Dyno is marketing hype

Everybody loves dyno graphs and performance figures. After all, HP sells cars. Based on my experience, I do not wonder – most ask me for unreal results such as 200PS from 140PS factory engine…they even get upset if I share facts about so called chiptuning.

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SUMMARY

• most chiptuners feed engines with artificially cool air – you will never get IAT 20°C in real life (perhaps in winter at -20°C), especially if you are spirited driver or even worst…track day guy.
• inconsistent results
• I assume that chiptuners are not that stupid and at least warm up engine oil to 80°C for optimal operating condition…still, warmed up engine is still miles away from overheating
• various losses that lead to inconsistency and imaginary results
• rolling road session lasts up to 30 seconds and it doesn’t reflect real full load fun for spirited drivers
• if you cannot drive flat out, chiptuning is not for you in first place
• I want to see some real life simulation of full load dyno session lasting at least 10 minutes
• no heat soaking effect

Chassis dynamometer fundamentals

I am not dyno designer and it is just my theory how it may work. We all know from BHG turbocharger article that it is all about air density. We also know that MAF is just modelling/estimate of air entering into engine.

I have not seen any dyno that is hooked up to OBD diagnostic port and reads live engine sensor data. Which means, dyno is just wild estimate of wheel power output. Since there is many variables in play, one wonders how you can trust results?

I know little bit about combustion theory, thermodynamics and MAF modelling. Dyno is basically similar system that is guessing engine power output. Chassis dyno aka rolling road simply guesses power output based on wheel radial speed, ambient temperature/humidity.

There is major flaws though:

• there is no losses (transmission, tire pressure, IC efficiency, MAF)
• transmission and final drive issues – somewhere between 3rd and 4th gear is 1:1 gearing
• wheel diameter, tire grip and effective chassis/suspension
• not to mention engine is fed by constant cool air flow

I was initially looking for a hardcore dyno run where someone pushes TDi at full load for at least 5 minutes where EGT limiter and heat soaking kicks in but I found only above by video, which supports my theory.

Perfect chassis dyno

Imagine Hilda HR I compared to “same” car with same ECU calibration – Hilda would be clear winner because she has got rally suspension and minimal losses in transmission. It is said there is about 5% transmission losses but normal car users usually have worn dampers or believe wide tires are better.

As you can see in above by video, it is very easy to fool dyno electronic and provide “more” power to customers. I am not surprised normals want it all, I see it by myself.

I recall a hot discussion on Briskoda forum (before they banned me for brutal honesty of course ROFL) where I shared knowledge about AFR. I brought it upon myself though – Briskoda is sponsored by commercial chiptuners, occupied by tExperts and last thing they need to know is how everything really works.

From all those poor misinformed fools there was only one guy that confirmed my field tests – excessive fueling reduces torque in long term. It is sad day for human kind if one from hundreds humanoids have brain.

Above by mentioned guy pushed his car to the limit more than usual 30 seconds dyno session and confirmed effects of torque limiting due heat soaking and overheating.

Perfect chassis dyno would read IAT, knows wheel diameter and pressure thus compensating for various wheel diameters. If you can read IAT, you can control “real” ambient temperature because no factory/upgraded IC has got 100+ % efficiency. IAT is always at least +10°C above ambient temperature and +30 to 40°C at full load.

If you increase 1HP on dyno, it is logical you need aerodynamics on 61HP racing car, no?

You have been warned

IAT/air density is main reason for engine power loss – for example an engine produces 140HP @ 40°C IAT (40ºC is usual IAT for 140HP TDi engine at full load for short periods of time such as acceleration) but you have got 150HP @ 20°C IAT (possible over winter at sub zero temps)

Of course it goes both ways…if you increase heat, as is usual byproduct of poor ECU calibration, you suddenly hit IAT 50-60°C and you have lost over 6% of torque/power.

Chassis dyno has no real value because even same car on same day has different results every time you do some dyno run. Sole purpose is marketing because duners love to brag about theoretical power gains for 30 seconds.

One wonders if “30 second” power is just coincidence with their usual bed performance. Beautiful things don’t seek attention.

I am not surprised though, if you suffer from SPS and have 2 cm penis…you need at least wide tires, aerodynamics and 300HP on paper…then you do only traffic-light-racing and shopping…rest of time, occupying SocNet and whine about small dick 😉