Jump to content
SAU Community

Recommended Posts

Nah, I'm talking about the fact that noone would run a 2835 at much less than 16-17PSI (someone tell me if I'm wrong here), because it's out of it's ideal band of operation, so the data below that area is kinda useless information.

300 RWKW using the GT-RS

That is one of the ppl I PMed (Al, I think, cbf going and checking), he had cams and a buttload of other mods. It's not "too high", it's correct. But yeah, kind of useless to the dataset since you're not including that kind of data.

Don't worry, you're gonna have a ball of a time with ur new turbo, as I should next week too :( Hope you've got all the supporting mods so it can really do it's best - ~280rwkw. I'm looking at about 250-260rwkw with mine.

Nah, I'm talking about the fact that noone would run a 2835 at much less than 16-17PSI (someone tell me if I'm wrong here), because it's out of it's ideal band of operation, so the data below that area is kinda useless information.

That is one of the ppl I PMed (Al, I think, cbf going and checking), he had cams and a buttload of other mods. It's not "too high", it's correct. But yeah, kind of useless to the dataset since you're not including that kind of data.

Don't worry, you're gonna have a ball of a time with ur new turbo, as I should next week too :( Hope you've got all the supporting mods so it can really do it's best - ~280rwkw. I'm looking at about 250-260rwkw with mine.

280 RWKW!

Mate, I'm hoping for 260rwkw at 18 PSI. If I get anything above 260rwkw I'd be over the moon!!

So what boost are you going to run with your GT-RS, 17-18?

18 PSI should get my turbo going good, shouldn't it?

In your opinion sl33py, what's the safe threashold for standard RB-25 internals?

Some people said 250 rwkw, others say 300 rwkw, big difference if you ask me?

It's not "too high", it's correct. But yeah, kind of useless to the dataset since you're not including that kind of data.

Well, it is too high to include in the data set, he's the only one who's obtained over 300 rwkw (with the GT-RS), thus, being an outlier. That is why I'm not going to include it in the data because it will distort it.

Edited by Turbz RB-25

Personally I don't think boost has anything to do with horsepower. So any table linking the 2 is pretty much useless. I can't speak of personal experience with GTRS's, but I certainly can with regard to GCG ball bearing high flows. A simple example, we have made 250 rwkw at 19psi and 265 rwkw at 17 psi and 275 rwkw at 18 psi. The difference? What else is done to the engine (cams, head work, valves etc), what fuel it runs on (all pump fuel) and how it is tuned.

I know I am being repetitive but........airflow makes horsepower, boost is simply a measure of restriction to airflow.

Cheers

Gary

Personally I don't think boost has anything to do with horsepower.

.... Is that a joke?

Correct me if I'm wrong, but doesn't winding up the boost, thus, increase air flow the turbo produces, increase your horsepower??

A simple example, we have made 250 rwkw at 19psi and 265 rwkw at 17 psi and 275 rwkw at 18 psi. The difference? What else is done to the engine (cams, head work, valves etc), what fuel it runs on (all pump fuel) and how it is tuned.

Of course horsepower is dependant on the car setup, and this was acknowledged before making the table (refer to first post- use ONLY as a rough guide as each car is different i.e different computer setup, different exhaust setup, some have cams, some don't, different tune etc etc etc)

Surely this is not to say however that more boost doesn't increase horsepower???

Thanks SK, ever knowledgeabe :(

Nah he's serious Turboz, boost is just a measure of how hard you're having to work to overcome the flow restriction of the engine. In a perfect world you would have very low boost or none (spelt: 'cubic inches' lol). There are engines whose design flow air really well and have unusually low boost levels to get the same amount of power as others who have to really crank it to get as much power (using the same turbo). And as SK said, the other things which REALLY change it are the tuning and other work etc etc.

Edited by sl33py
Thanks SK, ever knowledgeabe :(

Nah he's serious Turboz, boost is just a measure of how hard you're having to work to overcome the flow restriction of the engine.

Please do explain this to me further.

I was under the impression that boost (PSI) is the amount of pressure the turbo is producing and sending to the engine? Correct me if I'm wrong, please, I would love to learn more.

So your saying that a tune, cams and other supporting mods, would produce more power gain compared to winding up the boost from 10 PSI to 20 PSI?

Perfect example of what SK is saying - aftermarket cams. Bigger cams increase airflow by allowing the engine to breath better, therefore for the same or even less boost you make more power. If you're still not sure, think about blowing air through a straw, then blowing air through a short piece of garden hose. You wont have to work anywhere near as hard to blow air through the garden hose, yet you'll be blowing more air through it because it has less restrictions. In the case of the straw, you're probably applying a few PSI worth of pressure yet you'll be moving less air because of the restriction.

