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View Full Version : Road Dyno 3rd gear vs. 4th gear



Looney Tuning
09-20-2009, 07:51 PM
I tune Evo Xs in 4th gear. 3rd gear is just too darn short and the data collected is limited especially when tuning ECUboost and have to log WGDCC, passive and active WGDC along with all the other parameters.

On the last three Evo Xs that I tuned I decided to do 3rd gear WOT runs alongside the 4th gear WOT runs that I usually do. The 4th gear run was done first and it was immediately followed by the 3rd gear run with a little cool down drive around the block in between.

I did the logs on the same on-ramp, on the same day with about 5 minutes separating the runs.

On the first Evo X I did the runs after I tuned the car. Here are the results. The “Benchmark Power” is 4th gear and the “Your Power” is 3rd gear.

On this car the 3rd gear run produced 27 more hp than the 4th gear run. Most of the HP gain was centered above 6000 rpm. The torque gain was also higher at the low end by about 17 ft-lb of torque.

http://www.sr20deracing.com/looneytuning/Evo/DLL_4th_3rd/dyno_3rd_4th_gear.gif

On the 2nd Evo X I did the runs on the stock tune. Here are the 3rd and 4th gear runs overlayed.

The gains in 3rd gear over 4th gear on this Evo X was more striking. At 7000 rpm the car gained 27hp and 20 ft-lb of torque by simply using a different gear. Even more interesting are the gains beginning around 4300 rpm and holding all the way to redline.

http://www.sr20deracing.com/looneytuning/Evo/DLL_4th_3rd/dyno_base_3rd4th.gif

On the 3rd Evo, I ran the logs after the tune was finalized. Once again the “benchmark power” is 4th gear and the “your power” is 3rd gear.

Just like on the first Evo X, this one gained 23 hp by simply dynoing the car in 3rd gear instead of 4th gear. I did not do the torque at 7000 rpm, but as you can see there are at least 12 ft-lb gain at 7000 rpm.

http://www.sr20deracing.com/looneytuning/Evo/DLL_4th_3rd/dyno_3rd_4th.gif

If we average the hp gains from simply dynoing an Evo X in 3rd gear over 4th gear we get 25.6 hp. I was surprised to find out that there is that much gain between 4th gear and 3rd gear. When I checked the gear ratios I found that 3rd gear was 1.444:1 and 4th gear was 1.096:1. 4th gear is the closest 1:1 gear and should be the one used on the dyno. If you are into accurate peak numbers (I am not. I am into gains), then dynoing in 4th gear will give you a less inflated number than 3rd gear.

EvoPwr
09-20-2009, 08:13 PM
Good job bro, what i am more amazed by is the difference in rpm.* 4th gear spools earlier which we all know, but I did not know it was that much earlier looks like around 250rpm in some parts.

earlyapex
09-20-2009, 09:06 PM
I see hardly any horsepower difference in 3rd and 4th gear pulls on our Mustang dyno. The torque is higher in 4th because the turbo spools quicker so it's in a different area of VE of the motor.. It does not magically make "different" power in different gears.

3rd and 4th (dotted is 4th), the slightly different power up top was slightly higher boost then error correction kicking in:

http://norcalmotorsports.org/users/bryan/mods/EVO/evo_tunes/brian_j/081509_betaBBK/brian_BBK_beta_3rd4th_08150.jpg

3rd and 4th (solid is 4th)

http://norcalmotorsports.org/users/bryan/mods/EVO/evo_tunes/brian_j/010309_BBK/brian_j_BBK_E85_010309.jpg

3rd gear:

http://norcalmotorsports.org/users/bryan/mods/EVO/evo_tunes/Scott_S_082707/Scott_S_100oct_343whp.jpg

4rth gear:

http://norcalmotorsports.org/users/bryan/mods/EVO/evo_tunes/Scott_S_082707/Scott_S_100oct_4th_gear.jpg

Looney Tuning
09-20-2009, 09:28 PM
^^Are these dynos you posted for an Evo X or Evo 8/9?

earlyapex
09-20-2009, 09:30 PM
^^Are these dynos you posted for an Evo X or Evo 8/9?


They are Evo 9's. Why does it matter? I can print out some 10's as well if needed but they are the same.

EvoPwr
09-20-2009, 09:32 PM
just curious, do you have the log of the boost, to see how different it is between the gears? I am wondering if there is more boost holding up top for 3rd

Looney Tuning
09-20-2009, 10:13 PM
^^Are these dynos you posted for an Evo X or Evo 8/9?


They are Evo 9's. Why does it matter? I can print out some 10's as well if needed but they are the same.


