Sheet Inside - My First Dyno Run - I need your comments
Team Owner
Joined: Feb 2000
Posts: 45,535
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From: Texas
CI 1-4-5-8-9-10 Vet
St. Jude Donor '03 thru '10, '17
Team Owner
Joined: Feb 2000
Posts: 45,535
Likes: 892
From: Texas
CI 1-4-5-8-9-10 Vet
St. Jude Donor '03 thru '10, '17
Le Mans Master
Joined: Oct 2006
Posts: 5,474
Likes: 3
From: Bradenton, FL & Chandler AZ
St. Jude Donor '09
Instructor
Joined: Sep 2006
Posts: 148
Likes: 0
From: Norfolk Va
Not in the US, what is the octane of the gas you are running? Was it 87* at 11 pm when the car was dyno'd? Was the engine hot and was it pulled more than once and this was your best pull ? What gear was the pulls done in?
Race Director
Joined: Oct 2004
Posts: 10,516
Likes: 2
From: Virginia Bch VA
Cruise-In VI Veteran
Cruise-In VII Veteran
St. Jude Donor '06
Yep - looks like he's trying an old trick: making your "before" numbers artificially low so you'll be thrilled with the "after" numbers. Stay away from that place. Tell us who dyno'd your car. As stated above, tell us what city you live in and someone can probably tell you of a reputable shop.
"need" is right on
Melting Slicks
Joined: Oct 2006
Posts: 2,905
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Instructor
Joined: Sep 2006
Posts: 148
Likes: 0
From: Norfolk Va
Looking at the weather parameters only thing seems out of place is the rather low humidity. The SAE correction factor is still .99. I don't believe you can manually alter the correction factors on a DynoJet like other dyno's if the stack is hooked up. I am willing to bet that he is living someplace south of the US vice Canada 
Not sure if the C6 engine computer has two spark tables like a LS1 PCM, if so and and the owner is using gas with lower octane rating than we have here in the US it could be using the less spark advance tables and reducing the power, that is why the power is down from what we normally see in the US vice having a misfire conditon.
Before I pass judgment on the dyno shop I would like to hear where this dyno is at and more about the conditions car was dyno'd along with the quality of fuel it's being run on. More info might shine some light on to why it's low on power.
Not sure if the C6 engine computer has two spark tables like a LS1 PCM, if so and and the owner is using gas with lower octane rating than we have here in the US it could be using the less spark advance tables and reducing the power, that is why the power is down from what we normally see in the US vice having a misfire conditon.
Before I pass judgment on the dyno shop I would like to hear where this dyno is at and more about the conditions car was dyno'd along with the quality of fuel it's being run on. More info might shine some light on to why it's low on power.
Race Director
Joined: Feb 2006
Posts: 11,734
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From: SC
I'd dyno at another shop just to be sure, and make sure you run highest octane possible all the time. The stock PCM takes time before going from low octane to high octane timing tables, doesn't just "switch" from one tank of gas to another. FYI my 07 manual did 341rwhp 336rwtq stock.
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Le Mans Master
Joined: Mar 2002
Posts: 6,885
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From: Corpus Christi TX
you can manually change the back parameters like wet and dry bulb temps and vastly change a dyno, and have it all say SAE corrected and smooth whatever setting you want. A 400 sae rwhp turns to 450 sae rwhp, or vice versa, all printed like normal. It can/and has been done.
other "deliberate" tricks are to throw a wet, hot rag over the weather pickup device and have a little fun with the numbers
be careful out there
other "deliberate" tricks are to throw a wet, hot rag over the weather pickup device and have a little fun with the numbers
be careful out there
Le Mans Master
Joined: Mar 2002
Posts: 6,885
Likes: 2
From: Corpus Christi TX
the axis for tq and hp do not have to be scaled identical...rather confusing at first glance, but that in itself isn't necessarily "fishy". As long as they cross at the 5252 mark, it's all good in that regard.
Thread Starter
Racer
Joined: Nov 2006
Posts: 282
Likes: 1
I always run 95 on my Vette. It was run at around 11 pm. I left the engine to cool down for 30 minutes and then dyno'd it and this was the first run on the 4th gear.
Instructor
Joined: Sep 2006
Posts: 148
Likes: 0
From: Norfolk Va
Have you inspected your air filter to make sure it's not needing to be replaced?
If you can go back and ask them to print out the uncorrected numbers to see what it was actually making that night.
Race Director
Joined: Mar 2005
Posts: 10,399
Likes: 26
From: Austin Texas
WHICH octane is 95? US Octane is the average of two different tests, most other Octane numbers just state the highest number (Research Octane?)
