dyno question

[ak]

What's the difference between dynoing with 3rd gear as opposed to 4th gear? Would the result be any different?

Also, where's the best place to tap in for the ignition signal on NSX? For my dyno, they tapped into the wire that leads to the coil#1 on my nsx and the torque curve would spike like crazy esp at top end. I don't think my car was misfiring so there must be some interference or something...

 

[David]

Generally, you want to be in the gear that will give you the closest to a 1:1 final drive ratio. This is because the NET gear ratio at the wheels will affect the torque numbers. So, there will be a slight difference if you dyno in 3rd vs 4th. I believe 4th is the closest to 1:1 on the NSX.

 

[Sensei]

Also, where's the best place to tap in for the ignition signal on NSX?
On the passenger side located in the engine compartment will be a single green wire by itself attached to nothing. On the end of this wire will be a black rubber-like cap that can be opened to accesss the wire. This is the wire to get an ignition/rpm signal.

Choritsu-shi

 

[sjs]

Originally posted by Sensei:
Also, where's the best place to tap in for the ignition signal on NSX?
On the passenger side located in the engine compartment will be a single green wire by itself attached to nothing. On the end of this wire will be a black rubber-like cap that can be opened to accesss the wire. This is the wire to get an ignition/rpm signal.

Choritsu-shi

What if they use an inductive pickup?

 

[Sensei]

(scratching head)Hmmn...that's a thought. Well I guess if that doesn't work then you can get a signal from the ignition control module(ICM). (Located above the throttle body) It has a "service loop" wire for an inductive pick-up.

Saiyonara,

Choritsu-shi

 

[sjs]

Originally posted by Sensei:
(scratching head)Hmmn...that's a thought. Well I guess if that doesn't work then you can get a signal from the ignition control module(ICM). (Located above the throttle body) It has a "service loop" wire for an inductive pick-up.

Saiyonara,

Choritsu-shi

tried that but it didn't pick up. Hmmm, now I can't recall what we finally did.

 

[Nimbus]

I would do 3rd gear pull in the 5sp cars, and 4th gear pull in the 6sp cars.

 

[W]

Originally posted by David:
Generally, you want to be in the gear that will give you the closest to a 1:1 final drive ratio. This is because the NET gear ratio at the wheels will affect the torque numbers. So, there will be a slight difference if you dyno in 3rd vs 4th. I believe 4th is the closest to 1:1 on the NSX.

I believe 4th gear is .967 for the 5 speed and 1.12 for the 6 speed. 5th gear for the 6 speed is .91. For short gears, 4th gear is 1.033.

By contrast, 4th gear is 1 for both the LS1/MM6 and the LS6/M12.

Someone correct me if I've goofed here.

 

[mdoan300]

Some people have said that dynojet should adjust/account for gearing. I don't know how and I kinda doubt that, but it does make sense considering that although you may be in a 1:1 gear, your final drive ratio is not 1:1.

The only way to tell is to dyno in 3rd and 4th gears.

Michael.

 

[nsxlr8]

the full white wire coming out of your ecu.. try that one. if you use the one that the manual says to read RPm from the engine bay (Green wire with rubber cap) your tach will probably bounce all over the place while you're driving.

If you Dyno in third gear, you'll read LESS horsepower than you acually have.(5spd) 4th gear is the way to go.

 

[1BADNSX]

Originally posted by mdoan300:
Some people have said that dynojet should adjust/account for gearing. I don't know how and I kinda doubt that

It measures the RPM of your engine and the speed of the drum to calculate the overall gearing.

It also needs the overall gearing to adjust the torque graph because it reports engine torque, which has been reduced by driveline friction. The actual measured rear wheel torque is higher than reported due to the gearing multiplication. The horsepower transfer is not effected by gearing, only friction.

Bob

 

[Enzo]

Last monday, I dynoed my 91 NSX for the first time.

The dyno was a Bosch FLA-203 and we dynoed the NSX in fifth gear.

RESULTS :

213kW = 290HP
Top speed 286km/h = 178mph
294.2Nm @ 6400rpm

Here's the graphics : http://www.macs.ch/homepages/david/New_Pages/dyno.html

David

91 NSX / 70k miles
Remus exhaust
RM Cold intake
Comptech cat bypass pipes

 

[sjs]

Originally posted by Enzo:
Last monday, I dynoed my 91 NSX for the first time.

The dyno was a Bosch FLA-203 and we dynoed the NSX in fifth gear.

RESULTS :

213kW = 290HP
Top speed 286km/h = 178mph
294.2Nm @ 6400rpm...

Hmmm... with the mods you list it is highly improbable (to put it mildly) that the engine creates 290 HP at the rear wheels. It sounds like their software calculates an estimated value at the crank.

And of course, the top speed is meaningless since it does not account for aerodynamics. It is no different than calculating it from the gear ratios and tire diameter.

 

[Enzo]

Originally posted by sjs:
Hmmm... with the mods you list it is highly improbable (to put it mildly) that the engine creates 290 HP at the rear wheels. It sounds like their software calculates an estimated value at the crank.

Yes, exactly ... that's why I didn't write 290RWHP but 290HP

And of course, the top speed is meaningless since it does not account for aerodynamics. It is no different than calculating it from the gear ratios and tire diameter.

I don't know if it changes something but a BIG blower which simulates a 200km/h wind speed was in front of the car !

My speedo was at something like 310km/h !

MvM, where are you ? I really need your 320km/h speedometer !

You know, the Bosch FLA-203 is very very accurate. We did 2 run with exactly the same results.

It's the only dyno here homologated by the FIA to measure true race cars and the shop who dynoed my car is specialized in doing maintenance and tuning for several cars who competes in GT-FIA series or "Le Mans", mainly Porsche.

I am going to post a pictures of the dyno later ! It's an entire room !

Regards,

David



[This message has been edited by Enzo (edited 22 June 2002).]

 

[Enzo]

Here are the pictures :

Sorry for the bad quality !

 

[sjs]

Extremely cool!

I don't doubt the 290HP, that is reasonable enough given your mods. I erroneously assumed the RW because that is naturally the way everyone quotes from a chassis dyno. I don't recall a dyno reading like yours before, which is logical since cars have very different drive train losses.

As for the 200km/hr fan, I can't see that having any effect since you aren't really pushing through it, but it is a great way to minimize other errors related to intake air temperature and flow.