What is the proper way to dyno?

Hi, all

This is my one of my first posts so please be gentle ; .

I have just dyno'ed my truck and was wondering if it was done properly?

The guy who did it (Chris) said he needed to run it in third gear to get a 1:1 ratio on the transmission and a true reading on the RWHP, and as we all know that our stock trucks has a speed limiter set at around 98mph. During the test he hit this limiter at about 3,900rpm's and only showed 211.7 RWHP/281.6 TQ.

I then asked him to run it in second gear in order to stay away from the limiter and he said that we would not get a true reading due to fact that the transmission would not be at 1:1. He did the run any way and we got 248.0 RWHP @ 5,600rpm's/274.2 TQ @ 4,100rpm's.

Are this second gear run true RWHP?

I have a basicly stock 2002 AV 5.3. The only mod's I'v done are:
3"in x 2-2 1/4"out Borla Exhaust, K&N replacement filter and MSD 8.5 wires.

THK for your feedback

RGV-AV

HP is HP....it does not matter what gear you are in.......

The gearing effects TORQUE at the wheels not Hp.......since Hp is a function of Torque and RPM.......Hp should be constant at engine speeds......

The reason Flywheel Hp is less then wheel Hp is due to drivetrain inefficiencies or AKA LOSSES........

I might look for another dyno person myself.....but that is me

A dynojet chassis dyno (248C) will vary it's readings a good amount depending on what gear you dyno in...

For example, running in first gear will net a lower number than in 2nd ... It's the nature of the dynojet ... I have posted some info in why this is in a thread a good time ago ...

My shop I dyno at runs auto's in 2nd gear, and manuals in 4th ...

BTW, nice results ... How hot out was it and do you know the correction factor, humidity and elevation ?

Oh, is your av a 4x4 or 2wd ?

11H

First of all thanks for your responces. I sure do appreciate it

YGMN,

Unfortunatlly i do not have much of a selection on dyno shops down here in the Rio Grande Valley. Which is located just 15 miles from the Tex-Mex Border. Plus, also the dyno runs are very inexpensive @ just $20.00 per.

11H,

I also thought those were good numbers for the few mods that I have

Here are some of the factor for these two dyno runs:

Ambient air: 95deg.
Temp inside stock airbox: 105deg.
Humidity: 80%
Elavation: 125 feet above sea level.

My AV is Z66, 2wd. Chris also had a small shop fan about 12' infront of the truck to simulate road airflow conditions. I used a radio shack dual temp. sensor to get the airbox and ambient air temps during the runs.

The reason for the dyno is get some sort of baseline for future mods. (ie:Coldair Intake, HPP3 or Diablo and if I'm a really good little boy maybe one of these X-Mas's Santa will bring me a Radix S/C LOL)

Again THKs for your feedback

RGV-AV

Just want'd to bring this back up to see if anyone has any further input.

THK
RGV-AV