Plenum Insulators - Disussion wanted
Thread Starter
Racer
Joined: May 2005
Posts: 439
Likes: 0
Plenum Insulators - Disussion wanted
I have a set of plenum insulators laying around, thought I might bring up a discussion on the subject.
These go between the injector housings and the plenum, are about 1/8 inch wide. I think I have hood clearance, but need to check it out first.
I've talked to others and they say it's a waste of time, someone said just put foil paper between two plenum gaskets with the shiny side down. I do know after my lt5 warms up, the plenum gets very hot, I live in Houston, the summers are like a blast furnace.
These particular units do not have the coolant holes drilled thru that usually are used for the throttle body coolant hoses. They also came with a set of longer plenum bolts that are hex.
questions:
Has anybody used these ?
These insulators will block off the Coolant ports to the throttle body, thus cutting out this particular route of coolant circulation. Is that wise ?
These go between the injector housings and the plenum, are about 1/8 inch wide. I think I have hood clearance, but need to check it out first.
I've talked to others and they say it's a waste of time, someone said just put foil paper between two plenum gaskets with the shiny side down. I do know after my lt5 warms up, the plenum gets very hot, I live in Houston, the summers are like a blast furnace.
These particular units do not have the coolant holes drilled thru that usually are used for the throttle body coolant hoses. They also came with a set of longer plenum bolts that are hex.
questions:
Has anybody used these ?
These insulators will block off the Coolant ports to the throttle body, thus cutting out this particular route of coolant circulation. Is that wise ?
Melting Slicks
Joined: Jan 2002
Posts: 2,116
Likes: 84
From: Hope, New Jersey
i have heard there is hood clearance issue with the spacers, coolant to throttle body is for cold climates mainly,i believe it allows the throttle body to heat up faster in very cold weather.
Pro
Joined: Jan 2004
Posts: 631
Likes: 3
From: Virginia Beach VA
I'd be surprised if those insulators do any good. No matter what you do, the heat will always find it's way to the plenum. All I think the insulators will do is prolong the time it takes for the plenum to get as hot as the rest of the engine compartment.
Even if it does work, then you have the problem of the rest of the motor getting hot, because now the plenum no longer dissipates heat, so now there's nowhere for the heat to go.
I wouldn't be as concerned with the temp of the plenum as I would be the temp of the air going in. If you want cooler air, get cold air induction. If you want to cool the motor down, get a larger radiator or beef up the fans. Just my $.02.
Even if it does work, then you have the problem of the rest of the motor getting hot, because now the plenum no longer dissipates heat, so now there's nowhere for the heat to go.
I wouldn't be as concerned with the temp of the plenum as I would be the temp of the air going in. If you want cooler air, get cold air induction. If you want to cool the motor down, get a larger radiator or beef up the fans. Just my $.02.
Thread Starter
Racer
Joined: May 2005
Posts: 439
Likes: 0
Originally Posted by 90 Corvette ZR-1
I am planing to block off the coolant circulation to the plenum myself. Unless you drive your car in sub freezing conditions, you should be fine.
I guess the thing I'm worried about is the circulation, if you block the coolant passages to the throttle body, there is some circulation that will be lost, if that particular circulation point is blocked, what effect ( if any ) would it have on the engine & cooling system. I realize this particular circuit is just for the throttle body but will effect anything else ?
Drifting
Joined: Jul 2002
Posts: 1,932
Likes: 116
From: LPE Aerobody 416 ci, Oklahoma
I think the optimum way to use the spacers (assuming you decide to use them) is to drill the coolant passage hole in the spacers and then install a bypass coolant hose around the TB. LT5's are somewhat difficult to burp air out of the cooling system anyway, so leaving this coolant passage intact over the top of the engine would probably help in "burping."
That's what I did with mine anyway. You should know that the alum vacuum line that runs along the drivers side of the plenum base & bolts down with plenum bolts will need to be bent somewhat to reinstall with the spacers in place, leaving it a little crooked and in a bit of a bind.
The hex head bolts you mentioned sound like another problem. I recommend using allen head bolts that can be purchased at Ace Hardware.
