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15K views 123 replies 36 participants last post by  6104696 
#1 ·
I have read on this site that the V was advertised at 400H.P. and is not near that. I also read that Ford paid out on the 99 SVT for the same thing. You tech guys should keep us(me, the layman/hellman) informed. I will file first. FOR THE SIMPLE FACT THAT G.M HASN'T ANSWERED ANY MAIL(of any kind) ON OUR CONCERNS!!! '05's are being built and my oil alarm still goes off. F' them all. I work hard for my car. Every payment I make I take it out on that car. Who will help? I am already copying a lot of tech. posts just in case. You guys know a lot af stuff. I thank all you tech. guys.
 
#77 ·
Devil_concours said:
i would also argue that tiny fan that they use at dyno shops are no where near the real life highway speed travel. Hence dinan's article explaining impact of fan on dyno result
I would agree with your assesment if this situation was not isolated to just the CTS-V. Were that the case we would see similar issue with the Vettes, GTO, Camaros, etc, but we don't. GTOs are very consistantly putting 297 to the wheels on different days different dynos. If fans were the case it would be a bit more pandemic and stretch well beyond just CTS-Vs.
 
#78 ·
If the engine is starting to spark knock (detonate) due to low octane fuel and/or high inlet temps (characteristic of operation on a chassis dyno) then the knock sensor senses the knock and retards the spark advance to protect the engine. Same on all knock control systems. If the spark knock is persistent then the spark control algorithm in the PCM drops to a lower base spark table that is representative of lower octane fuel as a starting point for the spark delivery. There are a number of spark advance tables in the PCM that are calibrated for different octane fuels based on detonation characteristics of the fuel. The knock control system uses the different tables based on the knock level measured to avoid any driveability issues with low octane fuel and then trims from there.

The engine will produce the rated power if the proper, high octane fuel is provided. Period. If the knock control is retarding the spark to protect the engine then better fuel needs to be used and/or better cooling and cooler inlet temp air needs to be provided on the dyno. If the knock system is retarding the spark due to detonation then it will not make the rated power. Period. It is the operators responsibility to put good fuel in the car if max power is desired/required. Power is very sensitive to spark advance so if any retard at all is needed to prevent detonation then the advertised power will not be produced.

Understand that advertised power is run on an engine dyno under carefully controlled conditions with the engine maintained at a steady state condition for many minutes at each RPM/power point to establish a fixed and stabile power delivery as a reference. It is not the result of a 10 second dyno "pull" on an inertia dyno..... Understand, also, that the advertised power numbers are corrected for atmospheric pressure and temperature per SAE J1349 procedures....same as what other manufacturers use. Per SAE J1349 the inlet temp is corrected to 77 degrees F. What this means that if the inlet temp is above 77 F you are guaranteed that the observed power will be less than advertised. This is the same for all engines so nothing new here...but I see little or no mention of what the inlet air temps were for all the dyno pulls on chassis dyno's being referenced.

The chassis dyno numbers can be corrected mathematically for the actual ambient inlet air temp...but I would not really trust corrections that cover more than 10 degrees F. GM advertised power runs are run with controlled inlet air conditions so that no correction is necessary. The system to provide this "controlled" or "conditioned" inlet air to standard temp and pressure is standard in every dyno cell used for advertised power so it will be hard to argue with the data unless you have the same setup. If the chassis dyno is running on a day when the ambient temp is 90 or 100 near the car then the power is going to be way down as the inlet air is going to be 13-23 degrees F hotter than the correction used for advertised power.

GM advertised power levels are generally somewhat conservative to avoid any controversy over power in the cars......so.......

There is a huge difference in power measurements on chassis dyno's. The conditions are not nearly as well controlled as in engine dyno cells at the Powertrain development center at GM. Runs compare somewhat favorably run to run on any given dyno and operator but be carefull of absolute measurements from a chassis dyno. Be especially carefull of absolure measurements that are not corrected for standard temp and pressure. For the most accurate correction for ambient temp the ambient temp at the air inlet during the dyno run must be measured and used for the correction...not the temp on the wall 30 feet away.

