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Discussion Starter #1
Yesterday I took off my custom intake and replaced it with the factory air box. I drove around today taking data on the intake air temp. from my Scan Gauge. Here are just some reflections to compare aftermarket with factory:

-The factory air box will have lower intake temperatures than aftermarket exposed short ram intakes. All things being the same, about 10 - 15 degrees (maybe more) cooler.

-Intake termperatures will rise once the engine has time to heat up to normal operating temperatures. This will occur in both setups, but the short ram type intakes will suck in hot air faster.

-Ambient heat is still the enemy and will heat up the intake system (just like being in an oven) thus losing performance over time. The only way to help this situation is to somehow insulate the entire intake tract with heat repelling insulation.

-The faster that you go, more cool air will rush into your intake and drop the temperature. A steady stream of air rushing into the intake works best. City driving of slow speeds and stop and go traffic will heat up the intake big time (105 - 130 degrees F).

-Outside temperatures will have a big impact on intake temps. At one point in my drive; sunny (85 degree F) weather turned to torrential downpour and outside temperature dropped. So did the intake temperature. By as much as 10 - 15 degrees.

Any conclusions to be made from these observations:

-short ram type intakes will let in more air, but hot air will defeat any performance gains; especially after the engine bay heats up to normal operating temps.

-Getting more cool outside air at a steady stream is beneficial (i.e. air ducts, scoops, etc.)

-Insulating the intake tract will help big time from heat soak.

That's about all I can think up for now. Can't wait for the rest of you to get Scan Gauges so that you can check your own intake temperatures and make useful mods. to the RAV 4.1 intake. For now, I will leave in the factory air box and monitor it somemore. Maybe throw in a drop in K&N filter to gain back some performance loss from my old system. 8)
 

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Cool! Thanks for posting that, Derek. I did notice something with my CAI; on a local errand run to the local hardware stores and junk shops (for supplies to make an air scoop), the steel intake tube was very warm to the touch (city driving). However, after some highway cruising to a friend's house, I found the intake was much cooler - it was actually cold.

I've already done my own ram-air mods and added a small air scoop on the spash guard to hopefully force in more cool air. Only problem is, there isn't a shroud that fits my filter, so it still will suck in hot engine bay air no matter what.

What kind of insulation wrap you use? The same kind as what you would put around a header? What is that wrap called?
 

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I suppose you could feed the intake into the cabin. Then just turn on the A/C and away you go! :lol: You could even link the intake up to the blower and have an adjustable turbo type thing by adjusting the fan speed. Cool! :shock:
 
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Franco, do you have a pic of your shield, or even better, the plans to make it?
 

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Discussion Starter #8
Hi Franco :D

I thought the same thing too with my custom carbon fiber intake setup with shrouded filter.

Then I hooked up the Scan Gauge to read intake air temperatures and was surprised by my findings. Yes, it starts out cool when you first start up the engine and the temps. are still down. But about 10 minutes into your drive, the intake air temperature begins to rise along with the temps. in the engine compartment.

As mentioned above, there are some other factors that affect intake air temperature as well. Franco, you've gotta get the Scan Gauge and see for yourself, it is a real eye opener. :shock:

Now I am thinking of a way to design an intake that can let in more outside cool air without absorbing the ambient heat within the engine bay. Probably a setup similar to what Mensagero has now with a wrap to deflect heat :?: I need to conduct more data before making my decisions. As of right now, the factory air box is in. The engine hasn't sounded this quiet in a long time. :lol:
 

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How about a hood vent? I thought of doing a functional hood scoop for the ram-air intake, but wondered about the issue of water, so I thought at the very least, the hood scoop could be used to blow in some outside air to vent out the engine bay.
 
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Ummm.....IJ can't believe no one has thought of venting the engine.....kinda like an EVO. Basically, since we have hot engines, why aren't we letting the hot air out? This should cool down the overall temprature of the engine bay, and allow our intakes to run cooler. Just a thought.
 

