Is it important for the engine to breathe cold air - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

Reply
 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 07-19-2000, 11:05 AM
**DONOTDELETE**
Guest
 
Posts: n/a
Is it important for the engine to breathe cold air

After adding a York, Rancho compressor, tons of wiring, relays and dual batteries under the hood of my YJ, I only have space to attach the air filter (without any housing) directly to the air tube above the valve cover. I know this is supposed to give the best performance since it minimizes airflow restriction. However I'm concerned about the quality (temperature) of air inhaled by the engine. I usually wheel in an environment where the temperature is 95+ on a very good day. The temperature under the hood must be at very least two times higher.

The Question:
Is that high air temperature good for the engine? Does it only degrade performance or will it affect the engine as well? How much performance gains are we talking about it if I make sure that the engine inhales only cold air from outside the engine comptpartment?

I don't really like the external snorkel look. So I'm thinking of mounting the filter directly on the throttle body and cutting through the hood and installing a hood scoop. I will make a housing that surrounds the air filter under the hood so that the engines draws air only from the hood opening. Do you guys think it's worth it?

Thanks.

A.B.

If you didn't get stuck, you didn't wheel hard enough...[img]/wwwthreads_images/icons/cool.gif[/img]
http://www.DesertsOfEgypt.org - http://www.Badara.net
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 07-19-2000, 11:39 AM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: Is it important for the engine to breathe cold air

The cooler the air, the better the burn as you get a denser charge in the cylinder. So the cooler you can make the air the better (some people will argue you will notice little but I am not so sure about that). Now I dont know about putting in a hood scoop, as that just adds a lot of problems like getting water on top of the engine when it rains. I would try to build a intake tube assembly that draws from in front of the radiator. This to me would be a better choice.

dan
<font color=blue>"Artificial intelligence is no match for natural stupidity" (Anonymous) </font color=blue>


post #3 of (permalink) Old 07-19-2000, 11:45 AM
Keyboard Implanted
 
Join Date: Sep 1999
Location: Southeast Iowa
Posts: 6,394
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Is it important for the engine to breathe cold air

[img]/wwwthreads_images/icons/smile.gif[/img] I can see by your inquiry that you are "thinking" and that's always good[img]/wwwthreads_images/icons/smile.gif[/img]. Yes.....Naturally Aspirated engines suffer a de-rate for altitude AND temperature. I wish I could lay my hands on my engine data right quick but well.....it'll take too much digging, so here is the rule: HORSEPOWER is measured at the equivalent of 60 degrees F and at SEA LEVEL. So what you do is de-rate for the actual environment in which the engine will be used. I can't recall the numbers, but the de-rate is SIGNIFICANT for both temp and elevation. When we used to run the big Ford V8 gassers in trucks, I always liked the F-7 and bigger models because they had cold air induction. The air cleaner had a bellows attached to it which sealed off on the hood when the hood was in the closed position. The hood had a real nice scoop built into it with an attractive chrome trim on the leading edge. The scoop was offset because the air cleaner had an elbow on the side that the bellows was mounted on. The CJs have the tube which sucks out of the grille area to get cooler air to the carb as well. The two things that impede engine performance and cooling are: TOO MUCH STUFF under the hood so the hot air off the radiator cannot get OUT from under the hood to make way for more air; and HOT INTAKE air to the engine. Cold air is denser, packs better in the cylinders to begin with, and expands just a frackle to pick up compression when it is IN the cylinders. Cooler air also helps keep fuel vaporization down in the carb and in the fuel piping. There is hardly anything that you could do to your Jeep to help it more than get it some fresh air. How about one scoop facing forward to scoop air to the air cleaner bellows, and one facing backwards to VENT the engine compartment?[img]/wwwthreads_images/icons/crazy.gif[/img]

CJDave
Moonguy before coffee [img]/wwwthreads_images/icons/mad.gif[/img]....after coffee [img]/wwwthreads_images/icons/smile.gif[/img]
CJDave is offline  
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 07-19-2000, 12:44 PM
 
Join Date: Sep 1999
Posts: 3,478
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Is it important for the engine to breathe cold air

Not only is cold air denser but it is also drier. It contains more oxygen than than warm, humid air. The water vapor in the air actually displaces the oxygen.

