going to a dyno test on your car

[grumpyvette]

Many dynamometer operators go right for the gear that is the closest to a 1:1 ratio as it has the lowest drag in the gearbox and therefore the highest horsepower reading (usually) on a vehicle that is properly sized to be tested on this dyno. Of course, many cars don't have true 1:1 gear ratios, and many cars are not the exact proper size that the dyno was designed for, so blindly going for the gear ratio that is closest to 1:1 is not always the right answer. My dyno is sized for vehicles that are around 3000 - 3500 lb. A significantly lighter vehicle, even though it may have the same horsepower as a larger vehicle, will probably have a final gear ratio that is higher. Therefore it will seem to struggle a lot more than a heavier car. In such cases, the lower gears, like third, may give the highest horsepower reading.

BTW most dynos charge between $75-$120 PER HOUR but ask because there can be other charges added


have a good 10 lb CO2 fire extinguisher handy during any dyno test
http://www.bristoldyno.com/info/procedure.htm

http://www.speedengineeringanddyno.com/dynotips.htm

Dyno tuning your vehicle is one of those things that can greatly enhance the performance of your engine. Tuning your car through the use of a dynamometer should be thought of as more of a scientific experiment than a garage project. There are many different things that can be determined, and changed, through the dyno process. It is highly technical, but also easily learned by anyone who wants to keep their horsepower, performance and engine life at an optimum level. If you are looking into using a dyno, here are some tip to help you get more out of the process.
1. Know What You Want to See before Testing

There are a lot of variables in the engine while it is running. Things like fuel pressure, valve timing, problems with spark plugs and wires, exhaust and emissions, the throttle body, fuel injection, and other problems can be found after you roll you car up on the dyno testing platform. Having a plan beforehand will always help you see some things, while also helping you locate other problem areas.
2. Know What You Want to Change before Testing

Along with knowing which problem areas you want to look at, you should also have a plan thought out about the parts of your engine that you want to change. By knowing this you will be able to save a lot of time in the process by having the tools, and the parts necessary, on hand while the car is on the dynamometer.
3. Know What You Are Looking At

For one who is not well versed on the dyno tuner you can make a lot of assumptions without knowing the true reality of what the numbers are saying. You may think that the A/F ratio is a little off and go about changing valve timing to make it better. However, the truth may be that you only need to do a slight adjustment. Read about the dyno testing machines, and talk with skilled users before trying to read the numbers.
4. Perform Several Baseline Runs

The best way to determine your vehicle's performance and power is to perform several different baseline runs. This will show you where you car it at before you make any changes. However, because of the way that different factors can change performance (engine heat, oil breakdown, atmosphere, etc.) you should run several tests to make a true determination.
5. Change One Thing at a Time

Getting the most wheel horsepower, fixing some of the problems or making your engine fit emissions standards can not be done when you are pulling out parts, and changing things on the fly. It should be a systematic process where you only change out one thing at a time. When you swap out fuel injection, spark plugs and change the timing all at the same time, you will radically change the results making it seem like there are other problems.
6. Be Methodical in Testing

Using a notebook to write down everything is one of the most important things you can do when dyno tuning your vehicle's engine. Take one step at a time and do not try to rush the process by jumping to conclusions when there is minimal power gain with stock engines.

http://corrperformance.com/tips.htm

Information for a better dyno experience



Before you even sign up for a baseline or tuning session there are things that should be addressed on your vehicle. Below we have compiled a list of recommendations you should look at to make the dyno sessions a pleasant experience:

* Make sure that the tires are in proper working condition, the dyno can be cruel to tires as repeated dyno pulls are needed.

* Check all the coolants on the car and if there is a leak and there is a over heat issue, be sure to take care of it before the session.

* Inspect that the oil is a good level before the session and that the filters (air & fuel) are in good shape.

* It is a good idea to inspect the spark plug wires and if needed replace them for a new set.

* Please be conscious to the fact that an old clutch will & could fail in a baseline/tuning session. If the clutch fails, session is over.

* Make sure there are no check engine light or codes present before the tune.

* Inspect all wheel studs, so they are tight and secure.

* Brakes must be in good working order.

* Cars with Ignition Coils, please make sure that the coils are in good working order and there is no hesitation due to a misfire code. Inspect the gap on the plug, but if the gap is accordingly and it still does not behave, swap coils to see if that rectifies the issue. Cars with upgraded turbos over 650CFM must consider tightening the gap on the plug from .029 to .025 at least.

* If meth injection is to be used make sure that you have enough for the whole tuning session.

* On turbo systems, if we/you are tuning a turbo system, make sure all pipes are secured so they do not blow off during the tuning session.

* Make sure that proper compression is present in the engine. A healthy engine is vital to a proper tuning experience.
8:1-8.5:1 compression: 150-170 psi per cylinder
8.5:1~9.5:1 compression: 170-210 psi per cylinder
9.5:1~11:1 compression: 210-275 psi per cylinder
11:1+ compression: 250+ per cylinder

* Please DON'T make an appointment if there is a 20psi variance between cylinders. 3 good cylinders do not make up for one that is bad.

