My 91 came with short gears and a 4.55. Very quick going through the gears but I was wondering how much top speed and gas mileage did I lose with a 4.55 compared to the stock rear end?
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How much top speed & gas mileage did I lose with a 4.55?
- Thread starter SoCalDude
- Start date
You will not lose any top speed since the NSX will not red-line in high gear due to air resistance. You will just reach the same top speed at a slightly higher RPM with the 4.55 R&P vs OEM.
The difference is gas mileage, IMHO, is not worth thinking about, even at today's gas prices. Might make a difference of a hundred bucks or so a year, plus or minus.
I had the 4.23 R R&P in my 93, and now have the 4.55 Comptech R&P in the Zanardi both setups were/are great.
The difference is gas mileage, IMHO, is not worth thinking about, even at today's gas prices. Might make a difference of a hundred bucks or so a year, plus or minus.
I had the 4.23 R R&P in my 93, and now have the 4.55 Comptech R&P in the Zanardi both setups were/are great.
From the FAQ, the top speed for the short gears with the 4.55 r&p is 166mph which is well below the car's drag limit.
http://www.nsxprime.com/FAQ/Technical/gearratios.htm
SoCalDude, what is your gas mileage? I am getting about 24mpg with mixed city, highway, and spirited driving with an OEM gearbox.
http://www.nsxprime.com/FAQ/Technical/gearratios.htm
SoCalDude, what is your gas mileage? I am getting about 24mpg with mixed city, highway, and spirited driving with an OEM gearbox.
I've only had the car for two months and only filled it up once. My first tankful was 18 mpg. Not a good indicator since I kept flooring the gas pedal everytime I drove it. Will fill up again soon and I'll post a more normal driving experience mpg then.MRFreeze said:
Actually, 166 MPH is the speed at which you will hit redline with the 4.55 R&P. With the stock R&P, it would be 186 MPH, except drag limits it to about 168 MPH. Since the fuel cutoff is about a hundred RPMs past redline and since, at these speeds, there will be more wheel torque* with the 4.55 R&P compared to the stock R&P, it should be possible to slightly exceed the stock top speed - if you are comfortable with running above redline.MRFreeze said:
EDIT: *Wrong - see below.
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Should I or not?
I have a set of OEM Japanese short gears and was very excited about installing them, but after reviewing the comparison (if I read them correctly), I'm not so sure that it is worth the overall gains, or losses.
I have a '91 with stock gears/ring & pinion. While you do maintain higher RPMs with the short gears on a couple of the shifts (1st-2nd & 2nd-3rd), you lose RPMs on 3rd-4th & 4th-5th. Additionally, you lose MPH through all of the upshifts. PRIME shows the differences as follows:
RPM:
SPEED:
NOTE: The RPM and SPEED gain/losses above were my input for reference purposes only
Please keep in mind that above numbers is a comparison between stock '91-94 gears vs. Japanese short gears only, and with stock 4.062 R&P. Even though it wasn't posted this way on PRIME (post was probably done in 1999 or earlier), I suppose it could have said '91-'96 (instead of '91-'94) as '95 & '96 gears are the same as '91-'94.
You can view all of the comparisons by scrolling ~3/4 of the way down until you see Impressions of Various Setups by clicking this
.
I have a set of OEM Japanese short gears and was very excited about installing them, but after reviewing the comparison (if I read them correctly), I'm not so sure that it is worth the overall gains, or losses.
I have a '91 with stock gears/ring & pinion. While you do maintain higher RPMs with the short gears on a couple of the shifts (1st-2nd & 2nd-3rd), you lose RPMs on 3rd-4th & 4th-5th. Additionally, you lose MPH through all of the upshifts. PRIME shows the differences as follows:RPM:
SPEED:
NOTE: The RPM and SPEED gain/losses above were my input for reference purposes only
Please keep in mind that above numbers is a comparison between stock '91-94 gears vs. Japanese short gears only, and with stock 4.062 R&P. Even though it wasn't posted this way on PRIME (post was probably done in 1999 or earlier), I suppose it could have said '91-'96 (instead of '91-'94) as '95 & '96 gears are the same as '91-'94.
You can view all of the comparisons by scrolling ~3/4 of the way down until you see Impressions of Various Setups by clicking this
.
While what you say makes sense, it's also possible that there is LESS wheel torque at those speeds with the 4.55 R&P and you won't be able to reach/exceed redline. That's because you are further up in the revband, where torque is dropping. As you can see from the following graph, the torque at the crank around 7000 RPM, where the stock gears hit top speed, is significantly higher than it is at 8000 RPM, where the 4.55 R&P would be. From the graph, it looks like this would more than offset the gearing advantage.Ojas said:
Re: Should I or not?
