Re-circulation even with a blow through setup

[Calan]

I can't seem to find anything on this particular question.

I have a blow-through setup (MAFT and GM MAS, hard IC pipe, straight K&M filter, BOV to atmosphere) that came on the car. Can/should I recirculate the BOV? How can I do it with what I have?

After some research I'm thinking I can get my turbo to remained spooled and get smoother shifts if I recirculate it. As it is, when I hit the clutch the RPM's really drop and the shift is "jerky" for lack of a better word.

I want the best performance. I could care less about the "cool whoosh" BS.

Thanks for any help.

 

[DJYoshaBYD]

just run a hose from your BOV outlet back to your intake before the turbo... its very simple....

 

[FORMONTOYA]

The GM MAF/MAF-T setup is the only way you can "legitimately" vent your BOV to atmosphere. Although with your setup you don't have to recirculate, you're correct that recirculating the BOV will help keep the turbo spooled between shifts. As stated, you will have to get a hose from your BOV back to the intake "snorkel" pre-turbo which might mean you have to purchase/fab something.

 

[Calan]

As for why the BOV back to the intake smoothing things out.. this is a guess, but....

Does this help because the turbo (compressor side) would see this as temporary additional inlet pressure, which would unload some of the work from the exhaust side?

In other words, I guess by adding pressure to what the turbo is sucking in, you're temporarily reducing resistance which allows a smoother transition from spooled to not spooled. Is this correct?

Thanks

 

[FORMONTOYA]

When the BOV opens and recirculate it has the same effect as wind blowing on a pinwheel to help keep it spinning, not that it really needs help, but it does help to keep it from slowing down as fast.

 

[Calan]

Cool.. thanks Jim.

Just checked and my inlet pipe does have a "nipple" on it, about the same dia as the BOV outlet and maybe 1-1/2 to 2" long. (It's blocked off with a screw/washer and RTV, although I don't know what the screw is attached to inside it).

So just get 1-1/4" heater hose and a couple of clamps? Depending on what that screw is "screwed" into on the inlet pipe, I may need to open up the nipple.

The nipple on the inlet is damn close to the tranny linkage, so I'm hoping I can maybe find an elbow or form up the hose without interference and without kinks. I'm guessing I need as straight a connection as possible.

 

[FORMONTOYA]

More than likely what's in the recirculation tube on the intake snorkel is a rubber core/freeze plug. They have a large washer on top and a stud that is connected to the bottom of the rubber portion (in a way) and when you tighten the nut it expands the rubber, thus sealing the hole.

Just a guess, but I would be willing to bet money that that's what is in there.

 

[Calan]

Ahhhhhhh... I bet you're right. That "RTV" under the washer does look really consistent... and it's red. (I should of recognized this possibility... duh)

We'll find out in an hour or two. Gonna be doing some work on it this evening after family time, and if I can get a couple more answers on other topics

Thanks again Jim.

 

[Calan]

Well I'll just close this post by saying I'm an idiot

I spent about 2 hours driving around town trying to find 1-1/4" hose and a couple of clamps to recirculate my BOV like we've been discussing. NOBODY had this size. As a last resort, I bought some 1-1/4" SPA hose from Home Depot on the way home to use as a test (knowing it wouldn't last long).

I finally get home, slip the end of hose over the BOV... and it's too big. So as I'm headed back into the house frustrated and mumbling "screw it"... for some reason I happen to glance down at the box of spare parts in the corner that came with the car. Guess what was sitting right on top?

The original hose... that fits like a glove. It even still had the clamps on it.

me