10 I believe
New owner looking for some track advice (not new to tracking)
- Thread starter Aladdin9
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I would disagree. Gears are torque multipliers, and the JDM gears have lower ratios (higher numbers) in 2nd, 3rd, and 4th gear, so these three gears multiply the engine's torque more than the US gears which makes the car accelerate faster in every gear.
1st gear - 3.071
2nd gear - 1.8 (1.952 JDM)
3rd gear - 1.23 (1.4 JDM)
4th gear - 0.967 (1.033 JDM)
5th gear - 0.771
The top speed in each gear (for a 245/45-17 tire) is:
1st - 47
2nd - 80 (74 JDM)
3rd - 118 (103 JDM)
4th - 150 (140 JDM)
5th - 188
If you are in gear 2-3-4 at any RPM, the JDM ratios will be faster than the US ratios. The JDM ratios also has a much lower RPM drop from 1st-2nd and 2nd-3rd. However shifting from 3rd to 4th there is a 400rpm greater RPM drop in the JDM ratio, but at 5,900rpm there is only a ~5lb-ft of torque deficit compared to 6,300rpm for the US gear, but once the US ratio shifts into 4th, its higher ratio (lower number) will accelerate slower in 4th gear than the JDM 4th. The JDM ratios will improve lap time and acceleration when in any of these gears.
The JDM ratios will suffer shifting to 5th with a larger RPM drop, but in NA form, there are very few tracks where an NSX will see over 140-150mph and actually need 5th gear. On most tracks, the NSX is essentially a 3 speed transmission, using gears 2-3-4 where the JDM ratios are faster.
0.02
I wouldn't stretch a 255 on a 10" rear wheel. Do a 265 or 275
That's true. However, they are not faster at all SPEEDS. At any given speed, the shortest gearing produces the fastest acceleration. Because the shift points are different between the two sets of gears (45, 81, 114, 144 for the stock '91-94 gears, 45, 73, 101, 139 for the JDM five-speed gears), this creates "speed bands" which favor one set of gears or the other, depending on which gearset is shorter at that speed. Between 45 and 73 mph, there is a slight advantage for the JDM set using a 13 percent shorter second gear (1.952 ratio - the higher the number, the shorter the ratio) than the OEM set using second gear (1.727). But between 73 mph and 81 mph, there is a much greater advantage for the OEM set using second gear (1.727) which is 23 percent shorter than the JDM set using third gear (1.400). Similarly, between 81 and 101, the JDM third (1.400) accelerates faster than the OEM third (1.230). Between 101 and 114, the OEM third (1.230) accelerates much faster than the JDM fourth (1.033). And so forth.
Overall, the JDM gears accelerate faster up to 73 mph, but the OEM gears accelerate faster above that point. Bob Butler* has calculated the acceleration of both gearsets on a stock '91 as follows:
0-150 mph: OEM 37.78 seconds, JDM 41.06 seconds
0-70 mph (gears 1-2 on both setups): OEM 6.59 seconds, JDM 6.27 seconds
70-110 mph (gears 2-3): OEM 8.12 seconds, JDM 8.60 seconds
110-150 mph (gears 3-5): OEM 23.07 seconds, JDM 26.19 seconds
And this explains why the JDM setup accelerates quicker at stoplights (where speeds are primarily under 70 mph) and why the OEM setup accelerates quicker on the racetrack (where speeds are primarily above 70 mph).
This is not a concern, according to the tire manufacturers. Most 255/35-18 tires work fine on a 10" rear wheel, and are approved by their manufacturer for wheels 8.5-10.0 inches wide. This includes sticky tires like the Hoosier R6 track tire, Yokohama AD08R street tire, etc. The same is also true for 255/40-17 tires, most of which are approved for wheels 8.5-10.0" wide, including the BFG R1 track tire, Yokohama AD08R, etc.
*Bob is an owner of a Zanardi NSX who is a longtime track instructor/racer. He has an engineering background and in his professional career is an accident reconstruction specialist, so he calculates speed and acceleration for a living. (And yes, that's pretty cool.
) He has calculated the acceleration of the NSX under each of the various gearing setups, as well as for a 100-pound weight reduction and a 15-hp power increase (either of which provides a much larger improvement than any of the gearing setups do).