Regarding short gears with stock R&P: The way I see it, the main benefit would be getting rid of the annoying 2nd gear RPM drop at the expense of peak acceleration in 3rd, 4th gears. Also, even though the ratio is the same, part of acceleration in fifth gear will also be slower since you are forced to spend extra 300 RPMs in it (assuming you shift at redline in 4th).
I think this distinction was made since the 2nd gear ratio was made slightly shorter in 1995, when the NSX-T was introduced.SennaPerfected said:
Regarding short gears with stock R&P: The way I see it, the main benefit would be getting rid of the annoying 2nd gear RPM drop at the expense of peak acceleration in 3rd, 4th gears. Also, even though the ratio is the same, part of acceleration in fifth gear will also be slower since you are forced to spend extra 300 RPMs in it (assuming you shift at redline in 4th).
Actually, they made second gear slightly shorter starting in '95.SennaPerfected said:
As for your decision, I think it really depends on where/how you do your driving. The short gears will help your acceleration in second through fourth gears, but they will lower the shift points. The biggest difference is going to be in driving feel, because you will reach redline sooner; this creates the perception of faster acceleration, because you need to shift sooner, even though you do so at lower speeds. But the perception may be greater than the actual acceleration gains; the short gears drop 1/4 mile times by 0.11 second, which is roughly the equivalent of adding 5 horsepower to your engine. If this sounds appealing to you, go for it.
Two additional suggestions: (1) Try driving your car back-to-back with another one with short gears installed, preferably otherwise similar to yours. (2) If you decide to go ahead, wait until your transmission needs servicing for other reasons. Otherwise, the 8-12 hours of labor to open up the tranny just to put the short gears in makes it quite expensive.
What is interesting about the drop in acceleration is that people perceive it as less acceleration because you are at lower revs, which is not really true. Acceleration within a gear (in this case, second gear) is a function of engine torque and gearing, and as you can see from the graph above, engine torque at 4500 RPM isn't all that different from engine torque at 5100 RPM. The reason acceleration drops more when you upshift to second with the stock gears is because of the difference in gearing, not engine torque; the greater difference between the ratios for first and second is what creates the greater drop in acceleration.Ojas said:
My bad - You're absolutely correct.nsxtasy said:
At a given engine RPM, 4.55 will put down 12% more torque than the stock R&P. So if torque at 8100 RPM down at least 12% from what it is at 7225 RPM (RPM at which the drag-limited speed is reached), it will definately not be able to reach not 8100 RPM in 5th gear. When I made my assumption, I was incorrectly comparing torque at 8100 vs. torque at 8000 (rather than 7225).
So, based on the correct RPM and assuming I did not make another mistake, it looks like torque at the wheels with 4.55 will drop below torque at the wheels of stock around 7900 RPMs, which translate to an approximate top speed of 164 MPH (drag limited).
Thanks for correcting my careless error. I'll stop all this calculated stuff and allow the people who have actually performed this modification to reply.
My 93 has short gears with the 4.55 R&P. This is the way I purchased the car. Below 100 mph the car is a blast to drive! Zipping through 1st, 2nd and 3rd gear in the city makes the car much more fun for me to drive. It just feels lighter than my previous stock geared NSX. I know the car is not faster than a stock geared NSX, as I have raced friends several times from both stop and rolling starts. Each time I would get the jump, but would then lose ground with each shift.
Ken touched on a very good point. The 'perceived' difference when driving my car is HUGH! You can zip through 3 gears when stock NSX's can only get through 2. This give the illusion that you are hauling butt, when in reality, you are just shifting your acceleration away. What is gained down low is lost up top. Not a big loss I might add, but for the $$$ spent on the mod, you would like to see huge improvement.
As for top speed, who really cares? 165 or 184 are speeds that I personally have never gone, and probably never will. I'm not sure how much that would play into my decision if I had to do it all over again. Probably not at all I'm thinking.
The one down side to my tranny setup is cruising at 80 mph (@ 4000 rpm I might add) in 5th. A stock tranny could downshift into 3rd and take it up to ~115, where I on the other hand can only hold 3rd to ~90. This is a huge disadvantage I feel to my setup. Shifting into 4th at 90mph does not give the same 'pull' to 120 as you get accelerating to 115 in 3rd with the stock tranny.
I guess short of a 6 spd with 4.55, each tranny configuration is going to have pluses and minuses. Some gain here while others gain there. I know I would not have spent the money for the shorties and 4.55 R&P. However, since my car came with them I am enjoying them around town big time!
To answer your question. As for gas mileage. On the highway I get around 330 miles to a tank and about 220 in the city.
Ken touched on a very good point. The 'perceived' difference when driving my car is HUGH! You can zip through 3 gears when stock NSX's can only get through 2. This give the illusion that you are hauling butt, when in reality, you are just shifting your acceleration away. What is gained down low is lost up top. Not a big loss I might add, but for the $$$ spent on the mod, you would like to see huge improvement.
