This is just some helpful information.

After speaking with a representative from Dynojet, he noted that gear ratios play a small role when dyno testing cars. Gear ratios do change the peak horsepower numbers. But when comparing runs such as before and after comparisons or differences in horsepower, it is not as important as the baseline as long as the vehicle is tested with identical procedures and the variables are similar. Which means that if a baseline run was done in 3rd gear, then the comparison run with the aftermarket parts installed should also be done in third gear. The horsepower difference should similar, within 1-3 horsepower, through any gear whether it be 3rd, 4th, or 5th gear.

I'm listing a lot of factors that come into play when dyno testing cars which may or may not yield better results. This will be great check list for most of you when it is your turn to dyno your vehicle.

1. Tire pressure
2. Spark plugs
3. Outside Air Temperature
4. Length of Cool down period between runs
5. Wheel size
6. Oil pressure
7. Coolant temperatures
8. Gasoline Octane
9. Condition of the vehicle
10. Type of fan used in front of car
11. Altitude
12. Oil Viscosity
13. SAE correction factor
14. Line smoothing
There may be more, but please include them if you like.

I'm sure most of you will still have doubts regarding manufacturer dyno charts. However, at Injen we believe that the public should know the truth that is why we print actual dyno charts from our Dynojet. We do not make false graphs on Excel unlike other manufacturers. We are not in the business of making parts that do not work. We manufacture all of our parts in-house and we also have our own Dynojet Dynamometer. We make sure all of our intakes perform before they are released to the public.

Best regards,

Phillip Phong
Injen Technology
www.injen.com

 

Thanks for the post Phillip, I know there has been alot of misinformation about dynos in the past. I would like to see a collection of dynos. If anyone has any charts with modifications, please send them to me, with a list of modifications, and I will host them on our site.

-Jeremy

 

I lost 4 hp with y pipe, flowmaster and injen, so I can't say what the culrpit is.
This is someone from another forums dyno before and after the injen upgrade, no other mods. The intake was installed while the car was hooked up to the dyno, so all the other variables were unchanged.

 

Thanks for the info Philip.

Why did you decide to dyno the Injen intake on the 350z in 3rd gear, when 5th is 1:1? If a 1-3 hp variance between gears can occur, then is it correct to say that if you would of done the dyno test in 5th you MAY have seen only a 1-3 gain in peak hp from your intake? or a 5-7 peak hpgain?

This is not meant as an attack, but rather a legitimate question based on the information you provided. I do realize that a different ECU might be needed to for the Z to realize any signification gains from any intake.

 

If an aftermarket part was tested in 3rd gear with a 10hp gain, then the same car tested in 4th should net approximately 10hp as well [+-1-3hp].

 

So what is your explanation/impression of the above dyno?