Topic: Dyno numbers between Cobalt and Kappa (LNF)

[snaponbob]

So, at 2000 rpm there is still a 50hp loss? I know this sounds like beating a dead horse, but driveline loss is as unique as the power produced car vs car. There are no constants. I have yet to see factually derived numbers and the paper to back it up as to what the driveline losses are for any of the vehicles we have been discussing.

[POS VETT]

That's not quite what I'm saying.  Let's use an example.  A stock turbo Kappa was placed on a dyno and power was measured at 215 hp.  That's a loss of 45 hp from the advertised 260 hp; a 17% total loss.

Now put some tune (w/ the same redline speed), a nice freer-flowing exhaust, and maybe even run E85.  Put it back on the dyno with the same atmospheric conditions and measured power was 247 hp.  A nice bump of 32 hp.

In this case, the 32 hp bump also happens on the flywheel, thus putting the power measured at flywheel at 292 hp.

What I don't agree on is people using the 17% figure to calculate the power measured at flywheel; which would give a higher number, e.g. 247/(1-0.17)~298 hp.  A 6-hp (298-292) discrepancy.  A 6-hp discrepancy may seem small but at higher power levels (and higher loss percentage which is usually 20%), that discrepancy can run 30-50 hp.

Now, I'm not talking about producing so much more power/torque that the drivetrain is stressed to the point that deformation starts to affect tolerances, bending/twisting shafts/gears and increase loss.  You put 600hp in front of the stock solstice drivetrain, well, it's a different ball game.

Back to the topic, that explains the difference in measured power at the wheels between a turbo Kappa and a Cobalt/HHR SS; considering all else being equal (that the intercoolers have the same efficiency, piping too, air intakes are equally efficient, etc.) and the only difference is the drivetrain configuration.

[2.0 tspeed]

Whats the problem cobalts dyno higher end of argument

[snaponbob]

Heard something interesting on Speed last night during the Barrett Jackson auction. A 2011 Mustang was custom built with a blower. The engine was dyno'ed at ~550 crank hp. The car was dyno'ed at ~460 whp. Do the math ---- 16.7% loss. Sound familiar? The drive will create a power drain. The generally accepted math is to use a correction factor (in %) rather than simply adding an assumed hp amount.

Bottom line, driveline loss correction is based on a lot of assumptions unless the engine is dyno'ed first. HOW the correction is done, it boils down to measured increases on a given vehicle on the same dyno.

[snaponbob]

Whats the problem cobalts dyno higher end of argument

?????????? The Cobalt SHOULD show higher numbers for no other reason than the electric power steering. Assuming ALL LNFs DO produce 260 bhp in stock tune and no mods, then the ONLY way to KNOW what the difference in whp is back to back dyno runs with a stock 08/09 GXP/Redline and stock 08/09 Cobalt SS. Other than that, it's all mental masturbation. 

[2.0 tspeed]

They have less drivetrain loss there Fwd this isn't rOcket science allot of cobalts are over 300w and we are not I don't get why it's such a problem. Ill run sone cobalts and post vids but it won't b at the track if the mods are ok with it :-/ rwd Fwd loss no loss who cares just run em I'll find a cobalt and run stock tune against stock tune how about that I hope it helps

[Jebsmith]

I have 482 hp at the crank. The end.

[Critterman]

I have a flywheel at the end of my crank 

[snaponbob]

Cranky, aren't we?  

[Critterman]

Well Bob, I didn't want to tell him about the bazillion HP I have from my butt dyno.

(Please insert tongue in cheek icon here)

[snaponbob]

Well Bob, I didn't want to tell him about the bazillion HP I have from my butt dyno.

(Please insert tongue in cheek icon here)

BHP = Butt horse power

[kennysabarese]

In this case, the 32 hp bump also happens on the flywheel, thus putting the power measured at flywheel at 292 hp.

What I don't agree on is people using the 17% figure to calculate the power measured at flywheel; which would give a higher number, e.g. 247/(1-0.17)~298 hp.  A 6-hp (298-292) discrepancy.  A 6-hp discrepancy may seem small but at higher power levels (and higher loss percentage which is usually 20%), that discrepancy can run 30-50 hp.

I hate to bring this up when it's wildly off topic, but I have to politely say that you are incorrect here. You can't choose when to use percentages and when not to. They work in both directions, when adding and subtracting.

300bhp - 15% drivetrain loss is 255whp (300*.15=45; 300-45=255)

400bhp - 15% drivetrain loss is 340whp (400*.15=60; 400-60=340)

So if you dyno at 255whp, then improve your engine and dyno at 340whp that would be an 85whp increase, but it's actually a 100bhp increase. That's the only way to to get the two formulas to work.

If I am wrong here, someone correct me please.

[snaponbob]

I hate to bring this up when it's wildly off topic, but I have to politely say that you are incorrect here. You can't choose when to use percentages and when not to. They work in both directions, when adding and subtracting.

300bhp - 15% drivetrain loss is 255whp (300*.15=45; 300-45=255)

400bhp - 15% drivetrain loss is 340whp (400*.15=60; 400-60=340)

So if you dyno at 255whp, then improve your engine and dyno at 340whp that would be an 85whp increase, but it's actually a 100bhp increase. That's the only way to to get the two formulas to work.