A CTS-V makes the advertised power. Trust me. Get good fuel and the correct inlet temps and then complain.


BTW....octane rating at the station varies with the state, location, altitude, etc.... higher altitude states and cooler, northern states, tend toward lower octane "premium" due to the lower density of the air. Lower altitude states and hotter states tend towards the highest octane for Premium. A lot depends on where the fuel is being shipped from, etc...so this is a general summation.
 
#79 ·
That was one of the best technical, easy to understand posts I have read on here. Thank you ********* for your post. I feel that I am one of the people in your statement that said
********* said:
"If the chassis dyno is running on a day when the ambient temp is 90 or 100 near the car then the power is going to be way down as the inlet air is going to be 13-23 degrees F hotter than the correction used for advertised power."
I also think my pulls were being effected by more than one factor (hot inlet air temp, plus the oil temp alarm during the pulls).



Dgtal
 
#80 ·
BTW....one other thing to consider....exhaust back pressure.

The advertised power tests are NOT run with a full car exhaust system on the engine on the dyno. Instead, the backpressure of the car exhaust during a full throttle acceleration, with a moderately warm exhaust, is measured and then duplicated on the engine dyno with an orifice in the exhaust pipe or a gate valve.

This is done to provide a stabile exhaust backpressure reading during extended power testing....testing that might go on for hours and hours without bringing the engine down to idle.

The delimna with a car exhaust is that the backpressure changes constantly in the system with changes in temperature. This is due to the rapid cooling of the exhaust gases as they travel down the system and the changing volume of the exhaust gases as a result. The less volume of the exhaust gases the less backpressure will be seen. The hotter the exhaust system gets the hotter the exhaust gases stay and the more backpressure there is...and the less power will be made.

This is a huge problem with chassis dynos and repeated runs..and absolute power measurements on a chassis dyno. The exhaust system is rarely cooler with fans on a chassis dyno so the system hot soaks under the car in still air and the exhaust backpressure is rarely, if ever, representative of what the backpressure is on the street driving along with air flow under the car cooling the exhaust.

This change in backpressure is very very obvious in measured, instrumented testing. As an example, a system that is classified as a "15 inches of mercury backpressure system" for a transient condition at WOT/6000 RPM on a passenger car might measure as follows: 12-13 inches if the system is stone cold on a first 0-80 pass, 15 inches on a pass with a system that was running at 70MPH to stabilise, 18 inches on extened full throttle operation for 20-30 seconds, 20 inched on full throttle/top speed running continuously (autobahn), 23-24 inches if installed on a dyno and run continuously for several minutes (still air around system), 25-26 inches if run continuously on a dyno.

As you can see, there is NO WAY to run a car exhaust on a chassis dyno or an engine dyno and meet representative backpressure measurements on a typical , transient backpressure test. Absolutely no way. Even with fans and coolers the exhaust will still not be cooled the same as a 100 MPH blast under the car....no way. Been there, tried/done that...and failed.

The exhaust on a CTS-V is tucked up a bit more than some other cars so that may be causing some more of the variability between runs and on an aboslute basis. On a chassis dyno I would say that the system would have to be pretty "cold" to duplicate the backpressure seen on the street on a 77 degree day with high speed cooling air over it. The CTS-V exhaust system is a bit "quieter" than on the Corvette Z06 application (this is a Cadillac....LOL) so it will be necessarily a bit more restrictive and more sensitive to temp changes of the system. A hot CTS-V system will be a bit more restrictive on a chassis dyno than a "hot" Z06 system I would theorize.
 
#82 ·
********* said:
A CTS-V makes the advertised power. Trust me. Get good fuel and the correct inlet temps and then complain.
First kudos on a well written explanation of the variables affecting power and dyno reults, however your points do not support the above thesis. I'm been to dozens of dyno days, witnessed hundreds of dynos, and I still cannot subscribe to the logic you are presenting that a car that averages 320 RWHP on the dyno makes 400 crank HP.