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It's a flawwed test because the given speed ranges heavily favor the US ratios.That's true. However, they are not faster at all SPEEDS. At any given speed, the shortest gearing produces the fastest acceleration. Because the shift points are different between the two sets of gears (45, 81, 114, 144 for the stock '91-94 gears, 45, 73, 101, 139 for the JDM five-speed gears), this creates "speed bands" which favor one set of gears or the other, depending on which gearset is shorter at that speed. Between 45 and 73 mph, there is a slight advantage for the JDM set using a 13 percent shorter second gear (1.952 ratio - the higher the number, the shorter the ratio) than the OEM set using second gear (1.727). But between 73 mph and 81 mph, there is a much greater advantage for the OEM set using second gear (1.727) which is 23 percent shorter than the JDM set using third gear (1.400). Similarly, etween 81 and 101, the JDM third (1.400) accelerates faster than the OEM third (1.230). Between 101 and 114, the OEM third (1.230) accelerates much faster than the JDM fourth (1.033). And so forth.
Overall, the JDM gears accelerate faster up to 73 mph, but the OEM gears accelerate faster above that point. Bob Butler* has calculated the acceleration of both gearsets on a stock '91 as follows:
0-150 mph: OEM 37.78 seconds, JDM 41.06 seconds
0-70 mph (gears 1-2 on both setups): OEM 6.59 seconds, JDM 6.27 seconds
70-110 mph (gears 2-3): OEM 8.12 seconds, JDM 8.60 seconds
110-150 mph (gears 3-5): OEM 23.07 seconds, JDM 26.19 seconds
And this explains why the JDM setup accelerates quicker at stoplights (where speeds are primarily under 70 mph) and why the OEM setup accelerates quicker on the racetrack (where speeds are primarily above 70 mph).
*Bob is an owner of a Zanardi NSX who is a longtime track instructor/racer. He has an engineering background and in his professional career is an accident reconstruction specialist, so he calculates speed and acceleration for a living. (And yes, that's pretty cool.
0-150 is biased towards US ratios.
-150mph is redline in 4th gear for the US ratio while the JDM would have to shift to 5th with a GREATLY over-driven 0.771 5th gear. I would be intrigued to know what the time differences are if you bias them toward the JDM ratios (top of 4th gear) with a 0-140mph calculation.
0-70 is a bias towards JDM ratios.
-At 70mph, US is at 7,000rpm while JDM is at 7,600rpm.
70-110mph is biased toward the US ratios.
-Since it's an in-between ratio for TWO of the JDM gears. For this speed range, the US gears are optimized for 2nd and the top of 3rd gear while the JDM ratio requires 2nd, 3rd, and 4th gears. Whether you factor the time for two additional shifts (at 70mph, the JDM ratio has 400rpm until redline in 2nd and tops out at 103mph in 3rd gear, requiring a shift to 4th gear when the US ratio only uses 2 gears) or calculate the JDM ratio starting in its 1.4 3rd gear ratio (which is taller/slower than the US 1.8 2nd gear ratio) plus its shift to 4th gear, the speed parameters are HEAVILY in the US favor.
110-150 is biased towards the US ratios.
-At 110mph, the US ratio is at 7,500rpm (peak power) in 3rd gear 1.23 ratio while the JDM gear is at 6,300rpm in its 4th gear 1.033 ratio. At peak power with an additional 0.197 of torque multiplication, the start of this test heavily favors the US ratio. Since this time segment ends at redline in 4th gear for the US ratio, the JDM ratio is HEAVILY disadvantaged when shifting into 5th at 140mph and having to pull a heavily over-driven 0.771 final drive to reach 150mph at 6,400rpm in 5th gear.
You've posted this argument many times before and it's a poor attempt to argue the US ratios are faster since the speeds are specifically chosen to advantage the US ratios. If you change the speed parameters to favor the JDM ratios, it will swing even further in the JDM ratio's favor below 140mph:
0-140mph - redline in 4th gear for JDM, 7,500rpm for US ratio in 4th
45-100mph (a common speed range for race tracks) - heavily favoring JDM ratio despite both ratios staying in 2nd & 3rd gear.
