Lasershop

iTrader: (2)

How do "they" get the the horsepower numbers from any particular turbocharger (i.e. "Supports 900 HP")? Must be some kind of baseline because obviously hardly no two different engine designs have the same capability or power potential.

Adrenaline_Z

I would say it's good marketing. Take a somewhat stock looking car on the
outside, slap in a turbo...don't tell anyone about the $1000's of dollars spent
on head work, fuel system, cam, tuning and you have yourself a sale.

How many times have we read posts in the LS1/LS6 section about bolt-ons
not yielding the advertised numbers?

"I just spent $2500 on heads, but I only made 15 HP at the wheel; the
heads are good for 600 HP?".

Not really sure if that's the answer you're looking for, but I see that happening
way too often.

Nine Ball

iTrader: (38)

The get the ratings based on the amount of potential flow that the turbo can support. Potential flow can be used to calculate potential HP.

nitrorocket

iTrader: (12)

Yes, a certain amount of power requires roughly a certain amount of air.

Lasershop

iTrader: (2)

Potential flow based on what standard? Blowers are based on volume (6-71, 8-71 ect.,the "71" CID being the multiplication standard), but EVERYBODY seems to advertise the turbo's based on supported potential horsepower. Just wondering where the science of this originated.
P.S. I before E except after C doesn't work with the word "science".

2000 Tran Zam

iTrader: (2)

i think they use flow benches to measure CFM...

Lasershop

iTrader: (2)

Thanks for the input, and I am quite sure they know the flow and volume of the unit. But then to say it will support X horsepower had to be based on a particular standardized platform. Or........... they just make the **** up.

2000 Tran Zam

iTrader: (2)

Haha, I would say the biggest **** maker upper would probably have to be SLP

DanO

Its quite simple actually, you can only make so much power with a certian amount of air.

Where the differences come are the "efficiencies" of the engine. An engine burning a certian amount of fuel and air puts out an almost exact amount of "heat" a particular engine design would vary on how efficiently it uses that heat in converting it to power.

Combustion effiency, thermal efficiency, mechanical efficiency, etc... Those values are what detract from the maximum power. You can assume certian values for them and that is typically how they come up with thier power #

Brains

iTrader: (7)

As said already, its all based on airflow capability/potential. A turbocharger, no matter how fast you spin it or at what pressure ratio its running, will only pump so much air. That airflow, combined with the proper amount of fuel, can only make so much horsepower -- no matter what.

Lasershop

iTrader: (2)

I really don't mean to complicate the issue, and I am relatively intelligent. But I am apparently being unclear on my question. Back when the cavemen invented fire and turbochargers............... lets say they also invented a big block 454. They found that turbo "A" could move enough air to support X horsepower for 454 CI. Then later on the commies invented four cylinders and turbos are still based on supported HP numbers. I was looking for a black and white "standard" for the claims. Is it 900 HP based on a small block or on a detroit diesel? I totally understand you will not achieve the HP rating on any particular application but the extreme difference between a vtek and a rat motor is an awful lot of CID. If I hear what you are saying, the numbers originate on anything that has the capability of consuming all of the volume of the particular unit (turbo) can put out, which really is a ridiculous claim but everybody does it. Now I have myself confused. Bottom line is who gives a ****. Back to my blower example. A 6-71 means it will support enough volume for 6 cylinders at 71 CI each slug. A standard. I was shooting for what standard an "X" HP turbo came from.
Im just sayin'...........

DeltaT

iTrader: (5)

Check Corky Bell's book called Maximum Boost. It goes through a lot of the math and ratings. Turbo flow is pretty easy to map as a head unit - it's when you put it on different motors that the variability comes into play.

It took me 5 or 6 readings to pretty much understand everything Corky was trying to teach, so don't give up!

Jim

JZ 97 SS 1500

iTrader: (2)

This link below will help explain the theory....

Turbo help 101

As for a black and white answer, well the answer would be D. (none of the above). Turbos were not designed and rated using one particular engine.


Turbos are mearly tested on a gas stand and then applied a load, and then the pressure ratio is set manually from 0 to max of what the compressor wheel can efficiently compress. The results from this are what a compressor map is derived from.

Jose

will62085

iTrader: (4)

you also have to take into effect the mathmatical formula for getting horsepower is based on torque and rpms...not neccesarily airflow

TeeKay

LaserShop, listen to Jose, he does know turbos.

Let me add that turbos are rated for MAX hp based on the MAX pounds per minute (ppm) they are able to deliver. That varies according to the boost they are putting out (compressor maps). As an estimate, each ppm of air delivered developes 10.86 hp. Every turbo has a maximum amount of air (ppm) that it can deliver based on the compressor section and its efficiency. So a turbo that is rated at 90 ppm (now that's a MAX, not what you get every time), can produce a MAX of 977 hp at the crank. That doesn't guarantee that you will actually make enough flow to get 90 ppm from that turbo. It just says that the turbo will support that hp if it's done right. It all depends on boost (pressure ratio) and rpm and displacement to maximize a particular setup.

You need to start with the hp at the crank that you are wanting and work backward to estimate which turbo will do that for your setup. Take a hard read at the link for Turbo 101 and you will begin to see what's involved.

Now I'm no expert, I was where you are just a few months ago. You are a smart guy, so you can pick up on the basics pretty quick. HTH GL.

Edited for an easier read...

Lasershop

iTrader: (2)

There it is........ I kept saying standard, should have said formula. Damn I had too much coffee yesterday!!!

Brains

iTrader: (7)

The simple fact is, you could take a 1,000,000cid engine and restrict it to 100 lb/hr of air, and it will make the same amount of power (roughly) as a 100cid engine boosted to consume 100lb/hr of air. An engine is an air pump, and uses fuel as its motivation to do work. Air and fuel must be consumed in a known ratio to make the most power for the volume ingested. The fuel has a known amount of energy for mass consumed. Plug it all into a formula and you can find the max power for volume of air (or fuel) consumed.

Lasershop

iTrader: (2)

Where do I get one of those 1,000,000cid engines. I could make it fit......
I appreciate the brain food input from everyone. Im bettin' that im not the only one that has learned a little more about turbo sizing from this. I have ALL the books. I have worn them out. I have copies in each bathroom. This did give me more of an interest in reading turbo maps and maybe even understanding what they mean. Knowledge is power baby!