It's an epidemic: yet ANOTHER set of bogus dyno curves
I'm afraid that there's an epidemic of incorrect dyno testing going on in both the trade press and in examples where our own SSR Fanatic members have been misled by their "trusty" dyno guy.
I've documented a number of those on this wbsite recently, but today I found another really gross one in the February issue of Chevy Hi Performance magazine.
In an article starting on page 81, they claim to install and dyno test 3 products from Jet: a microtuner, a mass air sensor, and the always popular "throttle body spacer". They apply them to a 5.3L Silverado pickup engine - the same engine used in the 03 / 04 SSRs.
To spare you the details, the article claims that dyno testing showed the following results:
Stock: 249 hp at 5500 rpm, 298 ft lb of torque at 4000 rpm
Microtuner: 270 hp at 5500 rpm, 346 ft lb at 4000 rpm
Mass air & spacer: 284 hp at 5500, 358 ft lb at 4000 rpm
Sounds impressive - until you examine their accompanying graphs.
When you apply the classic physics formula (applies to ALL dyno curves):
HP = Torque x rpm / 5252
you see that the power and torque curves are ALL numerically impossible!
The stock torque curve shows 298 ft lb of torque at 4000 rpm, but that means the stock power curve should show 298 x 4000 / 5252 = 227 hp at 4000. It actually shows 178 hp!
Likewise at 4000 rpm, the microtuner curve shows 346 ft lb, which means 263.5 hp at 4000 rpm. But, the microtuner power curve actually shows 198 hp!
At 4000 rpm, the spacer & mass air torque curve shows 358 ft lb of torque, which means the hp should be 273 at that rpm, but the power graph shows only 207 hp!
So, it is an exceedingly polite statement to say that these results are "not accurate".
The sad thing is that I'm sure a bunch of Silverado and SSR owners are going to rush right out to buy these 3 Jet products based on this "proof" that they work so impressively.
By sheer coincidence, Jet has a large color ad on page 90 of this issue.
My SSR: '06 PB #21661 Born 8/29/05, GHL "Old School" True Duals, ADDCO bars, Eibach rear, Joe's Tune
Thanks for watching out for us Jim.
I have been in data acquisition and analysis for 25+ years and recognize misleading data faster than you can say "tink". There is absolutely no excuse for shamelessly misleading people into buying a product. In my book, this is called fraud. To misrepresent a product with this type of bad data is totally unacceptable. If a publisher puts out technical data without checking the simple math, they need to publish a correction as a minimum.
For all the non-technical types that will read this thread, I want to add a little to Jim's treatise on the misleading data.....
Torque is a MEASURED parameter. Even the poorest dyno has the ability to accurately measure torque. Back to back testing, even with errors in the basic data will show the delta associated with a change. Correcting dyno data back to standard day is not always evident, but that is again a calculation based on the original data and standard mathematical formulas.
Horsepower, on the other hand, is a CALCULATED parameter, using the physics formula in Jim's post. It's in every high school physics book. Even with the most tolerant measurement uncertainty analysis, you cannot get the HP numbers claimed by this manufacturer when using the measured torque as the base data.
I'm appalled at the sloppy technical reporting and certainly hope that Chevy High Performance publishes a retraction or correction. As for Jet, I will not be buying their products.
Disgusted,
Mike
__________________ Trust and Generosity are contagious.
As usual....when it sounds to good to be true.....it usually is......Companies....of all sorts seem to be wanting to play fast and loose with the CORRECT facts...To bad, now we have a tendency to not believe much of anybody, anymore .....To bad.
My SSR: added to Silver #5907, Pin Stripped, Hood struds (MPD), Turn Signal Mirrors, Mike's Aux fan, KnN
Super Charger
Quote:
Originally Posted by JimGnitecki
I'm afraid that there's an epidemic of incorrect dyno testing going on in both the trade press and in examples where our own SSR Fanatic members have been misled by their "trusty" dyno guy.
I've documented a number of those on this wbsite recently, but today I found another really gross one in the February issue of Chevy Hi Performance magazine.
In an article starting on page 81, they claim to install and dyno test 3 products from Jet: a microtuner, a mass air sensor, and the always popular "throttle body spacer". They apply them to a 5.3L Silverado pickup engine - the same engine used in the 03 / 04 SSRs.
To spare you the details, the article claims that dyno testing showed the following results:
Stock: 249 hp at 5500 rpm, 298 ft lb of torque at 4000 rpm
Microtuner: 270 hp at 5500 rpm, 346 ft lb at 4000 rpm
Mass air & spacer: 284 hp at 5500, 358 ft lb at 4000 rpm
Sounds impressive - until you examine their accompanying graphs.
When you apply the classic physics formula (applies to ALL dyno curves):
HP = Torque x rpm / 5252
you see that the power and torque curves are ALL numerically impossible!
