there are three plugs that go straight into the ecu. You unplug the wires that go in there and put the harness inbetween them. Plug it up to the vafc and you should be all set to have someone tune it. Have fun and keep us posted.

 

I just a little search because this topic has been debated over and over. Here quote off another forum (Mustangs I believe), where someone actually contacted Dynojet regarding gears and effects on their dyno.

What's interesting is that the hp would read lower! Hmmm, seems like a valid explanation. Learn something all the time.

This statement seemed to also suggest that you'd get higher hp # in 4th (since it's a wee bit closer to 1:1 than 3rd).

Love these threads where it makes you think and research information. One can always question the validity of the information and search themselves, or, call Dynojet for an answer.

Here's their reply:

These questions have been long standing debates among car enthusiast, so I recently emailed DynoJet and asked these exact questions. Below are the responses I received from the DynoJet representative.

QUESTION:
A car having 3:27 rear end gears is placed on a DynoJet chassis dyno and has a dyno performed. Then this same car is taken off the DynoJet chassis dyno and has the rear end gears changed to 4:10. The car is then placed back on the DynoJet chassis dyno and another dyno is performed. Will the second dyno show a loss of horse power caused by the 3:27 to 4:10 gear change?

ANSWER:
Yes

EXPLANATION:

"The 4:10 gear will show less horsepower than the 3:27. The reason is due

to rate of acceleration changes. The rate of acceleration is quicker with

the 4:10 because of torque multiplication being increased to the rear

wheel. The horsepower will show less because the targeted RPM is met

before the horsepower has a chance to overcome the rotational mass (dyno,

drive line, etc.) or moment of inertia in speed. Because the speed is

decreased and the RPM is met faster, the horsepower never has a chance to

catch up with itself, so to speak. The overall ratio of 1:1 will always

produce the most horsepower on the chassis dyno. Having said this, a

similar problem can occur with horsepower loss when the rear gear is too

high. The horsepower is being absorbed in just trying to keep the

rotational mass spinning. Please keep in mind that your engine's

horsepower never changes but what gets to the dyno or drive surface

does. If you have any further questions please don't hesitate to

ask. Thank you."

 

so with gears should I do it in 3rd or 4th for the best results?

 

If I read it right and you want higher numbers than go for third gear opposed to fourth.

 

Interesting stuff, but I have a comment about the 1:1 thing, and disagree with the response your quoted about gearing.

First, I've always understood the 1:1 thing to come from the fact that many manual transmissions used to have a direct shaft. No gears were involved, the input shaft directly turned the output shaft. Since it didn't go through the gear meshes like 1st through 3rd gears, there were less losses and therefore dynos read higher. My suspicion is that this has been corrupted to mean that the higher reading will come from whichever gear is closer to 1:1, even though they each go through the same amount of gear meshings. For example, the S2000's 3rd gear is 1.481:1 and 4th is 1.161:1, but I've never seen any evidence that 4th gives any more than 3rd.

Second, there are some really weird things said in that reply supposedly from DynoJet. What is this talk of the horsepower having "a chance to overcome the rotational mass"? It's completely nonsensical - the wheels instantaneously accelerate the rollers proportional to the amount of torque being generated. F=ma. The force doesn't need "a chance" to accelerate the mass. Horsepower catching up with itself? Please. The engine produces X horsepower a Y RPM regardless of how quickly it got there. Second, and this isn't as big a deal, the horsepower absorbtion thing - I think the reply simply meant to say that at higher speeds, there's greater friction to overcome. But the wording was a tad sloppy...

 

Elistan,

First off, I want to say I really appreciate your comments and input. It really gotten me thinking and looking into the accuracy of my knowlegde. So to you!

[QUOTE=Elistan,Feb 18 2006, 05:52 PM]Interesting stuff, but I have a comment about the 1:1 thing, and disagree with the response your quoted about gearing.

First, I've always understood the 1:1 thing to come from the fact that many manual transmissions used to have a direct shaft.

 

ok ill try to see if i can do 3rd and 4th..but for now its that I should dyno higher in 3rd?