Author Topic: Hood vents - rice even if they're beneficial?  (Read 486 times)

MiniVanMan

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Hood vents - rice even if they're beneficial?
« on: September 02, 2011, 07:34:06 PM »
I don't like the look of hood vents, but given the very high under-hood temp of the Jeep and the heat-soak issues, I'm considering getting a second "summer" hood, putting vents in it and hooking up an electric fan to the underside, with some sort of cover to attach when it rains. Obviously heat won't be an issue in the winter, so the stock hood would go back on then.

If I AM going to do this, I at least want it to look somewhat factory/not flashy.. you know, understated, but not shitty looking either.

I really like what this guy did:


It's pretty subtle, looks almost like a stock option if Jeep made a hardcore off-road edition of the XJ.

So... would it still be rice, even though it would be completely functional?

[ChaosweaveR]

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Re: Hood vents - rice even if they're beneficial?
« Reply #1 on: September 02, 2011, 07:48:47 PM »
Isn't rice something that has no function? If it helps with heat extraction, I'd say it isn't. I like the hood too, BTW.
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Kalgorn

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Re: Hood vents - rice even if they're beneficial?
« Reply #2 on: September 02, 2011, 09:10:31 PM »
But how functional is it? Would it actually make a difference? A couple degrees isn't a big deal.

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87Warrior

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Re: Hood vents - rice even if they're beneficial?
« Reply #3 on: September 02, 2011, 11:28:45 PM »
If you search hard enough, there are some reports showing where the hotter areas are under a Jeep hood. Usually right behind the radiator and between the wheel wells and block towards the rear of the engine compartment. There should be no reason to run a fan on hood vents. Heat goes up. you also don't want water dripping on your TPS, CPS or coil pack

From my understanding, a cowl hood on the XJ will greatly reduce under hood temps. This is why a lot of guys running strokers have the cowl hood. The problem is, nobody makes a cowl hood for the XJ anymore. A few guys have made a cowl hood out of two spare hoods.

The 98 5.9 Grand had hood vents from the factory.
« Last Edit: September 02, 2011, 11:34:09 PM by 87Warrior »

87Warrior

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Re: Hood vents - rice even if they're beneficial?
« Reply #4 on: September 03, 2011, 12:01:51 AM »
I really like what this guy did:


It's pretty subtle, looks almost like a stock option if Jeep made a hardcore off-road edition of the XJ.
This intrigued me. So I had to find out what this guy did. Judging by the ratchet strap roof top spare tire carrier, I figured it had to be simple
http://www.xjtalk.com/showthread.php?t=2033

I could really see that set up being perfected with actual mounting hardware and some drip pans. The biggest problem I see is their location. While it looks great most of the heat is up front and to the sides, not on top of the valve cover.

Onyx Dragon

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Re: Hood vents - rice even if they're beneficial?
« Reply #5 on: September 03, 2011, 03:30:03 PM »
But how functional is it? Would it actually make a difference? A couple degrees isn't a big deal.

XJs are known for high under hood temps when off roading.  I'm not sure why, there's not a lot around or in the way of the air flow, but they are.  I don't know if the 4 cylinder does it, or if it's just the 4.0 though.  But engine temps are a common thing on these.  Really, even on road the temps go up.

Nick, if you plan on offroading it, switch to a GC's fan clutch..I believe it's the 96-97 model year clutch.  If you do a little research you'll find it.  I did it and it is noticeable.  Of course you will take a gas mileage hit due to the lower temps, but I'd rather lose 1-2 MPG instead of losing an engine if something goes wrong on the trail.

Meatywand

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Re: Hood vents - rice even if they're beneficial?
« Reply #6 on: September 03, 2011, 07:52:40 PM »
Hood vents are kinda ugly broseph. I've never had much of an issue with over heating and I've wheeled hard in temps over 100, but I know my Tube Fenders let the motor breath than stock. I've heard alot of guys do what Onyx is suggesting, and an electric fan is always nice, but don't waste your time or money on the vents.
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Onyx Dragon

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Re: Hood vents - rice even if they're beneficial?
« Reply #7 on: September 03, 2011, 10:06:09 PM »
Hood vents are kinda ugly broseph. I've never had much of an issue with over heating and I've wheeled hard in temps over 100, but I know my Tube Fenders let the motor breath than stock. I've heard alot of guys do what Onyx is suggesting, and an electric fan is always nice, but don't waste your time or money on the vents.

Well, these have an electric fan as a backup.  If he's not going to be going through water up to his fan, I'd suggest he stick with the mechanical and the electrical setup.  Otherwise if you have an electrical failure that doesn't shut the engine down but does your fan, you're in trouble.

Meatywand

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Re: Hood vents - rice even if they're beneficial?
« Reply #8 on: September 03, 2011, 10:23:17 PM »
True, but the fans are awesome if they're wired in to a switch so they don't affect the whole motor....
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MiniVanMan

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Re: Hood vents - rice even if they're beneficial?
« Reply #9 on: September 03, 2011, 10:26:38 PM »
It's mainly the heat soak after shutting off. I just want a way to let heat escape the engine bay once I turn the engine off. It's only a problem on really hot days when I've been running the A/C, and it's a known problem. That fuel injector shield only worked for so long... now I'm looking at long term solutions to letting the engine bay breath when it's parked and there's no coolant flow/air flow.

Onyx Dragon

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Re: Hood vents - rice even if they're beneficial?
« Reply #10 on: September 04, 2011, 02:30:07 AM »
It's mainly the heat soak after shutting off. I just want a way to let heat escape the engine bay once I turn the engine off. It's only a problem on really hot days when I've been running the A/C, and it's a known problem. That fuel injector shield only worked for so long... now I'm looking at long term solutions to letting the engine bay breath when it's parked and there's no coolant flow/air flow.

Timer on your electric fan to turn off after a certain amount of time?  You're OBDII, so there's probably a tuner out there, tune the fan to stay on until it goes below a certain temp.

Meatywand

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Re: Hood vents - rice even if they're beneficial?
« Reply #11 on: September 04, 2011, 01:33:42 PM »
Look at trimming out some of your inner fender, more flex and more ventilation.
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87Warrior

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Re: Hood vents - rice even if they're beneficial?
« Reply #12 on: September 05, 2011, 11:02:26 AM »
Timer on your electric fan to turn off after a certain amount of time?  You're OBDII, so there's probably a tuner out there, tune the fan to stay on until it goes below a certain temp.
That shouldn't be too hard. On all XJs (Renix, OBDI/II) you can simply ground out a wire to the fan relay to manually turn the fan on. It does not alter the 'automatic' fan settings (on with AC and @ 230 degrees). I did this to my Comanche and it never got hot. Instead of hooking it up to a manual switch in the cab, attaching it to a temperature switch of your choosing would do the same thing. Then use that switches current to flip a relay allowing power to feed the fan when the key is not in the "on" position.