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I ordered my car in September of 97. At that time everything that I could find to research the C5 hated the air box. They would go as far as saying when you buy one, tell GM you want the box changed when it’s redesigned. Well it never was. When my car was delivered early January this was the only intake available.and yes it was better than the original. I wasn’t looking for more HP. Just trying to improve on a weak point. I did add LS6 MAF, LS6 intake. PRT exhaust, Tune. Woke her up
Stock C5 air intake is total garbage, has almost zero outside air going to it, and a pitiful air box and crappy little panel filter.
Mine is at least going to get more available airflow, and cooler than just underhood air, especially at speed.
And, I only have just a little over $100 out of pocket invested.
That is fine with me as I pad my 401k off guys who think like you. lol!
We love factory intake systems
Factory intakes in general are designed to produce specific temp and pressures within the intake tract while also providing protection against debris and water, and its also nice if they are easy to service.
The target pressure drop as measured on the crankcase exit areas at wide open throttle with a OEM paper filter thats been 'broken in' for a couple weeks (1,000miles of driving or around 5 to 8% of filter lifespan) is approx 1.2"Hg to 1.8"Hg for majority of vehicle manufacturers. Some may adequate 0.5 to 0.7"Hg with low mileage filters at factory output.
As output increases, pressure drop increases, e.g. 1.8"Hg becomes 2.5"Hg and so on, due to friction creating addl pressure gradient at higher intake air velocity.
The target temperature somewhere around the temperature of plastic insulating manifolds on the running engine, I think 112*F to 118*F? became available. Thus air just over 88*F seems traditional at low flow speeds, consider that air temp can be 112*F when engine is off and flow stops, and also 88 to 95*F while at idle in traffic, and ambient during the moments just after a full clear such as wide open throttle.
We can calculate the time required for a full clear by comparing engine bay volume with engine breathing rate volume as,
With 10cubic feet as underhood volume,
An engine producing 500bhp (~430rwhp?) consumes approx XCFM * .069(115*F iirc) = 50lb/min, X is 730CFM with warm air
730CFM is 730/60 = 12 cubic feet per second
12 cubic feet per second of flow through a 10 cubic foot engine bay - we do math
At 500hp less than 1 second to bring intake air down from 90*F or whatever to ambient, no matter where the filter is placed or how hot it gets the air coming in.
The warm air's purposes is help vaporize fuel and improve economy. All power plants in the world run the highest feasible temperature for efficiency = economy. The incoming heat energy of air is useful to help do work during combustion.
The heat is problematic when compression increases so anytime combustion engines switch from economy mode to power mode, they need to start clearing out that intake air heat so it doesn't upset the fuel and overheat the engine internal parts like the piston which can butt ring ends and over-expand while develop internal cracking at high temperatures. Oil and air cooling the pistons are important in racing and must grow with hp/displacement ratio.
The goal of the factory intake seems ultimately for those two things:
-conserve heat energy of the engine as part of incoming air. (and just like also it may utilize exhaust heat/velocity component energy to help clear a cylinder and does 'work' to bring in fresh air against friction so the piston doesn't have to do that work instead)
-clean the oil by producing a pressure drop during WOT transitions as fast as possible by using the smallest volume and direct attachment with no restrictions to the crankcase from the air filter tract
Plus it also provides protection from debris and water (usually)
We can summarize even better,
-economy (conservation of energy)
-cleanliness (high mileage potential)
When we mess with that factory good intentions we had better know what we are doing, such as during forced induction,
-We should measure and set the crankcase depression to around 1.0 to 2.0"Hg at wide open throttle with a sufficient response time
-Ensure filter tract and crankcase is air tight by performing pressure test(1psi only) and/or other testing as available
-Ensure filtering is being done down near OEM or better particulate ranges, 1 to 2uM is a kind of minimum requirement for engines that you really really care about. If the engine cost is very high then I would be double or triple filtering down to 0.1uM or whatever I could get because it beats finding another engine.
Air debris is a serious insult to an engine
Summary:
Mimic factory intake pressure / temp for ideal economy and oil cleaning effects
It takes about a second to clear out the hot air at 500bhp
Addl notes recommendation etc...
If you want power use forced induction to double or triple output, leave mostly stock for reliability and quality(untouched original is its own kind of quality)
So, something I have always done with my cone filters, and I even made one work with the panel filter in my F250 PowerStroke, was to add a pre-filter, makes the base filter go lots further before needing to be cleaned.
Well, I searched and searched trying to find one for the S&B filter I am using for my CAI on my C5, but nobody made one.
So, I emailed the company I got the pre-filter material for my F250 panel filter, https://filterwears.com/ and told them what I was looking for and if they had anything that might work, even if it wasn't the exact fit for my base filter.
So, they emailed me back that they had nothing that would work, but that they could make one for me.
I figured that would be pretty expensive to have one made, but they told me it would be the same cost as their regular production ones, $26.95, well HECK YEAH!
Told me it would take a few weeks to get it made and they would contact me when it was done and get my payment info.
So, after the third week without any word, I contacted them again, and they guy I have been dealing with apologized for the delay and said he would get it going and send it to me for free, all he wanted in return was my fitment experience and review.
So, it came in the mail a little while ago, and I got it installed in just a few minutes and took some pics to send to them along with my fitment evaluation and review.
It fits perfectly, and will for sure make my filter go a very long time before it needs cleaning.
So, if anyone else has a CAI with a cone filter, do yourself a favor and get one of these pre-filters to go on it.
Last edited by Ltngdrvr; Aug 18, 2025 at 06:27 PM.
Filter Wear... good new company to know. I've always used Outer Wear and sent them custom measurements.
I like the work here. Sorry I didn't peruse the forum until this late date and find it. I would have suggested simply a C6 Z06 air intake which will bolt up directly, though conversion to the blade maf and tuning is preferred.
Another option would have been to find a BPP Vortex ram air cai from the days of old. I sold my 3rd one two years ago. Theirs cuts through the radiator shroud and pulls fresh air from under the car without having to introduce different airflow or lift from the nose. Theirs was a cone filter with very little extending at an angle past the shroud depth, but did have a box which bolted through/to the shroud and was sealed using rubber foam strips. I drove those cars in all seasons of the northeast and never had a problem with water, which I believe is a wive's tale unless someone foolishly drives through a puddle. It worked great and did have a slight sotp impact at high speed. Otherwise, I consider CAIs to be largely snake oil other than providing greater surface area for filtration.
Filter Wear.... .can their logo label be easily removed?
Probably, I think it is just a stuck on label.
Or, just put it on the back side instead of showing.
I am anti label in general though I doubt people would see these. I'm just a purist in the form of the part was purchased with intent to reduce restrictions in the form of mid and large particulates..... yet they slap a label on there which creates the equivalent of a mid to large particulate being stuck on it like a leaf. Counter productive design in my opinion.
This is what I did. Initially I was running oiled K&N but then went back to good old paper - and surprisingly is doesn't seem to get that dirty. On occasion I just get under there and brush away any stuck debris.
This is what I did. Initially I was running oiled K&N but then went back to good old paper - and surprisingly is doesn't seem to get that dirty. On occasion I just get under there and brush away any stuck debris.
The more pre-filtering and paper filtering and 'labeling' (restrictions imposed) on the OEM crankcase breather hose (attached to that restrictive air filter) the cleaner the engine oil will stay, less deposits, higher oil quality and the longer the engine will be able to last.
Absolutely run pre-filters and paper filters and so on just measure the pressure (like any tire/boost/oil/coolant/trans/etc.... pressure measurement) and make sure its where you want it or need it.
