NSX Mods.

H

HapaHaole

Experienced Member
Joined
14 September 2000
Messages
296
Location
folsom CA
The question I have for you guys is what kind of gains should I expect from a combo of
aftermarket Intake, exhaust, and Headers?
from a '91 ~ '94 Coupe

Could it be possible to make the same power as a '97 + from these modifications if not what does it take. I would like to say CARB legal since I am in Cali.
Any imput would be grea
 
I have the Comptech header and exhaust with a modified intake and Dinan Stage III chip. I'm not all that sure that the chip is doing anything (I also have the RM chip and I will dyno them both back to back soon). My seat-of-the-pants gains were through the exhaust install.
I am currently making 271 bhp at the wheels.
 
Originally posted by ChopsJazz:
My seat-of-the-pants gains were through the exhaust install.
I am currently making 271 bhp at the wheels.
Click to expand...

Really.. wow.. man so getting a '94 and making mods can make just as much power as a '97+ can..
 
Originally posted by HapaHaole:
Really.. wow.. man so getting a '94 and making mods can make just as much power as a '97+ can..

Hapa,
I have the identical mods as Chops and dyno 269bhp to the rear wheels. If you adjust this for drivetrain loss of 10-15%, this gives you an output of 299-316 crank horsepower...greater than that of a '97 or newer. However, there are other significant improvements to the '97 and newer models. Most notably, in my opinion, is the transmission. The six speed is a big advantage over the five speed. The brakes have also been improved modestly. All food for thought.
Click to expand...
 
HapaHaole-

Although I have a '98, I have the mod's you mention. I'd be happy to let you drive my car, as I see you are in Folsom. Who are you, are you a part of the Sac. Chapter of NSXCA?
 
Originally posted by '98 NSX-T:
HapaHaole-

Although I have a '98, I have the mod's you mention. I'd be happy to let you drive my car, as I see you are in Folsom. Who are you, are you a part of the Sac. Chapter of NSXCA?
Click to expand...

Well I am going to become a new member this spring. I decided to hold back on getting a NSX till I get a house. Well as you know the house market is too high now so I got priced out. So might as well get the NSX and wait for housing prices to drop.
 
I agree that the transmission is your next barrier. The exhaust mods will will benefit you in power, about 25 or 35 rwhp with a chip. But the 5 speed is not a close-ratio box like the 6 speed, and will not keep the engine in the power band like the 6 speed will. The short gears and R&P will help in that respect, or for about a grand more, the 6 speed.
Good luck!
 
I don't know about the tranny info.

It seems that the mod of choice is the 4.32 R&P with short gears. However, it seems that (according to the lastest NSX Driver) your best bet is teh 4.55R&P with the stock gears (short of getting the 6spd).

The problem w/ the 6spd is that you need that reverse lock out modification which is nearly $1000 in and of itself.

Anyone know the exact price of one vs. the others?
 
If you get the C/T supercharger, it obviates both the r/p and the tranny change. Torque curve becomes flat enough that the stock 5-speed 1-2 shift "hole" becomes irrelevant and torque level is high enough that the r/p change is irrelevant. Plus, with the stock 5-speed and differential, hitting 80 in second is a hoot!

--twc

99 Zanardi (s/c)
95 Dinan M3 (s/c)
95 M3 (stock)
 
If you get the C/T supercharger, it obviates both the r/p and the tranny change.

If you look at the chart labeled "What are the Numbers?" in http://www.nsxprime.com/FAQ/Performance/gears.htm you'll see that adding 20 hp gives you a lot more acceleration benefit than the R&P and short gears do. And the supercharger adds several times 20 hp. What does that tell you?

The fact of the matter is, as you can see from this table (and as much as some folks with the gearing changes hate to admit it), the gearing changes don't make a whole lot of difference in acceleration. They'll improve it at certain speeds (say, 40 to 60) but take it away at other speeds (say, 60 to 80), so that overall, your acceleration hardly changes at all. Shorter gearing gives you the perception of faster acceleration because you reach redline quicker. However, you then have to upshift, at which point the shorter gearing actually hurts you by forcing you into a higher gear at a lower road speed. So shorter gearing is a mod that makes it seem like you're accelerating faster than you really are. Just check out the numbers.

The supercharger, OTOH, gives you a real improvement in acceleration, not just a perceived one.
 
Originally posted by nsxtasy:
If you get the C/T supercharger, it obviates both the r/p and the tranny change.

If you look at the chart labeled "What are the Numbers?" in http://www.nsxprime.com/FAQ/Performance/gears.htm you'll see that adding 20 hp gives you a lot more acceleration benefit than the R&P and short gears do. And the supercharger adds several times 20 hp. What does that tell you?

The fact of the matter is, as you can see from this table (and as much as some folks with the gearing changes hate to admit it), the gearing changes don't make a whole lot of difference in acceleration. They'll improve it at certain speeds (say, 40 to 60) but take it away at other speeds (say, 60 to 80), so that overall, your acceleration hardly changes at all. Shorter gearing gives you the perception of faster acceleration because you reach redline quicker. However, you then have to upshift, at which point the shorter gearing actually hurts you by forcing you into a higher gear at a lower road speed. So shorter gearing is a mod that makes it seem like you're accelerating faster than you really are. Just check out the numbers.

The supercharger, OTOH, gives you a real improvement in acceleration, not just a perceived one.
Click to expand...


Having taken a 93 Comptech SC with 5 speed and a 91 comptech SC with six speed and 4.55 R&P, the difference in trap speed is about the same but the ET is alot different. Only 2 passes in each car, the 5 speed ran 13.1@112 while the 6 speed with 4.55 R&P ran 12.4@112. The ability of the shorter gears to launch is incredible. The six speed with 4.55 R&P will take off quicker and pull away when the 5 speed is doing the 1-2 shift.
 