If you are coming in for a tuning session whether shop tune or customer tune here are some things to consider:

* Please bring your own tools if you are self tuning your vehicle, the shop is not responsible for supplying tools.

* Make sure you bring a correct set of extra plugs to change before the tuning session.

* If you are changing from pump gas to race gas during the session, make sure that you tell the dyno operator ahead of time.

* If your vehicle spills excessive fluids on the shop floor, you may be charged a clean up fee.

* Any damage to the dyno, the shop, shops equipment, or any person caused by your vehicle is your responsibility.

* Lastly the dyno operator will always be driving the vehicle and operating the dyno controls.



read thru the linked info below

http://www.hotrod.com/techarticles/gene ... _tips.html

http://www.highperformancepontiac.com/t ... index.html

viewtopic.php?f=50&t=9250&p=33361#p33361

http://wahiduddin.net/race/dynotest.htm

http://autos.com/aftermarket-parts/6-ti ... yno-tuning

 

[grumpyvette]

it should be obvious that a trailer should be used rather than a tow strap when towing your car,, and if you dyno test your car thats an excellent reason to have well anchored tow hooks on all four corners of your car WELDED AND BOLTED TO THE FRAME, if thats an option, but even on a trailer the car needs to be secured in place to prevent the weight shifting,

most cars don,t have a easy access location to hook up a tow strap ...or firmly lock the car in place on a trailer and randomly hooking straps or hooks to suspension components is asking for damaged parts,
yet another excellent reason to own a welder
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_371258_371258

7/16" thread u-bolts can be bolted into most car frames near the four corner points providing a significant tie down point for towing or dyno testing

http://www.tellico4x4.com/product_i...24689?osCsid=887efdc6ab2c4c8f67f8921794f30119

buy at least two (fours going to be much better) and bolt and weld them to the frame for easy access and security on a trailer transport, and emergency towing

http://www.truckaddons.com/Catalog/Extreme_4x4/Keeper_towhooks.htm

 

[grumpyvette]

Great write up on the dyno tuning...

I found a little info as to how each of them operate..

The basic reasons for the difference between a DynoJet and Mustang Dyno, is in part on how the power is calculated, and partially due to the amount of "load" the vehicle "sees" during the pull.

DynoJets measure horsepower and derive torque from that. Loaded Dyno's have a load sensor, and actually measure the torque being applied to the drums (it's a little 5volt reference load sensor). Horsepower is then derived from that information. Torque is an actual force (like gravity), where as Horsepower by definition is a derivited of torque (work over time).

The load sensor data is then sent to the computer where it takes two constants, vehicle weight and Hp@50mph (aerodynamic coefficient used by the EPA) where the computer then calculates the amount of resistance to be applied to the vehicle (PAU force).

For an example of why there's a difference due to load, imagine this. It takes less power (however you measure it) to accelerate the mass of a 2500lb roller from 300rpm to 400rpm in five seconds than accelerating the same roller (2500lbs) with 550lbs of resistance via load cell from 300rpm to 400rpm in the same amount of time (5 seconds). That's why if there's a car that made 425rwhp on a Mustang MD-1100SE dyno, it will be faster than a car that made 425rwhp on a DynoJet.

As far as the timing example that somebody brought up, I've found that to be true as well. Sometimes the cars are faster with 1 to 2 degrees less timing than they see on the Dyno. Best was without being at the track is to check the plugs. That's why, no matter how good the dyno is, the opperator, or the tuner is, it will really only get you about 95% there. The last 5% is going to be needed to be done at the track.

Because of these reasons, it's like trying to compare apples to oranges. As far as the "10%-15%" difference, we've found that to be untrue. In our tests it doesn't seem to be a constant at all. At 390rwhp on mustang dyno, the same car makes about 405rwhp on a local DynoJet. At 422rwhp on mustang dyno, the same car on the same DynoJet made 458rwhp. I've witnessed cars seeing close to a 80rwhp difference between a Mustang Dyno and a DynoJet at 600rwhp (Mustang MD-1750SE), although I cannot verifiy that with our dyno. More recently, I've found that a 2002 Vortec S/C Z06 that made 550rwhp on our Mustang Dyno, made 645rwhp on a DynoJet over the summer.
T
the difference is closer to 6-7%, but as you make more power, the difference increases as well. You must remember, Dyno's regardless of the type are tuning tools, and are in no means ment to tell people how fast their car is. Now which one is more "real world" is a totally different question. I like to explain it like this..... If you drive your car in a situation in which you have no mass and you're in a vacuum, so basically if you do intergalatic racing in space, use a DynoJet. If your car sees gravity, and has an aerodynamic coeffecient, and you race on a planet called Earth, then use a Mustang Dyno.