All that said, for a standard setup (unopened engine, no cams) measuring PSI vs HP for a given turbo can still be fairly useful as an indication of what power to expect, assuming basic mods (intercooler, 3" exhaust).

Edited by Ionos
Please do explain this to me further.

No problem

I was under the impression that boost (PSI) is the amount of pressure the turbo is producing and sending to the engine? Correct me if I'm wrong, please, I would love to learn more.

Half right. Boost is simply a measurement expression of pressure, pressure is created when you have airflow and a restriction to that airflow. So you can increase the pressure (boost) by either increasing the airflow OR increasing the restriction. Conversely, you can decrease the pressure (boost) by either decreasing the airflow OR decreasing the restriction. Keep that in mind.

So if I have a car with lots of restrictions, small pipework, restrictive intercooler, low lift & duration cams, small valves, tiny ports, poor exhaust manifold, small diameter exhaust pipes, compliance cat, quiet muffler etc etc and so it needs lots of pressure (boost) to push the airflow through those restrictions. It makes say 220 rwkw at 19 psi on an average tune using 98 ron fuel. I remove some of those restrictions, better pipepwork, decent FMIC, high flow cat & exhaust etc and stick 100 ron fuel in it and tune it properly. I could easily get 230 rwkw at 16 psi. Less boost and more power.

Why? Because I have removed some restrictions therebye allowing more airflow. It is that increased airflow that makes power, boost is irrelevant.

So your saying that a tune, cams and other supporting mods, would produce more power gain compared to winding up the boost from 10 PSI to 20 PSI?

Maybe, it depends on how many restrictions you remove. The RB25DET in the R33GTST produces more power (270 rwkw) now at 17 psi than it used to (250 rwkw) at 20 psi. Same turbo but with cams, valve springs, slightly bigger intercooler pipwork, forged pistons & rods (lighter), better ring sealing, GReddy copy inlet manifold (not a big contributor) and obviously a fresh engine. Not the least of which is a slightly more agressive tune because I know the engine internals can handle it.

I understand that you have prepared the table based on the the generalisations of FMIC, 3" exhaust etc. But not all FMIC's are the same, not all 3" exhausts are the same and most importantly an untuned Power FC on 98 ron is not the same as well tuned Power FC on 100 ron. I won't get into dyno differences, but they are a consideration none the less. Perhaps I am tainted by guys complaining to me that so and so's car with everything the same makes 10 rwkw more. Vary rarely is "everything" the same and that's the problem.

Cheers

Gary

  • Like 1

Very true, at the end of the day you have to realise that it is airflow that makes a greater increase in power then simply adding more boost. Obviously adding more boost gives more power (as long as the turbo is in its efficiency rating), but it is no where as much as increasing airflow or taking out restrictions.

Think of a GTRS on 20psi compared to a T04Z on 20psi. Same kind of theory with twin turbo setups, you can run them on low boost pressure but because there is 2 of them you have double the airflow (think about a RB26).

Tuning plays a huge ball game here, that's why it is very hard to compare. How far has the tuner pushed the car? Is he pushing it to an absolute limit where its about to ping its head off if intake temperatures increase by just 5 degrees, or has he made it safe as so you can sit it on limiter in 40 degree weather and not ping it at all. What does the tuner think is a safe knock level? Some tuners will push a car up to a certain knock because it is still relitively safe.

What fuel are they using? 91octane, 95octane, 98octane,100octane plus? How old is the fuel, people are kidding themselves if they think when they top up with 98 octane fuel it is always 98 octane, i know of a BP here in Townsville that got done a few years ago for putting normal unleaded into the ultimate bousers.

There are to many variables that people dont list or that are unaware of. Hence why one car can make 260rwkw on 20psi on a GTRS where as others can make 290rwkw on same boost.

on a side note its amazing how much power and response is locked away in the tune

i spent ages on my ign maps and you should see the car on its throttle response

its coco bananas, the car literally snaps when you open the throttle - its great ;)

on a side note its amazing how much power and response is locked away in the tune

i spent ages on my ign maps and you should see the car on its throttle response

its coco bananas, the car literally snaps when you open the throttle - its great ;)

Exactly right, tuning is everything in this day and age regardless of what modifications you have.

No problem

Half right. Boost is simply a measurement expression of pressure, pressure is created when you have airflow and a restriction to that airflow. So you can increase the pressure (boost) by either increasing the airflow OR increasing the restriction. Conversely, you can decrease the pressure (boost) by either decreasing the airflow OR decreasing the restriction. Keep that in mind.

