Rear End Gearing?

[arctic_blue83]

<div class='quotetop'>QUOTE (Greek8 @ Oct 28 2007, 05:05 PM) [url=index.php?act=findpost&pid=8550]<{POST_SNAPBACK}>[/url]</div>

Wow that's like dead right for the stock 6th gear. I am scared to ask how you did that because the answer will be so simple that I will feel stupid. If that's all the change in RPM I think I should still be ok on highway gas mileage.
Thanks[/b]

You're welcome lol.

In this gear calculator I posted:
http://www.turnzero.com/technical_resource...gear_calculator

Enter all the cars information, final drive, tire size, individual gear ratios (1st through 6th), then in the "Engine Max Speed (RPM)" just keep entering the RPM and hitting the "GO" button at the bottom until it says Maximum Speed in 6th gear is 65mph lol. With a stock redline of 9000rpm, it's about 186mph, so I just kept entering a lower/higher RPM until it said 65mph lol.

[GR-8]

<div class='quotetop'>QUOTE (arctic_blue83 @ Oct 28 2007, 06:15 PM) [url=index.php?act=findpost&pid=8552]<{POST_SNAPBACK}>[/url]</div>

You're welcome lol.

In this gear calculator I posted:
http://www.turnzero.com/technical_resource...gear_calculator

Enter all the cars information, final drive, tire size, individual gear ratios (1st through 6th), then in the "Engine Max Speed (RPM)" just keep entering the RPM and hitting the "GO" button at the bottom until it says Maximum Speed in 6th gear is 65mph lol. With a stock redline of 9000rpm, it's about 186mph, so I just kept entering a lower/higher RPM until it said 65mph lol.[/b]

See you just mad me feel very, very, outrageously [img]http://coloradomazdaclub.com/forums/style_emoticons/<#EMO_DIR#>/70bbd918.gif[/img] . [img]http://coloradomazdaclub.com/forums/style_emoticons/<#EMO_DIR#>/18756af5.gif[/img] I would have not thought of that at all.

[Huzer21]

<div class='quotetop'>QUOTE (Greek8 @ Oct 28 2007, 04:37 PM) [url=index.php?act=findpost&pid=8529]<{POST_SNAPBACK}>[/url]</div>

Half second off quarter time for a just gearing is great. What else gives you that for under $1000. The 4.77 gearing costs $300 for the 8 and whatever install is going to cost.[/b]

Where'd you find the Feed gears for $300? Used? I've only seen them at around $600-700.

[AIM WO4]

LOL. I used to drive my 1988 Mustang around town in 2nd gear. It did over 70 mph in 2nd. The sound of a V8 at 5K+ RPM, is just like music. My top speed (155) in that car was reached in 4th. 5th was OD, and it was too hard pushing air to be worthwhile.


<div class='quotetop'>QUOTE (arctic_blue83 @ Oct 28 2007, 04:40 PM) [url=index.php?act=findpost&pid=8531]<{POST_SNAPBACK}>[/url]</div>

On another note, for a car with a 9000rpm redline, the RX-8 has fairly tall gears... I don't know too many sports cars that 2nd gear goes almost to 70mph.... I'm assuming they kept the gears a bit on the taller side just to help out with gas mileage.[/b]

[arctic_blue83]

<div class='quotetop'>QUOTE (AIM WO4 @ Oct 29 2007, 10:32 AM) [url=index.php?act=findpost&pid=8675]<{POST_SNAPBACK}>[/url]</div>

LOL. I used to drive my 1988 Mustang around town in 2nd gear. It did over 70 mph in 2nd. The sound of a V8 at 5K+ RPM, is just like music. My top speed (155) in that car was reached in 4th. 5th was OD, and it was too hard pushing air to be worthwhile.[/b]

LOL, yeah tall gears are pretty common in V8 muscle/pony cars with lots of low end torque & broad powerbands, but in sports cars with narrow powerbands and high redlines gears that tall aren't that common.

[AIM WO4]

I think it came with 2.73 rear end. Something stupid like that...

