1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Question about Cold Air Intake..

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Old Nov 10, 2002 | 12:21 AM
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Question about Cold Air Intake..

Ok some people want to make a homemade CAI to gain some power... this may seem like a dumb question but why would someone want to get cold air when hot air is getting in also...? I took a picture to proove my point..



That "white pipe" is connected to the manifold(hot air) and is also connected to the air filter so if someone installs a cold air intake whats the use? It will get hotter anyway no? Do you need to pull out that pipe or I'm totally off track and the pipe doesn't have to do anything with that?

Thanks for the replies!
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Old Nov 10, 2002 | 12:40 AM
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Mmmm, That cold start assist hose is mainly used for starting the engine in the winter, from what I understand, although common sense would tend to make you think it'd alwas be suckign in hot air. What I do know for sure is that when i put on a homemade cold air intake, there was, from my point of view, a small but noticable increase in low end power, but a definite decrease in throttle response time (esp. in the low range). hope this helps.

-Fred
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Old Nov 10, 2002 | 12:51 AM
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you mean block it off like this??



the flap from inside it was removed too
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Old Nov 10, 2002 | 01:15 AM
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good question. but i think the idea of a fresh air,,,intake.
not a already warm under hood air.I know that on mine
it works as piping to a vent or naca duct, or scoop i fab'ed on the headlight cover.instead of sucking in the
air from within the engine compartment. the intake air
is drawn from the outside of the car. It's important that
the piping to the outside ,is airtight. or as best as one can make it. It doesn't hurt having 'fresh' air.
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Old Nov 10, 2002 | 01:49 AM
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Re: Question about Cold Air Intake..

Originally posted by Rex79



That "white pipe" is connected to the manifold(hot air) and is also connected to the air filter so if someone installs a cold air intake whats the use? It will get hotter anyway no?
No. Warm air is only drawn up through that pipe under cold start conditions, such as winter driving. This helps the engine reach operating temperatures faster, though with a lower PPM of oxygen (making the mix a bit rich and heating the combustion chambers faster, both of which are better for cold start). Once the engine approaches operating temperature the valve closes.

This same hose and valve system is very common on piston engine cars as well.

If you live in a cold climate and remove this pipe, your car will run like a bag of hammers in a clothes dryer before heating up.
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Old Nov 10, 2002 | 07:42 AM
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That hose caught on fire, so I removed it
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Old Nov 10, 2002 | 08:28 AM
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I have this ghetto cold air thing rigged up on mine, but i didnt intend for it to be like that.
I had the cone filter laying around so I bolted it to the plastic inlet tube for the air cleaner. It looks really cool, but no real change in performance.
Its funny seeing all the ricers look under my hood and be impressed with my engine compartment, not for the rotary engine, but the fact that I have THAT thing. . . . jackasses!
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Old Nov 10, 2002 | 11:02 AM
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From: Montreal,Canada
Originally posted by 357
What I do know for sure is that when i put on a homemade cold air intake, there was, from my point of view, a small but noticable increase in low end power, but a definite decrease in throttle response time (esp. in the low range).
-Fred
When you say you you lost some throttle response time.... how did you lose it? All a CAI does is it puts air from the outside(instead hot air from the engine compartment) into the chamber... how did you lose some throttle response?


Does your CAI look like this?

Thanks for the replies!
Nick
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Old Nov 10, 2002 | 12:44 PM
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From: Kamloops BC Canada
Originally posted by Adsy01
you mean block it off like this??



the flap from inside it was removed too

Oy.... yer brake cylinder is on da wrong side, eh?

Jeff
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Old Nov 10, 2002 | 12:56 PM
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From: Elsenborn, Belgian Eifel
Re: Re: Question about Cold Air Intake..

Originally posted by Manntis

If you live in a cold climate and remove this pipe, your car will run like a bag of hammers in a clothes dryer before heating up.

If you install a header it's gone too. But indeed, my car has no airpump, no thermal reactor, and a header and different carb, result: slight problems when cold... the car runs pretty unpleasant untill properly warm...
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Old Nov 10, 2002 | 01:29 PM
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From: SoCal.
Here's a pic of mine
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Old Nov 10, 2002 | 04:20 PM
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Where I live, that hot start assist hose is mandatory in the morning. The flapper inside the air cleaner is controlled by a linkage connected to a bimetal spring. When its cold, it automatically selects air from the hot hose. Once running temps are reached, the flapper cuts off air from the hot hose and only lets in air from the air cleaner horn. (I've checked several times.) If you live in a temperate climate like I do in Washington, and your car takes forever to warm up in the morning, fix it and you will be surprised at the improvement.

Nick, your CAI looks really clean! But how does it draw in cold air, it looks like it draws air from inside the radiator shroud. What did you use and where did you get the parts?
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Old Nov 10, 2002 | 04:36 PM
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Originally posted by Keaponlaffen



Oy.... yer brake cylinder is on da wrong side, eh?

Jeff
so is my steering wheel!
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Old Nov 10, 2002 | 04:48 PM
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(aren't the North American steering wheels etc. on the 'wrong' side, since RX-7's were originally designed for the Japanese market i.e. right hand drive?)
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Old Nov 10, 2002 | 06:32 PM
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Oh **** Adsy01 , you better fix that! How do you drive it???????????????
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Old Nov 10, 2002 | 06:46 PM
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Originally posted by Strider

Nick, your CAI looks really clean! But how does it draw in cold air, it looks like it draws air from inside the radiator shroud. What did you use and where did you get the parts?
I'm sorry that isn't my CAI I took the picture from someone else on the board... I'll give you the link for the rest of the pictures if it helps you out... I don't remember the user that posted these pictures though..sorry

Here's the link
http://3rdhour.com/gallery/album01

Nick
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