Tech Article: 1g BOV mods

Hey guys, this is the first of many tech articles to come from me this summer. I decided that I am too cheap to buy an aftermarket BOV, so its time to mod the stocker 1g. There's two ways to mod it, the "Dodge Garage" mod or crushing. Crushing BOV in a vice and tightening it down. The new pressure holding capacity depends upon how far its crushed, but if you crush it too far it wont open. I didnt want to fuck around with crushing due to the irreverisibility and how inexact it is, so I went with the Dodge Garage mod. The one downfall with the Dodge Garage mod, is that though it can hold much more boost pressure, it is no longer as fast releasing. Though the dodge garage writeup is available on tuners and other places, I found both fairly confusing plus I took it a step farther to account for this pressure holding vs quick release issue, so here is the Thor version.


Before I get super into this, I should cite my sources. Big ups to DSM90AWD on DSMtuners for his tech article (http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/220909-1g-bov-101-mods.html) which really helped me a lot. I cant find the link of the other article I used, but I used another one for the second part of the mod. So thanks to that guy too. :)

Here's a list of the things you're going to need:
-1g BOV
-JB weld
-some form of hard line, I used old brake line
-drill
-drill bit, will be used to drill into the BOV to make two new nipples out of the brake line
-a length of vac hose
-fuel pressure solenoid from your emissions
-wire
-switch

For a explanation of how the BOV actually works, visit the DSMtuners link above. It is not necessary to know that to mod your BOV, but you need to know that to be able to understand exactly how that works.

Look at the following pictures. See the "tube" looking deal running from the flange to the green cap?

http://img299.imageshack.us/img299/5140/1001084ja2.jpg (http://imageshack.us)

Follow that under the BOV. See that hole?

http://img78.imageshack.us/img78/3921/1001083qw8.jpg (http://imageshack.us)

The UICP pressure follows that hole up into the BOV to effectlively help tell the BOV when to *psshhhhhh*. If we plug that hole and vent that tube, only the vac source running through to the nipple on the top of the BOV affects the operation, and thus it will hold more pressure.

The first step in this is to drill a hole in the side of the flange to the hole running up that tube. Be sure to drill straight to it, and use a big enough bit so that the brake line will fit, but not too loose. I drilled a test hole in another piece of material just to be sure. It works best to drill a small pilot hole first, then size it out each time. I shoud also note that it does not matter whether the hole goes on the front side or the backside, its all user preference. I chose the back side as it will play better into my plans for later. Here's the hole I drilled.

http://img397.imageshack.us/img397/6466/1001085he7.jpg (http://imageshack.us)

Next cut 3/4 of an into to an inch from your length of brake line, this will become the first nipple you put in. Be sure to do it in such a manner that the brake line doesnt get kinked or out of round. Push the line about halfway into the hole you drilled in the BOV and use JB weld to seal. Be sure not to use so much JB weld that the passage gets clogged, this would be bad.

http://img397.imageshack.us/img397/6972/1001086ug3.jpg (http://imageshack.us)

The next step is to clog that hole in the bottom of the BOV. One write up I read used a small screw sealed with JB weld, while the other just used JB weld. I decided to just use JB weld as well, but again becareful not to get the JB weld and/or screw up into the passage way.

http://img299.imageshack.us/img299/7545/1001089ub1.jpg (http://imageshack.us)

You could be done here, connecting that new nipple to another boost source will go back to the quick release mode. The only problem is that switching between the two will be kind of a pain in the ass, plus you'll have just one more vac hose running.

This part of the write up makes it switchable between quick release and high pressure on the fly, from the comfort of your seat.

The next thing you will need to do is make a new boost source. To do this you will need to look at the bottom of the BOV and drill a new hole on the opposite side of the original hole about half way through the flange. Just as with the other side, we will drill another hole laterally through the flange to intercept the hole you just drilled. This will effectively make an L shaped hole in the flange that connects the under side of the BOV to outside air. Put a nipple in that hole just like you did the first one.

http://img299.imageshack.us/img299/9813/1001090dc4.jpg (http://imageshack.us)

http://img299.imageshack.us/img299/9168/1001092ct9.jpg (http://imageshack.us)

Now put down your BOV for a sec and turn your attention to your emissions system. If you wish to completely remove them as I did then check the vac line map below, otherwise I belive you should just be able to just remove the fuel pressure solenoid and connect the two vac lines that were attached to it. NOTE: I am not 100% sure that is the best way to do it, you should check before doing. Like I said, I took the whole mess of them out so I didnt have to cross that bridge. The emissions solenoids are pretty much just below the VIN number on the firewall. The solenoid we are after is the fuel pressure solenoid, and is pictured below. If you want to leave your emissions intact, you could also just go to a junk yard and pick one up as well.