<div class='quotetop'>QUOTE (arctic_blue83 @ Oct 29 2007, 02:01 PM) [url=index.php?act=findpost&pid=8706]<{POST_SNAPBACK}>[/url]</div>

LOL, yeah tall gears are pretty common in V8 muscle/pony cars with lots of low end torque & broad powerbands, but in sports cars with narrow powerbands and high redlines gears that tall aren't that common.[/b]

[GR-8]

<div class='quotetop'>QUOTE (Huzer21 @ Oct 29 2007, 10:22 AM) [url=index.php?act=findpost&pid=8673]<{POST_SNAPBACK}>[/url]</div>

Where'd you find the Feed gears for $300? Used? I've only seen them at around $600-700.[/b]

I found it on RX8 club. From what I understand from tht thread Here all you have to do is order it through kia. It will even fit an S2000. Shows that when it's sold as an RX8 part it's price is jacked up. Not a feed one but one that Mazda makes and distributes out to Kia. When I posted the price I didn't really read the thread and do research, I'm a little put off on the price now andsecond guessing the quality over the FEED setup. When I do put 4.77 in my 8 I might go with something I can trust. If future research in prices and whethter it is completly true the kia geering fits in the 8 I will go with FEED or someone else.

Quick Update: I was thinking also that I will most likely do this mod after I confirm that I do actually shift in to fourth before I hit the sensors for time to stop. If I remember right, I was really close to the sensors right before I passed the sensors. Would that be a good reason to do this and get a decrease in quarter time. Seeing as the RPM change does not change much in 6th gear at 65 I may go with 4.90 if I find anyone who sells it for the 8 or if it can be swapped from another car like the 4.77.

[Huzer21]

<div class='quotetop'>QUOTE (Greek8 @ Oct 29 2007, 11:59 PM) [url=index.php?act=findpost&pid=8791]<{POST_SNAPBACK}>[/url]</div>

I found it on RX8 club. From what I understand from tht thread Here all you have to do is order it through kia. It will even fit an S2000. Shows that when it's sold as an RX8 part it's price is jacked up. Not a feed one but one that Mazda makes and distributes out to Kia. When I posted the price I didn't really read the thread and do research, I'm a little put off on the price now andsecond guessing the quality over the FEED setup. When I do put 4.77 in my 8 I might go with something I can trust. If future research in prices and whethter it is completly true the kia geering fits in the 8 I will go with FEED or someone else.

Quick Update: I was thinking also that I will most likely do this mod after I confirm that I do actually shift in to fourth before I hit the sensors for time to stop. If I remember right, I was really close to the sensors right before I passed the sensors. Would that be a good reason to do this and get a decrease in quarter time. Seeing as the RPM change does not change much in 6th gear at 65 I may go with 4.90 if I find anyone who sells it for the 8 or if it can be swapped from another car like the 4.77.[/b]

Just read the entire thread on rx8club. About 3/4 of the way in (page 2,193), the Kia gears don't fit.

[arctic_blue83]

So I got bored today, and decided to use dyno info for an RX-8 that I got here:
http://www.dragtimes.com/images_dyno/8792-...a-RX-8-Dyno.jpg

It never ceases to amaze me that just entering torque numbers into a calculator can come up with a horsepower curve that's almost identical to the graph from where the torque numbers came from. I entered the numbers on a shift calculator over here:
http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html

Here are the results:



So given the RX-8's gear ratios, tire size, power & torque curves ect, the calculator recommends shifting at 9000rpm in EVERY gear for maximum performance. So unless you're trapping over 94mph, you should actually be able to ride out 3rd at the end of the 1/4 mile...

[GR-8]

That sucks. Would have been a nice cheap alternative if it worked. Looks like I will go with FEED or Knight Sports when or if the time comes to get it.

[GR-8]

<div class='quotetop'>QUOTE (arctic_blue83 @ Oct 30 2007, 03:29 PM) [url=index.php?act=findpost&pid=8912]<{POST_SNAPBACK}>[/url]</div>

So I got bored today, and decided to use dyno info for an RX-8 that I got here:
http://www.dragtimes.com/images_dyno/8792-...a-RX-8-Dyno.jpg

It never ceases to amaze me that just entering torque numbers into a calculator can come up with a horsepower curve that's almost identical to the graph from where the torque numbers came from. I entered the numbers on a shift calculator over here:
http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html...

