gitsum

Intake mod, Wow!

240 posts in this topic

The second tube that comes out of the bottom of the airbox on the drivers side is just a resonator box of some sorts, not sure what it is really for. But I took it off and used the existing down tube to draw air into the airbox from just above the fender well in a place that is well protected from water. This doubled the amount of air drawn through in conjunction with the stock snorkel.

Wow! I didn't think it would make much difference in performance, but it does. The sound level hasn't changed, maybe the frequency of the induction noise is slighter higher, but hardly any difference at all.

As soon as I revved the engine in neutral I could feel the engine spin up a little faster. Before the mod, I noticed with the air conditioner on there was a slight bog in first gear until the engine spooled up a bit. Short shifting and not revving the engine enough always produced a flat spot with lackluster acceleration until the rpm's got a little higher. Nothing that couldn't be managed by utilizing the slick shifting gearbox to keep the engine spinning a bit faster.

But not now! The engine revs faster and no more bogging with the air conditioner on or a flat spot at lower rpm's.

The power increase feels kind of like the boost you get when turning off the air conditioner. Not a huge difference, but a nice little bit of extra oomph. I've only driven it a third of a tank, but it looks like I'm getting about 2 more mpg's out of it, and I am accelerating a little more than usual.

It takes about 20 minutes to do, pretty straight forward. Turn the front wheels all the way to the left for access to the fender well. Remove two black hex/phillips screws on the bottom of the fender well right on the front wheel air dam (underneath the car), not the two silver ones. Starting at the front bottom inside of the fender well and working up, you want to remove the bottom two outboard grommets and a bottom inboard one. Use a flat bladed screw driver to pull the center cap out and unlock the grommets, they will slip out and be reusable.

You can now drop the fender well down far enough to reveal three 10mm bolts that secure the resonator. You will be able to pull the entire resonator off and there will be a small black pipe attached that came out of the airbox. Separate the tube from the resonator and trim the paper ring from the airbox end. Remove the lid from the airbox and pull the air filter, you will see the opening for the resonator tube. Firmly push the tube back in, making sure the resonator end points down towards the fender well. It fits pretty snugly, but I drilled a small pilot hole in the airbox collar and used a small sheet metal screw to make sure it didn't move.

Here's a pic of the removed resonator:

suzim9.jpg

Edited by gitsum
Emma Romero likes this

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I was conservative when describing the extra performance because there is always the "placebo" affect after modding your own car.

We did the same mod to my son's Spark and he was both surprised and happy. He estimated that the engine gained at least 4 or 5 horses, maybe even as much as 10%. My mechanical experience tells me 10% is not realistic for just opening the airbox, But my seat of the pants dyno tells me there is 5% - 10% more motivation.

Numbers aside, this is an absolute "must do mod" for every Chevy Spark. The gains are very significant and really add to the character of the car making it feel peppier and more lively.

Best of all it's free, completely reversible, and doesn't make the car sound obnoxious.

Edited by gitsum

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I'll have to check mine, but where does this connect in the airflow? Is it connect before or after the air filter, if it is before then no big deal, but if it is after like on a lot of cars it would need another filter.

Also if it was before, you might get worse performance on the highway, I'm almost positive that the intake gets high pressure air from the front of the car when it is rolling.

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The resonator tube connects underneath the air filter just like the stock intake. It would be insane to open up the airbox on any internal combustion engine to allow unfiltered air to enter the intake manifold..

The stock air intake is still functional, and if there is any actual "ram effect" (doubtful) it would be unaltered.

I can tell you right now that it definitely takes less throttle to hold 60 mph with the airbox modified.

Edited by gitsum

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I could use a 5% power increase when climbing these mountains out here in Washington.

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I may have to tape a piece of string near that open and stick a video camera watching it and go for a drive to see if the string is always pulled into the airbox, or if it gets blown out of the airbox at highway speed. Since this doesn't really affect emissions, there must be some reason they put the resonator on there.

.

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Maybe instead of removing the resonator, we should be looking at a way of attaching a larger diameter hose to the input side of the airbox. This should accomplish the same thing. Not free, but nicer looking.

Edited by Greg_E

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I'm not an engineer or scientist, but I am a decent mechanic. A small tube with a smaller opening that is angled and flows into a much larger enclosure is not going to compress air much. Not to mention the front lip of the hood is just a smaller crack that restricts the "ram air" effect even more. A engine is a pretty efficient air pump and if you ever put you hand over the intake of an engine and revved it up, you would see it sucks air at a very high velocity. The vacuum effect of the engine will suck air through the Spark's stock intake at a higher velocity than the "ram air" effect ever would push air in.

