Does Rear Gears effect HP #'s?

[VAMPIR3]

Just curious.... Stock Cobras have what 3.55 gears? And lets say he nets 500RWHP on the Dyno. Now same mods with the exception of 4.10 Gears, will that Dyno come out lower this time or the same and why?

 

[SVT03Chris]

Gears do not affect horsepower at all. They are simply a different ratio. They don't give you horsepower nor do they lose it.

 

[VAMPIR3]

Gears do not affect horsepower at all. They are simply a different ratio. They don't give you horsepower nor do they lose it.

I know that, but I thought I read that taller gears can effect Dyno numbers?

 

[SVT03Chris]

My bad. I thought you were talking about strictly losing or gaining horsepower because the title of your thread.

Yes, I think they do skew the numbers a little. I couldn't tell you why or how though.

 

[baby2000]

I have heard the same thing Vampir3. I just dont knoe if that is right though.

 

[rotor_powerd]

They will. You want to dyno in the gear that is closest to 1:1 with crank speed, to get the "realest" numbers. This is usually 4th gear. If you step up from 3.55 to 4:10, and dyno again in 4th, you will get different numbers. Same way you will get different numbers dyno'ing in 3rd vs. 4th.

 

[SVT03Chris]

They will. You want to dyno in the gear that is closest to 1:1 with crank speed, to get the "realest" numbers. This is usually 4th gear. If you step up from 3.55 to 4:10, and dyno again in 4th, you will get different numbers. Same way you will get different numbers dyno'ing in 3rd vs. 4th.

With that being said, I wonder what gear you should dyno a Cobra that has 4.10s then? I know I have pulled mine in 4th and I have 3.73s.

 

[94Gt5.0]

Simple solution, dont worry to much about dyno #'s, go out to the track and see what it does. The track doesnt lie!

 

[rotor_powerd]

Quick comparison,


4th gear @ 4000 RPM with stock 3.55's on 26" tire - 87 MPH
4th gear @ 4000 RPM with 4.10's on 26" tire - 75 MPH
5th gear @ 4000 RPM with 4.10's on 26" tire - 94 MPH

Either way, it's still going to be off with 4.10's, probably marginally though.

 

[SLEEPERSTATUS]

Gears do not affect horsepower at all. They are simply a different ratio. They don't give you horsepower nor do they lose it.

:read:+1000

 

[rotor_powerd]

I should re-iterate my last two posts - gears will affect dyno numbers only, not your actual horsepower. I wasn't quite clear on that. Any gains or losses seen on the dyno after gears are installed should be ignored, as the numbers are just skewed from a different ratio.

 

[Wayne64SS]

Simple solution, dont worry to much about dyno #'s, go out to the track and see what it does. The track doesnt lie!

speaking of that.... are you going tonight? i might actually go.

 

[94Gt5.0]

speaking of that.... are you going tonight? i might actually go.

Nah, unfortunately:fm:

 

[jm@ReischePerf]

They will. You want to dyno in the gear that is closest to 1:1 with crank speed, to get the "realest" numbers.

This is the way I understand it as well.

 

[BlackBeauty44]

Umm....I thought gears help track times

 

[Jomo1994z71]

Yes, they do...not by much...I have 4.10s and have asked this ? several times on the boards and have never gotten a great/clear answer...from the research I have done on the subject matter, the difference is minimal and the 4.10 gears will cause you to dyno with #s that are a tad lower than the stock 3.55s...

 

[cozmo2806]

I would say the dyno would read 5 hp less or so. Maybe not even that much.

 

[NITROS COBRA]

just curious.... Stock cobras have what 3.55 gears? And lets say he nets 500rwhp on the dyno. Now same mods with the exception of 4.10 gears, will that dyno come out lower this time or the same and why?

yes, the dyno numbers do move slightly, with more gear. However hp and tq are just numbers by the way. With the addition of more gear and more roll out=faster car. Buddy lost 10-20RWHP and went half second in the quarter mile faster (12.0 to 11.48). Just an example. (3.55 to 4.10's)

 

[Jroc]

BHP no.

WHP yes.

 

[94Gt5.0]

yes, the dyno numbers do move slightly, with more gear. However hp and tq are just numbers by the way. With the addition of more gear and more roll out=faster car. Buddy lost 10-20RWHP and went half second in the quarter mile faster (12.0 to 11.48). Just an example. (3.55 to 4.10's)

Yup. I have 4.10's in my car along with a 4000rom stall converter. Needless to say she didnt shine on the dyno, made 277rwhp, but went 11.81@112 the next day at the track. It dumbfounded the local ricers that use the HP/ET calculator :lol1: