NSX-R engine

[satan_srv]

But even still, the NSX reaches is top speed well below the redline, so the NSX-R should still be able to pull up to 175, no?

I'm not sure what you mean. The top speed of the car is the speed it can go at fuel cut. There may be an advertised top speed that is lower I suppose but that's not the mechanical top speed.

The mechanical top speed you can hit in any gear is determined by your max engine rpms, gear ratio and final drive together. Basically your engine spins at 8000rpms, the gear reduces it, then the final drive reduces the revolutions more, as you can't turn your wheels at engine speeds.

if you change any specific gear, you change the possible top speed you can hit in that gear. if the max is 40mph in 1st gear a shorter first will only be maybe 37mph and you will have to shift because for any given rpm the wheels spin less, but consequently get through the rev range faster. Problem with just changing one gear is you mess with the gear spacing...so if you make first really short and leave the rest you will likely find yourself bogging badly in 2nd as you are at a lower rpm given your speed shifting from 1st.

if you change the final drive, you effective lower the wheel rpms in all gears. The advantage is that you preserve all gear spacing (if oyu like) causing no difference to the rpm changes between shifts, however you increase acceleration as you are topping out at lower speeds in each gear. Thus an NSX-R has a lower top speed.

Here is a side by side comparison of top speeds for the two trannies with the 4.062 FD and th 4.235:

NSX - NSX-R

49 - 47
75 - 72
102 - 98
130 - 124
160 - 153
203 - 195

Assuming a 24.9 inch wheel at a max rpm of 8000

 

[JJCNSX]

how hard is it to switch to 4.235 in a 6 speed?

i was told that if we were to swap to 4.55, we might have "grining sound" problem?

has anyone done this conversion? and how hard is it.. and how much it might cost?

thx

-jjc.

 

[nsxtasy]

I'm not sure what you mean. The top speed of the car is the speed it can go at fuel cut. There may be an advertised top speed that is lower I suppose but that's not the mechanical top speed.

The mechanical top speed you can hit in any gear is determined by your max engine rpms, gear ratio and final drive together. Basically your engine spins at 8000rpms, the gear reduces it, then the final drive reduces the revolutions more, as you can't turn your wheels at engine speeds.

There may be two different speeds that are considered the top speed; or there may not.

As you point out, there is what you are calling the "mechanical top speed", meaning the road speed at redline in the highest gear, assuming that the car will actually go that fast. If the car can actually go this fast, it is called a "rev limited top speed"; regardless of whether it can or can't go that fast, it is called the "speed at redline".

Some cars can actually go this speed. Others are limited by the amount of aerodynamic drag on the car body, so they can't go any faster than a lower speed. A bone stock NSX is the perfect example. A '91-96 five-speed NSX would be going 186 mph at redline in fifth, and a '97-01 six-speed NSX would be going 202 mph in sixth. But neither car can go that fast; on level ground with zero wind, both cars will top out at 168 mph, and this actual top speed is considered their "drag limited" top speed.

The actual top speed (168 mph in the above example) is usually considered the "top speed", and AFAIK the other figure (what you refer to as the "mechanical top speed") is called "speed at redline", regardless of whether it is actually attainable or not. I don't know if there is any other term that is used for the latter.

 

[satan_srv]

There may be two different speeds that are considered the top speed; or there may not.

As you point out, there is what you are calling the "mechanical top speed", meaning the road speed at redline in the highest gear, assuming that the car will actually go that fast. If the car can actually go this fast, it is called a "rev limited top speed"; regardless of whether it can or can't go that fast, it is called the "speed at redline".

Some cars can actually go this speed. Others are limited by the amount of aerodynamic drag on the car body, so they can't go any faster than a lower speed. A bone stock NSX is the perfect example. A '91-96 five-speed NSX would be going 186 mph at redline in fifth, and a '97-01 six-speed NSX would be going 202 mph in sixth. But neither car can go that fast; on level ground with zero wind, both cars will top out at 168 mph, and this actual top speed is considered their "drag limited" top speed.

The actual top speed (168 mph in the above example) is usually considered the "top speed", and AFAIK the other figure (what you refer to as the "mechanical top speed") is called "speed at redline", regardless of whether it is actually attainable or not. I don't know if there is any other term that is used for the latter.

yeah I'm just making up terms anyway. I agree drag will prevent you from hitting these numbers. I was more trying to explain the effects of the final drive on the other gears, speeds that you can hit hehe.

 

[Procar Specials]

NSX-R

The sport-auto NSX-R datas are:
(Not from the supertest, because sport-auto didnt dyno and top speed their cars.)
The Racing guys experimented with several gearbox setups later,
thats the reason why I dont was sure which one is stock.

Supertest NSX-R (Nürburgring laptime 8.09 min)
HP at dyno: 312 (280 is the official worth)
Tire size rear: 255/40/17
Ratio 6 gear: 0,717
Final drive ratio: 4,235


D2 datas says speed at:
7.000 rpm / 6 th gear: 269 km/h = 168 mph
7.500 rpm / 6 th gear: 288 km/h = 180 mph

Top Speed
7.700 rpm /6 th gear: 296 km/h = 185 mph

Thats about 17 mph more than the standard worth.

A miracle stays, which setups and power rates the japanese guys did before as they drove Nürburgring lap with 7.56 min.
It was another NSX-R and it seems that he hast still more power on board. Thats amazing.

 

[naaman]

I'm not sure what you mean...

I was referring to the drag limited 175 mph factory claim.

 

[MvM]

Is the 312HP that was dynoed RWHP??
Because in that case the real engine output would be significantly higher. The official 280 after all is engine output, not RWHP

 

[satan_srv]

Could have been a Bosch Dyno as well, it gives Flywheel HP numbers.

 

[Ojas]

It will rev better but it's a big gamble that it makes more hp if you ask me.

Would you clarify what you mean by “rev better”?

 

[satan_srv]

Would you clarify what you mean by “rev better”?

A precision balanced crank and rotating assembly will rev smoother and faster as the torsional force of the crank is focused through the center of the crank at all the tested rpms, thus being more efficient, with less forces wasted.

 

[Ojas]

A precision balanced crank and rotating assembly will rev smoother and faster...

That’s what I assumed, but was not sure since your statement appears to be a contradiction: Revving faster would be a result of additional torque. If torque goes up, so does power.

 

[satan_srv]

That’s what I assumed, but was not sure since your statement appears to be a contradiction: Revving faster would be a result of additional torque. If torque goes up, so does power.

Not so. A better balanced crank absorbs less torque to spin, so at a given rpm and a given torque it will go faster. Same thing with lightweight flywheels. you may gain minor torque with the lighter weight. But releasing weight on the rotational mass has an exponential impact of the rev capabilites of the motor.

 

[Ojas]

Not so. A better balanced crank absorbs less torque to spin, so at a given rpm and a given torque it will go[rev] faster.

Yes, I know and did not disagree with this statement (although the qualification about a given RPM is unnecessary). The contradiction I was referring to was your statement that it will rev smoother and faster, but will not produce any more power.

Anyway, The point I was trying to make was simply: If the NSX-R engine is able to rev quicker, it would output more torque (and power) at the crank than a normal 3.2L.

 

[satan_srv]

Sure some power gains could be had, but I perceive them as minor. The page refers mostly to balancing http://www.honda.co.jp/factbook/auto/nsx-r/200205/07.html which will make it smoother, it doesn't take much gains off the rotating mass to make a big difference in rev/acceleration.

For instance I pulled the balancer shaft belt (which runs off the crank) off my prelude and gain 3hp and 2 tq across the board on the dyno. Didn't seem like much till I drove home. Ridiculous difference in acceleration because the drag was directly on the crank.

 

[Procar Specials]

NSX-R supertest car:
312 HP at the flywheel (crank)

NSX-R racecar:
Pipetec headers, HJS racing catalytic converters, Pipetec (Elbestahl)exhaust, add. modififications at ECU, air intake
335 HP at the flywheel

after the 24h-race:
270 HP, probably because the NSX-R dont have an oil-cooler and runed with 140 - 150°C during the whole race.
Healthy is 110 - 120°C.
Engine removed and changed against a new one.

 

[Twincam]

NSX-R supertest car:
312 HP at the flywheel (crank)

.

312HP on the crank of a totaly stock NSX, exactly that one tested in Auto Motor und Sport super test (8:09 nur.) ?



About best motoring in Nurburgring. It was a totaly stock, driven by the preson with passion and will to drive, mr. Kurosawa. Thats why the time is 7:56. These days BM team tested the new Mitsu Lancer EVO8 on the Nurburgring, it will be a special report in new BM edition. This time was driven by Akihiko Nakaya, the man that helps the Mitsubishi team in development in the car, and the owner/founder of a famous Nakaya Tune mitsubishi mark.

 

[NSX-Racer]

Twincam: Just to be correct - it was sport auto. Auto, Motor & Sport has no supertest, not even any laptimes - baaad!

For the HPs of the supertest car: Usualy the test cars given to the press are special prepared. Sometimes the cars for the public are not capable to keep up with the press cars. Good example is the BMW M3 where dyno tests revealed that many cars of the old series didn't come close to the 321 PS in the brochure.

Even sport auto was sometimes astonished when they tried to reproduce lap times from the supertest later with a normal series car (e.g. Porsche 911). The performance decreased remarkably.

 

[JJCNSX]

NSX-R supertest car:
..........., probably because the NSX-R dont have an oil-cooler and runed with 140 - 150°C during the whole race.
Healthy is 110 - 120°C. ....

is 110 - 120°C healthy operating temperture?

i was under the impression that "OPTIMAL" temp is 82 - 89°C ?

we do not have a oil cooler in our NSX? woow, i did not know that.. What is the "normal" operating temperture say.. on street, and track temp? has anyone tried oil cooler?

-jjc.

 

[NSX-Racer]

Use the old friend Mr. Wolf recommends: The search with topic "oil cooler". You may come to this thread

 

[Arata]

Normal operating temp is 180 degrees F. It would not be unusally for a vehical to go all the way up to 230 F and not cause any damage. As long as it was running antifreeze.
I prefer between 160 F to 180 F
And run as low as 140F on race bikes.

The higher temps are much better for emissions.

 

[Twincam]

Racer:

U are right about sport auto, I heard that the M3 CSL, was dynoed towards 380HP.