Jump to content
SAU Community

Recommended Posts

i care not for KKR plain bearing or journal bearing turbochargers.

boost pressure is simply that, pressure for a given manifold or space.

a car tyre at 40psi has a certain amount of air. a truck tyre also at 40psi has a given amount of air. clearly the truck tyre has more "air" as its larger volume despite being at the same pressure

volume does NOT equal pressure

volume of AIR makes power

pressure of AIR does NOT make power

larger turbochargers make more power at the same level thanks to the compressor wheel achieving more compression and stuffing more air in.

the large exhaust housing allows it to spin faster, in turn driving the larger compressor wheel to its required speed to dial in whatever amount of airflow you need.

airflow makes power, not boost.

dialing in more and more boost generally gives you more airflow only whilst you are still in the ideal "island" of the compressor wheel. for the stocker turbo we know that beyond 12psi is out of the effiency zone or island. the net resuilt is that you drive the compressor wheel too fast and it dials in more heat. this results in more and more heat into the engine intake and less air is actually achieved. a lot of people just believe more boost and you'll make more power.

a) talking to a friend and telling him or her your car runs a stock turbo at 16psi

b) talking to a friend and telling him or her your car runs a gt30 turbo at 8psi

everyone is likely to believe a will make more power as street talk, more boost makes more power. this of course is not the case

how stuff works.com

Exerting Pressure

The way a gas like air exerts pressure inside a container like a tire or a balloon is through the action of the air atoms colliding with the sides of their container.

Imagine that you have a single atom of nitrogen in a sealed container. That atom is in constant motion ricocheting off the sides of the container. The speed of the atom's motion is controlled by the temperature -- at 0 degrees Kelvin (absolute zero) the atom has no motion, and at higher temperatures the speed increases. By its collisions with the sides of the container, the atom exerts an outward pressure. So there are two ways to increase the pressure inside the container:

* Raise the temperature of the atoms inside the container - The hotter the atoms, the faster they move.

* Put more atoms in the container - The more gas atoms you put in the container, the more collisions you get and the greater the pressure they exert on the sides of the container.

When you blow up a tire on a car or a bike, you use a pump to increase the pressure of the air inside the tire by increasing the number of atoms inside the tire. A car tire typically runs at 30 psi, and a bike tire might run at 60 to 100 psi. There is no magic here -- the pump simply stuffs more air into a constant volume, so the pressure rises.

I agree with paulr33, more boost does not necessarily mean more power. However, I am still pretty new to turbos, things like the A/R and the compressor maps etc confuse me a bit.

That said, if my aim for 300-350rwhp with the mods previously mentioned, what sort of airflow or boost should I be running? Should I consider a slightly larger turbo? I would like something which hits full boost by 4-4500rpm.

Also, above 12 psi is out of the efficiency range for a stock turbo, how does having the turbo hi-flowed affect this? Is 14psi in the efficiency range for a high-flowed stock turbo?

my mods as follows

walbro fuel pump

Power fc

AVCR

FMIC

Hiflow cat

CES Racing split dump to cat

3" exhaust

When i had stock turbo on it was set on 12 psi

it made 201rwkw

i put my hiflow turbo on myself, not getting it tuned or anything.

i took it too test and tune, and noticed my car was maxing out way to early.

Set on same boost, with the bigger wheels was obviously flowing more air, and my car wasnt tuned to handle it.

Got it tuned, injectors flow rate went from 70% to 90% to accommodate for the increase of air

and afm is on its limit on 5.1volts, or however it works.

Just the difference made by having bigger steel wheels and a great tune

was 201rwkw to 230rwkw.

I believe the efficiency range for a hiflow ( plain bearing) safely is goin to be 18psi .

Ball bearing is going to be more,

and thats for a rb25 engine to my understanding.

and also would slightly change for what mods you have.

