Final Drive Ratio, wheel, and WHP changes

SS_Firehawk · 11-01-2017, 11:22 PM

347WHP/276WTQ

Regardless, the numbers kind of speak for themselves. I don't think there is any difference in dyno readings with the gear change. Which totally goes against what people were saying. I was expecting something in the 330whp neighborhood. The fact that it made 347 in the same conditions as the last dyno?!? Sorry for the abrupt end to the video, I shut the video early on accident. I wish I could've gotten my wheels on the dyno for a good reference. The dyno brake temp sensor took a dump before I could run with my normal wheels. I'll go back and get those done when the dyno is back up.

Elmo370z · 11-02-2017, 12:00 AM

Making old school dodge viper number with 4 less cylinders

jchammond · 11-02-2017, 01:47 AM

Good Job,
Didn’t realize your 342whp was made in 1:1 as well.....When are you putting in the Cam’s?
I’m ready to see it jump over the 375whp mark.

SS_Firehawk · 11-02-2017, 07:56 AM

Heh, I need to recover after spending some money on these + the install. I'm just so confused that power didn't go down.

Yeah, the 285/30/18 tires and wheels had to have definitely helped, just not 20WHP helped if you know what I mean. Theres a 2" diameter difference, the tires are 3lbs lighter than mine, and the wheels are lighter; I didnt have a scale, but the weight diff wasn't more than 7-10lbs max.

It was warmer outside last night than before, but the shop temps were the same. It's just interesting to me. Now I'm so closed to 350WHP, my balls hurt. And for reference, there was no retuning, just dyno. Afterwards I dropped by Martin's house and he kindly updated my gearing tables to fix SRM.

jchammond · 11-02-2017, 09:00 AM

Your speedometer stayed dead on because of speed sensor location,didn’t it?

SS_Firehawk · 11-02-2017, 10:05 AM

Not sure. I just know at 80mph I'm well over 3400rpm
And Ecutek fixed my SRM. It started screaming at over 100mph.

Jayhovah · 11-02-2017, 03:08 PM

DUDE. That is some serious NA power.

SS_Firehawk · 11-02-2017, 09:01 PM

Finishing testing Monday evening when I get back home. Wife says my car doesn't know how to shut the f#$k up and makes all kinds of noises lol

SS_Firehawk · 11-13-2017, 10:15 PM

I'm still waiting on the diff work to be complete, but I was doing some more research and this is what I came upon.

If you change your final drive, it should not reflect on a dyno when using a 1:1 gear. If you're running a lower final drive any dyno in 4th; your numbers will be lower because the rpm delta is greater when you calculate 4th gear with the lower final drive gear.

formula: rpm = (mph x final gear ratio x 336*) / tire diameter
(you get the gear calculation by multiplying the transmission gear ratio with the final drive gear ratio)

Using 4.08 as my final drive
with a 1:1 gear; 75 x 4.08 x 336 / 26.9 = 3822rpm
with a 1.27:1 gear; 75 x 5.1816 x 336 / 26.9 = 4854rpm
delta = 1032rpm

Using 3.69 as my final drive
with a 1:1 gear; 75 x 3.69 x 336 / 26.9 = 3456rpm
with a 1.27:1 gear; 75 x 4.6863 x 336 / 26.9 = 4390rpm
delta = 934rpm

Hopefully this helps make a bit more sense. There was a post on a forum talking about how the dyno calculates power, but I can't find it in my search history. It was a lot of math. But the calculations above at least make sense to my why anything but 1:1 reads lower.

chuckie311 · 11-15-2017, 04:00 PM

it did change my dyno numbers.. went 3.36 to 4.08 big change size
no matter what gear we dyno'd in the numbers were different..
both Dyno's between the 2 gears were exact same setup for my car..
i have done lots of research to find the answer and almost every forum i went to everyone had a change in dyno number with a gear change .
why your did not change is weird..

https://www.corvetteforum.com/forums...post1590896300

Quote:

Originally Posted by SS_Firehawk

I'm still waiting on the diff work to be complete, but I was doing some more research and this is what I came upon.

If you change your final drive, it should not reflect on a dyno when using a 1:1 gear. If you're running a lower final drive any dyno in 4th; your numbers will be lower because the rpm delta is greater when you calculate 4th gear with the lower final drive gear.

formula: rpm = (mph x final gear ratio x 336*) / tire diameter
(you get the gear calculation by multiplying the transmission gear ratio with the final drive gear ratio)

Using 4.08 as my final drive
with a 1:1 gear; 75 x 4.08 x 336 / 26.9 = 3822rpm
with a 1.27:1 gear; 75 x 5.1816 x 336 / 26.9 = 4854rpm
delta = 1032rpm

Using 3.69 as my final drive
with a 1:1 gear; 75 x 3.69 x 336 / 26.9 = 3456rpm
with a 1.27:1 gear; 75 x 4.6863 x 336 / 26.9 = 4390rpm
delta = 934rpm

