Chevy SSR Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Great website you guys have here, lots of useful information.
I purchased a black 05 six speed in march and though I have experienced some of
the same problems as some of you have mentioned such as rear end tink and noise
coming from the shift linkage I love the truck and am determined to get these minor
problems worked out.
I do however have a concern about the power my truck is putting out. The dealer tells
me there is nothing wrong with it but I had it run on a mustang dyno and got readings
of 263hp at 5250 rpm and max torque of 293 at 3750 rpm. since the run was close to
advertised max hp and torque rpms I was expecting some where around 15% loss to the
rear wheels not 30%.
Any thoughts or inputs on the subject would be appreciated.
 

·
Supporting SSR Hobbyist
Joined
·
10,205 Posts
davem,

How many miles do you have on your SSR?

If below 5000, perhaps this might lend some credibility to my suspicion that the software holds the engine back until some magic mileage breakin point.

Mike
 

·
Registered
Joined
·
4 Posts
Discussion Starter #4
mikem

The truck only has 900 miles on it.
Perhaps you are right about the engine being retarded till some magic number.
If so wish I knnew what it was
 

·
Registered
Joined
·
340 Posts
mikem-2005 said:
davem,

How many miles do you have on your SSR?

If below 5000, perhaps this might lend some credibility to my suspicion that the software holds the engine back until some magic mileage breakin point.

Mike
How do you say, " NO "!!!

Engines today are built with clearences acceptable to run "pedel to the metal " right out of the box. As for the HP there should not be a 30% loss. I'd definitely check into it.
 

·
Registered
Joined
·
254 Posts
I was told

by a Forum member that experienced the same thing, that his SSR "came alive" at 4,700 miles on the odometer. I don't know where he got the info regarding a break-in setting built into the on-board computer, but he assurred me that mine would "come alive" also. Seems the magic mileage number is around 4,700 to 5,000 miles. I am getting close, will let you know if anything happens. :thumbs
 

·
Registered
Joined
·
4 Posts
Discussion Starter #8
the dyno test was done in 4th gear. couldn't get any more rpms out of it because speed control kicks in.
 

·
Senior Privileged Member
Joined
·
4,100 Posts
DaveM: There are a few things at work here. Your engine is probably fine. Let me explain.

First, there are 2 kinds od dynos: steady state and inertia type. The inertia type gives higher results for technical reasons too lengthy to discuss here. The steady state gives results that are typically 15% or so lower in this horsepower range. The dyno type used for virtually all the reported results you are seeing is the inertia type (BECAUSE it gives higher numbers, which makes technically uneducated owners feel better about their engines :) ). The steady state dyno is actually much better as a diagnostic and tuning machine, and is used by most of the pros who build engines for THEMSELVES and not the public, because pros don't need to be reassured that they have the baddest engine in town. They KNOW it already). The Mustang is a steady state dyno, so your numbers are automatically going to be 15% lower or thereabouts compared to the "Dynojet" (brand of inertia type dyno that dominates the market because it is inexpensive).

Then there is the rpm that your dyno teater stopped at. I realize why he did that: he had no choice. The powertrain compter in your 2005 stops the festivities at 125 mph or so because the tires on our SSRs are only rated for that speed! If you do the math, you will find that this is about 5250 rpm in 4th gear. Unfortunately, your engine with the 6-speed tarnny doesn't actually reach pek horsepower until about 6000 rpm (check the Chevrolet website specs)! So, your engine never got a chance to show its stuff.

Your dyno operator could not defeat the speed limiter because the tuning software to do so has not yet hit the street. And, he SHOULD NOT defeat the speed limiter even in the dyno setting, or ESPECIALLY in the dyno setting, because the tires actually get HOTTER o a dyno thna o the road (no rush of 125 mph cooling air on the dyno . . . :) ). In 4th gear, you simply cannot and should not hit max engine power on a dyno with the 2005 SSR for YOUR safety! (The tires could be heat damaged and THEN fail later catastrophically on the highway). If the iperator uses 3rd gear for the testing, he won't exceed te 125 mph limit, BUT he will have notably higher driveline losses because of the greater frictional losses in the greater reduction AND the need to spin the accessories faster. On an inertia type dyno, he would also have had the problem of having to accelerate the driveline and accessories MUCH more quickly (3rd gear versus 4th accelerates faster), which would consume power to overcome more moment of inertia. With stock tires, there is no way to safely dyno test a 2005 SSR properly in 4th gear, period.

There's also the ugly issue of dynomometer calibration. Some operators do it very carefully and others are just plain careless or unkowning. Even when the operator wnats to do a good job, the dyno's "built-in weather station" soemtimes screws up and gives false temperature, humifity, or barometric pressure results that skew the results badly. The only cure here is to know your dyno operator's reputation for ACCURACY (not giving "good news" :) )

A better gauge of your actual power on a 2005 is obtained via a G-Tech RR test (search web using "G-Tech"), under SAFE conditions. If someone does such a test and sends me the data, I can probably interpret the data for you.

Bottom line: Disregard that dyno test. It did not measure your engine's output properly for all the above reasons. Enjoy your 05 SSR.

Jim G
 
1 - 9 of 9 Posts
Top