60-140mph - Favors JDM due to its 6,500rpm in 2nd while US is at 6,000rpm and ends at redline in 4th gear for JDM while US is at 7,500rpm.
120-140mph - just out of reach for US ratio to use 3rd gear, this speed range is in 4th gear for both ratios and ends at redline in 4th gear for JDM. While the ratios are close (0.967 for US and 1.033 for JDM), the JDM ratio will be slightly quicker.
At the end of the day, unless you are drag racing in the very fine windows (from the exact starting and finishing speeds as stated), the JDM ratios will be faster around a given racetrack especially if the top speed is less than 140mph.
You can run a 255 on a 10" wheel but I would personally size the tire's contact patch width closer to the rim width. So a 265 or 275 would probably yield more grip and better performance than the 255.
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- Joined
- 19 January 2011
- Messages
- 714
Hey Man, good too see you follow up posting, people usually ask something then disappear. I used to drive an RSX type S for a short while and did a competition or two with them, if your tracking around Socal im sure we've crossed paths.
To directly answer your questions:
Yes *I* think oil/water gauges are essential. Essential for your first few track days? ... depends, but probably NO. Essential if you plan to go once a month, or at all over the summer YES. You sounded like you were already decided on the BBK, take that money and do gauges for 1/4 the cost. By only doing 5 or 6 laps in a session you will not heat load the OEM rotors anyways but you can potentially run your oil thin, its cheap insurance.
2: For the non compliance stuff I got my from TiDave, he sent me a rear beam already pressed with the bushings, all I had to do was swap them out and send him back my core. Steve Ghent did my ball joints for me, it was a similar transaction to the rear beam. Everything else non-comp I have is just one off stuff I got here and there.
Everyone has touched on things to look out for or stuff you can get that may help under certain conditions, all good advise. I wouldnt be concerned with setting the car up so its all dialed for your first track event, thats something you can do over time. What you need to make sure to cover first is that the reliability will be there. The basics like TB, water pump, fluid etc will get you out on track. The car will still perform and you'll still have fun. From there you can mix and match parts till your hearts content.
I will say for you coming from an s2000 you'll notice that the 'out of the box' NSX is quite a few rungs lower on the ladder. Its no slouch, but very few cars have the reliability and speed the s2k has with almost zero modifications. Right when I got my NSX I did the services and threw some 17/18 with Azenis rt615. Back to back track days I did 2:05 at Buttonwillow and a 1:27 at Streets. Not too bad for a stock car that looked like a 4x4 but I could feel there was a ton of stuff that I wanted to adjust. Only recently i feel like im done noodleing and am happy.
To directly answer your questions:
Yes *I* think oil/water gauges are essential. Essential for your first few track days? ... depends, but probably NO. Essential if you plan to go once a month, or at all over the summer YES. You sounded like you were already decided on the BBK, take that money and do gauges for 1/4 the cost. By only doing 5 or 6 laps in a session you will not heat load the OEM rotors anyways but you can potentially run your oil thin, its cheap insurance.
2: For the non compliance stuff I got my from TiDave, he sent me a rear beam already pressed with the bushings, all I had to do was swap them out and send him back my core. Steve Ghent did my ball joints for me, it was a similar transaction to the rear beam. Everything else non-comp I have is just one off stuff I got here and there.
Everyone has touched on things to look out for or stuff you can get that may help under certain conditions, all good advise. I wouldnt be concerned with setting the car up so its all dialed for your first track event, thats something you can do over time. What you need to make sure to cover first is that the reliability will be there. The basics like TB, water pump, fluid etc will get you out on track. The car will still perform and you'll still have fun. From there you can mix and match parts till your hearts content.
I will say for you coming from an s2000 you'll notice that the 'out of the box' NSX is quite a few rungs lower on the ladder. Its no slouch, but very few cars have the reliability and speed the s2k has with almost zero modifications. Right when I got my NSX I did the services and threw some 17/18 with Azenis rt615. Back to back track days I did 2:05 at Buttonwillow and a 1:27 at Streets. Not too bad for a stock car that looked like a 4x4 but I could feel there was a ton of stuff that I wanted to adjust. Only recently i feel like im done noodleing and am happy.
I'd definitely like to sit with you at the track sometime and go over all of your findings. I won't be tracking the car any more than 4-6 times a year in the colder months (I don't bother going in summer at all) so the car doesn't need to be built solely for track use.
