3.9 FD and the Quarter Mile
#1
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I've searched and searched and...
So now I ask, has anyone taken their mildly modded Z WITH 3.9 final drive to the track and gotten numbers?
I learned that most of the guys with the FD got it for autoX purposes and that it doesn't help much in the 1/4 cause of extra shifting or whatever.
I would like to know if anyone has improved their 1/4 times as a result of this mod.
Thanks in advance for any useful input.
So now I ask, has anyone taken their mildly modded Z WITH 3.9 final drive to the track and gotten numbers?
I learned that most of the guys with the FD got it for autoX purposes and that it doesn't help much in the 1/4 cause of extra shifting or whatever.
I would like to know if anyone has improved their 1/4 times as a result of this mod.
Thanks in advance for any useful input.
#2
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"zillinois" posted a review a while back and the gains were only a couple tenths but i want to say that the track conditions were bad...he seemed happy with the gain if i remember correctly.
edit: After some searching i am wrong, it was more of a review for the tilton clutch but he threw the gears in at the same time. He has commented on the gears in a few threads though.
https://my350z.com/forum/showthread....threadid=98858 <---that is one of them
edit: After some searching i am wrong, it was more of a review for the tilton clutch but he threw the gears in at the same time. He has commented on the gears in a few threads though.
https://my350z.com/forum/showthread....threadid=98858 <---that is one of them
Last edited by kwiker; 04-19-2007 at 02:32 PM.
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Boy do I have good news for you guys...
I just went to the track on wednesday to test this out (sears point for us old timers, infineon raceway for the new school.) Here's what I have:
2003 350z track (a few ticks under 30k mi)
When I ran it with just the test pipes i was hitting about 14.1-14.0
Now I have the plenum spacer (don't really think it did anything)
central 20 3.9 final drive
275 bfg kds in the rear
pulled consistent 13.6s at about 102-103. Big problem in 4th gear though b/c i can't finish in 4th if i get a good launch (1.9 or lower.)
If i pull 2.0s it barely makes it out (hits the "soft" revlimit at the end)
last run of the night i was losing so i just stayed on it and hit fuel cut before the end (OUCH)
best run of the night was 13.6 @ 90mph (i consider this the best run b/c i might have hit 13.5 if i stayed on it but i was well ahead so i hit brakes.)
so now i'm probably gonna go with the technosquare l-spec so i can rev it higher and hopefully hit 13.5ish. at about 350 bucks it seems like its worth it.
so was it worth 1/2 a second? almost.. i'm sure the tires also helped my launches out. but end result is that i don't wanna go back without the raised rev limit!
***EDIT i'm stupid... i wasn't even hitting 102 and i was hitting the rev limiter. highest mph was only 101.8! I don't think i ever saw 103. don't know what i was smoking.
I just went to the track on wednesday to test this out (sears point for us old timers, infineon raceway for the new school.) Here's what I have:
2003 350z track (a few ticks under 30k mi)
When I ran it with just the test pipes i was hitting about 14.1-14.0
Now I have the plenum spacer (don't really think it did anything)
central 20 3.9 final drive
275 bfg kds in the rear
pulled consistent 13.6s at about 102-103. Big problem in 4th gear though b/c i can't finish in 4th if i get a good launch (1.9 or lower.)
If i pull 2.0s it barely makes it out (hits the "soft" revlimit at the end)
last run of the night i was losing so i just stayed on it and hit fuel cut before the end (OUCH)
best run of the night was 13.6 @ 90mph (i consider this the best run b/c i might have hit 13.5 if i stayed on it but i was well ahead so i hit brakes.)
so now i'm probably gonna go with the technosquare l-spec so i can rev it higher and hopefully hit 13.5ish. at about 350 bucks it seems like its worth it.
so was it worth 1/2 a second? almost.. i'm sure the tires also helped my launches out. but end result is that i don't wanna go back without the raised rev limit!
***EDIT i'm stupid... i wasn't even hitting 102 and i was hitting the rev limiter. highest mph was only 101.8! I don't think i ever saw 103. don't know what i was smoking.
Last edited by gotbooost; 04-21-2007 at 02:13 PM.
#6
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A 3.9 final drives sounds like a disadvantage if you cannot cross the finish line at the top of fourth gear. BTW nice numbers. Post a time slip here: https://my350z.com/forum/drag/233840-top-25-1-4-mile-times-for-tt-st-supercharger-nitrous-bolt-ons-stock.html.
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thanks davidv i posted the slip on the other thread.
well i know it did improve my time... if i go back before the technosquare l-spec reflash then i'll try shifting into 5th.
I think the central 20 3.9 fd is worth it if you don't care about gas mileage-if you thought your z was bad on gas wait till you try this out! I really don't drive the z every day since i have to park in some tight spots every day. Got a really crappy crx for that.
i'm in the left lane (69)
well i know it did improve my time... if i go back before the technosquare l-spec reflash then i'll try shifting into 5th.
I think the central 20 3.9 fd is worth it if you don't care about gas mileage-if you thought your z was bad on gas wait till you try this out! I really don't drive the z every day since i have to park in some tight spots every day. Got a really crappy crx for that.
i'm in the left lane (69)
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#9
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Originally Posted by RBlover69
i wonder why it makes your gas usuage worse. Never really got into it is it because of the power being avaible all the time earlier?
OP-nice times, Im surprised you cant go over 102mph with the 3.9FD, what size rear tires do you run you should be losing 10mph in 4th gear.
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they're 275/40/18 on the stock track rays 18s.
before i did this i went to http://www.miata.net/garage/tirecalc.html
to see how close the tire diameter would be in relation to stock and it was dead on (well about .5mm smaller)
i remember trying out some other calculator online where you punch in gear ratios + final drive ratio + tire diameter to get top speeds in every gear and it said i could hit 104 or 105. i figured i wouldn't hit that anyways but maybe the calculator i chose was off somehow.
i'm thinking the technosquare ecu will do for now until the 08 g coupe or the gtr comes out
before i did this i went to http://www.miata.net/garage/tirecalc.html
to see how close the tire diameter would be in relation to stock and it was dead on (well about .5mm smaller)
i remember trying out some other calculator online where you punch in gear ratios + final drive ratio + tire diameter to get top speeds in every gear and it said i could hit 104 or 105. i figured i wouldn't hit that anyways but maybe the calculator i chose was off somehow.
i'm thinking the technosquare ecu will do for now until the 08 g coupe or the gtr comes out
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#11
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Originally Posted by RBlover69
i wonder why it makes your gas usuage worse. Never really got into it is it because of the power being avaible all the time earlier?
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