Bazr33, it seems that you have basically the same mods as what I am going for. Around 230rwkw is right in the range where I would like my power to be. 250rwkw might be a stretch, 300rwhp (225kw) is my aim, any more than that is a bonus. That should be good enough for a 12.something on the track once I learn how to launch the car properly.

As i said before, one step at a time, I will get the PFC, EBC & FMIC done, then look at the turbo. I may be better off getting an aftermarket turbo, I will consider the options when I have the cash. I asked about the hi-flow turbo because I figured it would be a cheaper alternative to an aftermarket one, but it doesn't really seem that much cheaper...

I discussed the oil supply question with an engineer, he recommended a small reseviour that is pressurised from oil pump and naturally drains to turbo, I really don't like the idea much but he swears by it.

Thanks for that info - appreciated!

thanks paulr33. i knew that boost is not an indication of power, i know a gt30 at half the boost will make more the same, or more power, i just didnt understand how. but with a bigger turbo, it will spin slower, generate less heat, and with less heat u will physically need more air in the same space to generate the same pressure, i think... :D this is what i never understood.

my train of thinking before was that the amount of air was the same, because same boost, same manifold, same ic piping, so i figured same volume. wrong!

thanks again

you appear to have some of it wrong, the larger turbo would need to spin faster as its has a larger compressor wheel, larger means more lag and more intertia to get it moving. i suggest a read of turbobygarrett.com under the tech 101 section and read all the areas to cover the basics of turbocharging and how compressors work

it will cover any uncertain areas you may have

After having a look at the GCG website, a brand new GT3040R or something similar is only about $200 extra than the cost of getting the standard turbo hi-flowed. I think it also has a T3 flange. Would this be a better option than getting the standard turbo hiflowed? Is there any real drawback to getting a turbo like a GT3040R compared to a hi-flow?

is it int gate or ext gate?

does it bolt on stock manifold?

does it bolt up to standard dump?

does it require different oil and water lines?

does it fit only in highmount mode?

does the standard afm to turbo duct fit on?

drawbacks;

as above with lots of extra lag

The point that a lot of people miss when discussing the bigger turbos is the fact the exhaust side is also bigger, this is what allows the flow to be greater, not the fact it's just got a bigger compressor....that alone wouldn't account for much.

Restriction in the system is what gives you your boost pressure, less restriction on the exhaust side gives greater flow through the system...this is why you get equivalent power at lower overall psi

you appear to have some of it wrong, the larger turbo would need to spin faster as its has a larger compressor wheel, larger means more lag and more intertia to get it moving. i suggest a read of turbobygarrett.com under the tech 101 section and read all the areas to cover the basics of turbocharging and how compressors work

it will cover any uncertain areas you may have

My understanding is that the larger the impeller, the slower it needs to (or can) spin. It's about the speed of the wheel at the blade tips. The larger diameter, the higher the tip speed for a given rpm. All existing literature I have seen has mentioned a critical tip speed of Mach 1.

The turbobygarrett.com site will allow you to check compressor maps of different sized impellers to highlight what I'm suggesting. Garrett have provided a large amount of information and it is well worth the read.

Inertia is a function of mass and diameter of the impeller, so larger, heavier wheels take more to get going - shows itself as lag. It's comparatively easy to choose a turbo that generates X amount of power; getting one that responds well across a wide range of engine rpm is harder - keeps engineers gainfully employed.

cheers

Dale

thats what i thought, coz with bigger wheels, they are moving faster, but only at the outer edges, and not only that, the comp wheel itself is physically bigger, meaning it would move more air with one rotation.

think of a recirculating fans, the ones u used before u had aircon in the house, i've got two right here, one thats about 50cm across( big floor standing one), and one thats about 20cm (like a littel desktop one). the small one spins very fast and makes heaps of noise and moves moderate amounts of air, the big one is lazy, spins slower, makes less noise (well, a deeper noise anyway) and moves heaps of air. i know a room fan isnt a turbo, but thats my train of thought on it anyway

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...