vashthe3rd

On a GT with a 62 mm Hellion system, is it better to have the bypass valve, e.g. blow thru system, that comes with the system, or a BOV. I know a blow thru is better for low boost applications where a turbo is factory stock. Some say that a BOV is better for NA engines gone F.I. Some say it doesn't matter. Anyone got some first or second hand experience?
Would it even matter? Or just be a matter of preference? Personally I'd like to have a little BOV noise.

mygt500

Same here if I had a turbo....I would want others to know I do esp when I shift or decel....that BOV sound is sweet!. Welcome to the forum and IMO it doesn't matter....its personal preference!!!!

vashthe3rd

Thanks gt500
I'll ask my tuner and see what he thinks, if it's up in the air, I'll probably just change it up to hit the air and close off the inlet hole on the intake before the turbo. a bypass valve would still work the same as a BOV if I just dumped the boost to the atmosphere right?

RainsFather

it does matter. it depends on the placement of the air sensor on the setup. if the mass air sensor is before the turbo then you really want a bypass valve ( or recirculation valve ). the bypass valve should be after the turbo and recirculate the forced air back before the turbo but not before mass air sensor. the reason for this is your air sensor has already metered the air. if you use a blowoff valve then you can cause an overly rich condition which can cause two problems; you will lose off throttle response which is the purpose of using a valve in the first place, and the overly rich condition can cause your headers to become extremely hot and fail ( as in melt the welds, fun to watch not fun to experience ). now if your mass air sensor is between the turbo and the throttle body then it is personal preference as long as the valve is before the air sensor. there are some blowoff valves that you can do a 50% recirculation which will help from causing a rich condition when going off throttle. as far as sound, you can hear a bypass valve almost as much as a open atmosphere blowoff valve, it just depends on the type of valve. personal preference for me is the hks super sequential, no matter if you have it recirculate or not it is loud and has a very unique sound.

also just so you know, blowthru normally refers to where the air metering happens. as in blow thru and draw thru. most of the turbo and supercharger kits I have seen for our cars are draw thru with the exception of the STS kit since it would be a pain in the *** to run extension wires for the air meter from the front of the car to the rear bumper.

mygt500

I stand corrected and maybe I will leave this to the Turbo guys! I have basic understanding of it and thought you could incorporate either just as long as other conditions are met to make the car work properly and run at it best.

vashthe3rd

thanks Rains, I am now more educated
Yea, the MAF is before the turbo and the bypass recirculates after the MAF but before the turbo, as per the regular hellion kit.
If the overly rich condition is a danger, do you tink the turboXS BOV that Hellion offers is one of those partial bypass valves?

Lito

Do you want this?

https://mustangforums.com/forum/4-6l...blow-thru.html

vashthe3rd

Essentially, just a way to get the release to the atmosphere sound. I wouldn't like to do it if it required all that extra work. The sound would be nice, but if it sacrificed performance, I'd just stick with the regular set up.
Admittedly I feel a little ricey trying to get the sound, but it's a matter of recognition for me. Really want to make it known that it's not a regular GT, or even a regular modded GT, it's a turbo, which you don't see everyday.

Lito

Stay as you are then, a new MAF sensor, flange and some welding work plus a new tune is needed.

retfr8flyr

Draw through systems are harder to tune correctly than the blow through style. I think Hellion now offers a conversion kit for a blow through style but I'm not sure. If you stay with the draw through I would recommend relocation your IAT sensor to the manifold or intake piping just before the throttle body. The IAT is currently located in the MAF sensor so you are reading the temp of the intake air not the temp of the air entering the engine after boost. This is one of the reasons the draw through setup is hard to tune.

Earl