Fun with RAM Air... or not

[baldlobo]

not to mention you, can't increase static pressure without slowing down the air. ram air is a pipe dream; pontiac used it as a marketing gimmick, air flow over and around a car that is tight to the car skin is low pressure. and you'd need to be traveling faster then highway speeds allow in north america

[pete c]

tvago is right. a throttle is there to regulate power. ramming more air simply means you must close the throttle a bit more to arrive at X airflow, or more accurately X oxygen flow. A WAI makes the air less oxygen dense which means you have to open the throttle further which lowers throttle loss.

[oil pan 4]

Ram Air isn't for FE on gasoline engines.
On a diesel it provides more of both, FE and power.

[JRMichler]

Originally Posted by itjstagame

I did 1 run to/from work with HAI, then 1 with RAM and today back to HAI. I have numbers but they are not super telling:

Date of Run	Direction		Mins	Gallons		Miles 	MPG		Idle gal/hr	AVG IAT		Mode IAT	Max IAT	AVG Boost	Mode Boost	Max Boost
5/2/2012	To Work		HAI	60	1.002		54.6	54.49101796	0.2		122.9		122		136.4	-7.528		-10.784		0.239
5/2/2012	From Work	HAI	45	0.7238		37.802	52.22713457	0.209		129.26		127.4		156.2	-7.392		-10.784		0.09385
5/3/2012	To Work		RAM	45	0.825511111	38.281	46.37248304	0.22		78.46		78.8		95	-7.44		-10.639		-0.05
5/4/2012	To Work		HAI	68	0.924584444	49.42	53.45103987	0.188		166.29		168.8		185	-7.6153		-10.639		0.239

This test was so uncontrolled that the results don't say anything one way or the other. There's some good suggestions here: http://ecomodder.com/forum/showthrea...ery-11445.html

Unless, of course, you would rather just have fun playing with changes for the sake of making changes...

[itjstagame]

Yes I knew the numbers were pretty useless, I don't really have the time to do ABA testing as I don't get home until almost 7pm most nights and weekends are always busy, so I do what I can and log what I can. Again this wasn't to show the outcome of a lab test really, I was experimenting to see if it was even worth considering somekind of ABA test or if it was even useful. As shown it didn't even make sense to attempt ram air and even if the numbers aren't controlled enough to prove one way or another, I think it's pretty clearly it was the wrong thing to attempt. I think a lot of people start with experiments, see if it 'feels' better and then do and ABA to prove whether it is or not.

I know I didn't include weather conditions but can you think of anything that would cause a 6mpg drop? I think that is fairly significant, but like I said the numbers don't matter as much to me as I could tell by watching the gauges that FE dropped and so did power.

I do understand the point between warm air and cold air and yes I now see what you mean, about the ram air. Increasing pressure would require less throttle opening and therefore more pumping losses (or equal losses since the point is at less throttle we should have same vacuum/pressure/oxygen as before without 'ram'). It would only work without a throttle restriction, so at WOT or in a diesel (which has no throttle plate), in which case increased pressure would decrease pumping losses. I guess I fell in to the 'less throttle is good' and completely forgot the point of my WAI.

That said, it may still have a use (if it worked) just as CAI can have a point. Anything that can increase the efficiency of my 60-70% throttle pulse should be useful since otherwise my engine should be off anyway.

That said, I always wish I had a gauge like MPG/s or something so I can find for a given acceleration or power output what is the most efficient. For instance, maybe 4th gear at 4-5krpm on the DOHC is actually more efficient than 70% throttle at 2k rpm in 5th gear. I'm not sure, but the point would be even though 4th gear clearly gives worse MPG, it should really just be what uses the least fuel to pulse from 50-60mph. So if higher rpm was more efficient; then even if it got half the MPG as pulsing in 5th it should take LESS than half the time. Again, we can read about BSFC for a given engine, but I wish I could think of some gauge or some test to show in a given environment installed in a car what the most efficient acceleration is.