Tuning on a Chassis Dyno or @ Track?

[gmturbo]

I'm not sure which is a better way to dial in a car using the
fast system. I have heard conflicting stories that a chassis
dyno does not give the car ideal conditions to get the car
dialed in.
Any feedback from Turbobuick board would be welcome

 

[bruce]

Originally posted by gmturbo
I'm not sure which is a better way to dial in a car using the
fast system. I have heard conflicting stories that a chassis
dyno does not give the car ideal conditions to get the car
dialed in.
Any feedback from Turbobuick board would be welcome

Does the dyno generate a 100 MPH airflow under the hood?.
Does it generate the aerodynamic loading?.
A real pass includes 1-2-3 gear.

A dyno, depending on the tuner, can get you in the ball park. But, never assume it's perfect.

 

[nightdiver]

I did a dyno test yesterday and i saw the highest intake temps i have ever had. 177 * F
On the street i got no more than 120*-125* on a hot day
I saw 302 kw with 19 psi and with a very old motor
I will never tune on a dyno....

 

[bobc455]

On the other hand, there are things a dyno can tell you that you can't find out on a track.

For example, on my motor I found that my car likes 1 degree less timing above 4000 RPM than below. I did this by comparing the HP & torque curves of back-to-back runs. On a track, you could not find this out.

If keeping the intercooler cold is an issue, some dynos will offer to set up a small garden hose spraying on your intercooler (with a bucket underneath to catch the water), or make various accomodations to overcome differences between labratory & real-life.

But I have found the dyno to be a great way to make small changes and test under identical conditions (traction, temp variations, cool-down time, etc. can all be controlled and consistent, unlike a track).

-Bob Cunningham
bobc@gnttype.org

 

[gmturbo]

so it is safe to say a chassis dyno helps more with
normal day-to-day drivability conditions, rather than
track conditions in tuning for, hesitation, lack of power etc ?

 

[Chuck Leeper]

Dyno tunez??

My take is:
1. The I/C ratings are for a 10mph airflow, and any dyno operator that is into forced air/intercooled cars has a large fan to create this flow.
2.The dyno provides accurate atmospheric conditions for pull comparisons..
3. The time to baseline the system is compressed from several hours,[days] to less than an hour or two, in most cases.
4. It minimizes the "driver error" input.
5. The intake air should not be picked up inside the engine compartment. That's for stockers and the emission freaks!!
6. True, the final tune should be at a track, IF that's where the car's going to be used. Subject to retune on the street..
I've seen WAY too many aftermkt systems so far off that the car shouldn't even be started!! That's certainly a good reason to start out w/ a dyno session!
My story and I'm stickin to it!!

 

[gmturbo]

Thanks Chuck! That makes a lot of sense.
Off to the chassis dyno!