Ever notice that campfires burn much better in winter than in summer? Especially here in the Northeastern US, where summers can get very humid.[img]/wwwthreads_images/icons/crazy.gif[/img]


xjy173 is offline  
post #5 of (permalink) Old 07-19-2000, 12:50 PM
Keyboard Implanted
 
Join Date: Sep 1999
Location: Southeast Iowa
Posts: 6,394
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Is it important for the engine to breathe cold air

[img]/wwwthreads_images/icons/smile.gif[/img] Just one more reason why Leroy's motorhome doesn't perform well at high altitudes, yet it seems to ping so much more.....the more humid air at the low altitudes helps to supress detonation. They used to inject water into those big Wright "corncob" airplane engines to supress detonation at take-off boost pressures. The R2800-38W (I think that's right) was the WATER-Injected engine for the B-29??? W= water injection.[img]/wwwthreads_images/icons/tongue.gif[/img]

CJDave
Moonguy before coffee [img]/wwwthreads_images/icons/mad.gif[/img]....after coffee [img]/wwwthreads_images/icons/smile.gif[/img]
CJDave is offline  
post #6 of (permalink) Old 07-19-2000, 02:17 PM
 
Join Date: Nov 1999
Posts: 553
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Is it important for the engine to breathe cold air

Some might say that they feel no difference between cold and hot air.
Well, I can attest to the difference felt in horsepower when driving in two different air temperatures.

During the day (1:00PM) this week the temp has been around 105 degrees and my truck feels very sluggish on takeoff and during acceleration at this temp.
On the same day, but at (10:00PM) the air has dropped 20 to 25 degrees and on the same road my takeoff and acceleration are noticably better.

This is from my personal experience living in TX.

I would suggest that if you did not want to put a scoop on the jeep, you might try a tube through the fender well at a location where not too much debris can get into it.
If you can not find a location like this, you could always put a piece of metal screen material over the hole so it would keep all the big debris out of the tube.
From the tube go to the cleaner then to the throttle body.
If this will not work, then put the filter at the hole and run a tube directly to the throttle body.
If you could find space in the engine compartment, you might try putting an intercooler on it to cool the air before entering the engine.

Hope this helps.

If a mime cusses does his mother wash his hands with soap?
redbeard is offline  
post #7 of (permalink) Old 07-19-2000, 03:59 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: Is it important for the engine to breathe cold air

what about running a tube from the body tub (right behind the air filter housing) where your vent lets air in for the passenger compartment. have to cut a hole in the firewall though.

tj
[img]/wwwthreads_images/icons/cool.gif[/img] "it was a '76, '77, '78, '79...'83 automobile!" (johnny cash)
post #8 of (permalink) Old 07-19-2000, 05:13 PM
 
Join Date: Sep 1999
Posts: 5,383
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: Is it important for the engine to breathe cold air

With the race cars...
We put a sheet metal plate under the carb to keep excess heat off the carb float bowls.
We fabricate an air box that encloses the air filter, and the air box meets the hood. Seal is achieved by using a foam rubber strip on top.
On the hood, we cut a hole and cover it with a scoop.

Scoop type depends on the application of the vehicle.
On dedicated race cars we face the scoop forward.
On street driven or off road driven vehicles, we use a 'Cowl Induction' type scoop that faces backwards.
This helps keep debris out of the engine compartment.

Use as much air cleaner as you can get under the hood scoop.
It's perfectly OK to stack air cleaner elements, as long as they seal air tight with the housing and each other.
A foam 'Ear Muff' wrap around the air cleaner elements in severely dusty conditions.
The wrap will cut down on air flow efficiency slightly on the street applications though.

"I Have The Body Of A God... Buddha"
Junk Yard Genius is offline  
post #9 of (permalink) Old 07-19-2000, 05:36 PM
Keyboard Implanted
 
jamgood96's Avatar
 
Join Date: Jun 2000
Location: Tualatin, Oregon, United States of America, North America, Earth, Milkyway Galaxy, Universe...
Posts: 3,932
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Is it important for the engine to breathe cold air

Around my part of town, Honda's are really popular. One of the upgrades everyone does to them is put a cold air intake on them. The most popular one is an Iceman. I know they don't make them for Jeeps, but hold on. What if you tried to make a custom intake that kind of bends down under the engine and sucks up some cooler air? It might be worth looking into. You can run ASB plastic pipe or PCV. PCV isn't the best cause it get's hot and is dangerous, but I know lot's of people that use it for custom intakes. Look into it...

1999 Dodge Neon Sport, 35" Swampers w/7" Custom Skyjacker lift, RTI of 1034,
Blown 454 w/Turbo 400 tranny, 4wd drive conversion...okay, I'm BSing [img]/wwwthreads_images/icons/tongue.gif[/img]
jamgood96 is offline  
post #10 of (permalink) Old 07-19-2000, 06:01 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: Is it important for the engine to breathe cold air

Thanks guys for your input. I've now decided to go with the hood scoop thing.

TeamRush, could you please explain what does a 'Cowl Induction' look like? Is it simply a scoop facing backwards? Better yet, if you know where I can look for it on the web I'd be grateful.

Thanks.

A.B.

If you didn't get stuck, you didn't wheel hard enough...[img]/wwwthreads_images/icons/cool.gif[/img]
http://www.DesertsOfEgypt.org - http://www.Badara.net
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome