[Christ]

Originally Posted by Jyden

@ Chris - naturally the graphs are an avarege of several runs - we did things thoroghly!

Ok, if they're an average of runs, I won't discount them.

If you gain 2 hp you can travel at a given speed pressing LESS on the accelerator => save fuel.

This is completely untrue. Using less throttle means nothing when the fuel/air input is the same. Throttle is not the determining factor in fuel use. Also, your 2HP gain was made @ WOT... lessen the throttle angle, and the HP gain will decrease in a non-linear curve. In other words, at 50% throttle, there will be less than a 1HP gain, all things equal. The average vehicle cruises at much less than 50% throttle as is. How much difference do you think it's going to make?

On some cars, theres a good gain to find on FE by derestricting the intake system - on other none. It's enegine and model specific.

The throttle plate is the largest intake restriction there is. For normal purposes, the OE filter/piping flows plenty of air for what is necessary at a given throttle angle/engine speed. At WOT, or close to it, things change slightly. You still haven't shown me a dyno graph determining a generous gain in HP or TQ for a normal throttle opening.

I for the moment don't belive theres an much extra pumploss on cold air, but theres extra arodynamic drag to overcome in cold condistions. I think, that throttle valve resistance is far greater, which appears to be why HAI work, as throttel has to be open further to produce same amount of energy to move the car at a given speed.

Once again, throttle in general means nothing. Air and fuel are the measurements of HP, throttle only controls (to a given extent) the amount of air, and more indirectly, the amount of fuel. Colder air or warmer air only changes the amount of air mass in the same volume, changing the mass of air that gets drawn on intake. The volume is the same, regardless of air density, and the throttle plate is a volume control, not a mass control.

What we are all trying to do here is to get the max Kilowatts out of every unit of fuel. Depending on the specific engine this can be improved in several ways.

But you're not doing this. By adding colder air, you're telling the engine to inject more fuel, not get more power from the existing fuel mix. In either case, the amount of power capable of being generated is already more than is necessary.

- All engines will benefit from a derestricted intake system until a certain limit.
- Some will benefit from a cold air intake
- Some will benefit from a hot air intake.

Some will benefit from a cold air intake for making more HP. None will make more power with a HAI, (barring certain examples involving engine dynamics, but not combustion) since there is less air, and thus less fuel.

So you can't really conclude this or that. Further more what is right at one rpm, might not be so at an other rpm. So it's complicated stuff, and it would take many hours on the dyne to dertermind the best for each car, and each speed.

Math is more powerful than speculation, and so far, you've only provided a dyno graph which hasn't much to do with what were actually discussing here. Show me some math that supports what you're saying.

Everything is a compromise - what you gain in one end you usually lose in the other end. So better FE at low rpm, will mean less power and FE at higher rps, and vise versa.

Noone's looking for better FE at high RPM's, buddy. Power and FE are also at opposite ends of the spectrum, for most purposes, so better HP at the top means (generally) more fuel used, which means less FE. They're almost never lumped together as being universally better or worse.

I've been working with CAI and derestricting intake systemes for four years some time ago, and at the time we saw significant gains on both hp and FE.
But things has changed in the past 10 years, and car manufactors and the ECU programs has changed a lot, so now things might look different, because of changed demands on emmisions.

Prove it. I can mildly believe that you got better FE by removing intake restrictions, and smoothing flow, but adding a CAI just doesn't do it for me, especially considering that it appears that you don't (or didn't) understand BSFC until a few posts ago.

I'm not saying that HAI dosen't work - I'm saying that it will be different from engine to enegine what works best, as the engine, car driver etc. are different, and thus you are optimising for different situations each time.

Scientific results control all those variables down to engine only to determine which of the variables that are in play will produce the best result. So far, there has been nothing but anecdotal evidence (that I've read) which supports a CAI giving higher fuel efficiency in any case that couldn't have been explained by another variable having been changed, such as driver input.

I maintain my challenge.