Best NSX Performance Upgrades

[DrVolkl]

No, not at all. I'm comparing a five-speed with stock gears against a five-speed with short gears. The stock gears are quicker between 73 and 81, where they are in second gear, than the short gears, which are in third gear at those speeds. Similarly, the stock gears are quicker between 101 and 114 mph, and between 139 and 144 mph. And the difference in acceleration is much greater than at the speeds where the short gears have the advantage.

Well the graph you posted is a 6 speed, 3.2 car. And I agree with the other post about the #'s from the FAQ section, at least that's what I remember. I'll have to do some more research. Where are you getting your #'s from????

 

[nsxtasy]

As for as the numbers, where did you get those numbers from ??
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These numbers differ noticably from the numbers that you have

The numbers in the FAQ were from an article that Bob Butler originally wrote. He then published a revised version in NSX Driver, containing some corrections of calculations as well as a more robust analysis (more different combinations of gearing, etc). My numbers are from the revised version.

I should have prefaced this post with the fact that I'm rarely going to go over 100mph anyway. I'm looking for 0-60 acceleration, better stop light performance. My 91 is a daily driver, will never see the track.

As I said earlier, the short gears may be a good move for you.

looks like a few HP is the way to go. Beats gear changes easily.

BTW, all this tranny info is pertinent since my car is in snap ring range. Doing fine so far at 40k though.

If you decide to do any gearing changes (e.g. short gears), it would be a good idea to replace the snap ring and upper transmission case at the same time. That way, all it would cost is the parts cost, and you'll never have to worry about it again.

I would start with headers, then exaust.

The cost of 6-speed conversion (assuming used 6-speed) doesn't seem like it would be significantly higher than having short gears & new synchro/sleeve sets put in a 5-speed.

This may not be true. Used six speed transmissions are few and far between, and they command a high price. So it really depends on what kind of a deal you get on a tranny. I can assure you that it won't be inexpensive. That's why I don't recommend swapping transmissions. The six-speed might be a better setup (I would say that it is, in fact) but no matter how it's done, it's an awful lot of money to spend, and the performance difference is... well, you can see the numbers above.

Well the graph you posted is a 6 speed, 3.2 car.

The graph I posted shows the horsepower and torque curves for both engines - a 3.0-liter engine from a 5-speed car, and a 3.2-liter engine from a 6-speed. I apologize if this was confusing or misleading.

Where are you getting your #'s from????

See above.

 

[latzke]

This may not be true. Used six speed transmissions are few and far between, and they command a high price. So it really depends on what kind of a deal you get on a tranny. I can assure you that it won't be inexpensive. That's why I don't recommend swapping transmissions. The six-speed might be a better setup (I would say that it is, in fact) but no matter how it's done, it's an awful lot of money to spend, and the performance difference is... well, you can see the numbers above.

You might be right there (and I was way off base). I just ran the numbers (using numbers from SOS & dealership). If you figure $800 to 1700 for shorties (and optional shorter R&P), $1100 for all new synchro/sleeve sets, and $1100 for labor a tranny rebuild with short gears would run from $3000 to $4000 total (unless you're in snap-ring range...then you'd be a fool not to also replace the upper case, which would add cost although likely saving future cost and removing a resale issue). The 6-speed conversion would run $5700 just for parts...and would likely require a different clutch (or part + labor to switch out the imput shaft).

I've seen used 6-speeds with clutchs in the mid $4000 range (without the extra few bits)...but if you're going to start using non-vendor prices for the 6-speed, you'd have to do the same for the short 5-speed to make a fair comparison...so there would still be a bit of a difference. If you're comparing all new parts + dealer labor for 5-speed and cheapest-solution possible for 6-speed (as I was) it gets closer...but probably not as close as I thought before today.

 

[nsxtasy]

Of course, another way of looking at it would be to compare either transmission swap/upgrade against the cost of trading the car in for a '97-05, which also gives more horsepower.

The bottom line, as I see it, is that, in general, gearing differences rarely make all that much difference in performance, and they're expensive (for labor as well as parts). As others have noted here, you can get a lot more benefit, with less expense, elsewhere (e.g. headers/exhaust).

Incidentally, from what I've seen in the used market, gearing swaps don't significantly increase the market value of the car, either - another point in favor of trading the car on a '97-05, if that's an option for you.

 

[goldNSX]

You might be right there (and I was way off base). I just ran the numbers (using numbers from SOS & dealership). If you figure $800 to 1700 for shorties (and optional shorter R&P), $1100 for all new synchro/sleeve sets, and $1100 for labor a tranny rebuild with short gears would run from $3000 to $4000 total (unless you're in snap-ring range...then you'd be a fool not to also replace the upper case, which would add cost although likely saving future cost and removing a resale issue). The 6-speed conversion would run $5700 just for parts...and would likely require a different clutch (or part + labor to switch out the imput shaft).

I've seen used 6-speeds with clutchs in the mid $4000 range (without the extra few bits)...but if you're going to start using non-vendor prices for the 6-speed, you'd have to do the same for the short 5-speed to make a fair comparison...so there would still be a bit of a difference. If you're comparing all new parts + dealer labor for 5-speed and cheapest-solution possible for 6-speed (as I was) it gets closer...but probably not as close as I thought before today.