So if I have a car with lots of restrictions, small pipework, restrictive intercooler, low lift & duration cams, small valves, tiny ports, poor exhaust manifold, small diameter exhaust pipes, compliance cat, quiet muffler etc etc and so it needs lots of pressure (boost) to push the airflow through those restrictions. It makes say 220 rwkw at 19 psi on an average tune using 98 ron fuel. I remove some of those restrictions, better pipepwork, decent FMIC, high flow cat & exhaust etc and stick 100 ron fuel in it and tune it properly. I could easily get 230 rwkw at 16 psi. Less boost and more power.

Why? Because I have removed some restrictions therebye allowing more airflow. It is that increased airflow that makes power, boost is irrelevant.

Maybe, it depends on how many restrictions you remove. The RB25DET in the R33GTST produces more power (270 rwkw) now at 17 psi than it used to (250 rwkw) at 20 psi. Same turbo but with cams, valve springs, slightly bigger intercooler pipwork, forged pistons & rods (lighter), better ring sealing, GReddy copy inlet manifold (not a big contributor) and obviously a fresh engine. Not the least of which is a slightly more agressive tune because I know the engine internals can handle it.

I understand that you have prepared the table based on the the generalisations of FMIC, 3" exhaust etc. But not all FMIC's are the same, not all 3" exhausts are the same and most importantly an untuned Power FC on 98 ron is not the same as well tuned Power FC on 100 ron. I won't get into dyno differences, but they are a consideration none the less. Perhaps I am tainted by guys complaining to me that so and so's car with everything the same makes 10 rwkw more. Vary rarely is "everything" the same and that's the problem.

Cheers

Gary

Damn good explanation.

I think you just threw me off a little when you said 'I personally think that boost has nothing to do with horsepower'.

In the post above you admitted it does. I understand now that you can get more power by lessening restrictions and lowering boost at the same time, but boost still does increase power.

Thanks for taking the time to explain the above to me!

Edited by Turbz RB-25

Hi guys, I spoke to sl33py about this, and he said I should be getting at least 260 rwkw with the following mods at 18PSI:

3.5 inch straight through exhaust

GReddy Front Mount Cooler

Splitfire coil packs

Pod with customs cold air intake and heat shield

Bosch 044 Fuel pump

Z32 AFM

HKS GT2835 Pro S

Nismo 555cc injectors

Power FC

S.K, I am interested in your opinion.

Do you think I should hit 260rwkw at 18PSI on a safe tune?

And in your opinion, will this power be safe with my stock engine/internals?

Cheers

Edited by Turbz RB-25

Yep definetely will get that power, my tune is safe as all hell and im making that much power with a GTRS, so with a 2835 you should be fine, if not making more than that.

Edited by PM-R33

I've had a habit of tuning (properly) on lower boost with my cars as a base line for some time now. This is especially the case when I upgrade cams as the improvements to cam timing can be easily missed if the tuner assumes things about boost setting.

Upgraded cams as mentioned have an effect on flow restriction and I've found that rather than bashing in identical boost to the last setup right off , running substancially less than before and gradually bringing it up finds the best tune. As Sydneykid's examples seem to indicate. Dialing cams in at lower boost is a must do I reckon.

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



  • Similar Content

  • Latest Posts

    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
    • But first....while I was there, I also swapped across the centre console box for the other style where the AV inputs don't intrude into the (very limited !) space.  Part# was 96926-4GA0A, 284H3-4GA0B, 284H3-4GA0A. (I've already swapped the top 12v socket for a USB bulkhead in this pic, it fit the hole without modification:) Comparison of the 2: Basically to do the console you need to remove the DS and PS side console trim (they slide up and back, held in by clips only) Then remove the back half of the console top trim with the cupholders, pops up, all clips again but be careful at the front as it is pretty flimsy. Then slide the shifter boot down, remove the spring clip, loose it forever somewhere in the car the pull the shift knob off. Remove the tiny plastic piece on DS near "P" and use something thin and long (most screwdrivers won't fit) to push down the interlock and put the shifter down in D for space. There is one screw at the front, then the shifter surround and ashtray lift up. There are 3 or 4 plugs underneath and it is off. Next is the rear cover of the centre console; you need to open the console lid, pop off the trim covering the lid hinge and undo the 2rd screw from the driver's side (the rest all need to come out later so you can do them all now and remove the lid) Then the rear cover unclips (6 clips), start at the top with a trim tool pulling backwards. Once it is off there are 2 screws facing rearwards to remove (need a short phillips for these) and you are done with the rear of the console. There are 4 plugs at the A/V box to unclip Then there are 2 screws at the front of the console, and 2 clips (pull up and back) and the console will come out.
×
×
  • Create New...