When a car company builds and tunes an engine...
 

They do all the work to it before it goes into the car. They get the horsepower reading from the crank. So how accurate can an aftermarket tune be when they get all the numbers when they get the readings from the wheels? How safe is it?

I know it's more expensive to take the engine out and tune it on it's own, but wouldn't it be more reliable because of it?

(Wasn't sure where to put this thread)

why would the tune be less safe or reliable if done from a chassis dyno? You rarely drive your car with the engine sitting on a stand, its more typical to drive when the engine is powering the wheels

There's no load on the engine when it's not driving anything. You don't want to tune an engine that way. You want to tune it for how it's gonna be used: driving 2 (or more) wheels while they're in contact with the road and moving the weight of the car.

Tony (is VERY drunk, might not make sense)

When they tune it out of the car I would think that there is load on it as well. I worked on an engine dyno for our formula SAE car, and the thing was basically the engine driving a water brake, which provides the load.

Yes there is...

He means an extraneous load. Not the intrinsic static load that will eventually be overcome by the perpetual momentum of the dynamic inertia at the onset of rotational initialization.






:tip:

You're such a jerk!




LOL

I'm having a hard time understanding your question

An aftermarket tune will generally start off with a baseline, measured at the wheels. This lets you know where things are starting off. Post tune, you have your final figures, which lets you know where you ended up. Where is the problem?

Can you tune an engine on an engine dyno? Absolutely - but the process is essentially no different. You would compare your before figures, to your after figures.

Yes, but I am wondering if the tune on an engine alone versus a tune on a dyno at the wheels will produce better results, as in safer and more reliable.

And I guess I'm talking more about when the internals have been upgraded.

no

Any proper tune is never finalized on a dyno alone...because a dyno is not a real world condition. A full tune should always include dyno time coupled with street driving. The dyno is merely a tool, no matter if it's a chassis dyno or an engine dyno. It allows you to make changes in a controlled environment, and see the general trend that those changes result in.

This kind of reminds me of the antenna testing I do at work. If we are measuring the received power on a spectrum analyzer, the setup has to calibrated to account for the loss of dB in the cables and other intermediate hardware. If we didn't, it would be an inaccurate measurement because we are not compensating for the real world condition in which the device is used.

It's like saying you can benchpress 1000 pounds on the moon.

:tip:

A manufacturer's tune will be far more conservative, since it is a general tune for the class of engine (and for the "weakest" engine of the group) -- not for the specific engine.

Done well, an engine-specific tune should actually minimize the amount of stress on the various engine parts, and overall reliability should be maintained. However, it's very common for tunes to go beyond optimal and start to eat into reliability in favor of additional power.

Moved...