Agree with you calc on the shorties/4.23. About $3-4k. Here in Europe we have such very few 6-speed cars that none of them will ever be for sale and if then it's bad. So I have to buy a new one, preferably from the US (because they like to bill me over $8000 here in Europe), $5700 plus $500 shipping. Needs a new clutch $1500 (how much?) and doesn't have the 4.23 installed (!). Adding this is another $2000 (parts + labor). You don't have to calc the total of it, it's just a forget-about-it. With all this installed the 5-speed with shorties/4.23 is equal in gearing to the 6-speed with 4.23 in gear 1-2-3. In 4-5-6 or above 100 mph the 6-speed is better. Depends on the preferences and resources. My preference was clear that it's not worth for me to pay a bill twice as high for the 6-speed to gain a very small advantage and one gear more I'll never/rarely need.^

EDIT: The shorties are a must for a 91-94 if you really want to enjoy the car IMO. The car feels much better without that sluggish jump between 1st and 2nd.

 

[1BADNSX]

These numbers differ noticably from the numbers that you have, especially since the FAQ lists 31.94 secons for 70-140mph where you give an even faster time of 31.19 seconds (stock gears) for 70-150mph.

The high speed numbers are different, but the difference between setups is very similar at the lower speeds. Remember that these numbers should be used to compare one setup to the next. Of course they could be different to actual test data just due to wind alone at high speeds!

Adding to what Ken said, the numbers in the NSX driver are more refined. No corrections were made, but better assumptions went into the NSX Driver numbers. If my memory is correct, the article numbers included a 5th order curve fit for the dyno curve versus a simple linear approximation, and also improved the aerodynamic model slightly.

I gave up years ago trying to get Lud to update the FAQ.

Bob

 

[nsxtasy]

EDIT: The shorties are a must for a 91-94 if you really want to enjoy the car IMO.

I still think the stock gears are better for track use.

 

[goldNSX]

I still think the stock gears are better for track use.

Agree on this. But see melmark's intention: "I should have prefaced this post with the fact that I'm rarely going to go over 100mph anyway. I'm looking for 0-60 acceleration, better stop light performance. My 91 is a daily driver, will never see the track."

 

[latzke]

I still think the stock gears are better for track use.

Depends on the track. One would be inclined to think that shoter/tighter tracks in general would probably do better with shorter gears, where fast/long tracks would do better with taller, but even that is a generalization. The optimum for each turn on a given track will be different. So, what gear setup is best for a track will depend on the aggregate cost/beneift of each gear ratio across all the turns of a specific track (pick the ratio for that track which hurts the least and helps the most). We're obviously not going to run around and change setups per track...but I think it's a fallacy to say that any set of gears is "better for track use" (or even "better for street use").

I think goldNSX has a narrow enough set of criteria within the "street use" category to actually allow for him to determine the best gear setup for himself...but if one's criteria is simply "track use" or "street use" it's not so clear.

 

[nsxtasy]

Agree on this. But see melmark's intention: "I should have prefaced this post with the fact that I'm rarely going to go over 100mph anyway. I'm looking for 0-60 acceleration, better stop light performance. My 91 is a daily driver, will never see the track."

I already acknowledged that they might be good for his particular situation, in post #27 above.

Depends on the track.

Not really. I think the stock gears are better for pretty much any track. Realize that on almost all tracks, you're rarely driving slower than somewhere around 60-65 mph (even on the shortest tracks), and you're never in first gear (other than at pit-out). Think of it this way: since both setups use the same first gear and the same fifth gear, there is a fixed amount of spacing between first and fifth. The stock gears have a wide gap between first and second, and relatively closer spacing between second and fifth, whereas the short gears narrow the gap between first and second by widening the gap between second and fifth. The closer spacing of the stock gears between second and fifth is beneficial for track use.

The optimum for each turn on a given track will be different.

In theory, that's true. However, every track has a variety of turns, with enough variation in speeds that you can't optimize for any particular speed, other than the fact that you're likely to be driving between roughly 60-65 mph at the slowest corners, up to whatever speed you can get on the longest straight.

I've driven 25 different tracks, and I would say that the stock gears are better at all of them. If you drive on a hypothetical "go kart track", where you're spending most of the time below 65 mph, or on a hypothetical track where all the turns are taken at exactly the same speed that just happens to be at a precise speed where the short gears are better, that would be a different matter. But that doesn't describe any of the road courses I've driven.

 

[latzke]

Not really. I think the stock gears are better for pretty much any track. Realize that on almost all tracks, you're rarely driving slower than somewhere around 60-65 mph (even on the shortest tracks), and you're never in first gear (other than at pit-out).

I disagree with both with your conclusion and reasoning:

I think the optimal gears for a track are based on that specific track and the various turns it has (not to mention the power of the vehicle, the driver's ability, etc).

"you're rarely driving slower than somewhere around 60-65 mph"

I would estimate that half of the turns on the tracks I've driven cannot be taken greater than 60MPH.

"you're never in first gear (other than at pit-out)"

I find this to be an issue with the stock gears, not short gears, as the two tracks I have the most time at have true hairpins where the stock 2nd gear is way, way too tall to have decent acceleration when exiting. Shorties with 4.55 gives you a usable 2nd gear for the real slow corners and a 3rd gear that is just a hair taller than the stock 2nd (can do 90 instead of 80). If you're going faster than 80-90, stock 3rd is close to my 4th (both go to about 120) and you're only going faster than 120 once per lap at the tracks I'm familiar with (and sometimes never if you're normally aspirated).

Anyways, I don't disagree that for the tracks you drive stock may be the best gearing. I do disagree with a blanket statement that any gearing setup is better for "pretty much any track."

 

[omeys_berlina]

I have a full DC SS Headers & exhaust. The car came with a generic intake, so i took it off put a HKS Billet Aluminum intake on, SOS big bore throttle body, Cantrell Studios side air vent.....NIGHT & DAY difference....i highly recomend the side air vent and the big bore from SOS, I love it, i noticed the difference as soon as i left Barrie Acura.......the car sounded amazing....

I also SMOKED my buddies C32 AMG and he ran a 13.9 on the track...that was his best time...