No airbox = more power
#61
04-25-2017, 04:20 PM
Registered User
Join Date: Apr 2017
Location: Niagara Region
Age: 52
Posts: 400
Rep Power: 28 
Sounds good - if you do try the test make sure to get the rated CFM of the shop vac you are using and then plug the data into a website like this one:
http://www.ajdesigner.com/phpengine/...e.php#ajscroll
Engine Design Calculator
Automobile - Car
Conversions:
cubic inch displacement (CID)
= 261
= 261
= 261
engine speed (RPM)
= 2300
= 2300
= 2300
volumetric efficiency (VE)
= .80
= 0.8
= 0.8
air flow rate
= 138.95833333333
foot^3/minute
foot^3/minute
Since there are two airboxes on the car divide by two for CFM per airbox.
The Rigid website said my wet / dry vac flows at 69 CFM.
Last edited by 007V8Vantage; 04-25-2017 at 09:33 PM.
#62
04-25-2017, 09:26 PM
Join Date: Feb 2010
Location: Austin
Posts: 1,022
Rep Power: 65 
Hahaha that's awesome.
Only thing I'd "criticize" is that the paper filters do holdout from letting water in for quite a while, and once they do it comes through a lot faster, so a short test isn't going to show much water get through compared to a long test. Making the leap from shop vac test to real world, it'd be like driving 30 seconds of driving in the rain vs 10 minutes. While a few drops might have gotten through the filter in that short amount of time (~30 seconds), how much more would get through with the sustained period (~10 minutes)?
I've got a set of air box delete brackets on the way and I'll be installing them on my grey car. My dry filters are taking longer than I wanted (doesn't everything??) but they'll be going onto the grey one as well, which means I'll have to be a lot more cautious about running the car without air boxes. I might have to replicate your test, Ryan!
Only thing I'd "criticize" is that the paper filters do holdout from letting water in for quite a while, and once they do it comes through a lot faster, so a short test isn't going to show much water get through compared to a long test. Making the leap from shop vac test to real world, it'd be like driving 30 seconds of driving in the rain vs 10 minutes. While a few drops might have gotten through the filter in that short amount of time (~30 seconds), how much more would get through with the sustained period (~10 minutes)?
I've got a set of air box delete brackets on the way and I'll be installing them on my grey car. My dry filters are taking longer than I wanted (doesn't everything??) but they'll be going onto the grey one as well, which means I'll have to be a lot more cautious about running the car without air boxes. I might have to replicate your test, Ryan!
#63
04-26-2017, 08:48 AM
I'm not sure what to expect on the dyno. I'll be using dry filter intakes without air boxes, along with everything else I have on my car (headers, high-flow cats, muffler, lightweight flywheel, tune, etc) to see the total difference between my grey car and my red one (completely stock, even the tires). I'll also be weighing both cars to compare that difference, including weight distribution. I'm going to be comparing both cars at the same time in the same place on the same dyno and same scales - so everything will be a direct comparison
Hoping to also get some performance figures but that's going to be more difficult since we'll need a place to do it.The air box deletion is for a few reasons: weight reduction and incompatibility of my lightweight bumper beam with the intake inlet ducting being the main ones. Power and simplified maintenance are also factors, but minor in the overall scheme of things.
Between the lightweight bumper beam, mesh grille, and removing the air boxes and intake inlet ducting, I should be dropping around 25 lbs from the nose of the car (hopefully more). That should mean a total of ~170 lbs of weight loss from the car, without any sacrifice in comfort or amenities to get that weight reduction.
#64
06-12-2017, 10:43 AM
As a follow up, just went through a half hour downpour on Saturday at 70 mph and the filters were nice and dry, of course it took me a while to pull the pan to get a look at them.
I have dry filters without the lower half of the airbox.
I have dry filters without the lower half of the airbox.
#65
06-12-2017, 10:45 AM
Join Date: Feb 2010
Location: Austin
Posts: 1,022
Rep Power: 65 Thanks Randy and interesting thought removing just the lower half. I'm assuming this is to prevent hot air from being sucked in from above?
Do you have pictures?
#66
06-12-2017, 11:55 AM
No, I was also changing the ballasts on my headlights and did not even think of it. But I am due for an oil change in the next couple of weeks and I will take some pics then.
#68
06-27-2017, 08:41 PM
Join Date: Feb 2010
Location: Austin
Posts: 1,022
Rep Power: 65 
I think I will cut out holes in the bottom of the wheel arch liners to allow air flow up like the GT4 cars have.
#70
07-05-2017, 08:19 PM
The first few sets should be ready to ship next week 
I haven't noticed any extra induction noise on my grey car that's already running the prototypes because that car is pretty loud. I'll be putting a set on my red car as soon as they're ready, though. That car still has the stock exhaust so I'll be able to tell on that one. But I honestly don't expect much noise from it - the air boxes are so far forward that I'd be surprised if the extra noise was noticeable.
