Cost Of Getting A Turbo Hi-flowed

[paulr33]

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

[paulr33]

one of the given ways to increase pressure is to reduce air volume and increase temperature. exactly what you dont want in a combustion engine. you want more air

[paulr33]

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.

[Quinny]

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?

[bazr33]

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.

[The Dan]

Firstly...you will not make 250 + rwkw on a GCG highflow. 250 would be an absolute maximum.

Secondly...I can do the same job for you for $1750 plus postage (around $20-$40)

[Quinny]

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...

[Tangles]

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!

[VB-]

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... 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

[paulr33]

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

[Quinny]

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?

[paulr33]

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

[Quinny]

More confusing "turbo-talk" . I shall do some investigation. At least know I know what characteristics I need to look for when selecting a turbo.

[666DAN]

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

[TurboX]

Did you check out the turbo's from "SLIDE"

Less than $1K for a plain bearing hiflo AFAIK

Just another alternative to GCG...

[Dale FZ1]

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

[VB-]

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

[rb26s13]

I will have a look at injectors, and I got a price on a GTR pump brand new from Nissan $800, plus needs to get ordered from Japan - stuff that.

f**k that buy a 040 and install intank.. much cheaper and easier.. also flows more than a stock gtr pump