I have the SoS oil pan baffle on order, as well as my coolant hose kit. I need a new radiator too - was probably going to just get a Koyo unless someone recommends something better.
I'm using Shell Rotella in the engine and Billy mentioned to just use OEM Honda manual trans oil (white cap - whatever that means) in the transmission. I think for now that's really all I'd want to do before getting it on track. From just driving on the street I can tell the car is going to be a real hoot to drive. The manual rack is going to take the most adjusting too, do you guys get tired after sessions? It's not as effortless as an S2000 but damn does it feel good driving the car.
The SOS baffle does NOT sit flush with the bottom of the 'shelf'. It would be good to modify/hammer the baffle so it does sit flush and stitch-weld that seam so oil does not slosh up onto the shelf easily. If you don't you are not protecting your motor as well as you could have.
Once the baffle is welded in, or even placed in before welding, fill it with water and tilt the pan 45-degrees and see how fast the water rushes out...
S2K's have a ton of power assist. The NSX is a little bit of a work out but its not bad, especially if you work on your hand-placements. Or just go to the gym. Now a Ferrari 512TR is a manual-steering beast and are hard to drive.
Once the baffle is welded in, or even placed in before welding, fill it with water and tilt the pan 45-degrees and see how fast the water rushes out...
S2K's have a ton of power assist. The NSX is a little bit of a work out but its not bad, especially if you work on your hand-placements. Or just go to the gym. Now a Ferrari 512TR is a manual-steering beast and are hard to drive.
- Joined
- 19 January 2011
- Messages
- 714
Naw at speed the NSX steering weight feels great. though, I have sprained my thumb twice during track days since ive had the car (not kidding).
There used to be two versions of Honda trans fluid one had a grey cap and one had a white cap, apparently the one with the white cap was better. From what I understand Honda of America have phased out the other version and now they all have the 'white cap' on the grey bottle. You can call around to dealerships and only half of them will know what you mean when you ask for 'white cap'. You should be OK with a Koyo, thats what I have had for a while now. I'm just patiently waiting for Regan to sell me one of his bad ass radiators he'd developed.
There used to be two versions of Honda trans fluid one had a grey cap and one had a white cap, apparently the one with the white cap was better. From what I understand Honda of America have phased out the other version and now they all have the 'white cap' on the grey bottle. You can call around to dealerships and only half of them will know what you mean when you ask for 'white cap'. You should be OK with a Koyo, thats what I have had for a while now. I'm just patiently waiting for Regan to sell me one of his bad ass radiators he'd developed.
Nonsense. It's an unbiased test because the full speed range of 0-150 is exactly that, the full speed range, from first gear (same gear ratio in both setups) to fifth gear (again, same in both setups). And the sub-ranges are unbiased because they have the same number of shifts with either setup.
Not true. Redline in 4th gear is 144 mph with the US gears and 139 mph with the JDM gears. So either setup will have already upshifted to fifth to get to 150.
Yup, and they're both still in second gear. So there's no bias. And yes, the JDM gears are faster below 70 mph.
Well, you may have a point, because you need to go to fourth with the JDM setup and not the OEM setup. So instead, you can look at 70-120 mph, so that you have the same number of shifts (second to fourth) in each one. From 70 to 120, the OEM setup is still faster than the JDM setup.
Wrong again. As noted above, both setups require an upshift to fifth - at 139 mph with the JDM gearset, at 144 mph with the stock gearset.
If you change the speeds to look at acceleration under 140 mph, as you suggest, it becomes even more biased towards the OEM gearset (70-140 mph acceleration is 21.05 seconds with the OEM gears, 21.81 seconds with the JDM gears), because the JDM gears require the upshift to fifth at 139, while the OEM gears don't.
Here's another way to look at it, in terms of common sense. The ideal gearset has closely-spaced gears, so you can take advantage of the torque multiplier over more of the speed range (which is why the six-speed, with its additional gear and its closer spacing, is superior to either five-speed setup). Both five-speed gearing setups use the same first gear and the same fifth gear, so the overall distance from first to fifth is the same in both cases. Compared with the JDM gears, the OEM setup has a bigger gap between first and second, and closer spacing between second and fifth - so the OEM setup is slower while both setups are in second (up to 73 mph), and faster above that point. That's why the JDM setup is faster at stoplights, and slower on the racetrack.
