reclaiming parasitic loss

[kiwi303]

Another thing to remember is dynos have a variable setting called the "ramp rate". Different shops with the same brand dyno but different ramp rates will return you different HP numbers.

 

If you're going to use different shops, tell them the ramp rate to use so there is that one less variable.

[Tony D]

I ditto JC's all caps, bold comment from earlier.

 

An engine Dyno number is WORTHLESS unless you get the SAE SPEC the engine was tested against. Then, it will not apply to another run unless the same specifications are used on another ENGINE Dyno.

 

A chassis Dyno is the same way. The number you get, same as Dave's number is FOR COMPARISON ONLY ON THE SAME DYNO FOR CHANGES YOU HAVE MADE.

 

Dave didn't start out at 297, but that's where it ended up.

 

The value of the Dyno is not the terminal number, but relative change for the modifications or adjustments tested.

 

So he got 297 on the engne Dyno, and you got 217, those are then numbers. Each is useless comparing one to the other.

 

Where they have value is tracking relative change from jetting change, timing change, etc.

 

If you change to synthetic oil in your gearbox, and show 3% more RWHP, there is a relative improvement in a chassis component that gave you more available power to the wheels. An engine Dyno will never show you this. Putting wider wheels on gets you a higher number on a chassis Dyno, too...but it really will not relate to the engine reading at all. Never.

 

Like John said, end of sentence, period.

 

In the end you are making a contention that a LONG BLOCK ASSEMBLY run with different ducting and exhaust is attributable to "driveline losses" when the most obvious answer is the induction system. The differences in peak torque point RPM SCREAM that, loudly. I have seen a car spin 80RWHP, and the exact same engine and driveline spin 147.... Induction for 80HP was Weber DCOE's, Induction for 147 was Stock EFI. Some driveline losses there, eh? Not. Relative change. Thing is, each of those numbers was borne out with 1/4 mile passes that were very consistent and congruent with online 1/4 mile calculators.

Edited December 26, 2014 by Tony D

[roger280zx]

Same long block and cam. If the induction, exhaust, and tune were all changed it is NOT the same engine. If it was not tested back to back on the same machine with the same tuner at the same elevation, temp, barometer, etc it is absolutely not comparable.

[bradyzq]

Do you have Dave Rebello's engine dyno graph of your engine?

 

Though the numbers must be ignored, the shapes of the curves should be very similar on both chassis and engine dyno sheets, barring any huge non-proportional driveline losses that would be seen only on the Dynapack.

[Mikelly]

Been playing on dynos for well over a decade. You know how I use dynos? I use them to help tune, then I use them to simulate running on the track and the guys I work with tune the ECU to respond and compress time between certain RPM ranges. Beyond all that, Dyno numbers are entertaining to the same people who pick their "mods" based on the STAGE kits sold by vendors.

 

I'll know exactly how fast my car is by the laptimes I can turn and the segments I overlay from truly fast cars and my own data... Dynos are the most overly hyped tools used in the industry and when people stop racing them and stop buying based on advertised numbers, the industry will likely DIE!

 

Love-Hate.

Edited January 28, 2015 by Mikelly

[AZGhost623]

Well I am pretty sure I found my problem last night on accident while checking out something else. This was a 'full pedal press' for what was expected to be WOT on the butterfly on the carbs. It is not over rotating, as I recorded a video and got to see what it was doing, and this is just a still from it. The butterfly still has quite a ways to go before it gets completely horizontal.

Edited March 26, 2015 by AZGhost623

[260DET]

Any engine builder who is claiming power outputs that should be known to him to be false is getting close to fraud IMHO. After all, it's an important measurement that potential customers take into account when making their buying decisions, if the measurement is incorrect then there is misrepresentation, something that all consumer law has penalties for.

 

Anyone who thinks that's OK needs a moral overhaul.