It seems to me that ppl take their z's to the dyno and even if both cars are stock sometimes u get slight hp differences why is this.

i kno its a dumb question but plz tell me why

 

differences in altitude, humidity, temperature, barometric pressure, tire pressue, gas quality and even the dyno you test on can all contribute to variance in readings between to identically prepared cars.

 

so there is no such thing as a stronger stock motor?

 

strange i pulled 252 stock on 2 Seperate dynos. with about 50 between our dyno and the one in the next town over.

john

 

btw: both dynos were calibrated to give actual WHP. one was a clayton in ground dyno and the other was above ground.

the clayton dyno is a chassis dyno but has different calibration settings. since we race porsches we had to set it to the REAL figure.

i guess if our dyno is wrong than my friend chris barnes's Turbo S2000, on cover of the new turbo mag, didnt really pull 559whp? hmmm......

john

 

rrrrrr shytQ! npt ahian


sorry

 

yes but can one stock engine actually produce more hp under the same conditions then another??

 

depends on the engine then, i guess. there are soo many variables that would contribute to a lower or higher figure. such as driving style, mileage, even how the car is strapped to the dyno affects the figures.

john

 

There's some people that like to rumor monger about that. I don't think there's any major differences between any of the stock 350z engines produced in each run. However, there might be a small efficiency difference between 2004 and 2004.5 models maybe?

Imo these differences in dynos are caused by either the ECU having "learned" differently or differences in tire weights(17" v 18" v 19").

 

maybe this will answer you question. my brother and i both dyno'd our cars at the same time. both with a 200-400 mileage difference and both stock.

his pulled 240 and mine 252

so yeh they can show different figures but you have to take into affect that with each second the coinditions outside and inside the car are ALWAYS changing which can lead to lower or higher figures.

dynos shouldnt be used to make accurate figures of what cars make. they should be used to see a difference in mods to get the most hp out of a car. and most def. a dyno graph is always off, because thats what your car made that day, that second. tomorrow you could pull lower of higher.

john

 

thx guys u answered my question

 

at the factory, various components such as cam shafts, crank shafts, and many many other engine components are machined and grinded on the line.

but grinding wheels wear down, requiring them to be adjusted into the oproper position or replaced.

however with this they have a certain window that they are willing to tolerate high and low from perfect.

so, no, all engines are not created equal. to say if 1 is stronger than another due to these tolerance differences is impossible to say, as they keep these tolerances rather small. but even so, they are there.

 

No part is machined to *exactly* its design value. There is always a manufacturing tolerance, plus or minus, from the design value which is allowed during manufacturing. If the factories didn't make this allowance, parts would be prohibitively expensive to produce.

Now those tolerances often cancel out when a group of parts are assembled. In other words, roughly as many of the parts are plus as are minus in the assembly, and all is well. The particular engine will perform pretty much as designed.

*But* there are cases where the tolerances all stack one way in a particular assembly (engine). This can result in an engine that is rather far from design values. Power output can then also vary rather far from the design value because of the particular set of tolerance stackups in a particular engine assembly.

When hotrodders talk about blueprinting an engine, they're talking about hand selecting or modifying parts so that they are made as close as is humanly possible to design values (or to particular values the hotrodder knows will enhance performance). These blueprinted engines then perform optimally.

The factory can't afford to do this blueprinting. It is too time consuming and too expensive. So production engines will vary from one to the next, and their performance will vary from one to the next.

For big old slow reving V8 engines, tolerances can be pretty far out without much change in engine performance. But for our smaller higher reving engines, things have to be pretty close to design values, or performance will be fairly strongly affected.

Modern factories use CNC equipment which produce parts to pretty tight tolerances, so modern engines don't vary as much as engines made 10, 20, or 30 years ago. But you still won't find two engines that are *exactly* alike in a production run. Modern computer engine controls can compensate to a degree for these differences, but they aren't perfect either. So finding two engines which dyno exactly alike would be a matter of pure chance.

 

How do you calculate drive train losses for different cars?