NewbVetteGuy

As affordable composite intakes just don't exist today; and my 79 L82 mid rise hood can't accommodate the height of an Edelbrock Performer RPM AirGap, I plan to use the Edelbrock Performer RPM -non-AirGap, which with a drop base filter will just fit under the mid-rise hoods.


HOWEVER, one of the big benefits of the Air Gap is isolating the intake air from the hot oil underneath so you get a denser, cold air charge; I'd love to find a way to "hack" a Performer RPM to have this lower temperature benefit. I saw someone on here who had built an aluminum "heat shield" / "oil splash shield" under their intake for exactly this purpose. -Anyone know how to make one of these or anywhere that sells one? -If I'm not mistaken there were some old GM OEM steel intakes that came from the factory with splash guards so it seems like a reasonable thing to ask for.

I've also heard that there are some ceramic coatings that you can apply to the underside of the intake and bake in your oven to reduce heat soak--- I read a test article on a whole bunch of coatings and other than exhaust header coatings to reduce engine compartment heat, the intake underside coating was the only single coating that provided an actual benefit; the rest were categorized as essentially snake oil.

Heat-Soak-Be-Gone is the name I'm proposing for anyone who wants to start building and selling aluminum oil splash guards for Performer / Performer RPM intakes for us C3 folks with our low and mid-rise hoods. Feel free to steal the name; all I ask is to "Beta Test" your first product at cost. ;-)


Anyone have any tricks here for keeping carb/ intake air temps down other than a CAI (which I already have-79 L82 dual snorkel)?

Additional Context: I have an EFI system planned for this winter; if my boss is REALLY good to me this year, I just might upgrade my EFI plans from TBI to SPFI and the cooling effect of the fuel spray will be lost so intake air temperature becomes even more critical in that scenario; in either case, I'd love to plan to keep the cold air cold.


Adam

DUB

From what I know..if I am remembering this correctly.....the intake manifold that had the steel oil splash plate under the carb were on intakes that used exhaust heat to heat up the 'dog house' choke assembly....and under the carb for better fuel vaporization when cold.

When the GM went to electric chokes....I think that all stopped eventually....due to there was not more heat needed under the carb but the EGR still needed a path to function.

I honestly wonder if any coating is going to actually work due to the heat is going to migrate into the aluminum eventually.

I can tell you this...that I have removed the pins that hold the oil splash shield from under cast iron intakes only to find a lot of crusty oil that was laying in the bottom of the oil splash shield...and often times some actual oil that could not drain out of it.

I have had some people I know use the red coating that is used on electrical armatures inside the lifter galley so the oil would drain back into the oil pan faster....BUT I am always concerned about attempting any of this due to all I would need is for this stuff to flake or pop off and get into the oil system and cause for parts failures.

DUB

flyeri

My zz454 came with a stamped steel splash pan that sat just under the intake. I swapped to an air gap but used the pan also. Maybe that is a part you can get from GM Performance.

ddawson

Lifter Valley Shield.


The shields under the intakes are to prevent oil coking from the exhaust passage that goes under the intake.

The Lifter shield is worth it to took hot oil off the intake but make sure it will fit your roller rockers.

On my BBC and LS6 manifold it won't fit.

Metalhead140

...Aren't the performer rpm and performer rpm air gap manifolds the same height from memory?

Edit: Just checked, Edelbrock lists carb pad height as 4.72" for both the performer rpm and the rpm air gap for sbc.

NewbVetteGuy

I think you meant "Roller lifters"; I found the metal plate that Chevy Performance sells that goes under the intake but they only make it for BBCs and not small blocks. Moroso makes lifter shields, but they explicitly say that they won't work with roller lifters; as I plan on going retrofit roller I need to find another brand. Your picture is definitely NOT a Moroso; what is it?


Adam

NewbVetteGuy

hmm.. I had down the Performer RPM and Performer Air Gap (non-RPM) fitting under mid-height C3 hoods but the RPM Air Gap being larger and having no snowballs chance of fitting...


Adam

NewbVetteGuy

So Summit sells 3 different brand and none of the lifter valleys work with hydraulic roller lifters. I read another site that said that on SBCs splashing on the bottom of the intake is a rare event so they may not be needed... I guess I'll go without.


