power really came on (ie, at NVCS changeover). I haven't managed to find time to get it back to the dyno yet but i'm working on that. I can't feel the hole any more so we'll see what happens.

Cheers!

Guest Robo's

Guest Robo's

Posted
Posted
Robo's

Yeah I think so, turns out it was my knock sensor - one wire was loose and sending intermittant signals to the ECU, which would retard my timing and cause a big hole, particularly when the power really came on (ie, at NVCS changeover). I haven't managed to find time to get it back to the dyno yet but i'm working on that. I can't feel the hole any more so we'll see what happens.

Cheers!

You still running the SAFC and not a Power FC?

SeriesIIGTST Mentor

SeriesIIGTST

Posted
  • Author
Posted

Yep...but i've also taken off the z32 AFM. Seems to get closing to maxing out but never quite there so i'll see how far I can push it.

I'm not going to sing the praises of my S-AFC just yet, we'll wait for the dyno to see what it does but if it holds up, i'm going to be the biggest fan ever. I realise there's more power to be had from PowerFC but at this point, bang for your buck wise, it's probably not worth it as the turbo would be reaching peak efficiency anyway i'd imagine.

b0neR Community Regular

b0neR

Posted
Posted

But even if the peak power gain is not terribly high wouldnt the whole control of a PowerFC and the increase in low/midrange torque and power be appealing? Not to mention it would probably result in a safer tune (less chance of the engine sh*tting itself).

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

    • MBS206
      R32GTR R200 reverting from Nismo centre to stock

      By MBS206 · Posted

      It's about the same time for me from Bunnings, or the Fasteners. My big push away from takeaway food, and gluten in general keeps me away from the Bunnings Snags too! Weather up here, I've been out for two walks today in the beautiful sunshine. Had a few little drizzles, and some wind, that honestly, a tin of beans and I could compete on how harsh she blows Thankfully, being this bit inland, we're not getting anything much really. Will probably pick up a bit more when/if Cyclone Alfie decides to come ashore. A few areas in the GC though, and south into NSW are really getting smashed though! Right now, I'm just annoyed Alfie hasn't hit, as I'm not allowed to crack into the BBQ foods like the bacon and eggs until the Cyclone hits "In case we lose power"...
    • The Bogan
      R32GTR R200 reverting from Nismo centre to stock

      By The Bogan · Posted

      I love fastener joints, the price difference between them and joints like Bunnings or Super Cheap is amazing, and they either have exactly what you want, or they can get it to quick They have even given me some for free when I only needed a couple of specific size In saying this, I have paid premium for fasteners from Bunnings if they have the sizes I need, but only for convenience really, as my local is only 10 minutes away, the Sushi joint near them is also a consideration  How's the weather Matt? Stay safe mate
    • joshuaho96
      R32 update from 1990's spec.

      By joshuaho96 · Posted

      Wideband is worth setting up if only for tuning purposes. I would not mess with the ignition system unless there's a misfire. HKS crank trigger is popular out here for the relatively easily sourced Denso crank sensor, not a bad idea to install as well regardless of power level on a standalone. Boost leak test is worth thinking about. Oil pressure sensor tied to a fuel cut isn't a bad idea either. Getting the tune figured out is a good idea. Without putting eyes on it and getting under it there's no way for us to tell you exactly what it needs but most likely you're down to the last 10% that will make a big, big difference in how happy you are with the car.
    • PotatoCake
      Has anyone put in brand new full carpet? (not floor mats)

      By PotatoCake · Posted

      Doing a refresh of my 33 and can see a few websites stating they sell the entire main carpet for our cars, but they all have generic photos which is fine, i understand they are custom made to order.  Just seeing if anyone has got it done or had any experience with this, as i would only want to do it if the fit and finish was as good as oem https://carmatsdirect.com.au/products/moulded-carpet-or-vinyl-for-nissan-skyline-r33-1993-1998-coupe https://knoxautocarpets.com.au/moulded-carpets/nissan/skyline/skyline-r-33-1993-1998/
    • MBS206
      R32 update from 1990's spec.

      By MBS206 · Posted

      Any plans for E85? If so, add flex fuel sensor.   I'd probably add in the sensors I mentioned above if the Link will support using them for engine protection. With water pressure, you need to be able to effectively set it that "If temp > X, and pressure = atmospheric, shutdown" as at running temp, you should be able to read pressure in the cooling system. If pressure suddenly disappears, it means the water went some where, and this is a quicker reaction than waiting on water temp to go up (Which, can take a little longer than you'd like, considering it now has to wait for hot air to heat it up) Oil pressure, Oil temp, both would be on my list too if you're looking to add sensors. Wideband O2. And at least one EGT sensor. If you're feeling deluxe, put in individual runner EGTs. Single EGT sensor is more so forget about a specific number, get used to "What is normal EGTs", and then keep an eye on it, if it starts going away from "normal" it's a sign something is wrong (Also, things like the tune can still start going out of spec, but EGTs may not show it, for example one injector starts running leaning, so ECU richens everything up, now 5 out of 6 cylinders are rich, and running cool, with one cylinder lean and running hotter, so it's not perfect) Then there is your other things to look at non sensor related, but you may have already done, or have underway, and that would be things like building a sump for more oil, and better oil control under high G-Forces (Cornering, brakes, acceleration). Basically, the above is worth looking/thinking about, if the ECU can do protective stuff with it, and you continue to use it how you are (Drive it to the track, thrash it, drive home, repeat once every 3 to 4 months)
×
×
  • Create New...