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-   -   Final Drive Ratio, wheel, and WHP changes (http://www.the370z.com/engine-drivetrain/124439-final-drive-ratio-wheel-whp-changes.html)

SS_Firehawk 11-01-2017 10:22 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.

https://farm5.staticflickr.com/4478/...63c72d09_b.jpg

http://www.youtube.com/watch?v=nLk_15yNTSI

Elmo370z 11-01-2017 11:00 PM

Making old school dodge viper number with 4 less cylinders

jchammond 11-02-2017 12:47 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 06:56 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 08:00 AM

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

SS_Firehawk 11-02-2017 09:05 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 02:08 PM

DUDE. That is some serious NA power.

SS_Firehawk 11-02-2017 08:01 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 09:15 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 03:00 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 (Post 3707163)
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 02:11 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 11-30-2017 11:11 PM

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 01:46 AM

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

jchammond 12-01-2017 03:29 AM

Quote:

Originally Posted by SS_Firehawk (Post 3711561)
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 07:49 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.


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