To have a true "ram air" system, you would need a much larger opening that is funneled down in a smooth and progressive fashion getting smaller as it goes, leading directly into the intake manifold traveling in more or less of a straight shot without any sharp turns.

Edited by gitsum

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I thought about doing this...its usually a mod I do on everything I touch...however I wanted to reserve the pressure fed air box on this car.. Ill try it and report back.

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Just went outside and did this...but instead of using the stock tube. I clamped on a 2" silicone coupler onto the airbox and ran a cut down 45* aluminum bend with a 2.5> 2" coupler on the end to act like a funnel then secured with a ziptie to keep from hitting on the headlight. Heading out later tonight to see how she drives.

I can easily tie this into the foglight housing for a real ram air...but thats a later project

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I took a look at mine too. The possible ram air gets pushed in from the radiator intakes, not the hood lip, so it should have a good pressure in that entire area. That said I also looked at the resonator and the tubing at the airbox is not sealed so there is now no way to be RAM air on the intake, so this should do no harm. I didn't have time to go farther and pull either the resonator or its tube out of the airbox for testing, have to wait for another day. It also lends to the cold air intakes that are sold, might have to investigate one of those.

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It was almost too easy to mod the airbox and get such a big improvement. This got me to thinking about something, but it is just a theory.

The US Spark gets a stroked engine with 1250cc vs 1200cc for the rest of the world. It was supposed to give a nice little boost in torque over the smaller engine. I'm starting to suspect the US Spark engine was purposely restricted because GM did not want it to be direct competition for the 500 pound heavier and more expensive Chevy Sonic.

The stock airbox snorkel is not any kind of ram air scoop. It was simply routed that way to pull in cooler air.

After putting more miles on the car in different conditions, it feels like it's making at least 10% more power, if not more.

My son says the same thing about his modded Spark.

Someone else try the mod on their car and tell us we're not crazy...

Edited by gitsum

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Doubt you going to get any competition with the Sonic provided it's a 1.8L engine versus our 1.25L engine

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Can someone post some pictures of the actual engine compartment and point out were this "resignator" is as well as were it connects to the air box? Also a completed picture of what it looks like before and then after the mad? The first post of how to do it was great, I am more of a visual learner and want to make sure i am looking a tthe right things :drool:

Dean Johnson likes this

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She exclaimed the car got up to speed noticeably easier...maybe worth while mod. Ill try to get pics asap...

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Makes me think a cold air intake might be worthwhile if I can find one cheap.

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I've done some more experimenting, and my tuning experience with motorcycles and scooters came in handy.

I removed the lid from the airbox and taped the air filter in place. This gave the maximum amount of air to the engine, pretty much a straight shot with just the paper air filter to go through. As I suspected, power at upper rpm's increased. Mid-range rpm's felt close to the same, maybe just a bit stronger. But low rpm's were a little bit weaker, not as bad as stock, but not as good as with just the airbox mod. I'm guessing a cold air intake system would perform pretty close to running an open airbox with just a filter.

Great for racing off from every stoplight and shifting at the maximum power peak. But not so good in normal driving were a good deal of time is spent in the lower and mid rpm ranges.

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Now that people have had a few days to drive around with this mod, has nayone noticeda true change both positive and more importantly a negative change or problems that may of arose.

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My check engine light came on and a few miles later the motor seized up! Just kidding :headspin:

More power in the low, mid and upper rpm's.

Slightly better fuel mileage.

No extra induction noise to notice.

Completely reversible.

Screwdriver and 10 mm socket takes it apart, instructions included at the beginning of this thread.

My son and I have been driving our modded Sparks around for 5 or 6 days, no negatives.

Edited by gitsum

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Just did our spark. Ill report any gains etc after driving for a few days

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Does anyone have any pictures they took while doing the mod?? I'm a very visual learner haha

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Right now our overall MPG's is 38.2. Well see if it goes up any next time we fill up......

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Just did our spark. Ill report any gains etc after driving for a few days

Well? Whaddya think?

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38.3 is excellent mine gets 25

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I drove hers yesterday...oh yeah intake makes a noticeable difference

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Just did this.. Literally only took 20 minutes. Very straight forward, the instructions are right on. Haven't driven it yet (nothing like beer and working on cars). But did rev it up, does seen more responsive. Placebo effect? Possibly... Will see tomorrow when I drive it tho.

Edited by Dori

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