You've posted this argument many times before and your analysis is still full of errors (such as the shift point to fifth gear). It's an absolute fact that the OEM gearset is faster above 70 mph. This is proven by Bob Butler's analysis, which was published in NSX Driver. He shows all the formulas and assumptions used, and acceleration to every speed in 10 mph increments from 0 to 150, for each of the gearsets (as well as each of the final drive gears). There's no bias in looking at that entire range of 10 mph increments, since the starting gear ratio and the ending gear ratio is the same in both setups. I don't know why you insist on making the same error over and over again, but it won't change this simple fact: The five-speed with the stock U.S. gears is faster than with the JDM gears, overall from 70 mph to 150 mph as well as overall from 0 mph to 150 mph.
Thanks for the advice on the baffle. Are there pictures or a writeup? I want to make sure I don't screw that one up lol.
Not sure if it was mentioned in this topic, but I heard that these clamps are also a must do for the track oriented NSX
http://www.scienceofspeed.com/products/suspension_performance_products/NSX/Cedar_Ridge/pivot_clamps/
http://www.scienceofspeed.com/products/suspension_performance_products/NSX/Cedar_Ridge/pivot_clamps/
No it's not. Because the US ratio hits 150mph in 4th gear at redline with a 245/40-17 24.72" OD and 77.65" circumference. The JDM ratio tops out 4th gear at 140mph, so in order for the JDM ratio to get to 150mph, it has to use 5th while the US ratio does not.
Not according to my calculator based off of the tire I stated and the stock ratios. Top speed in 4th gear is 150 for US and 140 for JDM. The NSX Wiki is wrong since if you accept the 140mph JDM top speed at 8,000rpm in 4th gear (ratio 1.033) and you plug in the US' 0.967 4th gear ratio, you will get 150mph. That is with a 4.062 final drive and the tire size that I stated. If you want to split hairs and go with a 24.6" OD and 139.5mph for the JDM 4th gear ratio, then the US 4th drops to 149.1mph. Either way, there is not a 5mph difference between ratios if you plug it into a calculator holding everything else constant.
Bust out your gear ratio calculator and try it for yourself. There's no formula that will hit the incorrect speeds that you are quoting from the Wiki when swapping the 0.967 to the 1.033 JDM gear.
It depends on how Bob did the math, if he calculated the US ratio to start in 2nd and the JDM starting in 3rd, that's a huge disadvantage to the JDM ratio. If both were in 3rd gear, the JDM's higher torque multiplier would make it quicker since both cars have to shift to 4th to reach 120.
****IF you incorrectly go off of RPM drop alone, the JDM's shorter 2nd and 3rd gears also have tighter spacing since the JDM drops 2,262rpm to 3rd (5,738rpm) while the US ratio drops 2,533rpm to 3rd (5,467rpm) in addition to their lower ratio (1.4 vs 1.23). So there's no arguing the JDM ratio is faster to at least the top of 3rd gear (103mph) rather than the top of 2nd which you constantly state.
Again, the math in the Wiki is incorrect since even with a 24.6" OD as stated in the Wiki, that would drop the US ratio's 4th gear to 149.1mph at redline. So yes, both cars would technically have to use 5th gear but it's still a flawwed test for the stated reasons.
JDM's speed in 4th with a 24.6" OD is 139.5 -> 140mph Or 140.2mph with a 24.72" OD. You're splitting hairs there. The validity of those times depend on the accuracy of the gear ratios and how he factored in the time for additional shifts. Please provide the math because without it, it's as invalid as the NSX Wiki's speed per gear. And if you disagree, please show me the formula that supports the Wiki's findings. Simple math will show you otherwise.
The "ideal" gearset depends on a lot of factors, primarily the torque curve and the ideal top speed. Since the NSX cannot reach the its top speed gearing potential due to its heavily over-driven fifth gear, fifth was likely chosen for fuel mileage purposes.
