Give your head a shake. When the valve is closed it is closed. Where the air goes when it is open is irrelevant. You are not recirculating any air with the valve closed. Unless it leaks.......

 

You said this previously: "got tired of waiting on Sniper to fix the file. so we cranked the idle set screw up and it doesnt die anymore. with the new MAF sensor is picked up 25rwhp on a mustang dyno through 2nd gear with adding 4 timing and taking half a point of fuel out in mid and full throttle. also to fix the idle surge he increased the Pre pot table that pre positions the IAC open when it see's the TPS drop below a certain voltage. but total gains with the retune and new MAF was 35-40rwhp through 2nd gear on a mustang dyno, through a 3200stall."

To attribute 45 hp to a maf and bov doesn't make much sense. You added 4* and tuned the maf, that'll do it.

A bypass or bov won't make hp.

 

heat soaking the head unit is the main concern.

 

yeah sadly sniper has not and will not put forth and effort to fix compatibility issues with their software. recently i took the sniper files off my car and took my car in to get the latest calibration and the sniper files had corrupted my PCM severely and the dealer was not able to re calibrated my PCM even with all of the sniper files pulled off and it returned to stock. so that cost me 751 dollars for a new PCM.

 

How much hot air do you think goes back into the head unit when the valve opens. You do know that when compressed air is released it looses heat.

 

Im not exactly sure how hot the air is that is released, but was enough air to cause a pretty bad idle surge before I had my truck dyno tuned. Even at that, it will do it from time to time, because all that air is unmetered that it releases. Maybe my bypass sticks or something, and thats why mine was acting up. I dont know for sure though.

 

You are confused with what Faster and I are discussing. His argument is that a blow off valve, vented to atmosphere, gave him 45 hp over stock because in the case of a bypass valve, returning metered air back to the supercharger, heated up the air to the point that it heat soaked the supercharger.

In your case a properly functioning bypass valve will not cause an idle surge. By properly functioning I include one that is properly sized to your application.

 

I agree with JMC that the bypassing the air isn't a huge issue with heat. Though I won't argue that blow through is probably a little better.

When i'm driving my truck, the majority of time is spent in vacuum. Then there are those occasional times where I wanna have some fun and get into the boost. I don't boost it stoplight to stoplight every chance I get.

In a vacuum state, uncompressed air is circulated from the blower outlet, through the intercooler, into the throttle body of the motor, and proportionally through the open bypass valve back into the blower inlet. This is uncompressed/intercooled air that is being recirculated into the blower the majority of the time.

Getting into the boost, compressed/intercooled air gets rammed down the throttle body with none being recirculated since the bypass valve is closed. Whatever residual pressure that is left in the pipes when I let off the throttle is then recirculated into the blower inlet.

Yes that residual pressure contained some heat, and was redirected into the blower. But at the proportion of my driving that is done in vacuum vs. boost, I think the amount of heat accumulated is not a huge issue. Especially since I have relocated the IAT sensor from the blower inlet (near the bypass hose discharge) to directly in front of the throttle body (as well as tuned for this). Now the truck doesn't pull timing and power as much everytime the bypass valve vents off boost.

 

Oh, I understand exactly what you are saying. That does seem like alot of hp by just not recirculating the air. Is there enough of an advantage having the bypass vented to atmosphere to justify doing it? I was simply stating that the amount of air that is being recirculated was causing an idle surge on my truck. I have the bypass valve that ATI supplies with the 9psi kit. I only had the issue of idle surge when I was slowing down quickly after making boost. My tuner told me that once my engine returned to vacuum that it began to recirculate the air and that my engine wasnt able to guess the amount of air actually entering the intake. Thats why I upgraded to a larger MAF and he tuned most of it out to where it no longer has that issue. I know that has nothing to do with heat soaking the head unit, but I didnt fully understand what you guys were saying I think.

 

My MAF is a 90 mm set up as a draw through and I have the Procharger bypass valve and fortunately none of the problems that you describe.

With a bypass valve set up to recirculate the air is already measured and because the MAF doesn't re measure it it has to be re introduced into the system. It is directed to just in front of the compressor but after the MAF.

With it set up as a blow through the MAF measures the air flow after it is compressed and adjusts accordingly. There is no need to recirculate the air after the valve because the MAF will measure the new flow with the valve open.

 

It's been a while, I know, but I finally finished this mod. I went with a Vortech Maxflow bypass valve. It has a 1.25" inlet and 1.75" outlet along with an O-ring seal at its piston/plunger. What that means is it will actually seal off 100% under boost like a bypass valve should, unlike the Procharger Pro-flo bypass which does not seal off all the way. I calibrated the Maxflow bypass with a hand held vacuum pump, and verified that it would open at the same 4" of vacuum as the Pro-flo valve. Using the secondary fitting on the pump to simulate boost, I noticed that the Maxflow's O-ringed plunger will seal off even harder under positive pressure...an added bonus.

With the Vortech bypass installed the Procharger kit now performs as it should. I can get the boost gauge to snap to 5 psi and hold under part throttle runs now where before I could only hold about 3 psi. Overall it seems a lot more responsive to what the blower is doing compared to the sluggish and leaky Procharger valve.

To start off, here's the type of boost leak you are dealing with with the Pro-flo valve



Here's what I purchased to adapt the Vortech unit to the stock Procharger plumbing.
- Vortech Maxflow bypass valve
- 90 degree HPS silicone reducer, 1.5" to 1.75" to adapt Vortech outlet to Procharger surge hose (trim to fit)
- Vibrant 1.5" aluminum joiner (connect surge hose to silicone 90 reducer)
- Not shown: steel flange for bypass valve and silicone-friendly hose clamps


I had the steel flange TIG welded from the inside to the existing nipple that the Procharger bypass used to clamp to


I then had the discharge pipe stripped and re-powdercoated in "chrome" for a close match


Pretty seamless



Finished setup

 

How much did that run you?

 

Summit price matched Superchargersonline.com for the Maxflow @ $224

HPS silicone reducer - $28

Vibrant aluminum joiner - $7.28

Vibrant embossed hose clamps - $7

Total minus shipping, welding, and powder = $ 266.28

I would have loved to go with the Procharger big red race bypass, but it's like over $400 just for the valve alone, and is most likely overkill for my mild setup.