bustaMOVEs

iTrader: (31)

I'm looking at turbos and the ranges etc and seeing billets come up, so I'm thinking they must be the shizzle out there right now.

But as I research deeper as I do with most things as I'm never happy with good reviews until I find bad reviews that 'make sense'.

Then I came across this, quoted by someone from Borg Warner-

"BW AirWerks - In general... yes, we can make anything if you want to pay for it In the performance and/or racing world though, there is really no benefit to using a "billet" CW other than it's shinny. Basically, billet, or FMW (Forged Milled Wheel) compressors came about due to OE applications requiring them. When a turbo is constantly being cycled from high speed to low speed, the wheel becomes fatigued and can eventually lead to a hub burst (CW splits in half). Imagine the compressor acting like a big drag slick like you see on top fuel cars; during the burnout, you can see them get skinny and "grow" in height... On a much smaller scale, the CW sees this same process over and over again, and over time this weakens the wheel, eventually leading to a fracture and possibly a hub burst. Now ask your self how many times you've seen a race car's CW split in half... I have never, and I've seen a LOT of failures. Even the billet aluminum isn't enough in some newer applications and we've turned to titanium which in its FMW form, is nearly indestructible. I've heard all the propaganda surrounding the billet wheel myths: higher boost capability, higher flow, higher efficiency, etc... The higher boost capability is the only one which is true, but not because it's machined and not true for racing use. OE diesel applications using FMW compressors can run higher boost pressures more reliably simply because they are less susceptible to fatigue as they're cycled from higher speeds (required to make more pressure) to low speeds.
So, why would anyone offer a billet wheel to the racing/performance market? Couple/three reasons:
- Some people just want them because they look really nice... and are willing to pay the cost difference.
- Because it already exists in an OE production application and it's easily installed into performance turbos, sometimes they're even interchangeable with existing cast wheels.
- Applications where a cast wheel does not exist (maybe a larger inducer is needed) or production volumes are believed to never be high enough to justify tooling costs.
Are they cheaper than cast wheels? ...NO. Even in high production volumes, a billet wheel will always be more expensive than a cast wheel. However, if a company wants to make a compressor all their own (not using an existing "big" turbo manufacture's wheel ie. BW, Garrett, Holset) it would most likely be cheaper as they would have to tool up to make all the cast versions. If a company makes a mistake in the design of a billet wheel, they can simply keep changing the program until they get something that works... The OE manufacturer does all the development work up front to arrive at the best possible design for what's needed. Once the design is finalized, a "master wheel" is machined and used for the tooling master... that's right, all cast wheels get their start from a very nice billet wheel that when tooling is made, creates the same exact performance characteristics in a much cheaper and faster to produce cast version.
Phew... Sorry for the long-winded explanation, but hopefully this helps explain why billet wheels exist. Short version is billet wheels are no better than cast wheels for any performance or racing application I'm aware of... but they sure do look great!

stonejedi

iTrader: (51)

Borg Warner are the direct competitor of numerous company's that run billet wheels in there turbo's,there just throwing around mud to see if it sticks to potential customers in the market swaying them over to BW turbo's.Ask yourself How much people run billet bladed turbo's from the like's of Scooby Clinic,Lateral etc...without any problems and that are more then happy with the upgrade?Don't get me wrong BW make some lovely Turbo's i was even thinking of getting one of there EFR range of turbo's as turbodynamics supply them for my project,but decided to run with the SC3582R billet after driving a mates car with one fitted.SJ.

bustaMOVEs

iTrader: (31)

To me it's for more money with no real gain so another way of making money? Or have I got it all wrong?
As

Carnut

Because billets spool faster due to low weight does that mean they slow down quickly?

If yes, how could this affect performance if at all?

stonejedi

iTrader: (51)

Your thinking wrong mate,advances in technology will always happen usually for the betterAnd for that advance and research that initial development cost gets pass on to the consumer until it reaches the stage of being old hat i.e normalize,then more advances have to take place boundaries pushed etc...for the next in thing but its got to work to have any credence its just how business works.SJ.

stonejedi

iTrader: (51)

Why would you want a turbo to slow down?Its all about them boosting up quicker with as little lag as possible and stay on boost when accelerating .SJ.

Ian

iTrader: (10)

on my old s206 turbo I use to run 1,7 bar boost at around 450 bhp, on the billet version of the same turbo, it was around 2.0 bar. not sure on bhp, but i think a new owner of my car had it around 500 bhp

Carnut

You wouldn't, if a billet was to slow quicker than a cast it would that be 1-0 to a cast.

It's good that a billet spools faster but it would be bad if it loses spool quick?. I think the answer to my question is that the billets will spool longer because of the better barings but the cast is heavier so would that give it more momentum?

LuckyWelshchap

Firstly, imo this is one of those 'theoretical' areas that most industries enjoy - a company can say something that can't be disproved and has some merit, so it can say 'my product is better' (so I guess that this thread could be this weekend's 10-pager )

My understanding is that it's the lighter weight that's the big advantage. Not the fact that it shaves a bit off the weight of the car but that it makes the compressor get up to speed faster.

That's the key word (rotational) - speed.

The compressor's job is to shift volumes of gas of course. It doesn't matter whether it's made of titanium, billet alloy, iron, glass, wood or even paper, as long as the surface area of the segments of the blade are identical then it will shift the same volume/sec.
(Before anyone jumps in, obviously the strength of the material comes into play but the above is a good example).

Momentum doesn't come into it at all (unless you use Tesco fuel ).
It's inertia that's the key. The quicker it's overcome and the wheel starts turning - and of course the quicker the wheel gets up to max speed - the faster the turbo will fully spool.

The lighter the wheel, the lower the (Moment of) Inertia and hence the quicker it gets on with its job.

