Back in 1990 I got some nice looking stainless steel vents and put them into the side. I must say that when you stopped you could certainly feel a lot of hot air coming out of them. However, I never knew if they did anything when driving down the road.
A few years back I installed some of Darren Paget's insulating blanket pads under my floor and engine box cover. That really deadened the noise and the floor was much cooler. However, I then found that I was starting to get vapor lock which I had never encountered in several previous years.
An examination of this new problem revealed that the fender liners have a "standoff" where the screw goes up into the floor above the liner. If you examine this closely you will see that the liners have a "scoop" on the front which brings air up and over the liner and down to the back. This is something like an airplane wing shape and the air going over the liner (think wing) is going a farther distance in the same amount of time as the air under the liner (think wing). This creates a low pressure zone at the top which in the case of a wing gives lift. I feel that in the case of the fender liner the lower pressure will pull the heat from the manifolds which are adjacent to the wheel liner. When I blocked this passage with the insulation it no longer pulled air over the liners and air from the motor box so I started to experience overheating and vapor lock.
My solution was install some louvers in the wheel liners (house foundation block vents) and also to put some scoops under the bumper (house rectangle to 4" round duct adapters from Home Depot. The ducts have some aluminum dryer hose that goes to the back top corners of the engine box to force cool air into the top of the box which in turn pushes out the hot air.
All I know is that it has worked extremely well. I live in the hot southwest and often travel in 120 degree temperatures while pulling a toad and have never had any vapor lock since doing my modifications.
You can see this at:
http://www.gmcmhphotos.com/photos/showgallery.php?cat=3093 http://www.gmcmhphotos.com/photos/showgallery.php?cat=3093
They are not in the original order but there are not many pictures.
Emery Stora
emerystora
>
> I just don't run the fender liners, Maybe someday I'll put them back in
> ________________________________
> From: John Phillips
> Sent: Monday, June 14, 2021 12:23 AM
> To: gmclist
> Subject: [GMCnet] Re: Tips for installing engine vents
>
> I would consider using a large hole saw at each end so there are no stress
> corners.
>
> On Sun, Jun 13, 2021 at 10:17 PM RICHARD/MARLI SHOOP
>
>> Before you buy ANY look a like Multi-tool.... Be sure to test it in the
>> material you intend to cut. Some of them vibrate the handle more than the
>> blade! If you have ever used an original Fein Multi-tool, you will be hard
>> pressed to buy anything else.
>>
>> I did eventually buy a battery powered one and got a dewalt 20V lithium
>> battery powered one and it is ok. But if I need to cut something tough, I
>> drag out the extension cord and use the Fein. Saw blades for these things
>> are also expensive.
>>>
>>>
>>> Multi-tool is your friend here.
>>>
>>> Milwaukee M12 12-Volt Lithium-Ion Cordless Oscillating Multi-Tool
>>> (Tool-Only)-2426-20 - The Home Depot
>>> <
>>
https://www.homedepot.com/p/Milwaukee-M12-12-Volt-Lithium-Ion-Cordless-Oscillating-Multi-Tool-Tool-Only-2426-20/203111676?mtc=Shopping-B-F_D25T-B-D25T-25_9_PORTABLE_POWER-Multi-NA-Feed-LIA-NA-NA-PortablePower&cm_mmc=Shopping-B-F_D25T-B-D25T-25_9_PORTABLE_POWER-Multi-NA-Feed-LIA-NA-NA-PortablePower-71700000071858267-58700006317203701-92700062668014077&gclid=872c0b18305e10c50a656bde811c6a67&gclsrc=3p.ds&msclkid=872c0b18305e10c50a656bde811c6a67
>>>
>>>
>>> On Sun, Jun 13, 2021 at 7:13 PM Scott Nutter
>>>
>>>> I can’t tell you how many hours I’ve sat underneath the front quarter
>>>> panels eyeballing where to cut. I will only cut flat panels, nothing
>> with a
>>>> 90 degree angle on it.. I just don’t see the logic in cutting.. it
>> would
>>>> only be a couple inch of vent effectiveness to where the wheel well
>> insert
>>>> is. And that is with the long/skinny and/or shorter/wider vents. But
>> to
>>>> be honest, I was only looking at the rear area in the quarter panel.
>>>> If anyone has data to justify cutting, I am all ears.
>>>> Scott.
>>>> --
>>>> Scott Nutter
>>>> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21
>> final
>>>> drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
>>>> installed MSD Atomic EFI
>>>> Houston, Texas
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>>>>
>>>
>>>
>>> --
>>> Bruce Hart
>>> 1976 Palm Beach
>>> LaGrange, Wyoming
>>> GMC=Genetically Modified Chevy
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>>
>
>
> --
>
> *John Phillips*
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