: Is the N* overrated?



airfuel2001
07-10-07, 10:53 PM
Factory rating is 300hp, but this being said:


Our trannies use up about 23% of the power the motor is putting out.

So 300hp net with a 23% drivetrain loss is 231whp, correct? How many here have dyno'd 231whp on a dyno without any modifications of any sort? I have done some research and see that number is being achieved with mods like induction and exhaust, but not factory stock.
The original N* was rated 275hp so ~211whp, which seems more realistic assuming about 20whp is being gained from induction and exhaust mods = 231whp (which should have been the factory number).

So question is was the 25hp added to the newer N* real, or was it just for print? I would like to see dyno sheets for all N* if you have any, both 275hp version and 300hp version. Or if anyone has more details to this I have overlooked, I am open ears (or eyes in this case:bouncy:) Thanks for any input or opinions.

Links to some of my research:


http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/100904-few-numbers.html?highlight=dyno (and with more smoothing that would have showed even less)
http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/75675-so-i-put-my-sled-dyno.html?highlight=dyno

I would expect an L37 to put down 210 or so...

Hot Rod did a dyno test of a stock 300 HP mid-90's Eldorado a few years ago, and it put out around 216 HP or so.
Which is exactly in line with my 275hp theory?

AJxtcman
07-10-07, 11:10 PM
Factory rating is 300hp, but this being said:

So 300hp net with a 23% drivetrain loss is 231whp, correct? How many here have dyno'd 231whp on a dyno without any modifications of any sort? I have done some research and see that number is being achieved with mods like induction and exhaust, but not factory stock.
The original N* was rated 275hp so ~211whp, which seems more realistic assuming about 20whp is being gained from induction and exhaust mods = 231whp (which should have been the factory number).

So question is was the 25hp added to the newer N* real, or was it just for print? I would like to see dyno sheets for all N* if you have any, both 275hp version and 300hp version. Or if anyone has more details to this I have overlooked, I am open ears (or eyes in this case:bouncy:) Thanks for any input or opinions.



http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/100904-few-numbers.html?highlight=dyno (and with more smoothing that would have showed even less)
http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/75675-so-i-put-my-sled-dyno.html?highlight=dyno


Not all PCM programs are created equal

airfuel2001
07-10-07, 11:14 PM
Not all PCM programs are created equal

I agree, but GM created them all to equal 300hp and it seems they don't stack up?

In 1999 the Ford Mustang Cobra was rated 320hp and people complained that their dynos didn't show that power, and Ford was required (or heavily persuaded) to recall all the 32v Cobras that year and install better exhaust, so why didn't Cadillac do the same if what is said is in fact true? (Sorry 50% of my posts have reference to a Mustang) :(

AJxtcman
07-10-07, 11:22 PM
I agree, but GM created them all to equal 300hp and it seems they don't stack up?

I know better than that.
Trust me
I have about 50 on paper and they are all different. I am mostly looking at z or w rated tires. I have some odd country programs, but I have about 50 different ones. Most of them are just for 2000 to 03. If I started pulling up S and H rated tires I would be over whelmed.
.
I put together a DHS that ran against a VIN 9 car. It is Bert's Kill so you will have to wait, but that 275 horse is no 275 anymore. Nothing internal in the engine.

airfuel2001
07-10-07, 11:29 PM
I know better than that.
Trust me
I have about 50 on paper and they are all different. I am mostly looking at z or w rated tires. I have some odd country programs, but I have about 50 different ones. Most of them are just for 2000 to 03. If I started pulling up S and H rated tires I would be over whelmed.
.
I put together a DHS that ran against a VIN 9 car. It is Bert's Kill so you will have to wait, but that 275 horse is no 275 anymore. Nothing internal in the engine.

You are going to a different page, I know there are different spec cars. Issue is they were ALL rated 300hp, so they ALL should have made at least 300hp. We all are in agreeance that one of the biggest hinderances on these cars as far as making power is the factory PCM tune. But GM says their shitty tune (no matter the speed spec) is good for 300hp (231whp) and it is not.