From a Macroobservation all variables being equal, an honest power rating would result in similar power defficits on the dyno for other LSX platform cars. This is decidedly not the case as shown by the consistantcy of other platforms to make their advertised power within an acceptable drivetrain loss factor. Case in point of the dozen or so M6 GTO's that have been dynoed in variable conditions they have consistantly made 297 at the wheels. The observation based on your argument above would be that we should see only a handful of GTO's making 297 RWHP as a majority would have adverse conditions that would kill their power as seen with the CTS-V.

Rather the CTS-V has consitantly dynoed 20 RWHP above the LS1 GTO and 30 RWHP below the LS6 Z06. That would indicate either:

a.) The engine is not making the advertised 400 hp

or

b.) Some factor is making the car dyno lower than a 400hp car should.

I assume based on your argument that you are arguing for "b.)" so the next question is what would cause a CTS-V to dyno substantually lower than other LSX cars, which would again point to some sort of fault. We have already seen that CTS-V has some gremlins to shake out. So I think it is not a stretch to make the observation this is the case with the observed power output as well.

The regretable issue here is that some owners will have "emperor's new clothes" syndrome until some of their compatriots uncover a "fix" that consitantly recovers the 30 RWHP deficit. Either way the issue should be brought to Cadillac, otherwise I'm sure they'll "fix" later versions of the car iwth no explanation and 2004 owners will see a 30 RWHP deficit when compared to later versions.

-Adam
 
#83 ·
Maybe someone needs a little cheese to go with their whine.

I boils down to whether or not you like your car. Everyone seemed to like them until they found out their dynos were a little light. However I love mine and it has a very good seat of the pants feel. That simply means that it pulls hard like I expect and handles well to boot. Heck I had mine up to 146 mph yesterday in a short distance and it was still pulling hard in 5th gear until I ran out of my limited roadway.

Don't run any dynos unless you have at least 93 octane fuel in the car and don't expect it to pull what you want if you baby the thing around all the time. Cars run according to how they are broken in. I have always been a firm believer of that. Law suits seem a bit over reactionary to me. If you are not happy with the car, sell it. There are plenty of people out there willing to take it off your hands. I have picked on Mustangs, Trans Ams and Camaros with mine and love every minute of it.
 
#84 ·
I do agree with Shinkaze. He has some good points and above all he stays away from flaming. BTW, he never said he is not happy with the car but with some of its idiosyncrasies.

To give and read about such opinions is the foundation of a forum. Writing letters to each other just how wonderful our car is would be kind of boring, wouldn’t it?



If it were discovered that let's say the V’s resonator eats 25 RWHP would we not all be happy to learn about this? :bouncy: :bouncy:

 
#86 ·
RESURECTION Time

The other day I picked up an old car mag and started reading through it. I came upon an add, and just happened to read it. It was a Chevy 2001 Z06 add. 0-60 claimed? 4 second flat. However, in the SAME magazine they pit the Z06 against the C5-R (I think) and rate the tested 0-60 as 4.6s. I did a search on Road and TRack and Motor Trend. Seems the 2001 Z06 was testing at about 4.5-4.7s.

Let's add the Z06 to the class action lawsuit...

Also, let's add the Audi A4. Audi claims 0-60 for the 3.0L as 7s, but the best I can find in the mags is 7.7s (that just happens to be one that was together in the magazine as well). I bet you'd find some serious discrepancies between most manufacture claims (which is BEST times) and most mag tested times (which is AVERAGE times)...

Done. It can die again.
 
#87 ·
I believe GM produced a video showing John Heinricy doing a 0-60 in 4.0 or 4.1sec... lots of practice, insanely hard launch, and speed shifting. I'll search the Z06 forum if anyone cares... it's been a few years.

Also, a buddy of mine just dyno'd his bone stock '02 Z06 14K miles: 363.7rwhp (CF=1.00)... I'm going to take my V to the same dyno when it has a few more miles.
 
#90 ·
You have to use the same Dyno on the same days. I've been to a couple of Dyno days and know one thing, it is HARD to find a 100% bone stock Corvette that would pay to go on a Dyno. They all had some small mods. I say if there is any HP missing, it is all in the headers.
 