I have the intake ducts completely removed from the nose of my grey car (out of necessity due to the Aston Martin Racing lightweight front bumper beam). Removing the inlet, ducts, and N400 air boxes has dropped 11 lbs from the nose of the car (standard air boxes should be slightly lighter and I'll be weighing a set of those when I take them off my red car). It also has made the intake filters much, much easier to change since I no longer have to remove all those bolts for the covers. The OEM filters haven't moved at all, despite only being press-fit on - no clamps or anything else to keep them there. This fitment is part of why I'm going through such great lengths to ensure my high-flow filters are perfect - any looseness or poor fitment will result in the filter not staying in place!
Another bonus is that removing the air boxes simplifies the system to remove another point of failure. If there is any difference in the air flow between the two air boxes, the MAF sensors will throw a fault because they're out of correlation. I've had this issue myself when I had a crack in one of my air boxes. It's also an issue if the cover on one side isn't sealed properly, which also happens. Removing the air boxes entirely eliminates a few potential issues with all this. (Side note: this is one of those things that's way, way too complicated on the car - seriously, what does it matter if the air boxes aren't getting perfectly matched air flow? They join up post-MAF anyway! *rant*rant*rant*...) My grey car has been driving beautifully since removing the air boxes, no issues at all and very smooth power delivery.
You do have to keep in mind that the filters are no longer protected, so there is that added risk (don't submerge the front of the car in water and you'll be fine). In my testing so far, I've had no issues at all, and I'm exposing the filters to far more hazard than most people ever will.
As for cutting out the bottom of the fender liners, I personally wouldn't do it. Far more risk than reward there, in my opinion. If you leave the inlet and ducts in place, air from the nose of the car will be pointed at the intake filters same as the standard setup, and that's a really good supply of air when you're at speed. You may get extra airflow by opening up the fender liner below the filter, though, since there might be enough high-pressure air to push up into the area around the intake filters.
I haven't noticed any extra induction noise on my grey car that's already running the prototypes because that car is pretty loud. I'll be putting a set on my red car as soon as they're ready, though. That car still has the stock exhaust so I'll be able to tell on that one. But I honestly don't expect much noise from it - the air boxes are so far forward that I'd be surprised if the extra noise was noticeable.
I have the intake ducts completely removed from the nose of my grey car (out of necessity due to the Aston Martin Racing lightweight front bumper beam). Removing the inlet, ducts, and N400 air boxes has dropped 11 lbs from the nose of the car (standard air boxes should be slightly lighter and I'll be weighing a set of those when I take them off my red car). It also has made the intake filters much, much easier to change since I no longer have to remove all those bolts for the covers. The OEM filters haven't moved at all, despite only being press-fit on - no clamps or anything else to keep them there. This fitment is part of why I'm going through such great lengths to ensure my high-flow filters are perfect - any looseness or poor fitment will result in the filter not staying in place!
Another bonus is that removing the air boxes simplifies the system to remove another point of failure. If there is any difference in the air flow between the two air boxes, the MAF sensors will throw a fault because they're out of correlation. I've had this issue myself when I had a crack in one of my air boxes. It's also an issue if the cover on one side isn't sealed properly, which also happens. Removing the air boxes entirely eliminates a few potential issues with all this. (Side note: this is one of those things that's way, way too complicated on the car - seriously, what does it matter if the air boxes aren't getting perfectly matched air flow? They join up post-MAF anyway! *rant*rant*rant*...) My grey car has been driving beautifully since removing the air boxes, no issues at all and very smooth power delivery.
You do have to keep in mind that the filters are no longer protected, so there is that added risk (don't submerge the front of the car in water and you'll be fine). In my testing so far, I've had no issues at all, and I'm exposing the filters to far more hazard than most people ever will.
As for cutting out the bottom of the fender liners, I personally wouldn't do it. Far more risk than reward there, in my opinion. If you leave the inlet and ducts in place, air from the nose of the car will be pointed at the intake filters same as the standard setup, and that's a really good supply of air when you're at speed. You may get extra airflow by opening up the fender liner below the filter, though, since there might be enough high-pressure air to push up into the area around the intake filters.
#71
07-05-2017, 08:26 PM
Registered User
Join Date: Jun 2016
Location: South Jersey
Age: 64
Posts: 1,476
Rep Power: 73
I just threw my 4.7 box on the scale [the one Summit broke, glued back together, and never mentioned] and it weighs in at 3lb 15oz. that is with the stock filter inside.
#72
07-05-2017, 08:34 PM
Join Date: Feb 2010
Location: Austin
Posts: 1,022
Rep Power: 65 As for cutting out the bottom of the fender liners, I personally wouldn't do it. Far more risk than reward there, in my opinion. If you leave the inlet and ducts in place, air from the nose of the car will be pointed at the intake filters same as the standard setup, and that's a really good supply of air when you're at speed. You may get extra airflow by opening up the fender liner below the filter, though, since there might be enough high-pressure air to push up into the area around the intake filters.
Looking forward to trying them out Rich!
The idea for cutting out part of the bottom of the fender liner came from my discussions with TRG and AMR. They indeed mentioned additional air being pushed up around the filters. Mentioned that they will "cover it up" if down pouring during a race!
