Gearing an the 1/4
#31
Joined: Jun 2005
Posts: 8,185
Likes: 0
From: Alabaster, Alabama
#32
Originally Posted by trey's wife
What the hell is this stuff with you shifting slow? I have now heard 2 people say this. I would be damn hard pressed to find someone who shifted faster. I would like these people to show what "fast" shifting is if yours is slow. There is a reason I hate riding with you.
#33
Originally Posted by cc1012
Slow shifting on your part and honda/acuras are actually geared pretty good. Way better then are cars. Our cars are geared like dirt
#34
#35
Originally Posted by IP05G35
Right now stock 5AT G35's finish the 1/4 mile at the end of 3rd gear right before the limiter... this is pretty good but I think if the gearing was lower, like 3.90-4.10, and you can finish at the end of 4th gear that would be ideal.
#36
Originally Posted by DaveB
I completely disagree. The Honda 5AT is geared like absolute crap (way too long of 1st and 2nd) and the G35 5AT is geared perfectly for the 1/4 mile (do the calculations and you'll the truth). The 6MTs are geared just about right too. The 07 cars have deeper gearing, but it's needed to match the slightly different powerband, the much heftier curb weight, and the taller tires. Overall, the gearing is about the same between the 1st and 2nd gen car. Keep in mind if takes quite a bit of gearing change to make a difference in the 1/4 mile. A great example is the 1996-1998 Cobras. They come stock with a 3.27. Adding a 3.55 or even a 3.73 won't really make any difference in the 1/4 mile, but adding a 4.11 or even 4.33 gear will help things dramatically. From the seat of the pants, the 3.73 geared Cobra "feels" quicker, but it's not.
#37
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Wow, nice excel sheet! Glad to see my car is closest to perfectly geared!
My tire is 25.9" vs stock 26.3".
I have since added ME spacer based on a post from My350Z, the guy whold sold me this S/C. A ME spacer gave him additional 17hp on this S/C when he did a before/after Dyno. I can't really feel the difference, but I haven't done any hard runs after ME spacer either.
Assume I am half as lucky & only get 10hp. That's another 0.1 in1/4 mile.
My stock tire is on 17x7 16 lb forged wheels, if I put that on, save 8lb per wheel from my 24lb PIAA (when I run 13.2), 32lb total unprung weight =120lb normal weigh loss, that's another 0.1 in 1/4 mile.
Now, the factor of 26.3 vs. 25.9" tire, hope to help me staying in gear longer (My second gear is non existant, I had to shift to 3 right after shift to 2, it revs up too fast with the S/C.)
Perhaps, this will give me another 0.1?
Will take this set-up to track in Oct. when it's cooler out there, my goal is high 12's. 12.999 is fine with me.
I brake torqe launch at 2500 rpm, should I be launching at 3000?
My tire is 25.9" vs stock 26.3".
I have since added ME spacer based on a post from My350Z, the guy whold sold me this S/C. A ME spacer gave him additional 17hp on this S/C when he did a before/after Dyno. I can't really feel the difference, but I haven't done any hard runs after ME spacer either.
Assume I am half as lucky & only get 10hp. That's another 0.1 in1/4 mile.
My stock tire is on 17x7 16 lb forged wheels, if I put that on, save 8lb per wheel from my 24lb PIAA (when I run 13.2), 32lb total unprung weight =120lb normal weigh loss, that's another 0.1 in 1/4 mile.
Now, the factor of 26.3 vs. 25.9" tire, hope to help me staying in gear longer (My second gear is non existant, I had to shift to 3 right after shift to 2, it revs up too fast with the S/C.)
Perhaps, this will give me another 0.1?
Will take this set-up to track in Oct. when it's cooler out there, my goal is high 12's. 12.999 is fine with me.
I brake torqe launch at 2500 rpm, should I be launching at 3000?
#38
Originally Posted by DaveB
If you're crossing the line at just north of 6K, then you're gearing is pretty ideal. The general rule of thumb is that you want to be crossing the finish line through the heart of your powerband and in a gear near a 1:1 ratio. You wouldn't want to gear any lower (ie a 3.7+ gear) nor would you want to go taller (3.3). Your MPHs are in the upper 103mph range and honestly, I think that's about the limit your car will ever see unless you start digging into the motor itself. The MPH is there, but the ET is not. As you know, your ET problem is due to your 60' and I also think it's due to the light weight flywheel which is killing the moment of inertia on the initial launch and bogging the motor down when the tires eventually hook about 15' out. My recommendation, and I believe your only viable option, to fix this ET problem is:
1) Slicks
2) OEM flywheel assembly
There are plenty on people on the 350Z site that use full blown slicks or cheater slicks mounted on 16" wheels that clear the same size brakes you have on your 05 G35. I'd research the wheel and tire types these Zs are using. I believe most of these guys are running 26" tall slicks which would work out perfectly because they would fractionally increase your gearing to bring you closer to crossing the line at an even more ideal 6500rpm and the extra gearing would overcome some of the drag associated with slicks on the far end of the track. I don't know about the Z crowd, but I know the Maxima crowd that uses 26" slicks typically see an ADDITIONAL 1mph gain with slicks because the car dead hooks (mid 1.7-low 1.8 60 foot) and all the power is placed to the ground in every gear even on the shift.
1) Slicks
2) OEM flywheel assembly
There are plenty on people on the 350Z site that use full blown slicks or cheater slicks mounted on 16" wheels that clear the same size brakes you have on your 05 G35. I'd research the wheel and tire types these Zs are using. I believe most of these guys are running 26" tall slicks which would work out perfectly because they would fractionally increase your gearing to bring you closer to crossing the line at an even more ideal 6500rpm and the extra gearing would overcome some of the drag associated with slicks on the far end of the track. I don't know about the Z crowd, but I know the Maxima crowd that uses 26" slicks typically see an ADDITIONAL 1mph gain with slicks because the car dead hooks (mid 1.7-low 1.8 60 foot) and all the power is placed to the ground in every gear even on the shift.
You certainly understand drag racing... and you even mentioned cheater slicks...
-john (old time drag racer)
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