AJxtcman
07-10-07, 11:36 PM
You are going to a different page, I know there are different spec cars. Issue is they were ALL rated 300hp, so they ALL should have made at least 300hp. We all are in agreance that one of the biggest hinderances on these cars as far as making power is the factory PCM tune. But GM says their shitty tune (no matter the speed spec) is good for 300hp (231whp) and it is not.

No
.
That is my point.
.
A engine that was on the dyno was rated at 300. It was not certified.

.
please read this paper
.
http://www.sae.org/certifiedpower/details.htm
.

AJxtcman
07-10-07, 11:40 PM
http://media.gm.com/us/powertrain/en/product_services/2007/HPT%20Library/Premium%20V/2007_46L_L37_Cadillac_DTS.pdf

You know that they didn't go backwards since 2000. If the 07 did not make 300 then what did?


275 sheet
http://media.gm.com/us/powertrain/en/product_services/2007/HPT%20Library/Premium%20V/2007_46L_LD8_DTS.pdf

airfuel2001
07-10-07, 11:41 PM
No
.
That is my point.
.
A engine that was on the dyno was rated at 300. It was not certified.

.
please read this paper
.
http://www.sae.org/certifiedpower/details.htm
.

So then are you saying they are over rated but it is ok because it is before SAE requirements?

AJxtcman
07-10-07, 11:47 PM
So then are you saying they are over rated but it is ok because it is before SAE requirements?

I am not sure if it is a requirement.

airfuel2001
07-10-07, 11:49 PM
http://media.gm.com/us/powertrain/en/product_services/2007/HPT%20Library/Premium%20V/2007_46L_L37_Cadillac_DTS.pdf

You know that they didn't go backwards since 2000. If the 07 did not make 300 then what did?


275 sheet
http://media.gm.com/us/powertrain/en/product_services/2007/HPT%20Library/Premium%20V/2007_46L_LD8_DTS.pdf

You posted again before I could even reply to the first, slow down:bighead:

But you said it yourself, which of the 50 tunes was applied to those test motors?

AJxtcman
07-10-07, 11:54 PM
You posted again before I could even reply to the first, slow down:bighead:

But you said it yourself, which of the 50 tunes was applied to those test motors?

All I know is that I have one slick program.
.
I am working on some for 99 and prior.

HodgeMcGuyver
07-11-07, 12:02 AM
So what really is the rated HP of a vin 9 1996 North*? & am I wasting my time trying to use this motor for my project ,when I already have a 235_250 motor in it already????

jadcock
07-11-07, 07:15 AM
I think that what AJ is saying (regarding the SAE ratings) is that both ratings are correct. The older L37 Northstars are rated at 300 hp. The newer L37 Northstars are rated at 292 hp, UNDER THE SAE J1349 spec. It's like gross vs. net ratings. Or old EPA MPG ratings vs. new EPA MPG ratings. Both old and new are "correct" in that the results are accurate to the method. The methodology was updated to try to better replicate real world conditions (in both examples, hp rating and EPA MPG rating).

The rating of a VIN 9 1996 Northstar engine is 300 hp. Will you see that at the wheels? Who knows -- it depends on the condition of your transmission and fluid, the weight of your wheel/tire package, etc. But there are too many unknown variables in a chassis dyno to know FOR SURE what your engine makes. We can guesstimate that the transmission consumes 23% of the hp. What if it's only 20%? What if it's 25%? At 20%, 300 = 240 hp on a chassis dyno. But at 25%, 300 = 225 on a chassis dyno.

The only true measurement would be to dyno it at the crank, just as Cadillac did, and find out. Otherwise, you're just spinning your wheels, so to speak, trying to ascertain how much hp your transmission consumes to figure out how much hp an engine might make. Keep in mind also that an engine with 80,000 miles won't likely make the same power numbers as a new one.