The stock torque curve shows 298 ft lb of torque at 4000 rpm, but that means the stock power curve should show 298 x 4000 / 5252 = 227 hp at 4000. It actually shows 178 hp!
Likewise at 4000 rpm, the microtuner curve shows 346 ft lb, which means 263.5 hp at 4000 rpm. But, the microtuner power curve actually shows 198 hp!
At 4000 rpm, the spacer & mass air torque curve shows 358 ft lb of torque, which means the hp should be 273 at that rpm, but the power graph shows only 207 hp!
So, it is an exceedingly polite statement to say that these results are "not accurate".
The sad thing is that I'm sure a bunch of Silverado and SSR owners are going to rush right out to buy these 3 Jet products based on this "proof" that they work so impressively.
By sheer coincidence, Jet has a large color ad on page 90 of this issue.
Buyer beware.
Jim G
Hi Jim
Thanks for the data. I was getting ready to order the Jet stuff on Ebayl
I have a few questions for you if you wouldn't mind answering them.
Will a supercharger that is used on 5.3L Silverado pickup work on an 04 SSR? I read an artical by Whipple showing the dyno curves for a Silverado 5.3L after supercharging. A 150hp gain. Not sure if that is at the rear wheels.
Will the transmission handle the added hp?
What should one look for in a shop that will do a dyno test (ie equipment, data handling, etc.)???
Thanks Richard
Last edited by RAL 04 #5907 : 12-17-2005 at 07:08 PM.
Thanks for the data. I was getting ready to order the Jet stuff on Ebayl
I have a few questions for you if you wouldn't mind answering them.
Will a supercharger that is used on 5.3L Silverado pickup work on an 04 SSR? I read an artical by Whipple showing the dyno curves for a Silverado 5.3L after supercharging. A 150hp gain. Not sure if that is at the rear wheels.
Will the transmission handle the added hp?
What should one look for in a shop that will do a dyno test (ie equipment, data handling, etc.)???
Thanks Richard
Richard: The kit may or may not be "adaptable". Let me explain.
Although the Silverado 5.3L and the 03 / 04 SSR use the same 5.3L engine (except that the block on the Silverado MIGHT be iron versus aluminum), there are two factors that can create big problems in the adaptation:
1. differences in available underhood space and hood clearance (the Silverado setup might not hysically FIT into an SSR), and
2. the Silverado uses a mechanical versus electric fan, so has an entirely different accessory drive system. This is critical because the supercharger is driven from that accessory system.
A good mechanic who doesn't mind the extra time and fabrication ptentially required, could probably make it work, but I doubt he'd be willing to give you a firm price for the install based on these unknowns. And, he might need to buy a lot of extra components to make a drive system that will work, instead of using a pre-engineered one.
The kit to get if you are buying NEW (i.e. not getting a used one at a bargain price) is the Magnacharger kit, which is sold by one of our members here, 2005ssr6speed and thus reliably supported (Joe knows that if he screws up the whole website will know!).
The 150 hp gain would be in the right ballaprk for a crankshaft versus rear wheel number. The rear wheel number is still subject to some debate based on conflicting dyno reports from different dynos, but 110 to 120 rwhp seems to be in the right ballpark.
The tranny will take this only if the power is used sparingly. Remember, that an automatic transmission rarely fails ebcause something breaks, but rather because it overheats. Overheating is easy to prevent: don't apply the power for long periods of time or before the tranny has had a chance to cool down again. Regretably, this is counter to most people's actual actions, as power seems to be addictive. If you go racing down a LONG winding road, or worse, a roadrace track, expect destruction "soon". The torque limits of the 4l60-E and 4L65-E automatic transmissions used in the SSR are challenged by STOCK power, let alone supercharged engines. GM would gloss over this, but if you want the truth, check out the Sallee Chevrolet website. Sallee sells hi performance parts and publishes the torque ratings of the transmission there, as provided by GM itself. They will get your attention.
The dyno question cannot be answered intelligently within the space of this thread. My book devotes approximately 26 pages to this topic, because of its importance and potential for errors. If you read those 26 pages, you will be an informed consumer who will be difficult to fool. At the risk of sounding like I'm selling, I'm going to suggest you think about buying it. See my ad in the "For sale" section of the website.
I have also, as time permits, been voluntarily analyzing dyno curves for members here. If you are considering doing your dyno testing at a specific shop, casually ask them for an actual sample of their client report, preferably for an LS series engine (LS1, LS2, LM4, or LM7 engine), get it scanned, and email to me. I cannot promise to do every one I receive, but try to do as many as time allows. I have a lot of pressures on me right now.
The book is the best solution.
Jim G
Last edited by JimGnitecki : 12-18-2005 at 07:51 PM.
Take a look at the site called performance trucks and see what has to be said about all the different brands of superchargers. You will get a real world account of all the good and bad with each manufacturer.
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