C10 LS Swap Actual Cold Air Intake

Torrey · Monday at 11:33 AM

Finished up my LS swap (L76 aluminum block 6.0 with LS3 heads) and got it tuned. My tuner said the open element "cold air" intake I had was getting crazy heat soak and costing performance. He recommended I get an actual cold air intake.

Here is the issue: no one makes an actual cold air intake for an LS swapped C10. Nothing to worry about, I've got a band saw, TIG welder and lots of fab tools.

Had to decide on a location. Close to the factory core support intake hole on the passenger side seemed like a good fit. So I made the box and used some nut zerts on the inner fender to get the basics done.

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Next up, I used the "CAI" kit with MAF and ventilation fitting I was already running. I welded it into a single piece and added tubing to pass through the box to the filter. Two silicone couplers seemed better than three.

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I didn't want water blowing directly on the filter, so I added a diverter. I also took a 90 and cut it down to where it points to and through the factory hole.

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A few more nut zerts and a lid and we have ourselves a real cold air intake. I'm dropping if off for powdercoat today and will put a rubber seal on the lid lip. Real happy with how it all turned out. I would love to make a whole batch of these for other guys running an LS swap, but I'm not sure they'd like the price tag!

Let me know what you all think!

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CalSgt · Monday at 12:00 PM

Looks really nice, good job

90Supurban · Monday at 3:54 PM

Very nice! It might be helpful to put a drain hole on the bottom of the box for water. You could even put one of those duckbill rubber drains on the outlet to keep hot air out, but still let water out, may be overkill, I dunno. Are you logging your own data? I would be curious to see intake air temp data while cruising, in stop and go traffic, or just after a hot soak. No matter what, I'm sure it is drastically improved! Did you move your battery to the left side?

Edelbrock · Monday at 4:11 PM

Nice work man. Your hired!

The only things I might look at is matching the ducting diameters, h20 drain tube in the bottom of the air box, putting an oiled foam cone over the filter (or just switching to a paper filter), and maybe insulating the air box and ducting so that the radiator heat does not heat up the air intake tube. There is going to be LOTS of very hot air blasting all that stuff when the fan kicks on.

TotalyHucked · Tuesday at 10:38 AM

Looks great! I need to do that on my truck, I've got my filter sitting on a battery tray in that same spot but obviously it still gets hot air. I've got an OBS storage box I'm thinking of hacking up to do something similar.

Torrey · Tuesday at 11:28 AM

90Supurban said:
Very nice! It might be helpful to put a drain hole on the bottom of the box for water. You could even put one of those duckbill rubber drains on the outlet to keep hot air out, but still let water out, may be overkill, I dunno. Are you logging your own data? I would be curious to see intake air temp data while cruising, in stop and go traffic, or just after a hot soak. No matter what, I'm sure it is drastically improved! Did you move your battery to the left side?

Thanks! It absolutely has drain holes, I just didn't mention that part. Good idea to run a hose for the drain! My tuner got some numbers for the initial intake config, so I'll post results once it's all buttoned up and he runs it again. I expect a drastic improvement, as we were in the 135 degree IAT range before. I actually relocated my battery to under the passenger seat on the frame rail using the GSI fab bracket.

Keith Seymore · Tuesday at 11:32 AM

Looks good to me.

I did the original design for the GMT800 engine induction system. Many of the part are still in use today.

For those of you still considering doing this you might be able to find an airbox at a junkyard and use that as a starting point.

K

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Torrey · Tuesday at 11:37 AM

Edelbrock said:
Nice work man. Your hired!

The only things I might look at is matching the ducting diameters, h20 drain tube in the bottom of the air box, putting an oiled foam cone over the filter (or just switching to a paper filter), and maybe insulating the air box and ducting so that the radiator heat does not heat up the air intake tube. There is going to be LOTS of very hot air blasting all that stuff when the fan kicks on.

I actually considered a headlight intake cone and it does have a drain. What's the benefit of the oiled foam cone or paper filter?

I'm hoping the air gap will help with heat dissipation. The box is mounted to the inner fender and the tube doesn't touch the core support. There should be some fresh air at least on the fender side. There's definitely a lot more I could do, but I think this will drastically improve things. At least now there's a path for fresh cool air to get in. Before it was just festering in its own power killing heat.