#91 ·
I have been thinking about buying a V for a couple of months and have held off based on all of the problems that I have read about with the car on this website. I find it interesting that most visited posts are this one and the wheel hop post. It makes me wonder who tests these cars before they sell them to the public. I don't want to spend $50K on a car that can't achieve what the manufacter claims.

Have you guys tried a letter campaign to Detroit? It might help if you got one of the major car magazines to check it out......Motor Trend, Car&Driver, etc. Surely somebody has some connections. I first heard about the Cobra issue in Motor Trend.

Good luck. Still on the fence for now.
 
#93 ·
WannaV said:
I don't want to spend $50K on a car that can't achieve what the manufacter claims.
I guess that was my point in the post above. I can't find many cars that attain manufacturer claims in the books/mags, because manufacturer claims are the extremes (as evident above in the Z06 run). I can list car after car that does not live up to it's manufacturer claims unless you really run it hard, and I think someone on this board posted a 4.7 or 4.8 run, but with some heafty clutch feathering.

HP claims, one thing. But that still has not been adressed to the level where we can make accurate judgements. Anyone do a flywheel yet?
 
#94 ·
WannaV: I started the other big thread on the HP issue (Why the PATHETIC rwhp?)... that was before I owned the car. At that time, I (and Adam) were very surprised at the reaction from the owners... *for the most part* it didn't seem to bother them! And read the 'problem' threads... reactions from the owners taking their cars in for diff leaks, broken diff's, etc... again, for the most part... taking it very well. Til the day I bought my car i did not understand this one bit.

After owning the car... i will say this: the car is so over the top enoyable... so insanely fun to drive... drive it easy, drive it hard, or drive the snot out of it... it's an unbeliveable car.

It is more rewarding to drive then the M5 (friend has one, drive it all the time), S4 (lots of test drives), M3 (couple friends own these), the list goes on, and even my Z06... (yes, the V is slower, but the overall driving experience is more rewarding).

So what i am saying is: I have no problems forgiving it's couple-of-horsepower shortfall (if there really is one), and it's few 1st year production issues.
 
#95 · (Edited)
The wheel hop is a real issue. With traction control off and one dumps the clutch from a high rpm, the hop will happen. From my perspective, it is not a big deal unless you want to take the V drag racing.

Now this whole thing about the V engine not making its 400 horsepower is a big giant bunch of crap. Yes, the average driver will never be able to hit GM's claimed 0-60 time of 4.6 seconds or 1/4 mile times due to lack of skill, finese, practice, etc. One member of the forum here did get down to a 4.7 second 0-60 run with many, many practice launches and I believe ClintonMills has run at least a 13.2 second quarter mile. (You out there Clinton to confirm?)

Remember the thread we had a while back about top speed? During the past months, I've been continuing to work on refining the numbers. Look for a set of nice graphs, etc. in the coming weeks but since this horsepower subject has resurfaced, I'll share an overview of the numbers I've got to date.

Assumptions:
Drag Coefficient = 0.354
Cross Sectional Area = 24.3 sq. ft.
Weight with driver & fuel = 4150 lb.
Weight distribution on rear axle = 45.6%
Center of gravity = 15.0 in.
Wheelbase = 115.2 in.

The following calculations were done assuming factory published power numbers, launching at 2000 rpm, slipping the clutch until the tires hooked up, no wheel hop and a 6400 rpm shift point.

Zero to Terminal Velocity Speed Run
------------------------------
60' time = 2.31 seconds @ 34 mph
60 mph = 4.59 seconds
1/8 mile = 8.65 seconds @ 87 mph
100 mph = 11.34 seconds
1/4 mile = 13.23 seconds @ 108 mph
162.11 mph = 39.00 seconds (terminal velocity in 5th gear)
164.23 mph = 93.45 seconds (terminal velocity in 6th gear)

The calculations have confirmed GM's numbers very closely. The difference between their numbers and our track/G-tech numbers is wheel hop and the loose nuts behind the wheel.

IMHO, all this "lack of power" discussion is doing is accelerating the depreciation of our wonderful cars.

