Chassis Dyno Question's

[Dave Noll]

Found out we have a chassis dyno in town. Gonna make an appt. when I get enough money together. I want to get jetting & timing close and maybe fiddle with collector length. Should I focus on this or something else ? Mark, what do you need to know for the convertor ?

[Mark Yacavone]

Originally Posted by Dave Noll

Found out we have a chassis dyno in town. Gonna make an appt. when I get enough money together. I want to get jetting & timing close and maybe fiddle with collector length. Should I focus on this or something else ? Mark, what do you need to know for the convertor ?

If you can find peak torque , that would be great.
Ed Wright posted something about that recently?

[Dave Noll]

Found it Mark, Thanks.1 more thing to check IF they have a Dynojet. I do have some street tires to swap on. Didn''t know about the knurling on the rollers.

[Ed Wright]

If it's a Dynojet dyno, and an automatic car, the torque peak will appear exaggerated and at the RPM where the converter flashes. I don't know that the torque peak RPM will be correct on another brand dyno.
If it's a Dynojet you may need to add about 5% to your WOT fueling, since they don 't load the engine as hard as moving the car.
Of course, make your pulls, of course, in high gear.

If the rollers are knurled (like a Dynojet) and you have some old, hard. (Or even better: street) tires you will want to use them. Knurled rollers are hard on slicks. I would not use my good race tires. It won't bother street tires.

If I can help with anything please just let me know.

[Dave Noll]

I havent seen it yet but I think its @ least 12 years old. Ed, yes my car is auto & Mark built the convertor. If its not dynojet, how far off will peak torque be ?

[Ed Wright]

Originally Posted by Dave Noll

I havent seen it yet but I think its @ least 12 years old. Ed, yes my car is auto & Mark built the convertor. If its not dynojet, how far off will peak torque be ?

Can't tell you, Dave. I have only owned and used a Dynojet. Probably that's what it is, weren't so many out there twelve years ago. On cars with lock up converters I would (for only a pull or two) lock the TCC and roll into the throttle slowly just off idle to take the flash out of it.
Any chassis dyno will not give accurate numbers due to converter slip. Especially below the RPM where the converter hits. If you can make the torque numbers bigger there, you helped it. Just still won't know your torque peak RPM.
Street cars with, for example, a 2800 converter and a torque peak around 4000 will show it OK.
Stick cars get more usable data on a chassis dyno.