While I agree there is a shorter gap from 2-5th in the US ratio due to the taller 1.8 US 2nd gear, acceleration thoughout 2nd gear will be quicker in the JDM's lower 1.952 2nd gear, and further quicker in the lower 4th. Given any gear at any speed below terminal velocity in the JDM's 4th gear (140mph), the JDM ratio will be quicker. When you shift into 3rd in the JDM ratio, the RPM drops to 5,738rpm while the US ratio drops further to 5,467. But you seem to be ignoring this fact which supports your only point of the US ratio's being tighter at higher speeds. Only until you get to 4th gear does the JDM ratio have a further drop than the US ratio.
My analysis is spot on. The Wiki's math is incorrect. Please provide the formula that accurately links the given speeds for each ratio with a constant tire OD. Also please provide Bob's math, which would be incorrect if he went off of the Wiki's speeds, and it's still important to understand the testing methods and the gears used in these 'inbetween' ratio scenario.
The simple fact is that conclusion is wrong just like the Wiki math and your argument. I'm really done with arguing this until you can show some proof and math behind your claims.
No, but here's an old link to the STMPO baffle. Note it sits flush against the edge:
http://www.nsxprime.com/forum/showt...to-Australia)-Buy-STMPO-in-this-special-offer
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If you aren't welding the baffle into your own pan, I would highly suggest getting it through Titanium along with some other stuff.
http://www.cedarridgefabrication.com/NSX_Motor
The welding and power coating looks great. Price is reasonable. A few of us also put heat reflective foil on the pan around the front bank headers to help protect it from the heat.
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Bob's analysis didn't use the top speeds shown in the Wiki, which I will admit, do appear to be in error. He used the actual gear ratios, along with Newton's 2nd Law and the Conservation of Energy equation, to determine vehicle acceleration. He did so assuming maximum acceleration within each gearset from 0 mph up, allowing 0.3 second for each upshift, and broke acceleration time out into 10 mph increments. As noted above, even if you assume that both gearsets go up to 140 mph, so both are in fourth gear at the top of that range, overall acceleration from 0 to 140 mph is quicker with the OEM gears than the JDM gears (27.64 vs 28.08 seconds), and in particular, it's quicker from 70 to 140 mph with the OEM gears (21.05 seconds vs 21.81 seconds). So we can restate the simple fact of his analysis thus, so as to take away from the bias of that extra shift to 150 mph: The five-speed with the stock U.S. gears is faster than with the JDM gears, overall from 70 mph to 140 mph as well as overall from 0 mph to 140 mph.
Please show the math. For the 0-140mph example, the JDM ratio is optimized for 140mph since it redlines at 8,000rpm in 4th at 140mph while the US ratios leaves 500rpm on the table. 4th gear is a lower ratio than the US, and the 1-2 rpm drop is 4-600rpm less than either 91-94 or 95-96 gear ratios, is 50-300rpm less in the 2-3 shift, but 380rpm lower in the 3-4 shift but again, it has a slightly lower 4th gear ratio.
Please show me the math that proves the US ratio is faster than the JDM up to 140mph. Either way, hairpins on most racetracks are ~45mph, and the acceleration off of these corners is hugely increased from the JDM ratios vs. the US.
Not sure if it has been discussed, but a new radiator should be on your list too. I have a Koyo and it held up to 100 F track days at altitude. It holds about 30% more coolant than the stock unit, which on you car is probably dented and leaking after many years of service. Don't want to get into the huge debate, but I tracked my NSX with the USDM gears (Glen, Lime Rock) and then the JDM gears with NSX-R diff (HPR) and I find the JDM to be better. But the real difference is on the street. With the Fujitsubo exhaust, probably the best mod I've done to my NSX.
P.S. I calculated the exact top speed at redline in each gear using the stock 225/50-16 tire size, and in fourth it's 141.0 with the JDM gears and 150.6 with the stock gears. I'll check with Lud about getting the chart updated.
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I was right about the incorrect wiki, and i'd like to see you do some leg work and back up your claims too. :wink:
Is Bob "BBU" who made this passage in the NSX Prime FAQs: http://www.nsxprime.com/FAQ/Performance/gears.htm
[BBU] Many people want the numbers, therefore last night I did some more numerical computer calculations to show the impact of different gearing. The calculation is a finite-difference solution of the energy equation which governs acceleration. The solution includes weight, tire size, horsepower, and of course gear and R&P ratios. In order to go to higher speeds, this time I also included aerodynamic drag and rolling friction. The baseline or stock case is a 91-93 geared NSX with the stock 4.062 R&P, producing 245 peak horsepower to the road, weighing 3200 lbs including the driver. I included 0.3 seconds to complete shifts. Although the exact magnitude of the result may have a little uncertainty, the numbers will allow you to compare different cases side-by-side and make your own decisions.