If I am wrong here, someone correct me please.

You're right.

[Gentleman Jack]

I hate to bring this up when it's wildly off topic, but I have to politely say that you are incorrect here. You can't choose when to use percentages and when not to. They work in both directions, when adding and subtracting.

300bhp - 15% drivetrain loss is 255whp (300*.15=45; 300-45=255)

400bhp - 15% drivetrain loss is 340whp (400*.15=60; 400-60=340)

So if you dyno at 255whp, then improve your engine and dyno at 340whp that would be an 85whp increase, but it's actually a 100bhp increase. That's the only way to to get the two formulas to work.

If I am wrong here, someone correct me please.

I don't know who is right or wrong, but what POS VET is saying is that the drive line loss is a fixed amount of power, not a fixed percentage of power.  Much like a supercharger or air conditioner, it sucks away a set amount of power to turn the compressor.  If you put the same ac system on an engine with twice the output, it doesn't take twice the power to run it.  He is applying the same theory to the driveline.  If a driveline takes 75 hp to spin and get up to speed, it shouldn't matter what power source you have spinning it.

GJ

[snaponbob]

GJ, a supercharger takes a certain amount of power to run it, but as engine speed goes up so does the supercharger speed. As the supercharger speed increases, so does the load on the engine. More load, more drag. NOT a constant. Same as road speed. Aero load increases with speed. Speed up mechanical parts and friction load increases. Drag is drag, and as drag increases, so does the work load to overcome the drag. Want proof? Push your car. Now, push the car FASTER. It takes more effort.

[Gentleman Jack]

SOB,
I get that 100 percent.  What I'm not sure of (and PS, I was trying to help explain POS VET's thoughts, but I see both sides) is why a more powerful engine requires more power to spin the same components.  I get the higher RPM = more power required, but that is independent of engine output power.  Help?

[Kelu]

I have 482 hp at the crank. The end.

How come?
Having a 240 whp and 240wtq as stock on same dyno you did 412whp, how you can have 482 bhp?

[DeepBlueGXP]

Kelu, i

How come?
Having a 240 whp and 240wtq as stock on same dyno you did 412whp, how you can have 482 bhp?

Kelu, goto my post http://www.kappaperformance.com/forum/index.php/topic,6050.msg84679.html#msg84679

download the excel spreadsheet, he's pretty close to 485 BHP

[Kelu]

DBGXP: EXACTLY, your excel confirms my expectations
For 239whp stock means 8% loss
Entering 8% for Ugraded LNF, 412whp -> 448 BHP

Common math is same everywhere.

[snaponbob]

DBGXP: EXACTLY, your excel confirms my expectations
For 239whp stock means 8% loss
Entering 8% for Ugraded LNF, 412whp -> 448 BHP

Common math is same everywhere.

That assume that a given dyno is perfectly accurate. As has been discussed in the past, different dynos produce different numbers. The ONLY completely TRUE number is BHP, and that means taking out an engine. There are too many people that have spun out ~220whp from a LNF Kappa, and that is about 15% loss. And there is Lyndon Wester who produces LOWER output numbers because he has a more "conservative" dyno. Dynos can be programmed to produce whatever one wants to see. This is why "dyno racing" is useless, and only before/after numbers (for a given car) are all that matters.

[Brazen17]

It seems to me you can't just use a set % to get the whp. It works well for the horsepower ranges range we are dealing with but I don't see how it would hold at higher numbers. E.G. - 300 hp (crank)  - 15% loss = 255 whp. All things being equal except an increase in hp (say a tune and race gas) getting us 1,000 hp (crank) - 15% loss = 850 whp. Why does it take an extra 105 hp to move the same engine mass?  

This also assumes ( I know, I know) the engine is operating in the same rpm band (just different peaks for hp and tq). Where did the 105 hp go?

[snaponbob]

This also assumes ( I know, I know) the engine is operating in the same rpm band (just different peaks for hp and tq). Where did the 105 hp go?

Sometimes up in smoke !!!!!!!!!!!!!!!

[snaponbob]

It seems to me you can't just use a set % to get the whp. It works well for the horsepower ranges range we are dealing with but I don't see how it would hold at higher numbers. E.G. - 300 hp (crank)  - 15% loss = 255 whp. All things being equal except an increase in hp (say a tune and race gas) getting us 1,000 hp (crank) - 15% loss = 850 whp. Why does it take an extra 105 hp to move the same engine mass? 

We have been speaking in relative terms. As I have said, the only TRUE numbers are derived on an engine dyno. My 285whp could easily be someone else's 295whp. If one were to service the u-joints, and such, with better lubricants, one could expect less loss. Blueprinting a diff or trans would help as well.

[Brazen17]

Sometimes up in smoke !!!!!!!!!!!!!!!

I can believe that!

[Critterman]

GJ, a supercharger takes a certain amount of power to run it, but as engine speed goes up so does the supercharger speed. As the supercharger speed increases, so does the load on the engine. More load, more drag. NOT a constant. Same as road speed. Aero load increases with speed. Speed up mechanical parts and friction load increases. Drag is drag, and as drag increases, so does the work load to overcome the drag. Want proof? Push your car. Now, push the car FASTER. It takes more effort.

and uphill, come on GJ PUSH, PUSH HARDER AND FASTER