Personally, I'm not sure of any tangible benefit for the phenolic spacers. Mine are hanging on the wall.
That's what I did with mine anyway. You should know that the alum vacuum line that runs along the drivers side of the plenum base & bolts down with plenum bolts will need to be bent somewhat to reinstall with the spacers in place, leaving it a little crooked and in a bit of a bind.
The hex head bolts you mentioned sound like another problem. I recommend using allen head bolts that can be purchased at Ace Hardware.
Personally, I'm not sure of any tangible benefit for the phenolic spacers. Mine are hanging on the wall.
Thread Starter
Racer
Joined: May 2005
Posts: 439
Likes: 0
Originally Posted by A26B
I think the optimum way to use the spacers (assuming you decide to use them) is to drill the coolant passage hole in the spacers and then install a bypass coolant hose around the TB. LT5's are somewhat difficult to burp air out of the cooling system anyway, so leaving this coolant passage intact over the top of the engine would probably help in "burping."
That's what I did with mine anyway. You should know that the alum vacuum line that runs along the drivers side of the plenum base & bolts down with plenum bolts will need to be bent somewhat to reinstall with the spacers in place, leaving it a little crooked and in a bit of a bind.
The hex head bolts you mentioned sound like another problem. I recommend using allen head bolts that can be purchased at Ace Hardware.
Personally, I'm not sure of any tangible benefit for the phenolic spacers. Mine are hanging on the wall.
That's what I did with mine anyway. You should know that the alum vacuum line that runs along the drivers side of the plenum base & bolts down with plenum bolts will need to be bent somewhat to reinstall with the spacers in place, leaving it a little crooked and in a bit of a bind.
The hex head bolts you mentioned sound like another problem. I recommend using allen head bolts that can be purchased at Ace Hardware.
Personally, I'm not sure of any tangible benefit for the phenolic spacers. Mine are hanging on the wall.
Mine are hanging on the wall also, been there for over a year, reason why I brought up. I bought them on a whim but when I started to put them on, I decided not to. But I thought the discussion may generate
someone who actually have used them and saw some gain, but I really haven't seen any astonishing results from anyone.
Hey ( light goes on over my head ) maybe I'll just put some duct tape over them and use them to keep stuff out of my injector housings when I have the plenum off.
Safety Car
Joined: Aug 1999
Posts: 4,862
Likes: 118
From: Texas
The spacers do work to lower the manifold temp slightly but they were originally designed to lower the temp under the manifold to prolong the coil pack life for road racing. Just be sure you have the hood clearance. Some rub and some don't.
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Instructor
Joined: Jan 2004
Posts: 119
Likes: 0
From: Phoenix Az.
Put some modeling clay on the plenum top and the air horn. Put some Saran wrap on top of the clay and shut the hood. Then you'll know how much clearance you have. The insulators I bought had terrible alignment issues. If the bores lined up, the bolt holes didn't. If the bolt holes lined up but the bores didn't. The ones I got were opened and looked like they had been returned previously. They had a crack in the material around the bore. I finally got some .200 thick phenolic and made my own. When your car gets shut off hot, all the heat from the hot cylinders with intake valves that are open let the heat rise to the plenum. So the manifold gets hot anyway. Too bad the plenum isn't the nylon type material the LS1 and LS6 use. I considered ceramic coating the inside but with the oil coating the inside I was afraid it wouldn't stick. It would work better than a spacer/insulator with a new plenum if the coating worked. That would insulate the plenum from rising heat and outside heat. Ultrasonic cleaning may clean a used plenum ok but it would be a gamble. Just a thought.
Pro
Joined: Dec 2004
Posts: 670
Likes: 28
From: Mitchell SD
My car had the spacers on it when I bought it and the air duct does rub on the hood a little. Some rub even without the spacers, as far as the power gains I doubt that it can be much. Since they were already on the car I have left them on but I drilled out the throttle body coolant holes. The reason I drilled them out was someone from LPE told me that there is no measurable power gain on a dyno with them blocked and the cars cool better with them open.