Just to warn you, the cases that had to shift to the stock 5th gear to reach 140 mph really dogged at the end. The times are heavily dependent on the shift speeds, for instance the short gears by themselves produce the fastest time to 140 mph (in the 1st table), because that speed is very near the redline. This same case is the slowest to 80 mph because it had to shift. But pick the speeds that you think are important and make your comparisons at that point.
In addition to looking at gearing, I included two cases that did not modify the gearing, but instead either added horsepower or reduced weight. The following table lists the time it takes in seconds to reach the given speed.
speed = [RPM x Diameter x Pi x 3600(sec/hr)] / [gearratio x R&Pratio x 5280(ft/mile) x 60(sec/min) x 12(inches/ft) ]
Speed
0-MPH Baseline Japanese
5-speed 6 Speed 4.235 R&P 4.55 R&P Japanese
5-speed
4.55 R&P Japanese
5-speed
4.235 R&P Baseline
+ 20 HP Baseline
- 200 lbs.
0-30 2.16 2.16 2.16 2.08 1.94 1.94 2.08 2.00 2.03
0-40 2.92 2.92 2.92 2.80 2.62 2.62 2.80 2.70 2.74
0-50 4.16 4.11 4.11 4.11 4.02 3.91 4.04 3.86 3.92
0-60 5.56 5.34 5.34 5.45 5.27 5.00 5.22 5.15 5.23
0-70 6.99 6.60 6.60 6.82 6.54 6.60 6.42 6.46 6.58
0-80 8.46 8.52 8.50 8.23 8.45 8.24 8.44 7.82 7.96
0-90 10.74 10.46 10.38 10.65 10.42 9.94 10.28 9.92 10.11
0-100 13.13 12.48 12.36 12.91 12.49 12.33 12.58 12.08 12.34
0-110 15.66 15.67 15.45 15.31 15.40 15.39 15.64 14.37 14.72
0-120 19.02 19.25 18.60 19.02 18.72 18.38 18.98 17.38 17.88
0-130 23.56 23.27 23.53 23.24 23.42 23.26 22.72 21.20 22.15
0-140 28.93 27.91 28.73 28.13 28.90 30.36 30.04 25.84 27.18
0-Xmph is a somewhat trivial measure anyway if we are not concerned about drag racing. And I stay behind my previous statement that due to the numerically higher JDM gear ratios from 2-4, for a given speed range on a track (2nd gear and typically >45mph), the JDM ratios will be faster for most tracks.
Yes. However, that is an earlier version. As he stated in the article in NSX Driver: "The results below differ slightly to earlier results published in the NSX FAQ due to improvements in the calculation by using a non-linear power curve."
The article also states, "In the 91-94 setup, the engine revs drop to 4499 RPM after an upshift from 1st to 2nd gear. After this shift, the 95-96 2nd gear ratio of 1.80, the Japanese short gears or the 6-speed would improve the acceleration. At higher speeds, the stock 5-speed will have better acceleration than the Japanese short gears after a shift from 3rd to 4th or 4th to 5th. The 6-speed is superior or nearly equivalent in every shift as compared to the 5-speeds." He neglects to mention the fact that the stock five-speed is also faster at all speeds at which it's in a lower (shorter) gear than the JDM gears.
I stand behind my previous statement that, due to the shorter gears used by the stock gearset at speeds in which it is in a lower gear than the JDM gears, as well as the closer spacing of gears in the stock gearset above second gear, which cover most of the speed range for speeds used on the racetrack, the stock gears will be faster than the JDM gears for most tracks.
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This is why I struggle with debating with you. Please provide Bob's original source and math otherwise this conversation does not move forward and we continue to hear your repetitive statements. I gave my reasoning for why your beliefs are wrong and have math to support it. Please bring something new to the table, otherwise we both said our pieces.
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