:hide:
 
#97 ·
miscreant said:
RESURECTION Time

The other day I picked up an old car mag and started reading through it. I came upon an add, and just happened to read it. It was a Chevy 2001 Z06 add. 0-60 claimed? 4 second flat. However, in the SAME magazine they pit the Z06 against the C5-R (I think) and rate the tested 0-60 as 4.6s. I did a search on Road and TRack and Motor Trend. Seems the 2001 Z06 was testing at about 4.5-4.7s.

Let's add the Z06 to the class action lawsuit...

Also, let's add the Audi A4. Audi claims 0-60 for the 3.0L as 7s, but the best I can find in the mags is 7.7s (that just happens to be one that was together in the magazine as well). I bet you'd find some serious discrepancies between most manufacture claims (which is BEST times) and most mag tested times (which is AVERAGE times)...

Done. It can die again.
Miscreant,
My Concern has nothing to do with drag launches and 0-60 times, rather a generally low dyno result that would imply the CTS-V is more likely a 360-370 hp car. That by no means is Underpowered but it is below the advertised rating. Whats even more conern is there are a couple of cars that appear to be making 340hp, which is more indicitve of a 400 hp car. So that begs the question, what is different and how can the other CTS-Vs make sure their cars recover the 20-30 hp?

FWIW I'm still on the fence with the CTS-V bad after some serious car shopping last week its back on the top of the list. So far it seams to tbe the most affordable blend of comfort and performance. At this point though I think I will get my car in October, so hopefully I can try on the new LS2 GTO....sadly the worthless trunk and lower-par interior of the GTO have put it behind the CTS-V for me. My "front runners" right now are (in order)

545 Sport with the new M5 Fascia
At the same price I would probably get the 545 over the CTS-V, in day to day driving I'm finding its 90% as good as the E39 M5, it just lacks that extra 10% that makes you absolutly adore th car.

2005 CTS-V
I'm not totally in love with the interior, I do love all the gadgets and gizmos and with my GM discount it's price very well.

M3
Loved this car for a long time, but it's lack of practicality and more dated interior has moved it to the back of the pack

2005 C55
Holding off judegment until I drive one, the C32 is fun, but small.

2005 S4
B*O*R*I*N*G exterior, very nice interior, but the center console rubs my thigh...not crazy about that.

Anyhow I've strayed off topic mainly because I feel what I need to say on this topic has been said, despite it's short commings and problems it still is high on the list, but we'll see how things change as I get closer to purchase.

-Adam
 
#99 ·
As someone who has a Camaro that puts over 320 hp to the rear wheels (the same ballpark as most V's I've seen dyno'd), I can personally assure you the V makes every single one (or more) of its 400 horsepower. My theory why the dyno pulls are so low on the V is simply a matter of the engine not getting enough air sitting on the dyno, running hot and pulling timing.

If I remember right, Dinan, of BMW tuning fame, explained that over 70 hp can be "found" by properly blowing air over the engine compartment. Thus, the dyno pulls for the V don't mean squat on the true power put down on the street.

There is a night and day difference between how my V and Camaro pull in the same gears. The V feels like it has 100 more horsepower than the Camaro, yet it weighs hundreds of pounds more. Between both cars, they have the same transmission, same rear axle ratios, about an apple to apple comparison as one can get with the buttometer.

Come to my house, you drive the Camaro, I get the V and I guarantee you will see nothing but taillights. The V hooks up and launches harder than I ever can in the Camaro and the Camaro has got the factory SS 275/45-17 Eagle F1 Supercar tires on it which are quite a bit wider than the stock V rubber.

How can naysayers explain the reality of my V walking on the Camaro if the V is under powered and makes no more power than my Camaro? By making the same power and weighing 400 pounds more, the V should get spanked by the Camaro but it doesn't. You know why? Because the V does make the power.

But then again, as I've said in the past, maybe my V is one of those factory "ringer" cars like the media gets. :lildevil:

THE V MAKES 400 HORSEPOWER!

:deadhorse: :deadhorse: :deadhorse: :deadhorse: :deadhorse:
 
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