In other words, I would totally believe a street-driven car with 50,000 miles putting down a number of 215 hp on a chassis dyno, even if the engine is supposed to put out 300 hp. Maybe the transmission is eating up 27% of the power (81 hp). 215 hp + 81 hp loss = 296 hp. If the difference between the rating and the actual output is only 4 hp, as in this case, I'd be impressed.

codewize
07-11-07, 07:25 AM
The G-Tech Pro says I put down 242. I will have a whole folder full of dyno slips soon. :) just hang on.

eldorado1
07-11-07, 09:38 AM
Another question you have to ask is what were the conditions of the test for the 300hp and 275hp ratings? Is this installed in a simulated vehicle? With factory induction and exhaust? Are all the accessories installed? (water pump, alternator, power steering, AC compressor)

I don't know the answer to that... I know they recently changed those conditions, and the 4.4L SC N* was rated at 469hp then changed to 440hp. Same engine. 29hp "disappeared". Or maybe it was vice versa.

AJxtcman
07-11-07, 10:12 AM
I know this is not what you want
http://www.sae.org/certifiedpower/brochure.pdf

jadcock
07-11-07, 10:25 AM
I don't know the answer to that... I know they recently changed those conditions, and the 4.4L SC N* was rated at 469hp then changed to 440hp. Same engine. 29hp "disappeared". Or maybe it was vice versa.

Yeah, it was vice versa. It was originally rated at 440 hp, and when re-run using SAE's new guidelines, it came out to 469 hp. For some reason, the new spec was favorable to that engine, but some other engines "lost" power. Some Toyota engines "lost" a sigificant amount of power (10%).

In the FWD Northstar world, the 300 hp engine "lost" 8 hp and 8 lb*ft of torque with the new SAE spec, and is now rated at 292 and 288 respectively (from 300 and 295 originally).

The 275 hp engine didn't "lose" any hp, and "lost" 5 lb*ft of torque with the new SAE spec, and is now rated at 275 and 295.

Again, none of these engines actually "lost" power. It's simply using a new measurement. It's like getting on an exercise bike and setting the resistance to zero, and seeing how many RPM you can turn (which you could convert to hp). Then set the resistance to maximum and then re-measure. Your strength didn't change, but the test conditions did. That's all.

weister42
07-11-07, 05:38 PM
Well when a car owner wants to go faster they go buy performance parts, but that's not an option for us :crybaby:

Does anyone here have a Northstar in a different vehicle controlled by a manageable ECM?

AJxtcman
07-11-07, 06:18 PM
Well when a car owner wants to go faster they go buy performance parts, but that's not an option for us :crybaby:

Does anyone here have a Northstar in a different vehicle controlled by a manageable ECM?

I run mine on a 99 SLS program. I hope to have mine very tunable soon. I made the wrong choice on power plants. I had a 2000 and a 99.

Raze
07-11-07, 07:58 PM
I thought even older SAE ratings were at the crank, not the wheels, put the engine on an engine test stand like GM, Ford, etc all have to do in order to get SAE cert and see what it runs under a given ambient/load combination. Until then trying to 'estimate' drive line losses or arguing the 'true' hp level of the engine is a futile exercise...

just my .02

jadcock
07-12-07, 07:20 AM
I thought even older SAE ratings were at the crank, not the wheels, put the engine on an engine test stand...

Yes, that's correct. The advertised power ratings have always been measured at the crank. The general difference between "gross" and "net" ratings from the 1960s/1970s, as I understand it, is the "net" ratings include all the engine accessories and full exhaust and the "gross" ratings did not. The new SAE Certified spec is similar, but the changes are much more subtle. Things like (again, as I understand) certain motor oils having to be used (no super-thin oils) and stuff like that.


Until then trying to 'estimate' drive line losses or arguing the 'true' hp level of the engine is a futile exercise...