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Discussion Starter #11
So far, I've cut holes in my front fenders for side marker lights and even drilled a hole in the top of my roof for an rear antenna. However, I am a bit hesitant to cut the hood. :eek:

This is something that would be hard to fix if I screwed up. :lol: Although, if I had a carbon fiber hood; I wouldn't mind messing around with the stock hood to add some functional vents. My only concern would be the entry of water into the engine bay. :shock:

For now, I am probably going to try a less invasive approach to this solution. :thumbs_up:
 

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Cold air intakes

Derek; If you look in my album you will notice I still have my factory air box along with a ram air cold air system from the undertray through a 4.5'' grill & aluminum flex hose. according to wind tunnel tests and air flow research, a Stall Box is needed to maxamize a cold air system. F1-Nascar-IRL-CART & World Super Bikes to name a few all use stall boxes, of coarse a high flow air filter is needed. Cubby has a K&N.

In my opinion a hood scoop with nothing to do would just pack more air under the hood and create more drag. Less Gas Mileage.


If you want a cold intake put ice in a bucket of water with a 12 volt submerseable pump and some copper tubing wraped around the intake and back to the bucket. you could run a coiled fuel line in & out of the bucket to. Sounds Crazy they do it in Drag Racing and I have done it for street racing.

I hope this will help shed some light on things.

:cheers: from an old racer

vicco27.......Keep Rollin.
 

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Discussion Starter #13
Thanks for the info. Victor. :thumbs_up: I am really interested in how you've attached the 4" aluminum hose to your factory air box. From your pictures, it looks like you bored a hole into the side of the air box and attached the hose there. I was considering doing the same thing, but to try and use the factory location up front.

Thinking about removing the factory duct that leads up towards the grille area. Then relocating my ram air duct to the factory entry point on the air box. If you have any close-up pictures that you can e-mail me, I'd really appreciate it. :D
 

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Cold Air Intakes

Derek; The air box oval inlet is just over 4" OD so I simply squoze the 4.5" ID Aluminum flex hose, about half of the full 4' length, down around the oval then used a cut down adjustable SS hose clamp tightened as tight as I could to clamp the hose down and hold it on the air box snout, the 4.5" Aluminum flex hose attached to the air box can then be fed down through to the undertray, you do have to remove the fan wire holder and move the wire out of the way a little, the wire seemed happy in its new location on the engine side of its new best friend so I left it to do its thing and moved on to the location and modifying of the 4.5" dryer vent, I carefully pryed the lip up around the perimeter of the deflector removed the deflector and replaced it with screen then tapped the lip back down with a body hammer and backing the lip up with a dolly, with the hole for the vent towards the center brace edge of the undertray, see album picture, the vent neck slipped right up inside the flex hose, which seemed tight enough in its cramped location that it won't move. it has not moved:

I did drill a pattern of 3/4" holes in the bottom of the air box and made a flapper valve out of some 1/8" neoprene rubber riveting it down on one end, it can then lift up and let air in if Cubby should take on to much water and plug the cold air intake flex hose for a split second.

I will take some pictures and email them to you as soon as I can.

:cheers:

vicco27......Keep Rollin.
 

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In my previous post about my ram air cold air system I inadvertently stated the box neck at 4'' and the Aluminum flex hose at 4.5'' when in reality the box neck is 3.5''OD and the aluminum flex hose is 4.0''ID also the dryer vent is 4.0''OD however the 2.0' length was correct. Sorry about the brain fart. :oops:


:cheers:

vicco27.......Keep Rollin'
 

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i also have a temp sensor in the intake and have noted the same effects as derek. intake air temp can get up to almost 60 deg C when stuck in non-moving traffic and it's 36 C outside!

i have some ideas on how to keep the intak air at the same temp as outside, but i'll keep them to myself until i can try them out and get some positive results.

as for removing the duct hose from the filter pod to the engine guard, air temp goes above 70 C (limit of my sensor) real quick when stuck in traffic!
 
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