I have read that all dynos are not created equal.

Some show higher results than others. Obviously, I'm not looking for the one that shows false high results. I wanting something that shows accurate results.

Does the Dyna Pack tend to overinflate the results? Lately, I've read several dynos on Dyna Pack systems that seem to show G35s pulling higher numbers than the DynoJet systems do.

Is this a coincidence or is there truth to this statement?

 

As long as the dyno is consistent with its readings, then it's good.

It's just a different way of measuring things. It's like how tall are you? 5 feet, 60 inches, or 152 cm?

What you'll want to see is how your car compares on that dyno to other 350z/G35s on that day.

You could have a dyno say that you are making 1000 HP. Everyone would be ecstatic right? But what if a Geo Metro makes 995 HP on that machine?

You can't compare dynapack readings to dynojet. It's apples and oranges. There is no simple conversion factor. I've tried to come up with one, but it's not simple at all.

The dynapack at church automotive is very consistent though. 6mt 350z's are repeated getting 255 HP. 2005 G35 6MTs with 298 HP are getting 267-268, and you can take the graph of one car and almost have a perfect overlay on top of another car with the same configuration.

That's why when people get their car dynoed at a random shop on their own, come on the forum, and asks if 2XX WHP is expected for their car, it's an impossible question to answer. But if they were dynoed with other VQ35s, and they are 20 WHP more than a stock car on that day, then it's safe to say that they made some good gains with mods.

 

From what I understand dynapack is more repeatable accuracy wise than dynojet but it is going to give you higher numbers since it is done with the wheels off.

 

it is true that different types of dyno's will show different HP/TQ numbers on the same car. Like was mentioned, it is hard to compare one to another without having many baselines to go off of. By now though, you should be able to look up what is "normal" on a DynoJet, a Dyno Dynamics, DynaPack, Mustang, etc.....

BUt, if you are talking about tuning a car on different types of dynos, ... that makes a BIG difference, ... as all dynos can not give you all the 'tools' necessary to tune properly.

 

DynaPack dynos connect straight to the hub with the wheels off, DynoJets are inertia type roller dynos.

 

http://www.dyno.com.au/usa/usa_index.htm

http://www.dynapack.com/

http://www.dynojet.com/automotive_dyno/index.php


IMO, Most of the better tuners would prefer the Dyno Dynamics dyno.

 

[QUOTE=NoLimit
IMO, Most of the better tuners would prefer the Dyno Dynamics dyno.
[/QUOTE]

I guess Jim Wolf isn't one of the better turners.

 

I dyno on two different dyno's...both Mustang dyno's....they both come with in 2 or 3 whp of each other

 

He said "most" not "all". I've done a fair bit of research on dynos and the dyno dynamics does seem to have a few nice features. YMMV

 

The Dyna-pack will almost always result in numbers about 10-15% higher than what you'll see on the Dynojet.

Dyna-Pack
Removes the wheels and measure directly from the hub. Removing 40-52lb in unsprung and rotational weight is very significant. This dyno is also a load/brake dyno which means the operator can vary the load (brake) therefore influencing the numbers. Brake dynos are great for tuning purposes since you can vary load and tune for real world driving situations.

DynoJet-
This is an inertia dyno. You simply roll the drive wheels onto a set of ~2000lb drums. You put the car in a 1:1 gear and measure the time it takes to spin the drums in relation to engine rpm. From there, torque is read and HP is calculated.


Words of wisdom:

1) A dyno is a tuning tool...that's all. You use it to measure gains and losses from mods.
2) All dynos read a little differently
3) Only be concerned about what your car gets and not what Joe Blow's car did 5 states away. It's apples to oranges.
4) A 220whp G35 run on a Dynojet will most likely run the same ET/MPH as a 255whp G35 run on a Dyna-Pack.
5) You can make any dyno show power that's not really there (ie adjusting load, correction factors, atmospheric conditions).

 

as someone pointed out, I said "most". I guess I should have said, "Most of the better tuners would prefer a Dyno Dynamics or Dynapack." Would that be ok with you??? There are obvious advantages to either.... And as DaveB stated, they are just tools to do a job.

oh, ... I'm not sure how good of a "turner" Jim Wolf is, ... I've never seen him drive! lol J/K

Sean

 

He would be in my eyes if he could install a CARB certed TT on my car!!! - I read somewhere that it kicks @ss! (that was my impression)

It's ironic that just 20 minutes ago I edited my sig to delete all the mods and ad what I did (dynapack hp)... I admit dyno numbers vary and are not indicative of true performance, but it's fun to have good results on any dyno... that being said, if dyno hp isn’t enough - I think my sedan would hold it's own in any (NA) circumstance.

Dyno results are a pretty good measure of a cars performance… the actual hp & tq will always vary. I have heard 10-15% variation from dyno-jet to dyna-pack… but I think that’s impossible to determine as well (with all the variables). I dyno’d on dynojet with CAI and exhaust only at 247 – my last dyno on Churches dynapack was 271… the car is WAY faster now than it was with CAI and exhaust only, but if you use the 10-15% loss calculation it wouldn’t compute.

Bottom line, as others have stated – what your car does compared to other cars same day same dyno will tell you if your mods are working. And/or go to the track and race some VQ’s (I’ve faired well so far).