Hopefully this helps make a bit more sense. There was a post on a forum talking about how the dyno calculates power, but I can't find it in my search history. It was a lot of math. But the calculations above at least make sense to my why anything but 1:1 reads lower.

jchammond · 11-16-2017, 03:11 AM

I'm gonna find out soon on mine next month.
7A/T made 309/253 whp/tq in 4th gear (1.41:1) & 314/264 in 5th (1:1)
5th was on same type Dynojet Dyno at different place,,,as when tuned-Tuner's Dyno didn't support speeds above 170mph....so should be under the 170 mark w/3.69 gearing in 5th.
Only performance changes since tuned are the up-graded hi-flow air filter kit from Z1.

SS_Firehawk · 12-01-2017, 12:11 AM

So I finally got my car back in the shop to finish Dyno testing. The only changes made was my oil and I added Z1 motor and transmission mounts.ill post up data when I have the DRF's. I'll also combine the videos of the runs. Temps were mildly warm and humid, but not terrible. So the runs...

4th gear... 331whp
5th gear: 340whp 3x in a row.

When I had 3.69's and the same wheel/tire combo, I made 342. So between environmental variables, I'll say its negligible. The 347whp result must be a combination of a 12lbs loss of wheel weight and a smaller diameter wheel and tire combo.

Calg37USMC · 12-01-2017, 02:46 AM

So you’re the guy off YouTube. Ha great numbers! Car looks great.

jchammond · 12-01-2017, 04:29 AM

Quote:

Originally Posted by SS_Firehawk

So I figured Ally got my car back in the shop to finish Dyno testing. The only changes made was my oil and I added Z1 motor and transmission mounts.ill post up data when I have the DRF's. I'll also combine the videos of the runs. Temps were mildly warm and humid, but not terrible. So the runs...

4th gear... 331whp
5th gear: 340whp 3x in a row.

When I had 3.69's and the same wheel/tire combo, I made 342. So between environmental variables, I'll say its negligible. The 347whp result must be a combination of a 12lbs loss of wheel weight and a smaller diameter wheel and tire combo.

Un-sure what kinda #'s mine will make on 12/9,,,but gonna roll with what's on the Z.
Wheel's & tires are a bit heavier than last tuning; but it's what i'm running & gonna hit the dragstrip with same set-up.
I'll post up when i get result's...Most importantly want the AFR/Timing correct on Z for optimal power for the few mod's i have.
Then we're going down in the 12's w/345's on 12's & 285's up front on 10's.....Wheel/tire setup will change for the dragstrip for sure-as i know these will stunt me back somewhat.

SS_Firehawk · 12-01-2017, 08:49 AM

Heh, yeah, I make a few. Mostly Mexico stuff. Idk. I just started playing with Adobe premiere and I have a Go Pro and Waylens set up. Thinking of getting an OBD2 splitter and run Harry's lap timer as well. Debating doing a car overview, but idk if I want to do all that video blog ****. Most of the time I like straight and too the point.

11-01-2017, 11:22 PM	#16 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	347WHP/276WTQ Regardless, the numbers kind of speak for themselves. I don't think there is any difference in dyno readings with the gear change. Which totally goes against what people were saying. I was expecting something in the 330whp neighborhood. The fact that it made 347 in the same conditions as the last dyno?!? Sorry for the abrupt end to the video, I shut the video early on accident. I wish I could've gotten my wheels on the dyno for a good reference. The dyno brake temp sensor took a dump before I could run with my normal wheels. I'll go back and get those done when the dyno is back up. JARblue, Rusty, Hotrodz and 3 others like this. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

11-02-2017, 12:00 AM	#17 (permalink)
Elmo370z A True Z Fanatic Join Date: Apr 2013 Location: st. petersburg Posts: 5,709 Drives: 09 nissan 370z Sp M6 Rep Power: 295378	Making old school dodge viper number with 4 less cylinders SS_Firehawk and Hotrodz like this.

11-02-2017, 01:47 AM	#18 (permalink)
jchammond A True Z Fanatic Join Date: Nov 2014 Location: South Carolina Age: 58 Posts: 15,204 Drives: 13’ 370Z TS 7A/T Rep Power: 2684395	Good Job, Didn’t realize your 342whp was made in 1:1 as well.....When are you putting in the Cam’s? I’m ready to see it jump over the 375whp mark. __________________ MazWorx built long block \| FI-TT-100 Stage 2.75 \| IPT built 7A/T http://www.the370z.com/members-370z-...s-musings.html