Even now, I 100% concur with that statement.

stbtt
07-12-07, 08:23 AM
I put the car on the dyno yesterday and did a negative hp run and I am loosing 86 hp through the drivetrain with my baseline runs putting out anywhere from 211 through 215 that gives my stock numbers 297-301 hp at the motor I will post the graphs up later if I can get my scanner to work

eldorado1
07-12-07, 09:57 AM
Wow! That's incredible. That's nearly a 29% loss. If that's typical of a 4t80e, that would mean I have 360 crank hp :eek:

What gear was this run done in?

I'd be interested in your graphs... I'm curious how many shops can do this negative hp dyno run?

jadcock
07-12-07, 10:00 AM
Assuming 215 hp at the wheels...If you know you lost 86 hp, and your engine is putting out 301 hp, your drivetrain is sucking up about 28.5%.

20% loss = 270 hp
22% loss = 276 hp
24% loss = 283 hp
26% loss = 291 hp
28% loss = 299 hp
30% loss = 307 hp

stbtt
07-12-07, 11:38 AM
here is the neg hp run you do not have the car in gear when you do this type of run and any shop with a dynojet dyno can do this
http://i149.photobucket.com/albums/s77/stbtt/1.jpg

jadcock
07-12-07, 11:46 AM
How does it work if the car is not in gear? Does the Dynojet spin the drivetrain itself to see the parasitic drag?

Raze
07-12-07, 01:04 PM
A negative hp test is done by running to a constant speed on the dyno at a constant rpm and then taking the car out of gear and allowing the dyno to measure the drag basically...

stbtt
07-12-07, 01:06 PM
the dyno calculates hp (positive) by measuring how fast the drums accelerate. if drum deceleration was measured and graphed,we would be veiwing negative hp.negitive hp allows you to view the performace of your car when it is not under load

Submariner409
07-12-07, 08:34 PM
:alchi:Too bad we didn't have Internet in '67. This thread is now 53 years old, based on phone calls and letters from high school. Whether it's a Chevy 327, 427, Ford 289, Chrysler hemi, Ferrari 3L, Dodge 440 pushbutton 6-pack, we've all been there. If I want my 280ci engine to stack up in the advertising wars, I'll go to the best numbers from the highest paying lab for my front page. It's politics: you go with the lobbyist that gives you the highest ratings and the most bang for your advertising buck. 1/1000th of 1% ever have an idea of what's really the truth. Good thing you're asking questions.

AJxtcman
07-12-07, 08:57 PM
:alchi:Too bad we didn't have Internet in '67. This thread is now 53 years old, based on phone calls and letters from high school. Whether it's a Chevy 327, 427, Ford 289, Chrysler hemi, Ferrari 3L, Dodge 440 pushbutton 6-pack, we've all been there. If I want my 280ci engine to stack up in the advertising wars, I'll go to the best numbers from the highest paying lab for my front page. It's politics: you go with the lobbyist that gives you the highest ratings and the most bang for your advertising buck. 1/1000th of 1% ever have an idea of what's really the truth. Good thing you're asking questions.

The shop I worked at built an all original LS6 454 and it made 396 HP.
They built a 426 HEMI with roller rockers, roller cam, bunch of thing done to it. It made 425 HP and the customer was very unhappy.
Dyno was a Super Flow. It was top of the line in the late 80's.

airfuel2001
07-13-07, 12:12 AM
I am saying my 4T80 draws 45%, yeah, now I have 400hp.

Maxb49
07-13-07, 03:11 PM
Short answer: Yes, the Northstar engine is an overrated glorified V6 engine.

Discussion: It's my fault. I bought the stupid thing before doing serious research. The engine barely makes 1 hp per unit of displacement - which is fine for a commuter car but doesn't cut the mustard in a $50,000 luxury car. NEVER AGAIN!

Maxb49
07-14-07, 07:35 PM
I'm retracting the above post. As it turns out, the problems I have had with my car are unusual to the Deville and now they are all fixed. It is a rather nice engine now that I can look at it in the proper perspective. :)