I know most people tune in 4th because it's gear ratio is closer to 1.

 

Anyone?

 

the advantage is that when you're paying hourly for dyno time, you can take more pulls since 3rd pulls faster through the rpm range.

3rd gear always give me less peak #'s... so you know it has a little more in it when you go to 4th.

for the final run, i do 4th - just to make sure she's nice and smooth - 4th has better resolution and detail (imho). more load, y'know.....

 

Does it have anything to do with 4th being a 1:1 direct drive ratio on most 5spds?

 

Kenny, I was always under the impression that third would result in higher readings.

 

I think 3rd gear would give more hp because of the gear reduction.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RYANR1 &raquo;</TD></TR><TR><TD CLASS="quote">I think 3rd gear would give more hp because of the gear reduction.</TD></TR></TABLE>


.....well on the several different dynojet's I've used, 3rd gear always reads lower.

It doesn't matter, since it's only a couple hp either way.

The point it to get consistent readings.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RYANR1 &raquo;</TD></TR><TR><TD CLASS="quote">Does it have anything to do with 4th being a 1:1 direct drive ratio on most 5spds?</TD></TR></TABLE>

4th isn't 1:1 on many FWD transmissions, if any. (I'm sure there's at least a few out there) It is on a lot of RWD, but FWD skips around it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RYANR1 &raquo;</TD></TR><TR><TD CLASS="quote">I think 3rd gear would give more hp because of the gear reduction.</TD></TR></TABLE>

Remember, horsepower is the same for each gear. It might be a little different due to changing torque readings from the loss in the transmission, but mathematically it's the same.

Also, don't forget the gear ratio correction the ecu performs for each gear...

 

So why 4th instead of 3rd?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black R &raquo;</TD></TR><TR><TD CLASS="quote">


.....well on the several different dynojet's I've used, 3rd gear always reads lower.

It doesn't matter, since it's only a couple hp either way.

The point it to get consistent readings. </TD></TR></TABLE>

Same here.

All my posted plots are 3rd now that I think of it.. Doh

 

on a Dyno Jet 4th gear allways makes more peak .....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MAX_CFM &raquo;</TD></TR><TR><TD CLASS="quote">on a Dyno Jet 4th gear allways makes more peak .....

</TD></TR></TABLE>
unless you have an ATS 3-4-5 gearset. then you'd want to use 5th.. since it redlines at about 110mph anyway.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mike K &raquo;</TD></TR><TR><TD CLASS="quote">
unless you have an ATS 3-4-5 gearset. then you'd want to use 5th.. since it redlines at about 110mph anyway.</TD></TR></TABLE>


Actually, that is a good tip!


-t3h r0ck3r, who has yet to install these bad boy pieces sitting in his trunk.....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MAX_CFM &raquo;</TD></TR><TR><TD CLASS="quote">on a Dyno Jet 4th gear allways makes more peak .....

</TD></TR></TABLE>
Almost always. On my last trip to the dyno we made a fourth gear pull after tuning and the car made less.

 

Sorry Let me rephrase that .. With High Horsepower setups.. and tuned in each gear..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cruzersi00 &raquo;</TD></TR><TR><TD CLASS="quote">I know most people tune in 4th because it's gear ratio is closer to 1.</TD></TR></TABLE>

sometimes we spin in 3rd and strapping harder doesn't always help (plus eats away at power), so we use 4th ... it puts alot more load on the engine

also remember Larry W said that it may also help settle the exhaust timing events in the higher gears.

Greg

 

sometimes it depends on the horse power but its more accurate to tune it in whatever gear you are when you crossed the 1/4 mile..

 

The rate at which at which the mass of the engine is absorbing energy is higher in 3rd gear. On engine dynos there are inertia factors to compensate for this.

 

awww boo no more switching wheels for more power