Venting to atmosphere on Paxton

[o2sys]

On a Paxton A2A intercooler setup, why can't you vent to atmosphere on the draw thru setup that it comes with originally?

It has a dual bypass setup one right before the throttle body and one before the compressor.

They both recirculate back to the intake which are post MAF so it's venting back into the system that's unmetered isn't it?

I ask because I really don't like the location of bpv and find all the hose routing a bit of a mess.

I will eventually go blow thru but it will have to wait for now.

 

[Towelie]

Anything after the maf is metered air. If it is redirected to after the maf then the total air consumed across the maf will still reflect correctly. Now venting metered air to atmosphere is a bad thing. The computer will think the engine is consuming much more air than actual and add fuel to compensate.

 

[hockeygod]

On a Paxton A2A intercooler setup, why can't you vent to atmosphere on the draw thru setup that it comes with originally?

It has a dual bypass setup one right before the throttle body and one before the compressor.

They both recirculate back to the intake which are post MAF so it's venting back into the system that's unmetered isn't it?

I ask because I really don't like the location of bpv and find all the hose routing a bit of a mess.

I will eventually go blow thru but it will have to wait for now.

The cars computer can't compensate for the unmetered air and will stall right out. Before I switched to know through I once popped an intercooled hose on mine and it would not start or run due to the unmetered air.

 

[o2sys]

Ok so it's still metered air, I thought since air was being recirculated after the MAF the ecu wouldn't know but I see how it can affect it since it's a closed loop system.

Can't wait to go blow thru. Just really don't like how everything is jammed under the blower with the dual bypasses and their 1" hoses.

 

[hockeygod]

Ok so it's still metered air, I thought since air was being recirculated after the MAF the ecu wouldn't know but I see how it can affect it since it's a closed loop system.

Can't wait to go blow thru. Just really don't like how everything is jammed under the blower with the dual bypasses and their 1" hoses.

Be prepares for the noise increase depending on what bov you go with. I have the tial Q bov and the steady noise of it venting air is a definite sound increase.

 

[o2sys]

Yea I don't want that air venting noise the bpv makes when you vent to atmosphere. But seen guys here who put carb filter over to reduce the noise.

 

[TheKurgan]

Yea I don't want that air venting noise the bpv makes when you vent to atmosphere. But seen guys here who put carb filter over to reduce the noise.

I've thought about doing that but I think it would reduce your air volume and therefore cause some blow back. What's the point of getting a large volume BOV only to reduce it with a filter ? I tried putting some washers in my Tial to up the spring rate, but I noticed quite a bit of difference in the air trying to blow back into the supercharger and reverse the gears. Not a good thing.

 

[o2sys]

Well the carb filter is not a particle catcher like an air filter and more line a thin gauze of sponge so restrictions didn't seem like a problem.

Of course nothing is better for sure.

 

[Postman]

I run the Vortech mini Race valve on my blow thru set up with no air filter and the noise is minimal. From my experience the bigger the valve the less the noise because you don't have all that air trying to get out a little hole. Then again I run twin turbos so maybe thats you there isn't a bunch of noise.

 

[TexasBlownV8]

+1 on just do a blow-through setup, and it'll get the maf issue taken care of.
The sound of blow-off is not really annoying, IMO; with loud enough supercharger whine or exhaust, you won't hear it at all! I hear it with the twin turbos, but it's like a semi-quiet fart...pshhhhhhh

 

[o2sys]

Yes but for now it will be draw thru.

I do have a Forge Performance bypass valve which I would like to replace the stock dual bypass to a single bypass. Would this work?

 

[MassMustang]

Just to resurrect an old thread on the topic, I finally have my Novi 2200 set up installed with the blow through using a TurboSmart Kompact. I still need to get a MA inspection sticker and a proper Dyno tune. Right now, at lower RPMs with minimal acceleration the BOV is releasing pressure but fluttering. I'm nervous to tighten or loosen the spring setting for fear of triggering a CEL.

Anyone else get the fluttering while just cruising?

 

[Postman]

It will not trigger a CEL. IMO the spring should be loosened until the valve is discharging air at idle. This will give you the cleanest MAF signal at idle.

 

[MassMustang]

It will not trigger a CEL. IMO the spring should be loosened until the valve is discharging air at idle. This will give you the cleanest MAF signal at idle.

So, optimally it would be to let it stay wide open at low RPMs and have it close only under high boost?

 

[Postman]

So, optimally it would be to let it stay wide open at low RPMs and have it close only under high boost?

Correct. The valve should be placed between the blower and the inter-cooler. (The MAF should be between the inter-cooler and the throttle body) The blow off valve should be wide open and venting as much air as possible. That way hot air coming out of the blower will not preheat the inter-cooler.

Venting the maximum amount of air also helps keep the MAF in a vacuum scenario. A vacuum scenario in most cases will yield the best case of steady MAF voltage. While your idling and cruzing your blow off valve is dumping hot air. Your MAF count is very steady. Once you hit the gas the spring in the blow off valve will slam the valve shut and now the vacuum line that once held the valve open now has boost helping the spring to keep the valve closed.

Else where in the forum Khall has a YSI-B supercharger pulled for 23lb of boost with cams and sheet metal intake yet his MAF counts only fluctuate from 149 to 152 at idle. 3pt signal idles very smooth compared to when he had a draw thru setup that would bounce up to 50pts.

 

[MassMustang]

OK, so the fluttering/chattering/rattling continues even with the softer spring in the 25mm Kompact dual port. TurboSmart is sending an even softer spring to see how that goes, but I believe the fluttering noise is coming from the air intake, not the BOV.

Anyone else running a centri blower with a blow-thru setup and dealing with (or resolved) the fluttering noise? It only happens when just cruising and keeping the RPMs roughly around 2500-3000.

 

[hockeygod]

Sounds like compressor surge due to the Bov. The softest spring possible which I believe is around 2psi should help.

 

[MassMustang]

The TurboSmart Kompact 25mm comes with a "pink" spring rated at -24 InHg to -14 InHg. I tried the "green" spring so far which is -19 InHg to -9 InHg and it helped a bit. They're sending me a "blue" spring which is rated -13 InHg to -3 InHg.

I'm hoping that does the trick. Otherwise I'm looking for a different BOV.

 

[MassMustang]

Doe the location of the BOV on the down pipe between the head unit and the intercooler matter? I'm using the OE location from Vortech/Paxton where the return connects but I see plenty of people mounting the larger BOVs down closer to the intercooler.

 

[o2sys]

It doesn't matter but its preferable to be closer to the compressor as possible. The stock vortech/Paxton location is good but people who go with bigger BOVs can't fit it there so do it right before it enters the IC.