Chassis Dyno Opinions?

[HooversTurbo]

Hey Everyone,

 

Locally to me, there are only dynojet 248's or inground dynojets. Is there a reason why these seem to be so popular? The company is somewhat of a newcomer.

I've been wanting to try out a different dyno to see if my HP numbers are different.

 

Do any of you have any experience or information about dynos in comparison to the dyno jet. I've spoken to Land and Sea, Mustang, SuperFlow, dynapak but can't seem to get a straight answer, they just keep trying to sell me a dyno.

 

Oh well, back to the dyno again Tuesday.

Hoover

[johnc]

My own personal opinion - for whatever it might be worth:

 

Chassis dynos (of which the Dynojet brand seems to get the most respect) are good, convnient tuning tools if you have a well trained and thorough operator. They measure how well a vehicle accelerates a mass and thus, are a good way to measure the accelerative capabilites of that same vehicle. Plus, you can make changes quickly and run another test.

 

Despite what the dyno companies say, they do not measure horsepower and are not good at coming up with quantifiable nubmers to compare with other dynos, your buddies, etc. They are excellent tuning tools and lousy bragging tools.

[Guest Anonymous]

i know u guys will probably laugh at me but i found something called the home dyno online the other week. i looked it up on google. i also looked at some other websites to see what people have said about it and they all pretty much said that is was a consistant 5 hp off from a real dyno. it gives you torque and hp on a graph like real one but it only cost something like 50 bucks plus the parts. it might be worth a try. i think i am going to buy it next month and give it a try.

[Bob_H]

Hoover,

The dynojet is is more prevelant because it is cheaper. The Dynojet 248 has two large intertial rollers,(I think 2400 or 2800 lbs each). Other dyno's like Mustang use a eddy current or some type of resistance to resist acceleration,(that sounds good! ha). Basicly an electric motor to put a load on the car/motor - but an elaborate setup which can cost. They tend to be more expensive, up to $150K on the high end, while a dynojet is much cheaper. And they have two types of dynojets, one is the 248(H - which is a heavier set of rollers), which can be above or below ground, and one they have specifically for inground, which is a lighter/newer design.

You can try others, but expect a lower hp reading. Dynojets tend to be the highest of the various chassis dyno's.

Some food for thought about your Z, with it weight in the 2000 lb range. The following is an excerpt from a mustang dyno user site:

However, the downside to this measuring form is that, in the real world, the vehicle is working harder than what is required in accelerating the rollers on a Dynojet. Between the weight of the car itself, elevation changes, and surface friction, the actual environment the engine works in during use is quite different from its experience on an inertia type dyno. This is an important factor to consider when interpreting the hp gain of a particular modification or performance product. For example, lots of ignition timing can be thrown at an engine to produce big hp numbers on an inertia dyno, but the same ignition setting can result in less hp when the engine is actually required to work on the street. Under load, (on the street or on a load dyno) pre-ignition or detonation can occur, tripping the knock sensors and causing the ECU to roll back the timing to less than stock. This is not good for power. Another example is fueling. Leaner fuel maps may work well numbers-wise when subjected to the relatively gentle inertia rollers, but can be disastrous when under load on the street.

 

I have found that cars tuned on load type dynos tend to run better than dynojets. My experience.

-Bob Hanvey

[BLKMGK]

Use them for tuning not for absolute HP numbers. SportCompact had a writeup recently (as I recall) where one of their staffers tried a Mustang and a DynoJet (2 of them) nearly back to back. The results were more torque on one of them with the rest being VERY close. Just goto the same dyno and use that for comparing mods along with any track time you can get. Supra folks tend to spend lot's of time on dynos and recommend race gas due to the lower cooling found on a stationary dyno. They've also found that the added resistance while driving on the street allows for better boost response. Hard to explain but while a dyno gives nice numbers and makes tuning easier it's not the only way to go....