As for top speed, who really cares? 165 or 184 are speeds that I personally have never gone, and probably never will. I'm not sure how much that would play into my decision if I had to do it all over again. Probably not at all I'm thinking.
The one down side to my tranny setup is cruising at 80 mph (@ 4000 rpm I might add) in 5th. A stock tranny could downshift into 3rd and take it up to ~115, where I on the other hand can only hold 3rd to ~90. This is a huge disadvantage I feel to my setup. Shifting into 4th at 90mph does not give the same 'pull' to 120 as you get accelerating to 115 in 3rd with the stock tranny.
I guess short of a 6 spd with 4.55, each tranny configuration is going to have pluses and minuses. Some gain here while others gain there. I know I would not have spent the money for the shorties and 4.55 R&P. However, since my car came with them I am enjoying them around town big time!
To answer your question. As for gas mileage. On the highway I get around 330 miles to a tank and about 220 in the city.
pbassjo said:
Hey Joeyyy!
Come siete? You have a 4.35 R&P? Who makes that?
Without bringing in the NSX-R 4.23 or Comptech's 4.55 R&P into the equation, I am evaluating my decision on whether or not to install the Japanese short gears with my stock 4.062 R&P. From the information I provided above, it doesn't appear to be worth it.Ojas & nsxtasy, thanks for the heads up on the shorter 2nd gear introduction for '95.
Agreed. If I were going to do it, I would wait until I had to replace the clutch and get it done then.
Ken, thanks for the explanation. The perception of faster acceleration with the Japanese short gears is indeed greater than the actual gain. As for me, I'd rather be actually going faster with the stock gears (higher speeds throughout the shifts at redline), than perceiving to do so with the quicker shifts from the Japanese short gears and lower speeds. And from the numbers I posted above, the loss in speed with the Japanese short gears (especially 2-3, 3-4, & 4-5) are quite significant.
Agreed...
Agreed...
Ahem... I do!
Honda gave it to me in the stock set up, so why should I give it away? It's better to have it and not need it, than to need it and not have it.SennaPerfected said:
Ahem... I do!
True. A mod should never take something away from the car if possible. However, how often are you going to be driving at that speed compared to... say... 0 to 120? You are the only one that can answer this obviously, but I for one, see very little use for speeds over 150mph. At least in South Florida that is. Now if I lived in Germany I would be thinking differently.
All of this just makes me realize I want the 97 with the 6 speed and not bother with all that.
NetViper said:
Some people run with authority. Me, run from authority!
j/k...NetViper said:
Agreed. Having the OEM 6-speed set up is the best way to go. They state that on the evaluations as well.
Filled up for the second time today. 20 mpg on a blended highway (2/3) city (1/3) tank. Not too bad for the performance gain.MRFreeze said:
You also need to evaluate how you use your car. The short gears and R&P can hurt you if you drag race (or I think that was the consensus a few years back), but in other applications it's a great help. I have a 6-speed with the 4:55 and the 4:55 made a HUGE difference when autocrossing. With the stock R&P the revs would get too low in 2nd gear and I'd bog or even have to down shift to first (yuk!), but with the 4:55 I could just stay in 2nd and have a lot's more torque. On the autocross course it felt like an all-new engine was slapped in the car. But driving to and from work it meant worse gas-mileage and more shifting. At the big tracks it really helped to launch out of some corners, but also took away from some other corners so it balanced out, but then, that's why the big boys have different gear sets for every circuit.
Solution: FI and you can reach red line in all gears with 4.55/4.23 R&P and short gears. Enough torque will be available:biggrin:nsxtasy said:
I have a 6-speed and I can only get to about 98-100 at redline in 3rd gear. I have 10k miles on it. Is it that the engine needs to be broken in more or what?
It's what.timothyaw said:
If you go to the NSX FAQ (answers to Frequently Asked Questions) and look at the Gear Ratios section (under the Technical heading), you will see that the stock '97+ NSX third gear reaches redline at 102 mph. (The difference between that and your 98-100 can be due to tachometer error, speedometer error, etc.) Folks who talk about going faster than that in third gear are probably referring to the stock five-speed, in which third gear is good to 114-116 mph.
What a difference. My top speed in third gear is about 92 mph!nsxtasy said:
SennaPerfected said:Hey Joeyyy!
Come siete? You have a 4.35 R&P? Who makes that?
Miled!!
I know this thread was old but I stumbled back upon it.
Should read 4.235.
Sorry you didn't drive my car at NSXPO 2004 but you will eventually. Then you will want the gears. :biggrin:
I have never run out of top end, just courage.
Merry Christmas and hope to see you at the party 1/15/05.
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