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Discussion Starter #1
From the threads I've looked at, most have used a Dynojet for their numbers and are 350 give or take for RWHP on a stock Z06.
I just had my done on a Mustang Dyno and got these numbers:

250.9 RWHP @ 114 MPH
389.1 RWTQ @ 99 MPH

Are these dynos that much difference in the way they calculate numbers? :-?
 

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02EBZ06 said:
From the threads I've looked at, most have used a Dynojet for their numbers and are 350 give or take for RWHP on a stock Z06.
I just had my done on a Mustang Dyno and got these numbers:

250.9 RWHP @ 114 MPH
389.1 RWTQ @ 99 MPH

Are these dynos that much difference in the way they calculate numbers? :-?

Mustang dynos read quite a bit lower, however, thats too low to be accurate. I don't understand your power [email protected] mph thing as well.
 

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Dyno's are not to measure absolute HP as the end all be all teller. It is simply a tool to take a base line measurement, make any mods and then use it for tuning. Then with the SAME dyno you took the base line with you can take a final reading to see the gains by the mods. Is it the absolute measure for HP?? NO. Almost every dyno will give a different reading.

JMHO

Chris
 

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The mph thing is just that the car was put into 4th gear and run on the dyno without the engine's rpm's being measured, only the speed of the rear tires. So, 114 mph = 5000 rpms and 99 mph = 4400 rpms on a stock Z06.

However the horsepower number is bogus. Because 389 ft-lbs of torque at 4400 rpms is 327 horsepower. My Z06 makes 320 horsepower at the rpms that it makes peak torque at, so this number seems to be close. But this is more than was reported at 5000 rpms so the 250 hp number is too low. You need to have them verify the numbers and give you the true ones. Also, my pure stock Z06 made it's peak torque at 4700 rpms (close to your number) and it's peak horsepower at 5700 rpms (much higher than yours). So, anyway, you've got a bad HP number, one that can't be explainded by not having been corrected to standard air preasure and temperature.

A Horsepower IS an exact amount of power. It is not open to interpretation. Any dyno that does not give acurate numbers is a poorly designed peice of equipment and shouldn't be used. Like a 1 foot ruler that's 14 inches long. Sure it can be used and if you always use it everything will come out right but you must always us that ruler. That's not the right way to do things.

Dynos DO give exact absolute HP. However, your engine gives different HP depending on the air temperature, humidity, engine temperature, gasoline octane rating, etc. So an engine will give different numbers on different days of the week, different times of the year. You make more HP in the winter, when it's cold, than in the summer, when it's hot. The dyno will show this. It's not an error in the dyno readout, it's a difference in the HP your engine produces in hot temperatures and cold temperatures. This is why you must use "Corrected" numbers only. They will be close to accurate and can be compared between different dynos. There are a lot more things that affect the HP of an engine than I want to go into here, but the measuring device shouldn't be one of them.

Rod
 

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I got the scoop on Mustang dynos recently, when I got similar numbers. The guys that run Mustangs have the whole spiel prepared, because someone (like me!) is coming to them, waving dynojet numbers and talking about 100 more horsies.

Mustangs have many more settings than Dynojets, and are capable of generating load on the rollers for the car to push against. So most of the time, when you run on a Mustang, you are working against a load that the operator has specified. Your numbers are going to be ALOT lower. However, there are some good things:
1) You will find where the car is detonating/knocking more easily, under load.
2) You can test vehicles that tow stuff, and simulate the load.
3) You can tune forced induction cars more easily on a Mustang, because if you tune on a dynojet, under inadequate loads, it is easy to tune too lean and mess up your investment.

I'm not an operator, I'm a driver. I bet Mustang's website could explain it better, or a good operator. I would also bet that it's easier to mess up a Mustang dyno run, since there are more knobs and settings to twiddle, but I trust the local Mustang crew. Thus, what I plan to do is tune on the Mustang and get my bragging numbers from the Dynojet. Best of both worlds.
--Yak
 

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Oh, and by the way, 5700 rpms is about 130 mph in 4th gear on a Z06. So those of you who have HP/MPH should be getting your peak HP at about 130 mph.

Rod
 

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Your "numbers" are way out of whack with reality for anything resembling a stock C5. Dyno operators who hand out such "test results" to car owners are obviously not interested in practicing good customer relations, but rather acting like ticket takers, that provide no added value at all. Did they do your car's dyno test for a fee, but too lazy to hook up the ignition spark wire and AFR sensors? My advice, stick with Dynojet shops. They are seemingly more car enthusiast oriented and do a better (more accurate) dyno performance evaluation of the cars they test.
 

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Discussion Starter #8
Thanks for all the replies..

There definitely was a lot of setup. He added #'s for temp, humidity. Pulled others out of tables like 11.5 for "HP at 50MPH". One thing I did wonder about was the table only had 1 number for weight of all 2002 Corvettes (3375 lbs)
He spent about 45 minutes just getting set up, had a lot of problems getting an RPM reading. Not quite sure what he did to straighten it out, but it kept dropping to 0 when I got to 2000 RPM.
 

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Actually, I witnessed just this sort of thing a few months ago on a friends car being dyno'd. The dyno was "hard" to initially set up. Mainly b/c the rpm pickup sensor was faulty, with a rats nest of improperly insulated/shielded wires running all over the shop floor from behind the computer; grease everywhere - you get the picture. I have yet to see a dyno shop really well organized, CLEAN, properly ventilated, adequate area for spectators to watch, PC/printer equipment in top notch condition, etc.

Actually, by and large, for the fees charged by the average shop, we get very little in return. :mah:
 

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02EBZ06 said:
Thanks for all the replies..

One thing I did wonder about was the table only had 1 number for weight of all 2002 Corvettes (3375 lbs)
That seems quite high for a Z06. I have seen them as light as 3000 or so, with no driver. Unless you are pretty large person, that weight might be off.
--Yak
 

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All weights of cars used to figure HP or 1/4 mile et's and speeds have to be with the driver. In my DragRace program I use 3315 lbs for the weight of a stock Z06. This is with driver, gas, oil and fluid in the radiator, etc. I think that Chevy (or maybe it was some car magazine) says the Z06 weights 3115 without any fluids and I add 200 lbs for the driver and fluids. So, 3375 might be high, but it's not that high.

Rod
 

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Discussion Starter #14

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Discussion Starter #15
Yakisoba said:
That seems quite high for a Z06. I have seen them as light as 3000 or so, with no driver. Unless you are pretty large person, that weight might be off.
--Yak
That was a number he pulled out on a table in the software for corvettes. Coupe, vert, Z, only one number. Maybe they are
adding in driver, fuel, etc. to get that number.

I've heard 3100 also for the Z.
 

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Could the tranny have been in 3rd gear during the test?
 

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To FRISKY, I don't think the car was in 3rd because it can't go 114 mph in 3rd gear, only about 103 mph.

Rod
 

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Discussion Starter #19
It was in 4th for that test.

Here's some videos.

wwww.collindaleperformance.com

Click on Videos at left.
His comment about the cluch slipping is wrong, he was hitting the governor.
 
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