Torrey · Tuesday at 11:42 AM

Keith Seymore said:
Looks good to me.

I did the original design for the GMT800 engine induction system. Many of the part are still in use today.

For those of you still considering doing this you might be able to find an airbox at a junkyard and use that as a starting point.

K

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That box would definitely make a great start! In a perfect world I would 3D print the box and tubing with a more heat resistant polymer, but I'm a metal guy.

Keith Seymore · Tuesday at 12:07 PM

I hope you don't mind if I share some stories, since I have a minute:

The system was capacitized for the "big engines" of the day: the L18 8.1L large block and the 6.2L diesel.

Flow restriction specification (from GM Powertrain) was a ridiculous 1" Hg restriction at "max flow", from the ambient air inlet to the intake valve. Since that was essentially unachievable, and since we (the vehicle side) cannot control what goes on inside the engine, we negotiated that back to "from ambient air inlet to the throttle body inlet", which was more in line with what we could control. Max flow was established as 272 g/s.

Since the system was designed around the biggest engines, that means it was over achieving for all the smaller engines (4.3L, 4.8L @ 212 g/s, 5.3L @ 230 g/s and 6.0L @ 242 g/s). So, from a restriction standpoint, you shound not see any improvement in going to an aftermarket air induction system.

From a cold air standpoint - the gains from air inlet temperature reduction are enough to offset any increase in flow restriction, but we also had stringent air inlet temperature increase requirements that were met. The fender inlet shields the intake from hot underhood air, while also preventing water ingestion (those two requirements are typically at odds with one another).

Lastly, the tuning devices that you see: quarter wave tuners and helmholz resonators, are not in the flow stream and do not affect restriction. They are tuned to attentuate specfic targeted frequencies, and absorb the energy pulses as they radiate backwards out of the throttle body.

Bottom line - the production system was designed by a "hot rodder" and was consciously packaged and components chosen to minimize flow restriction.

K

Keith Seymore · Tuesday at 12:07 PM

There are some "architectural" things we did, too, that you might not notice. These were required to even give us a shot at getting in the game.

The '96 and beyond GMT400 models had the round element air cleaner on top of the fender, with the battery in the RF corner (passenger front) of the engine compartment.

It became obvious to me that I needed a flat filter in that spot to minimize the turns in order to even have a chance at meeting the aforementioned very aggressive flow requirement. So - I started a movement to displace the battery to some other location. Naturally the battery guy wasn't very happy about that.

We were stuck in a stalemate until the Chief Engineer, Ken Sohocki, took notice and called us into his office. He made each of us pitch our idea. In my case, I had actual flow data generated on the bench using rapid prototype material, and could demonstrate the effects with objective test data. The battery guy's response: "but we've always been right here".

The Chief's direction was swift and clear: "Seymore - you get the front corner. Schaule - find another spot".

So he moved the battery to the front of dash (rear of the engine compartment) so that he would have some structure to support his bracketry.

The engine air induction has been in the RF corner since that time, for GMT800, GMT900, K2 and now T1 generations of full size truck.

K

Keith Seymore · Tuesday at 12:08 PM

We weren't out of the woods yet, however.

The next hurdle was that the engine coolant overflow bottle was on the front of dash. That allowed the assembly plants to evacuate and fill the coolant system prior to fender install.

With the battery now on the front of dash that meant the coolant bottle had to move somewhere else, the only other place being top of the wheelhouse on the RH fender. Unfortuately that meant you couldn't fill the sytem until after the fender was on - or - you had to move the filling station. That wouldn't work because it was one brazillion dollars to move a "monument" per plant times 7 truck assembly plants = 7+ brazillion dollars.

So here is what we did: we developed a way to "stage" the coolant bottle on the radiator support temporarily by adding two "buttons" on the rad support and a tab on the bottle. The bottle could be hung in this temporary location, evac and filled, and then moved to its permanent location on top of the wheel house after the fender was installed. Problem solved, with no tooling change and pennies in piece cost.

We briefly discussed if we should remove those buttons or if it made more sense for them to remain on the truck for the life of the vehicle. In the end it was cheaper and didn't hurt anything, so they stayed. If you look at any GMT800 fullsize truck you should see those two buttons on the back of the rad support, just going along for the ride.

