C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Makeshift cowl induction

Old Jan 27, 2005 | 01:52 AM
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Default Makeshift cowl induction

Here's a tip, don't know if it's common knowledge or what, but here goes anyway.

I got sick of the plenum being so damn hot that you can't put your hand on it after driving for a while. Also got sick of watching my temps actually RISE after the fan kicks in for a bit, then drop SLOOOOOOWLY..

So here's what I did. Pop your hood. Look at the weather stripping/seal thing that runs against the top of the firewall. It meets the hood, and its made of rubber. Well grab a knife and slice that sucker down to size, so when the hood is closed, there's like an inch or so gap on either side. I left the middle intact to protect the distributor (pointless for Opti people?) and it was shortest in that section anyway. The rest I took off meybe an inch off of. Left a 1/4 inch height everywhere else, to channel water away from the engine bay if it ever rains. I'll take pics tommorow when I'm not drunk and tired (it was a long day, but I managed to get this in there anyway)

SO basically.. at low speeds it acts as a vent. I can feel the heat flowing out of there. In traffic, at stop lights, etc - when the fan comes on, the temps drop FAST, and as soon as the fan kicks in. Like, that very second.

Once I get going on the freeway, it starts acting as a cowl induction deal, and air is rammed in. I didn't even realize this at first, but a thermometer glued to the windshield for testing confirmed this. Temps rose during low speeds as hot air escaped, and dropped on the freeway.

Result - I can now lay my hand on any part of the plenum. The TB (after collant bypass) is as cold as the airbox, literally. The booster, the dist cover plate, battery, all that good stuff is cold as well (didn't use to be).

I think it worked well, and recommend it for anyone looking to drop their underhood tempretures. I washed it afterwards, and all the water beeding down the windshield would be stopped by the remaining 1/4 inch of rubber, and flow as it always has into the gutters. No water got inside the engine bay, but I made a point not to spray the hose in there from that angle.

Tips: use a sharp utility knife for easy "hot knife/butter" type job.
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Old Jan 27, 2005 | 02:28 AM
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That's my only real gripe, is the "heat sink" syndrome for these cars. Anyone else have tips

Does that affect the hood alignment at all?
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Old Jan 27, 2005 | 03:03 AM
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Hmmm, interesting idea. And it might even halp to clear frost on a cold morning.

This could really help keep engine temps down at the track while waiting to stage up.

Maybe I'll cut a section out from either side of the dist area, leaving the center and ends in tact. Think I'll start by cutting out the 1/4" and leaving the inch. I can always cut out more, but it's tough to put it back.

Thanks for the tip.
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Old Jan 27, 2005 | 03:19 AM
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Cool idea! Did you test the little 1/4 inch section you left to channel water with a garden hose?? I'd still be nervous about it being parked in a heavy rain.

Let us know how it weathers a storm...

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Old Jan 27, 2005 | 06:31 AM
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Sounds like a cool idea thanks for the tip
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Old Jan 27, 2005 | 07:24 AM
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sounds like a "Cool" idea
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Old Jan 27, 2005 | 07:48 AM
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Default That was the best line I've read on the Forum....

I'll send pics tomorrow when I'm not drunk and tired.
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Old Jan 27, 2005 | 11:14 AM
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Originally Posted by elefkow
I'll send pics tomorrow when I'm not drunk and tired.
Well, I will - going to the store today to get some bearings to fix my lights with (not using bushings... ball bearings are tougher and easier to find anyway) Then I'll snap some pics.

As for heavy rain, the hood overhangs the weatherstripping by about 2 inches, and the windshield comes up at a pretty steep angle - so the rain would have to be fairly magical to make it in there at such a harsh angle. As for cutting it gradually, good idea - that's what I did, except I practically guarantee that you'll end up going back to slice that sucker down to basically nothing (all you need is a ridge to channel water) - that's what I did, having cut only a half-inch or so at first...

More driving this morning and I'm quite certain now that this was a worthwhile hack. We got a light sprinkle too, and gravity pulls the water drops down in front of the remaining strip before it has a chance to sneak inside on the freeway - I didn't find any moisture on anything, but I guess it could have been the heat/moving air that dried anything that might have gotten in.

A windshield defroster was a benefit I thought I might get too, except when you start moving faster then 12mph or so, the air stops coming out and starts getting rammed in (seemingly, according to the thermometer) - so that perk would only be realized if you spend a lot of time creeping in traffic in the morning, or sitting still in your driveway with the fan on.
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Old Jan 27, 2005 | 12:30 PM
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Hmmm, I wonder if the cowel induction would tend to make the nose a little light above 150mph or so...

