Pure dyno results .....why? HELP

[thanosb850]

i recently dyno my 350z 2004 (EUROPE) and what i found out was not too promising. 282 crank hp and ONLY 203 rwhp at 6450rpm ( 231,1km/h), and 34,9kg torque at 4830 rpm (173,2 km/h) and maximum rpm 6596rpm (236,7km/h). He used the fifth gear. ( ???) .......Also the guys there found out at the mashine and later on that the obd reader meausures 450rpm lower than the indication on my instrument rpm cluster.....Why??? the tachometer also indicates less than the digital one ( i was expecting to be the opposite)......is it possible that someone tappered with the mileage, is a used car, but in an excellent contdition as the NISSAN mechanics told me. Please any answer ??? Why such a loss in hp?? the dyno is MAHA LPS 3000.

[audtatious]

I don't have an answer for you but I do know a lot of Nissan owners do dyno-pulls in 4th gear and not 5th nor 6th.

[thanosb850]

Thanks for the reply......, but do u really think that the gear will matter in the result numbers? I mean the guy told me he supposed the fifth gear is closer to 1 to 1 ratio, or sth like that.

[audtatious]

Yep, you are correct.

Unless something is wrong with your tune, then I will have to defer this to the 350z pro's (when they get done with their weekend it seems)

[thanosb850]

i would be very grateful, thanks a lot.......

[zozoka1212]

i recently dyno my 350z 2004 (EUROPE) and what i found out was not too promising. 282 crank hp and ONLY 203 rwhp at 6450rpm ( 231,1km/h), and 34,9kg torque at 4830 rpm (173,2 km/h) and maximum rpm 6596rpm (236,7km/h). He used the fifth gear. ( ???) .......Also the guys there found out at the mashine and later on that the obd reader meausures 450rpm lower than the indication on my instrument rpm cluster.....Why??? the tachometer also indicates less than the digital one ( i was expecting to be the opposite)......is it possible that someone tappered with the mileage, is a used car, but in an excellent contdition as the NISSAN mechanics told me. Please any answer ??? Why such a loss in hp?? the dyno is MAHA LPS 3000.

Can you post the dyno result?

zozo

[RED_DET]

Is the dyno similar to a dyno jet? Some dyno's read lower numbers. A dyno jet dyno will yield a higher hp reading than a mustang dyno.

[thanosb850]

what u mean to post the dyno result? The result i wrote. U want a photo??I dont know about dyno jet. The dynometerwas -MAHA LPS 3000- What about the rpm problem and the speed ? I am desperate.

[RED_DET]

Read:

Okay here's a long overdue couple of dynographs that were referenced in the second article in the magazine but didn't make it in but before that allow me to refresh people about the MAHA 3000 LPS dyno:

For those unfamiliar with dynamometers, there are two basic types of dyno's:

The first being the Engine Stand dyno, which requires bolting a complete engine to a horizontal engine stand and measuring how much resistance it can overcome or how much work (measured in torque or horsepower) it can produce. While this is the most exact measurement possible, it means removing the engine from the vehicle and after testing, reinstalling it again. Obviously the downtime and expense do not make this a practical option for most owners. The advantages are the engine is being tested in a controlled environment and there are no driveline loses to compensate for in calculating the engines output. However, for development work where many options are to be tested before the engine goes into the vehicle, it can be an invaluable tool.

The second type of dyno is a chassis dyno, which merely requires driving the vehicle onto the rollers and strapping the vehicle down, so it doesn't run off the dyno, and then measuring the amount of resistance/work it can overcome.

There are 2 main obstacles when using a chassis dyno, the first is airflow. Most fans used on chassis dynamometers are taken from contractor suppliers and struggle to simulate a 10-20 MPH road speed, which is equivalent to your doctor asking you to submit to a fitness test while in a sauna. Needless to say, your score will be low. The MAHA approved custom built, "AIR 8" fan on the AMS MAHA dyno, flows over 80,000 CFM (cubic feet/minute) or a road speed of 60-70mph!

The second obstacle, is that most dyno's only measure "wheel horsepower" - that is the power that isn't sapped away by everything located after the clutch (transmission, differentials, driveshaft, axles, even the wheels and tires themselves!). And since wheelhorsepower readings are dependent on the temperature of your transmission and differential oils (cold oil is like molasses and warm is like water, warm oil eats less power) and tire temperature (cold tires offer less resistance than warm sticky tires) so driveline loss can be inconsistent or as an expert referred to it "a moving target"!

Many people simply add back a "guesstimate" of the parasitic drag of these components anywhere from 10-20% for FWD or RWD cars and 25-40% for AWD or 4WD cars. The final flywheel numbers are only as accurate as the tuner's best guess.

The inherent beauty of a dyno system like the MAHA LPS 3000, is that after it has measured the wheel horsepower, it measures the resistance of the entire drive train from the clutch to the tires by letting the car "coast" down while in gear, so instead of dynoing a vehicle with a reported 200 horsepower and measuring only 150HP at the wheel, and assuming that 50hp was eaten up by the drag of the drive train and wheels The LPS 3000 actually measures the drag loss during the coast down phase. In fact, if the drag loss is only 30hp , you know beyond a "guesstimate" that your engine only made 180hp, or if the drag was 50hp, you will know exactly how much power your vehicle is really making. However, with a drag measurement you can rest assured that you have isolated only the engine's horsepower and not the engine's power minus an unknown amount of drag. The system also corrects for environmental conditions such as humidity, air density, and temperature.

I didn't write the article.

But from what I gather, that particular dyno can simulate normal driving conditions which would yield a more accurate hp reading, although it maybe lower.

[evildky]

even on a chassis dyno not all things are equal, mustangs tend to read lower than dynapack models, and one thing many people dn't account for is wheels, large, heavy aftermarket wheels take more power to turn, also how are you plugs and oil? stock new condition is 287 chp old oil and old plugs are gonna cost you a few ponies as well, also auto or manual? auto's have tu turn a heavy torque convertor and power the trans pump which equals more parasidic loss, it's been a while since I've seen a stock Z33 on the rollers but I seem to recall seeing about 220 whp, so you're only about 20 hp off, also the dyno itself needs to be calibrated from time to time so the dyno could be out of wack as well