K

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Keith Seymore · Tuesday at 12:08 PM

One more story: I mentioned earlier that water is the bane of any engine induction system engineer's existence.

The problem with the GMT800 was that not only was the truck new but the engines were a new design, too. That meant there weren't many around and you sure as heck didn't want to damage one.

Water ingestion testing is, by definition, a destructive test. If you put enough water in the cylinder you will break it, the rod, the piston or whatever is weakest. If you don't break it you don't know how far you can push it.

We debated for a couple months about how (and if) we were going to test our design. Finally we hit upon an idea: we found an "old" prototype GMT800 radiator support and fender in the trash, so we added those to a carryover GMT400 pickup, and then installed our new induction system to emulate the new front corner. We remote mounted the engine air cleaner in the existing truck and then plumbed our new system to a shop vac (and generator) in the pickup bed. That allowed us to (a) drive the truck in the water trough, (b) not damage a current production engine (c) flow air through our new system in a somewhat representative environment and (d) collect and measure any water that was drawn in. Pretty clever, I think.

I still remember the first time we hit the 1000 ft trough at 25 mph with 12" of water: water was spraying over the top of truck and flowing big time into the cab through the heater box. I felt like I was on the Titanic, pulling my feet up on top of the instrumentation and screaming like a little girl. But - our basic idea worked and we were able to continue the development process.

I was still pretty nervous, though, the first few times we had rain once we started driving the trucks on the road.

K

TotalyHucked · Tuesday at 12:20 PM

I love your stories Keith. Especially on the GMT800 side since that's what I was (and still am) big into before getting into classic trucks. I always wondered what those little buttons were for on the core support and now I know! I've also argued about the flow of the stock setup vs an aftermarket "cold air kit" for years. The most I'll ever do on one of these trucks is the AirRaid MIT tube mainly just because it cleans up the looks of the bay, is plastic for heat control and still retains the stock air box

Torrey · Tuesday at 1:28 PM

Keith Seymore said:
One more story: I mentioned earlier that water is the bane of any engine induction system engineer's existence.

The problem with the GMT800 was that not only was the truck new but the engines were a new design, too. That meant there weren't many around and you sure as heck didn't want to damage one.

Water ingestion testing is, by definition, a destructive test. If you put enough water in the cylinder you will break it, the rod, the piston or whatever is weakest. If you don't break it you don't know how far you can push it.

We debated for a couple months about how (and if) we were going to test our design. Finally we hit upon an idea: we found an "old" prototype GMT800 radiator support and fender in the trash, so we added those to a carryover GMT400 pickup, and then installed our new induction system to emulate the new front corner. We remote mounted the engine air cleaner in the existing truck and then plumbed our new system to a shop vac (and generator) in the pickup bed. That allowed us to (a) drive the truck in the water trough, (b) not damage a current production engine (c) flow air through our new system in a somewhat representative environment and (d) collect and measure any water that was drawn in. Pretty clever, I think.

I still remember the first time we hit the 1000 ft trough at 25 mph with 12" of water: water was spraying over the top of truck and flowing big time into the cab through the heater box. I felt like I was on the Titanic, pulling my feet up on top of the instrumentation and screaming like a little girl. But - our basic idea worked and we were able to continue the development process.

I was still pretty nervous, though, the first few times we had rain once we started driving the trucks on the road.

K

That is some awesome and clever insight into the design! Most of the cold air intake kits in the aftermarket seem like a compromise of literally everything else for the sake of intake sound.

I didn't consider using a later model box and adapting it, but I see the benefits.

Do you think I should be concerned with water, or will the diverter and drain holes suffice? Should I run the factory core support cap/diverter as well? I'm sure you're aware of the piece I'm talking about. It occupies that hole and has the front blocked but the sides are open. I could trim back my pipe and run a coupler. I don't plan to drive it in the rain or through any standing water, it's more of a precaution for if I ever do get caught in a storm. I'd love to hear a real deal engineers feedback on that!

C10 LS Swap Actual Cold Air Intake

Torrey

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CalSgt

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90Supurban

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Edelbrock

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TotalyHucked

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Torrey

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Keith Seymore

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Torrey

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Torrey

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Keith Seymore

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Keith Seymore

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Keith Seymore

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Torrey

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