2 passes in each car, the 5 speed ran 13.1@112 while the 6 speed with 4.55 R&P ran 12.4@112.

The "What are the numbers" analysis shows that of this measly 0.70-second difference in the 0-112 time, around 0.25 second is due to the difference in gearing. The rest of the measly 0.70-second difference is due to driver ability, not to the gearing setup.

Also note that the supercharger alone probably decreased the time in the quarter-mile by two full seconds.

All of which proves my point - adding horsepower is going to give you way more acceleration than changes in gearing.
 
Well with the input about the transmission I have seen it is impressive how much you guys know.

I am not one for pure specs. I dont plan to "DRAG" the car more for fun street driving and occasional auto-x events.

Now with the shorgears how much labor are we talking to get it installed? I looked at comptech and called them and they quoted me around 8 hours +, is this right?
Also would just getting a stock '91 ~ '94 NSX plus the Headder, intake, exhaust and the Comptech ECU make it a fun car to drive? or is the short gears that much of a difference?
 
Also would just getting a stock '91 ~ '94 NSX plus the Headder, intake, exhaust and the Comptech ECU make it a fun car to drive? or is the short gears that much of a difference?

There are different ways to have fun. For example, some people like the sound of a particular aftermarket exhaust - to them, it's fun, whether it increases acceleration or not. Same thing with the short gears - if you're looking for a feeling of fun, they may do it for you, because you'll zip up to redline very quickly, albeit at lower road speeds than with the standard gearing. The header, intake, and exhaust may do more for your quarter-mile time... but they might not be as noticeable in your driving as reaching redline sooner. So which is more important - actual acceleration, or a feeling of acceleration? It's really up to you to decide what will create the most fun for you.
 
The "What are the numbers" analysis shows that of this measly 0.70-second difference in the 0-112 time, around 0.25 second is due to the difference in gearing. The rest of the measly 0.70-second difference is due to driver ability, not to the gearing setup.

From 50 mph on, you probably won't see a difference between the 2 cars, but from 1/4 mi times, .7 seconds is about 7 car length, that is getting smoked. Everyone knows how important the take-off is in a drag race, the gears will enable you to take-off alot quicker. The gears will also help alot on road racing as alot of tracks have sharp turns.
 
Originally posted by nsxtasy:
2 passes in each car, the 5 speed ran 13.1@112 while the 6 speed with 4.55 R&P ran 12.4@112.

The "What are the numbers" analysis shows that of this measly 0.70-second difference
Click to expand...

This comment shows a lack of experience with drag racing. There is nothing measly about a 7 tenths difference in quarter mile times.

7 tenths is a huge margin. Night and day.

In the 1/4 mile, a .7 second difference is the difference between a 3.2 NSX and a new Viper (beaten any Vipers with a stock 3.2 NSX lately?). As a refresher, the Viper has over 150 more horsepower than the NSX.

Or conversely, take away 7 tenths on a 3.2 NSX and you'd get beat by a common BMW 328. 7 tenths is very noticeable. Am not trying to go off on ya about this (really!) but as a long-time drag racer who fought for every tenth, statements like that are a total call to arms
smile.gif


I don't disagree by the way re: a supercharger vs. tranny & R&P. I'd take the SC too!
smile.gif



[This message has been edited by SpeedDemon (edited 12 December 2000).]
 
Anything over .5 seconds is a big difference in the 1/4 mile.

nsxtasy makes a good point though. There is a big difference between speed and the perception of speed. 80 MPH in an old MG or other '70s roadster with the top down feels a lot faster than 120 MPH in an NSX coupe. Likewise, you never have any real perception of going 600 MPH on a commercial jet airliner (unless something goes wrong!) You feel the acceleration to a fraction of cruising speed at takeoff and that's about it.

A turbo car with really peaky torque curve and short gears may feel faster than one with a flat torque curve even if the latter is really the faster car. Which is right for you? It's just personal preference.
 
Originally posted by Lud:
nsxtasy makes a good point though. There is a big difference between speed and the perception of speed.
Click to expand...

Agreed.

Another thing that contributes towards "feeling" faster is sound. When you add modifications that make your engine sound louder or different (ie it sounds "more sporty"), it will often add to the feeling that your car is now faster.

How fast would our cars feel if that's all you heard in the cabin was silence and the sound of birds chirping outside when getting on the throttle?
smile.gif
We look to all our senses to tell us how fast we're going.

Marc
 
Well thanks for the input guys.. I guess I will take my car to comptech when I get it soon this spring.

Yet I have one last question.. how is the Comptech ECU?
 
If you're running the same trap speed and tires, I don't see how you wouldn't be able to run a 12.4 in your 93.

I think the 6 spd just accomodating your driving and launching better.

Isn't the difference in ET indicate differences in traction if the trap speeds are the same?
 
If you're running the same trap speed and tires, I don't see how you wouldn't be able to run a 12.4 in your 93.

I think the 6 spd just accomodating your driving and launching better.

Isn't the difference in ET indicate differences in traction if the trap speeds are the same?
 
OK, Im late to this thread but I'm also confused here.

If you have 2 NSXs with identical trap speeds in the 1/4, why can't they both get the same ET (or at least close) if both are launched the same?

Nsxtacy, you mention that the CTSC probably took 2 full seconds off the 1/4. Are you saying a stock 91 NSX does 15.1 and a stock 93 does 14.4? I thought the 13.1 time was a little slow for a CTSC NSX.
 

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