General For General 240sx/Silvia (s-chassis) discussions.

ram-air,airfuel question.

Old Aug 31, 2005 | 06:14 AM
  #1  
KeN VeRsUs RyU's Avatar
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ram-air,airfuel question.

After i removed my resonator i've been losing some gas mileage and I never understood why. I've got a Greddy header and those b1tches emit so much heat it sucks the living day light out of everything around it. There's a small piping from the stock box that leads down to where the resonator would be and a 3 inch hole (i think it's for another plastic pipe... but the pipe is missing.. lol). I just recently realized that the second hole is killing my mileage by sucking in the heat coming from the header (yes i realize the hole is facing the front of the car and yes i can feel the heat on the plastic around that hole.. very warm to the touch.)

So i devised a little ram-air system from my stock intake box(second hole) to the bumper, next to the fog light. I"m sure you've all seen it in some shape or form by other members using home depot stuff.

Now assuming i'm not running excessively lean or rich across the board... wouldn't the ram air thrust more air into the engine and therefore causing the ECU to dump MORE fuel to compensate for the extra air coming in? Or would this extra air cause my ECU to run excessively lean? Or would all of this have no effect whatsoever to the air fuel ratio?

Sorry for the long post but i'm just real curious.
Thanks in advanced. BTW, throttle response is pretty good but it might just be in my head.
Old Aug 31, 2005 | 05:34 PM
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Unless you're driving at like 150mph, I doubt the ram is forcing enough air into the engine to have a noticeable effect on the air fuel ratio. The ecu will always compensate for more air, until you have so much that your fuel system or MAF can't keep up.
Old Aug 31, 2005 | 05:46 PM
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well, what you can do to check everything out is undo your battery cables and let them sit for 30 min to reset the ecu...this will make the care learn all over again

if you are getting more air to the MAF/engine this will make your ecu provide more fuel

after reconnecting the battery cables, drive around for like 15-30 min WITHOUT beating on it. just drive normal. after that you should be good

Jay
Old Aug 31, 2005 | 07:38 PM
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the "ram air" just brings more 'cool' air into the engine... does nothing like boost or whatever
Old Sep 3, 2005 | 03:54 AM
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KeN VeRsUs RyU's Avatar
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Originally posted by Hagis
Unless you're driving at like 150mph, I doubt the ram is forcing enough air into the engine to have a noticeable effect on the air fuel ratio. The ecu will always compensate for more air, until you have so much that your fuel system or MAF can't keep up.
That's what i'm most scared of, the MAF crapping out on me because of too much air. I've heard of horror stories with the ram-air setup. Maybe i'll remove the ram air and just have a pipe leading to where the resonator would be.
Old Sep 3, 2005 | 07:21 AM
  #6  
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I dought it helps other than going "150mph" but i think it does a at least a small part of cooling the engine just that much. Even if hardley at all. What i did:
Old Sep 3, 2005 | 08:40 AM
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So let me understand. The second O2 is not functioning?
Also right after the header is the Catylitic, the resonator is right underneath your *** from what I understand. Are you shure you removed the right piece? Got any pics to figure it out better?
Old Sep 3, 2005 | 10:39 AM
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The resinator is under the air box.
Old Sep 3, 2005 | 10:43 AM
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it's 80 mph and above if the ram air intake is big. the ones done on a 240 have no big effect
Old Sep 3, 2005 | 11:13 AM
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Originally posted by l3ooherS14
The resinator is under the air box.
Oh snap, I see it's the vacum line next too the air intake resonator, not the exhaust resonator.....LOL My bad......
Old Sep 3, 2005 | 08:38 PM
  #11  
KeN VeRsUs RyU's Avatar
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Originally posted by l3ooherS14
I dought it helps other than going "150mph" but i think it does a at least a small part of cooling the engine just that much. Even if hardley at all. What i did:
You have an automatic though correct?

Anybody else know if the MAF will die on me with this ram air setup?
Old Sep 3, 2005 | 08:39 PM
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Originally posted by KeN VeRsUs RyU
You have an automatic though correct?

Anybody else know if the MAF will die on me with this ram air setup?
No it won't the KA MAF was designed to take enough CFM to make 200CHP.
Old Sep 3, 2005 | 10:17 PM
  #13  
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dude the MAF isnt gonna crap out^ as he said its 200chp. If you have the time and desire, go for it, but it's not gonna 'boost' anything, just cool air
Old Sep 4, 2005 | 12:20 PM
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l3ooherS14's Avatar
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It will only gain cooling power. Maybe if i was running 140 of the original 155hp, it might gain back a lost hp and make it 141.
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