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Old 05-05-2012, 08:59 AM   #1 (permalink)
itjstagame
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Join Date: Sep 2008
Location: Thomaston, CT
Posts: 23

Commuter Plus - '98 Saturn SW2
Last 3: 37.12 mpg (US)

Rover - '07 Land Rover LR3 HSE
Last 3: 17.6 mpg (US)

Blackie - '16 Ford Focus Titanium Hatchback
90 day: 33.25 mpg (US)

Bertha - '11 Four Winds Chateau 31a
90 day: 7.79 mpg (US)

Van - '15 Honda Odyssey EX
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Fun with RAM Air... or not

Ok, so I have been playing with a couple different setups on my Saturn SW2. I started with HAI pulling from behind the exhaust manifold and then thought that maybe I should pull from the air dam and run behind the header and then in, so maybe I could get heated ram air.

I have since actually read up on ram air and how little you can expect (I think I saw something like 0.1psi at 60mph or so and 0.2psi at 120mph).

Anyway, the 'ram' was a 3" hole in my air dam through 3" heating duct past exhaust header and into a new hole in side of stock air box. Ducting taping everything liberally, but clearly not 'sealed'.

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:
Code:
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
All of these runs are engine on P+G from 50-60mph, although looking at the mins >60 is due to stop+go traffic for 10-20 mins everyday. My From work didn't go through from RAM, phone was spasing out, but I did have gauges for a while and it was the same thing. Clearly more vacuum and could see/feel the less MPGs. The average vacuum looks higher, but I think that's because I was pulsing longer (with less power). I can definitely feel more power with the HAI, I need to do a run with stock to confirm but it really feels like more power than stock too. I did read that cooling the exhaust header should increase power and scavenging (helping 'pull' exhaust from the cylinder to the cooled header), although I doubt my HAI is having that much of an effect, it does make me wonder what heatsinking to the hood would do :-).

Basically, I dropped MPG with the RAM Air and noticed increased vacuum probably due to colder air and longer pipe. I then thought, maybe I just need a larger scoop, information online suggests that somehow the scoop size doesn't matter, but I don't fully understand that.

So I did some before/after runs with 3" RAM and with a 4"x10-12" ducting that reduces to the same 3" pipe (I can post a picture if it doesn't make sense, looks like a vacuum cleaner).
Anyway, I have numbers for that too, but not much too see, it looks like it might have .2psi less vacuum at idle and maybe .1psi less at speed but never went positive at 65mph. Either way the HAI had less vacuum (probably due to less density).

One of the suggestions I read was pulling the ram air from behind the radiator. This might still be something I try, moving the fan just a little bit will give me 4"x10" for my 'scoop' and then I'd have warmer air, sort of 'rammed' and could still run past exhaust header. I know any gain would be super minuscule though so definitely not a top priority.

Of course it might be 'easier' to just put a small turbo and somehow resist the urge to run boost (my goal is just to decrease vacuum and warm air, turbo would do both but more money and more involved).

Anyway, thoughts, comments, suggestions?

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