I find it interesting that there is no difference in hp when it comes to gearing on your dyno. Here is my old Evo 8 on TT's dyno with 3rd and 4th gear back to back. The behavior is close to what DLL showed on the X. The 3rd gear trace was 16 hp higher than the 4th gear trace.

http://www.sr20deracing.com/looneytuning/Evo/DLL_4th_3rd/Evo8_dyno_3rd_4th.gif

Here is my SE-R in 3rd vs. 4th gear on another dynojet. 3rd gear produced more power than 4th gear; 158.51 hp in 3rd to 155.46 in 4th gear.

http://www.sr20deracing.com/looneytuning/Evo/DLL_4th_3rd/SE-R_3rd-4th_dyno.gif

Looney Tuning
09-20-2009, 10:20 PM
just curious, do you have the log of the boost, to see how different it is between the gears? I am wondering if there is more boost holding up top for 3rd


I will try and overlay the boost plots in 3rd gear and 4th gear.

earlyapex
09-20-2009, 10:23 PM
Did you synch it to each gear or synch it to one gear but do the pull in another?

Why do you think the car should make different power in each gear? If it was because of the gear ratio I would imagine it would be in the whole curve. Do you see the car hit different load cells in each gear?

3rd and 4th:

http://www.norcalmotorsports.org/users/bryan/mods/EVO/tech/3rd_and_4th_load_boost.gif

1st through 3rd:

http://www.norcalmotorsports.org/users/bryan/mods/EVO/tech/Me_1st3rd_052108.gif

x[corwyn]
09-20-2009, 10:33 PM
Im considering a road tune, just to get my car to run better and to hopefully increase its mileage some. However.... Where on earth are you doing 4th gear runs to its redline?! Thats pretty fast for most roads here.

Looney Tuning
09-20-2009, 10:51 PM
]
Im considering a road tune, just to get my car to run better and to hopefully increase its mileage some. However.... Where on earth are you doing 4th gear runs to its redline?! Thats pretty fast for most roads here.


Freeway on-ramps are your friend :D

SDevo
09-20-2009, 11:07 PM
Mr loney tune, did you get my PM :)

Looney Tuning
09-20-2009, 11:10 PM
Did you synch it to each gear or synch it to one gear but do the pull in another?

Why do you think the car should make different power in each gear? If it was because of the gear ratio I would imagine it would be in the whole curve. Do you see the car hit different load cells in each gear?


Here is the 3rd gear chart:

http://www.sr20deracing.com/looneytuning/Evo/DLL_4th_3rd/psi_afr_tim_3rdgear.gif

Here is the 4th gear chart:

http://www.sr20deracing.com/looneytuning/Evo/DLL_4th_3rd/psi_afr_tim_4thgear.gif

They are almost exactly the same per rpm tag. The only difference is the gear used. 3rd gear produced more power than 4th gear for some reason.

4G63 FEVER
09-21-2009, 10:17 AM
]
Im considering a road tune, just to get my car to run better and to hopefully increase its mileage some. However.... Where on earth are you doing 4th gear runs to its redline?! Thats pretty fast for most roads here.


Freeway on-ramps are your friend :D


Just come up to the high desert miles of open roads to do this on :D :D :D! One of the few good things about living here.

Ask Naji about Looney Blvd :grin: :grin:.

spdracerut
09-23-2009, 06:35 PM
Does the DLL take into account air drag? If not, that's your answer. I know Evoscan does take into account drag though.... The other possibility, the ramp is not of equal grade over the distance of the 4th gear pull. The 3rd gear pull will finish a lot sooner, so the average grade of the ramp will be different as 3rd gear is hitting redline at a different point.

anxiouz
09-23-2009, 08:30 PM
If this is the onramp I think it is, it's fairly flat for the most part. I don't think grade is a factor here. I believe it actually slopes slightly downhill by just a bit if anything. But I dunno.

Doctor Evo
10-14-2009, 02:31 PM
uhh.... how arcurate are road tunes? and are they even safe?

has anyone ever gotten a ticket before? LOL

Looney Tuning
10-19-2009, 09:25 PM
uhh.... how arcurate are road tunes? and are they even safe?

has anyone ever gotten a ticket before? LOL


Before dynos became cheap and popular, almost all of the Evos tuned in SoCal were tuned on the road. RRE did not have a dyno for a long time and their tunes were praised by a lot of people on these boards. All the cars that I have tuned have had ZERO mechanical problems. Not one of them have blown up. I would say that would qualify as safe and accruate. Don't you?

To date I have tuned 131 cars and not one ticket. Never gotten pulled over or harassed by the cops.

SoCalRedLine
10-19-2009, 10:10 PM
I think what you're seeing is how dll calculates power v. The dyno. Third gear is a larger ratio than fourth, and you will see a quicker acceleration, this fooling the calculation by a certain percentage. Iirc, the dyno program can take this into account and average the power between third and fourth better than a datalog capture can.
Also, wind drag increases exponentially with speed (^2) so the difference in drag force between 80 and 120 is pretty big.*

Iunno, tho, it's just an educated guess...but good writeup as always Naji :)