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Hi, I'm planning to use the Van's Filtered Air Box (FAB) instead of the regular ACS carb box, and was wondering if it has been done by others before, on a 0-540. I searched the old BH group and found nothing, except for 0-360. From what i can figure, the o-540 carb with the van's FAB may protrude way to much forward. Fitting all this nicely under the cowl/fairing is my concern. Mike.
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I have the FAB on a 360 engine. Vans uses the FAB on the RV-10, which seems to be an indication that they think it's up to the job as far as flow is concerned. Here is a link that shows some pictures of where the box falls on mine: http://jaredyates.com/bearhawk/?p=1257
Would it really be that much different on your engine? Bob built our 360 with a 90-degree intake elbow, as he usually does. See a picture here: http://jaredyates.com/bearhawk/wp-co...3/P1000296.jpg
Isn't the final placement of the carb going to be about the same for a 540 with the usual vertical sump? Even if they are not, I think you'll still run into the same issues with just about any airbox. The bottom of the carbon fiber box that we discussed on this site a while back may sit higher, since I think it was designed to have the carb flange occur below the top of the box. I keep hoping someone will put one of these to work so that I can hear how it goes, and whether it's worth upgrading if my FAB fails beyond easy repair.
If you do use the FAB, spend some time on the VAF site to read about the durability and weak spots of the FAB. It is exposed to some pretty harsh harmonic conditions and while it doesn't seem to fail as quickly as the ACS box, it is not immune to problems. In spite of researching those problems, I've managed to have mine fill with water because I forgot to drill a drain hole, and I found a crack in the top plate after about 75 tach hours and have had to build a new one. There is concern about chaffing between the fiberglass and the bottom of the filter if the filter isn't fitted very tightly, so I think the key takeaway is to spend some time carefully inspecting the box periodically. Mine didn't make it to the first condition inspection without cracking, and I would not have noticed the crack if I had not removed the box for another issue, so I would recommend inspecting a new one around the time of the first oil change off of mineral oil. -
Thanks for your reply. I've consulted your website quite a few times already. Very helpful... The carb position on the o-540 is about 6" forward, as compared to your setup. Looking at some of your photos, moving the FAB box 6" forward will make most of the box to protrude out of the cowling. It might then be difficult to adapt the air scoop in order to get a nice looking fit. I would really want to see someone that did it on a 540...In regards to the FAB box reliability, i've built a RV-7a few years ago and flew it for about 300 hrs, trouble free. I was aware of the cracking issues and double up the top plate up front during the construction phase. Another weak point reported is the cable end connection wearing off the carb flap actuation arm. My work around was to put a thin layer of RTV on the cable end pivot point to dampen the vibration. Don't use to much RTV as it will prevent the cable end to pivot freely, but just enough to add some friction. The guy that bought my plane has 500hrs on it, still no issue.Comment
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Even with those extra 6 inches, wouldn't you still have less of a gap/buildup than the typical RV, and less than the ACS box? Short of going with some sort of fuel injection, it seems like you are going to have something protruding.Comment
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