Another catch can fitting size question

[jpmxrider489]

Ok I know there are plenty of threads out there about catch cans and fittings. And calan is probably going to shoot me for this. But I guess I need to think out loud and and get this together. Im going to be ordering my JMF catch can on monday and im debating a fitting size for my goal. Just to put this out there IM AGAINST welding the fittings. So I would like to use the breather port and PVC port. I was going to order the stm fitting but seems pointless to me. I see people are running anywhere from 6an to 12 an. I have a bunch of 8an hose laying around so that would be my preference. My goal is 600whp if that matters. I wont be connecting a vacume sorce to the can because I have the FP intake. I know the walls are thin but what tap and fitting would be best for my goals?

 

[Gamble97]

Why are you against welding the fitting? Putting those stm 6an pieces on don't do anything for you at all. I did a thread on this a long time ago and it would have been a waste of money.
So don't do it, weld them on or wait for FF to finish the CNC valve covers with the threads in there for bigger AN fittings and go that route.

 

[blktalon3]

I just got done doing mine without welding. I used a 9/16 drill bit and a 3/8 npt tap. Then used a -8 to 3/8 npt fitting. With that drill bit your getting real close to the top of the VC so you have to real careful. The other thing is I couldnt get the fittings to screw all the way in, which it still seals fine but doesnt look as good. I put some JB weld around the fittings to make it look a little better. I can post some pics up tomorrow when I get home.

 

[jpmxrider489]

Why are you against welding the fitting? Putting those stm 6an pieces on don't do anything for you at all. I did a thread on this a long time ago and it would have been a waste of money.
So don't do it, weld them on or wait for FF to finish the CNC valve covers with the threads in there for bigger AN fittings and go that route.

I saw your thread actually.

What size hose would be best for my goal? Is 8an bigger than stock?

 

[Gamble97]

Yes 8an is bigger than stock. You typically want to go with the largest possible.
You ever see the catch can setup on the 4g63 Rx7 by MAPerformance? It's amazing.
I think 8an is a good size to do.

 

[jpmxrider489]

I never seen it but you have a link? ( on my phone).

What's the biggest I can tap? 8 is probaly the limit? What size fitting then?

 

[99gst_racer]

I personally like -10, but -8 would be a size improvement over stock.

So, what made you want to go with vented catch can?

 

[jpmxrider489]

I personally like -10, but -8 would be a size improvement over stock.

So, what made you want to go with vented catch can?

Its cheaper and my intake pipe doesnt have ports. Its just a preference for me.

Like I said, I have a bunch of -8 hose. So what would be the biggest you think I can tap would be? 10 is probably way to big to tap.

 

[Gamble97]

I would never do a vented catch can. Ever.

 

[jpmxrider489]

Maybe in the future I can tap the can for a vacumme source. But as far as the biggest tap for the valve cover?

I noticed in the other thread that he tapped the breather port for a 1/4 to 8an and the pvc port 1/8 to 6an. How well do you think it would work if I did 1/4 to 8 an on both as far as tapping and performance?

So I went to look for a 1/4 npt tap but it looks pretty big. Would a 1/4 make the walls to thin? Whats the best solution as far as a tap size. Im hoping to order my fittings ans stuff tonight or tomorow so Ill have them for the weekend.

99gst_racer PM sent.

 

[jpmxrider489]

I just got done doing mine without welding. I used a 9/16 drill bit and a 3/8 npt tap. Then used a -8 to 3/8 npt fitting. With that drill bit your getting real close to the top of the VC so you have to real careful. The other thing is I couldnt get the fittings to screw all the way in, which it still seals fine but doesnt look as good. I put some JB weld around the fittings to make it look a little better. I can post some pics up tomorrow when I get home.

If 3/8 is bigger than 1/4, how did you get the fitting in there. Some people said even 1/4 is pushing it. -8 is equeal to 8/16 which is 1/2. Anyway that would fit .?

 

[Manik511]

I just got done doing mine without welding. I used a 9/16 drill bit and a 3/8 npt tap. Then used a -8 to 3/8 npt fitting. With that drill bit your getting real close to the top of the VC so you have to real careful. The other thing is I couldnt get the fittings to screw all the way in, which it still seals fine but doesnt look as good. I put some JB weld around the fittings to make it look a little better. I can post some pics up tomorrow when I get home.

Did you tap right where the breather and pcv was? I'm about to do mine and originally was going to use 1/2 npt to 10an but finding out that's a lil big to do it on the sides of the valve cover. I looked at your pics and looks like you did it in the stock locations