Just did a search on Octane; US pump Octane is a combination of Research Octane Number (RON) and Motor Octane Number (MON.) The US posted pump Octane is RON plus MON divided by 2: i.e. 98 RON/90MON = 94 Octane pump gas. Many other areas or Countries post only the RON number, not the MON and not the combined /2 method. It's very possible that the 95 Octane is just the RON number, without the MON number there is no way to figure the comparable US rating.
These motors are extremely knock sensitive, I had an exhaust vibration that the ECM decided was knock and lost 20+ HP on a Dyno run. From what I've read over the last 2 years on this Forum the ECM is based to run 400HP/400TQ on 92 US pump octane and reduces timing (and power) if lower Octane is used or if knock is sensed (or predicted!).
Just did a search on Octane; US pump Octane is a combination of Research Octane Number (RON) and Motor Octane Number (MON.) The US posted pump Octane is RON plus MON divided by 2: i.e. 98 RON/90MON = 94 Octane pump gas. Many other areas or Countries post only the RON number, not the MON and not the combined /2 method. It's very possible that the 95 Octane is just the RON number, without the MON number there is no way to figure the comparable US rating.
These motors are extremely knock sensitive, I had an exhaust vibration that the ECM decided was knock and lost 20+ HP on a Dyno run. From what I've read over the last 2 years on this Forum the ECM is based to run 400HP/400TQ on 92 US pump octane and reduces timing (and power) if lower Octane is used or if knock is sensed (or predicted!).
Last edited by haljensen; May 24, 2007 at 11:55 AM. Reason: Addl info
Racer
Joined: Aug 2004
Posts: 371
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From: California Missouri
???HMM Check this out
According to what I looked up HP = Torque ftlbs x RPM divided by 5252
in this scenario with peak torque of 338 X 5250rpm = 1776495 divided by 5252 = 338 hp which would on par with the other guys.
I looked up the formula on the net, I am assuming it would be applicable.
just my two cents.
in this scenario with peak torque of 338 X 5250rpm = 1776495 divided by 5252 = 338 hp which would on par with the other guys.
I looked up the formula on the net, I am assuming it would be applicable.
just my two cents.
Pro
Joined: Jun 2005
Posts: 693
Likes: 2
From: Los Angeles CA
Tell the dyno guy to try again with WOT instead of 3/4 WOT. Just kidding, my Z51 feels weak some times and strong in other times, depending on season, weather, time of day, whether she's in the mood, etc...
Intermediate
Joined: Dec 2003
Posts: 38
Likes: 0
From: stanford ca
Who cares what the number is? You just need to ask yourself "is this a reputable tuner. And does he have cars running on his tunes for a year, 2, 3, 4 years without problems?
Realize there's no magic in tuning, but a lot of uneducated, underqualified tuners who you are paying $200/hour to half mess with your car. Searching this forum you KNOW what kind of numbers the TOP TUNERS can do with a given set of mods. There's plenty of graphs from those best possible tuners for xyz mods on dynojets, dynopacks, mustangs, LSAs, and every type of dyno.
If your guy makes a bigger gain than them, well that's questionable right? simple as that.
Always do the research and then use it to grill your tuner or mechanic. Interogate them. It's YOUR money they are taking, so they need to prove to you they can do a good job and are worth 100, 200/hour (cause that's medical doctor time worth). Ask for references, ask for proof. Too many people (including myself in the past!) go to a shop expecting there to be a standard of quality whereas there is not (somehow I don't think these guys are ISO 9000 certified)
Realize there's no magic in tuning, but a lot of uneducated, underqualified tuners who you are paying $200/hour to half mess with your car. Searching this forum you KNOW what kind of numbers the TOP TUNERS can do with a given set of mods. There's plenty of graphs from those best possible tuners for xyz mods on dynojets, dynopacks, mustangs, LSAs, and every type of dyno.
If your guy makes a bigger gain than them, well that's questionable right? simple as that.
Always do the research and then use it to grill your tuner or mechanic. Interogate them. It's YOUR money they are taking, so they need to prove to you they can do a good job and are worth 100, 200/hour (cause that's medical doctor time worth). Ask for references, ask for proof. Too many people (including myself in the past!) go to a shop expecting there to be a standard of quality whereas there is not (somehow I don't think these guys are ISO 9000 certified)
Last edited by verc; May 25, 2007 at 02:36 PM.
Safety Car
Joined: Jan 2007
Posts: 4,332
Likes: 0
From: Kuwait
Yep - looks like he's trying an old trick: making your "before" numbers artificially low so you'll be thrilled with the "after" numbers. Stay away from that place. Tell us who dyno'd your car. As stated above, tell us what city you live in and someone can probably tell you of a reputable shop.
Melting Slicks
Joined: Oct 2006
Posts: 2,905
Likes: 1
It probally is better than that. Those numbers would only make it about 375BHP, and GM states all C6s are 400BHP. Yes, the torque is almost always lower than the HP, esp. on Automatics. The exception is trucks, where the torque is used for towing.