Adam

NewbVetteGuy

Ok, so I just learned about Intake "exhaust crossovers" -little did I know that this is a more insidious source of heat. Understand it's about driveability under cold starts; but I'd definitely want to block that thing off. There's got to be a way to warm the FUEL without warming the AIR.


If I'm reading right the Edelbrock Performer has an exhaust crossover passage and the Edelbrock Performer RPM does NOT --hmm wonder if the colder air is partially responsible for it's greater perf.


Adam

biackbenz

How does the L82 aluminum intake compare to the Edelbrocks? If doing a mild upgrade to Dart or AFR heads at 170 to 190 cc's will the L82 intake work OK?

DUB

Adam,
YEP this is kinda like a 'double edged sword'.

Trying to keep the AIR cool...but yet still have the fuel perform under cold conditions...because if you stop and think about it....not all Corvetes are in the southern states and being driven in the summer. Driving a Corvette when it is 10 degrees F outside is a huge difference than when it is at 90 degrees F.

GM has figured out the 'air' part by pulling it from in front of the radiator(as you probably know). Trying to keep the fuel cool by having some of it return to the fuel tank.

I do not think you need to worry about heating the fuel up...it will do that all on its own due to the fuel line on the frame rail is close to the exhaust and it will get heated up in time when drivign it.

I would much rather have a hot engine (so to speak )and cold fuel going into it. But that is just me.

DUB

mobird

They are the same size. The difference is that the Performer RPM has a spreadbore bolt pattern for the Quadrajet carb (7104), and the Airgap has a square bore bolt pattern which requires an adapter that adds .75" to the overall height of the carb, making it too tall for the stock hood.


If you have a Quadrajet, buy 7104 and use a drop base air cleaner and it will just barely fit under the hood.


If you have a carburetor with a square bore pattern, buy the Airgap intake.

GOSFAST

Just a tip, but if you're using factory heads or even aftermarket heads but with similar port sizes, I would simply use some "LPG" intake gaskets. This solves any heat issues at the carb or below it.

Been using these for years now an many builds with not a single issue.

Thanks, Gary in N.Y.

P.S. We use both Detroit-Gasket's and/or Fel-Pro's. The Detroit's look closer to the factory gaskets if/when painted.

F4Gary

I cut the butterfly valve out of my heat riser but left the the shaft intact so it looks normal from the outside. Felpro makes a gasket,1204, with metal inserts to block the exhaust crossover. Hopefully this will keep out a lot of the heat.

I live in Texas, so I don't need a lot of carb choke to get going. I may go to a wood spacer too since I have almost an inch of space between the air cleaner and the hood.

cv67

Excellent Dawson did you make that?

Guessing once the engine is warm the fuel will atomize fine shield just keeps excess off could be wrong

Again nicely done!

Thought about making one for my Team G that screwed on not sure it really needs it thoguh couldnt hurt. plus I cant fabricate worth a damn and wotn pay anyone 100/hr to try

ddawson

No just a picture I found.

Because the LS6 intake runners go deep into the lifter valley I couldn't run a shield on my BBC.

NewbVetteGuy

Has anyone come across a solution that allows for externally REMOVABLE metal inserts? (So if it gets properly cold you can pull the metal inserts out without removing the intake but then put them back in when it's warm for better PERF -or pull them out when you want better fuel economy?)


Adam

NewbVetteGuy

Thanks for that really good for me to note as I'm switching from the Quadrajet to Holley-style patterned EFI this winter...

Adam

NewbVetteGuy

Is there such a thing as a drop base dual snorkel?

Sorry if this is a dumb question but the "Drop base air cleaners" require taking off the dual snorkel CAI, right?

I really want to have a good performing intake cake and eat it too (keep my dual snorkel CAI).

I don't really understand if the drop bases are a replacement for the dual snorkel assembly or if they can work WITH them. (everyone calls them "drop base filters" but they have nothing to do with the filter; they're actually drop filter bases, right?(its the BASE that's special; not the filter, right?))


I really hope there's a dual snorkel drop base solution... (If not, I heard that replacing the motor mounts with solid motor mounts will gain you a little bit more hood clearance and I might explore that as an option...)


Adam

BKbroiler

They will both fit under the hood of a 78 easily with a drop base air cleaner. The OP doesn't seem to want to believe that however.