Now for a discussion on how the solenoid works. When there is no current through the solenoid, the air normally flows as shown below, from nipple A to nipple B.

http://img397.imageshack.us/img397/6485/solenoid2ef6.jpg (http://imageshack.us)

However, when current is flowing through the solenoid, the air flows like below, from nipple A to nipple C.

http://img299.imageshack.us/img299/555/solenoid3tq3.jpg (http://imageshack.us)

See where we're going with this? We will hook up the very first nipple that we made (the quick release nipple) to nipple A on the solenoid, then hook the new boost source nipple (the second nipple we made on the BOV) to nipple B on the solenoid. Here's a picture of how it should look.

http://img165.imageshack.us/img165/276/1001097al9.jpg (http://imageshack.us)

Just a note, I will be using much longer vac lines and installing the solenoid and a couple other to-be-announce things in a much better way... this is just to show how to hook it up. Now mount a switch in the cabin wherever you want it, then run a lead from the positive terminal to the switch, then from the switch to the positive terminal on the solenoid. Then run another lead from the negative terminal on the solenoid to the negative terminal on the the battery. Now its complete! With the switch off the BOV will function like normal but when you flick the switch it will go into the high pressure capacity mode! In my car, I will cruise and do normal driving with the BOV switch off so its in quick release mode. When I go to a track or race off a light I can just flick the switch and BAM, shes automatically in high pressure mode. :D

I should also say that you need to be sure you shut the switch off whenever you leave the car, otherwise it will just sit and draw current. The way to combat this would be to tap into a the ignition switch or something else that will only turn on when the key is on, which is what I plan to do eventually, but I am not sure which wire to tap just yet.

All you have to do is mount up the solenoid and have fun! Well, I hope this was helpful, any questions just post up here or dont hesitate to PM me. Ill post up pictures of the final installed thing when I get them.

Good writeup. Not sure why this would be useful since you have to manually turn it on and all. So...


What would be awesome would be to tap it into the rpm signal. So once you hit a certain rpm, it automatically turns on. You could probably do this using a shift light where you can set the shift point. Then when you hit a certain rpm, instead of the light going on, it turns on the valve. Yeah it would be on it everyday driving, but why not? Better to have a better hold then a weaker one IMO.

Nice pics too. About time people learned about macro mode and how to have a steady hand/tripod. Dustin +1!

EDIT: And after thinking about it, wouldn't it be better for shorter vac lines for all of this and keeping the valve as close to the BOV as possible? Will allow for quicker response time and less chance of holes in lines.

Thanks Dave!

I see it as useful as it will be responsive when you need it to be, such as during cruising, but once you need it to hold a lot of pressure such as when you are going to race then you can just switch it.

You are right, short vac lines are better, but maybe not that short. I feel that when they are that short, the sharp bends cause a cross sectional area reduction to the point of being bad. My lines wont be long by any means, maybe 4"-8" once installed depending on where I decide to mount the box.

I like your RPM idea, but there was a better one I read about on the site I cant find/remember. They used a pressure switch so that it was responsive to like 15-18psi, then after that it was in "high pressure" mode. I like the simplicity and cost effectiveness of this, but I wouldnt have any idea where to get a pressure switch like that. Maybe someday.

So if you turned the boost up, say higher than 15psi, it would automatically switch over then? That's a good idea too. Seems like you can somehow run a MBC inline to the BOV and set it to that certain PSI point then. Not sure how that would all work together as I was just thinking outloud. Awesome.

I thought you were talking vac lines like x-feet long! :lol: I would run the vac lines around the BOV ICP, run the 2 lines on either side of the piping, and keep the valve hidden underneath that.

You could use a pressure switch made for a meth inj. kit. You could just change the setting to the correct psi and them it would provide power or a ground to the solenoid.

Oooh! Good call, I'll look into that. I did find some useable ones here (http://www.omega.com/ppt/pptsc.asp?ref=PSW21_PSW22&Nav=preh02) as well. While I was taking a shit like 15 minutes ago I thought of a way to make it switchable from either automatic with the pressure switch or back to hi/lo manual switch too. I think thats actually the way I am going to do it, just because I like being difficult. :)

Best thinking happens on the can.

nice thore! good write up! interested in seeing/reading more about this Auto adjustment thing with the pressure switch! for sure!

Interesting variation on the "Gus Mod". I likes.