I've dyno my 01 Z with an intake and tune and it went 357rwhp on a Dynapack. Now I was told a Dynapack read about 5% lower than a dynojet. Which one is more accurate?



-Jerry

 

Jerry,

I just did my car with Dynapack and then 4 days later with Dynojet.
The difference was 2.5 HP or 0.7 percent.

I also had a friend use the same Dynapack and then travel to Ohio and the Dynojet there showed a 3 HP difference or in his case 0.6 per cent difference.

In both cases the Dynapack showed the higher number. I was really impressed and didn't expect this close a correlation.

J.R.

 

Thats good info and spot on IMO....(Ive been on both style dyno's many times).

If you have reasonably lightweight rims and tires (like for instance a factory 10.5 inch wide Z06 rim....say total weight with rubber slightly less than 50 lbs) a dynapack will be very close to a DynoJet in terms of recorded power output. If you have an aftermarket wheel tire combo that has some heft to it (approaching 60 lbs) the DynoJet would definately read lower because that combo will be robbing some power trying to accelerate the heavier rim/tire combination. A Dynapack dyno on the other hand is bolted directly to the hub so the variable of the rear tires mass is completely negated.

Bottom line is both dyno's read very similar IMO, but in some cases the Dynapack might give you a slightly friendlier number. Now if you dyno with ET streets and a lightweight rim (total rim/tire weight around 40 lbs) you may actually dyno higher on the DynoJet.

When the smoke clears there probably isnt plus or minus 10 RWHP between them. The real key is repeatability and always using the same dyno to evaluate any mods or changes to the vehicle you have made. Every dyno reads a little different....even dyno's from the same manufacturer. Personally I like using the hub style dyno as it feels alot safer and more secure at high speeds compared to the same situation with your tires spinning 150 MPH on the drum (car is alot less busy feeling during the pull)....and for tuning unless the DynoJet is a load cell type the Dynapack has advantages there as well.

Hope this helps....

Tony

 

FYI.....

My car did 417rwhp on the dynojet and 421rwhp on the Dynapak........the same 2 machines and shop that you're dealing with.

 

Sweet! Thanks for the info.



-Jerry

 

We have owned a dynojet 248 for years and now we are using a Dynapac. Its strange but the medium to lower hp cars read a lot lower on the Dynapac. The higher hp cars seem to be pretty close with our Dynojet numbers. As far as tuning capabilities, there is no comparision.

 

My shop uses a dynapack also, and we have run into the same problem. Big V8 cars dyno about the same as anywhere else. Its the guys coming in with the 2-300hp cars that wind up getting the really low numbers.

 

Its all about how you spin a set of 3200lb drums on a Dynojet. This is where the difference lies.

There is no tuning comparison to the Dynapack, it does not get any better.

R

 

Can anyone post pics of a car on the Dynapack hub style dyno. I've never seen one. Thanks

 

Here ya go

 

Thanks Chris! I'll be darned! I didn't expect to see anything as portable as that.
What is the rear of the car supported by? Something like jackstands or a transmission jack under the crossmember? I've got to believe whatever it is it must be secured to the floor as well as the car?