...So given the RX-8's gear ratios, tire size, power & torque curves ect, the calculator recommends shifting at 9000rpm in EVERY gear for maximum performance. So unless you're trapping over 94mph, you should actually be able to ride out 3rd at the end of the 1/4 mile...[/b]

I'm trapping no where near 94. If I remember right it was 83 or 84 mph. I'll go dig up a time slip I think I have in my glove box. I'm always at redline and have to change to 4th before I get to the crossing line. Something sounds off to me about 3rd reaching 94 mph, though I have not tested that either.
Ok I an't find any of my old slips. I think I threw those out. I found one from Sep 2006 when I ran a horrible time of 17.02 sec. My speed was 82 so on my best runs of 16.2-16.4 84 mph seems right.

[arctic_blue83]

<div class='quotetop'>QUOTE (Greek8 @ Oct 30 2007, 03:38 PM) [url=index.php?act=findpost&pid=8917]<{POST_SNAPBACK}>[/url]</div>

I'm trapping no where near 94. If I remember right it was 83 or 84 mph. I'll go dig up a time slip I think I have in my glove box. I'm always at redline and have to change to 4th before I get to the crossing line. Something sounds off to me about 3rd reaching 94 mph, though I have not tested that either.
Ok I an't find any of my old slips. I think I threw those out. I found one from Sep 2006 when I ran a horrible time of 17.02 sec. My speed was 82 so on my best runs of 16.2-16.4 84 mph seems right.[/b]

Sometimes the little "beep" the redline indicator makes happens a few hundred RPMs before 9000rpm, are you sure you're at redline and not just hearing the beep?

If you can in fact finish out the 1/4 mile in 3rd, adding gears that would require a shift to 4th might be counterproductive.... although they would be great for road racing. I'm pretty sure the calculator was correct, as I know the info for the STI & MS6 was correct (I've owned both), the 4.77's would still allow you to run up to 86mph in 3rd and the 4.90's up to 84mph, so you might still be able to finish in 3rd if you're only trapping at 82mph... even though I would expect your trap speeds to go up with shorter gears.

Do you have aftermarket wheels? If so, what is your tire size? As your tire size would actually alter your gearing ratio slightly, and effect what speed you spin out to in each gear.

Either way, try pegging the rev limiter in 3rd on an open road with no traffic and see what speed it tops out at.

[GR-8]

No, I can't even here the beep really over the exhaust I always look at the tach. My tires are the same size as stock. Time didn't change from having stock tires to the all season I have on. Maybe me not being able to stay in third is because when in second I shift at 8500 rpm and not 9000. Or would that make me stay in third longer? IDK. Maybe I'll ride it out whe Bandi opens again untill I hit the rev limiter.

[arctic_blue83]

<div class='quotetop'>QUOTE (Greek8 @ Oct 30 2007, 04:07 PM) [url=index.php?act=findpost&pid=8932]<{POST_SNAPBACK}>[/url]</div>

No, I can't even here the beep really over the exhaust I always look at the tach. My tires are the same size as stock. Time didn't change from having stock tires to the all season I have on. Maybe me not being able to stay in third is because when in second I shift at 8500 rpm and not 9000. Or would that make me stay in third longer? IDK. Maybe I'll ride it out whe Bandi opens again untill I hit the rev limiter.[/b]

Are you sure you're not just shifting at 8500 in 3rd as well? It's been a while since I've driven an RX-8, but I'm pretty sure you can hit at least 90mph in 3rd.... someone who pushes their RX-8, feel free to chime in lol.

[GR-8]

<div class='quotetop'>QUOTE (arctic_blue83 @ Oct 30 2007, 04:13 PM) [url=index.php?act=findpost&pid=8933]<{POST_SNAPBACK}>[/url]</div>

Are you sure you're not just shifting at 8500 in 3rd as well? It's been a while since I've driven an RX-8, but I'm pretty sure you can hit at least 90mph in 3rd.... someone who pushes their RX-8, feel free to chime in lol.[/b]

You know, I'm not sure if I do shift at 8500 rpm. I'll have to see when Bandi opens. I'm 65% sue that I did go to 9000 rpm in 3rd. When Bandi opens I'll see for sure. I'm pretty sure I went all the way to 9k in third. Maybe if I go to 9k in second as well I will be able to ride it out. I whish bandi was open. It's been nice this week and cool night temps. Perfect wheather. Except for tommorows rain.