11-02-2017, 07:56 AM	#19 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	Heh, I need to recover after spending some money on these + the install. I'm just so confused that power didn't go down. Yeah, the 285/30/18 tires and wheels had to have definitely helped, just not 20WHP helped if you know what I mean. Theres a 2" diameter difference, the tires are 3lbs lighter than mine, and the wheels are lighter; I didnt have a scale, but the weight diff wasn't more than 7-10lbs max. It was warmer outside last night than before, but the shop temps were the same. It's just interesting to me. Now I'm so closed to 350WHP, my balls hurt. And for reference, there was no retuning, just dyno. Afterwards I dropped by Martin's house and he kindly updated my gearing tables to fix SRM. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

11-02-2017, 09:00 AM	#20 (permalink)
jchammond A True Z Fanatic Join Date: Nov 2014 Location: South Carolina Age: 58 Posts: 15,204 Drives: 13’ 370Z TS 7A/T Rep Power: 2684395	Your speedometer stayed dead on because of speed sensor location,didn’t it? __________________ MazWorx built long block \| FI-TT-100 Stage 2.75 \| IPT built 7A/T http://www.the370z.com/members-370z-...s-musings.html

11-02-2017, 10:05 AM	#21 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	Not sure. I just know at 80mph I'm well over 3400rpm And Ecutek fixed my SRM. It started screaming at over 100mph. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

11-02-2017, 09:01 PM	#23 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	Finishing testing Monday evening when I get back home. Wife says my car doesn't know how to shut the f#$k up and makes all kinds of noises lol Rusty, Hotrodz, Elmo370z and 1 others like this. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

11-13-2017, 10:15 PM	#24 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	I'm still waiting on the diff work to be complete, but I was doing some more research and this is what I came upon. If you change your final drive, it should not reflect on a dyno when using a 1:1 gear. If you're running a lower final drive any dyno in 4th; your numbers will be lower because the rpm delta is greater when you calculate 4th gear with the lower final drive gear. formula: rpm = (mph x final gear ratio x 336) / tire diameter (you get the gear calculation by multiplying the transmission gear ratio with the final drive gear ratio) Using 4.08 as my final drive with a 1:1 gear; 75 x 4.08 x 336 / 26.9 = 3822rpm with a 1.27:1 gear; 75 x 5.1816 x 336 / 26.9 = 4854rpm delta = 1032rpm Using 3.69 as my final drive with a 1:1 gear; 75 x 3.69 x 336 / 26.9 = 3456rpm with a 1.27:1 gear; 75 x 4.6863 x 336 / 26.9 = 4390rpm delta = 934rpm Hopefully this helps make a bit more sense. There was a post on a forum talking about how the dyno calculates power, but I can't find it in my search history. It was a lot of math. But the calculations above at least make sense to my why anything but 1:1 reads lower. __________________ Old Car:GTM TSC'd* 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction Last edited by SS_Firehawk; 11-13-2017 at 10:17 PM.

11-16-2017, 03:11 AM	#26 (permalink)
jchammond A True Z Fanatic Join Date: Nov 2014 Location: South Carolina Age: 58 Posts: 15,204 Drives: 13’ 370Z TS 7A/T Rep Power: 2684395	I'm gonna find out soon on mine next month. 7A/T made 309/253 whp/tq in 4th gear (1.41:1) & 314/264 in 5th (1:1) 5th was on same type Dynojet Dyno at different place,,,as when tuned-Tuner's Dyno didn't support speeds above 170mph....so should be under the 170 mark w/3.69 gearing in 5th. Only performance changes since tuned are the up-graded hi-flow air filter kit from Z1. __________________ MazWorx built long block \| FI-TT-100 Stage 2.75 \| IPT built 7A/T http://www.the370z.com/members-370z-...s-musings.html

12-01-2017, 12:11 AM	#27 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	So I finally got my car back in the shop to finish Dyno testing. The only changes made was my oil and I added Z1 motor and transmission mounts.ill post up data when I have the DRF's. I'll also combine the videos of the runs. Temps were mildly warm and humid, but not terrible. So the runs... 4th gear... 331whp 5th gear: 340whp 3x in a row. When I had 3.69's and the same wheel/tire combo, I made 342. So between environmental variables, I'll say its negligible. The 347whp result must be a combination of a 12lbs loss of wheel weight and a smaller diameter wheel and tire combo. jchammond likes this. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction Last edited by SS_Firehawk; 12-01-2017 at 07:23 AM.

12-01-2017, 02:46 AM	#28 (permalink)
Calg37USMC Base Member Join Date: Oct 2017 Location: Seattle Posts: 40 Drives: 12’G37sSedan GAC 6MT Rep Power: 8	So you’re the guy off YouTube. Ha great numbers! Car looks great. SS_Firehawk likes this.

12-01-2017, 08:49 AM	#30 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	Heh, yeah, I make a few. Mostly Mexico stuff. Idk. I just started playing with Adobe premiere and I have a Go Pro and Waylens set up. Thinking of getting an OBD2 splitter and run Harry's lap timer as well. Debating doing a car overview, but idk if I want to do all that video blog **. Most of the time I like straight and too the point. __________________ Old Car:GTM TSC'd** 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

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