Anyway, think I'll give it a try; interested in seeing the pics of it too.
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Old Jan 27, 2005 | 12:40 PM
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Interesting idea. Has anyone else experimented with this mod?
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Old Jan 27, 2005 | 01:52 PM
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Originally Posted by 65Z01
Hmmm, I wonder if the cowel induction would tend to make the nose a little light above 150mph or so...

Anyway, think I'll give it a try; interested in seeing the pics of it too.
Interesting question. As I see it there's 2 ways to look at it.
1. By changing the intended design of the air flow thru and around the front end it could end up creating lift. or........

2. If a high pressure (lift) situation developes in the front end the extra openings at the rear of the hood could allow an escape avenue for the pressure.

I'm just throwing ideas out. Maybe somebody here knows more about areodynamics than I and can figure this out.
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Old Jan 27, 2005 | 02:38 PM
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the aftermarket hood loovers must have the same effect, but they cost money, but you might have fewer problems and the louvers probably cost about the same as new hood rubber.

anything that works well and cools my pig is worth trying--especially if involves higher intake air flow. you get double the money for one mod.

frog
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Old Jan 27, 2005 | 03:09 PM
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Originally Posted by ClarenceT
As for heavy rain, the hood overhangs the weatherstripping by about 2 inches, and the windshield comes up at a pretty steep angle - so the rain would have to be fairly magical to make it in there at such a harsh angle.
I wasn't saying that it would be a problem. Just a concern. Mainly a very hard rain while car is parked. We get some real turd floaters here in Texas. I dont think the rain would have to be "magical" just very hard and steady where the amount pouring down the parked windsheild exceeds the drain off ability.

I'm not condeming your idea by any means. Sounds like a good one. Just a concern I had before running out to the garage with the cutters.
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Old Jan 27, 2005 | 03:54 PM
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"Turd floaters"? Hahahahahahahaha I have never heard that one!
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Old Jan 27, 2005 | 08:15 PM
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I may just try it. I don't plan on any high speed runs in mine-It's just weatherstrip, can't hurt. Every little bit helps.
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Old Jan 27, 2005 | 09:45 PM
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ZumZum,

I have the back of my hood open and it doesn't have any adverse effect at 133+

In fact, I've forgotten to latch the hood for a run and it didn't lift at all until the shutdown area.

Dave
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Old Jan 27, 2005 | 10:40 PM
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Hey hooked up, that's an awesome sig pic!
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To Makeshift cowl induction

Old Jan 28, 2005 | 12:10 AM
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ericcer used to have this done, but went back to stock because of fumes entering into the a/c intake and into the cabin... Maybe he will chime in with his thoughts.
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Old Jan 28, 2005 | 01:59 AM
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Originally Posted by GeosFun
"Turd floaters"? Hahahahahahahaha I have never heard that one!
Rains so hard, that the cow patties will float!
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Old Jan 28, 2005 | 03:02 AM
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Originally Posted by ALLT4
Hey hooked up, that's an awesome sig pic!
Hehe see, thats what happens if you get rid of that stripping and hit it 130+

Originally Posted by JrRifleCoach
Rains so hard, that the cow patties will float!
Haha I didn't get it at first, but that's pretty damn funny

Originally Posted by skateparkdave
I wasn't saying that it would be a problem. Just a concern. Mainly a very hard rain while car is parked. We get some real turd floaters here in Texas. I dont think the rain would have to be "magical" just very hard and steady where the amount pouring down the parked windsheild exceeds the drain off ability.

I'm not condeming your idea by any means. Sounds like a good one. Just a concern I had before running out to the garage with the cutters.
Oh, sorry if it looked like that was sarcasm at you, I was just wondering out loud so to speak. In a huge downpour im sure something might get through. But then again, I get hosed if I take it through one of those high-pressure automatic carwashes inside the cab... doubt it'd harm anything - dist has a cover plate, everything else is fairly imprevious to water. If I start having problems I'll let everyone know, don't worry.

As far as the pics go, well, I got drunk and tired again

I promise everything will come tommorow, as I'll be doing a headlight bearing-conversion pictorial as well (all those bushing replacement guides can suck it, all of them are too vague and the pics are tiny and worthless. im making a good one)
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