I'm not sure of the density of billet alloy but I'd guess it's a far bit less than titanium, so purely on the 'get it going' angle a billet has to be more effective than cast or titanium.

In theory of course........

Carnut

Yes but once the turbo is spooling does the heavier wheel keep momentum for longer than a billet? Say the turbo is spooling and you come off the throttle, when you reapply the throttle will the cast have less spooling to do because it's not slowed as much.

The op is looking into the advantages of a cast turbo, iam not sure if there are any but just fishing.

neil-h

Yes the heavier compressor will have more momentum (as its a function of mass), it also has more inertia. So although it maybe spinning faster after you lift off, it will take longer/more energy to respond to the reapplication of the throttle.

stonejedi

iTrader: (51)

Having driven cars with different turbos installed you would have to be a white beard masterto feel the actual difference when boosting or on boost,a billet turbo is just one piece of many pieces to try to achieve a quicker power delivery and when in conjunction with other mods show's its true potential and why its a worth while upgrade when compared to standard cast wheel turbos.A similar argument was had back in the days with journal vs ball bearings for turbochargers,we know who won that one,advances in tech is always a good thing.SJ.

Carnut

LuckyWelshchap

Beat me to it !

Momentum doesn't come into it.
I think there's been a thread on here where identical turbo models - but one cast and one billet - were put on a car and tested.

Carnut

LuckyWelshchap

Yes, good point.

All companies will imply that their product will make your life/possessions etc. better but in reality it's a combination of bits and pieces that enables you to see, feel etc the difference.

neil-h

It does to a certain extent as momentum and inertia are interlinked in this particular scenario.

stonejedi

iTrader: (51)

I'm talking this type Chris.SJ.

Jay m A

iTrader: (2)

'Make sense' ? Only if you are talking about billet wheels designed with the restrictions and constraints that the casting process requires!! Otherwise it can't be used as a master....

However if you design a billet wheel without the casting limitations, then you can make a wheel with thinner vanes and more complex / efficient vane shapes to increase performance... does that make sense?

If Borg warner attempt to use their competitors billet wheels as a master for their cast wheels they'd fail the production process let alone make it to the test bench!

Dave Y

iTrader: (52)

Just read this thread,now i am thinking which turbo do i go for when i have my 2.1 forged engine built?I will be looking for 400bhp + or thereabouts but i dont want the turbo running at the top of its range.would a billet turbo be stronger.?

stevebt

iTrader: (8)

I ran a gt35r non billet wheel on a .63 housing and I was making full boost on a 2.5ltr engine at 3400/3500rpm I then went with a billet gt35r and a .82 housing but on a 2.35ltr.
I should of had more lag in theory but the pick up point was exactly the same and due to the better turbo you can run it on higher boost so mine was ran at 2.3bar

bustaMOVEs

iTrader: (31)

Interesting points, I'm just qurious to what turbo would be ideal and wanted to know the differences.
So are they worth the price difference? So better spool which is a tick for me and lighter in weight which is also good.

But I can help to ignore the last sentence from the guy in post 1 that I posted
Short version is billet wheels are no better than cast wheels for any performance or racing application

LuckyWelshchap

A billet turbo isn't necessarily 'stronger', and it isn't necessarily better than other non-billet turbos (classic example being size and spooling - a smaller non-billet turbo might spool in exactly the same way as a billet larger one, going on our points about weight of wheel, momentum and inertia for example).

However, like for like (eg the MD321 that's been mentioned) the billet turbo will (should?) out-perform the non-billet version.

Re. 'which turbo' there's lots of threads on this. I'd like to think that your builder will be able to give you some very helpful options when the time comes.

The Trooper 1815

iTrader: (31)

Twin Scroll spool quicker.

The Trooper 1815

iTrader: (31)

What's your experience of billet turbo's and their performance vis a vee non-billet?

ALi-B

iTrader: (1)

The post in teh OP makes sense from a metallurgist's point of view.

Billet just means the method of which the compressor (or turbine) wheel is made.

Yes it "could" be stronger and lighter, but as said who has ever seen a compressor wheel shatter? You'd have to be doing something very wrong for that to happen, and it wouldn't be the turbo's fault.

So what are you looking for? The design. Not the material or production method. Simple as that. A good design will out-perform one using lighter or shinier parts.

Is it better? Well that's down to who made it - is it a one-off machined part made in-house or something taken off another manufacturer and shoved in someone else's housing. Or even a Chinese copy?

One thing is for sure as the Borg Warner guy correctly states is a cast item is more likely to have a bit more care taken with the design as the costs of tooling to make it are pretty high so it has to be right from the start....where a low volume production using billets can adjust it as they go along...if they f**k up, they can easily sort it out for little outlay.

So IMO its not billet vs non-billet. But WHO made/built it.

Bit like "forged" engines....anyone can throw a set of forged piston in a engine, it doesn't make it better - if its been done to a poor standard then it'll fail or under-perform.

Maz

iTrader: (34)

Ali you've muddied the waters further here
Billet turbos command a premium over non billet. What you're saying (and others) is that a billet turbo is not necessarily better than a non billet. It's about the complete design.
That would be fine BUT we are being charged a premium for 'billet' turbos. When they may or may not be any better than a non billet! Is it a case of marketing hyperbole again?!

bustaMOVEs

iTrader: (31)

You see where im coming from maz

Nice post ali.

Im considering a turbo for future and just trying to get the knowlede prior so i can make my own mind up.

What about titanium or ballbearing

Shaun

If you want to know what differences a billet wheel can make, read my project thread.

It's certainly not sales spin!

stonejedi

iTrader: (51)

here's a article that i read a while ago and found it quite interesting:
http://www.enginebasics.com/Advanced...%20Wheels.html.SJ.