Help trying to pick out a good price/performance bypass/BOV

[Power Surge]

yes, your right, blowing metered air isnt good, might as well have a massive vacuum leak.
.

Same basic idea, but the effect is the opposite. By venting off metered air, the motor will be overly rich because the MAF has already read that incoming air and then commanded the fuel to match it.

 

[Bringetto]

right, i just used a vac leak because it too is unmetered air not seen by the maf when venting metered air is air that the maf saw didnt make it to the motor.

 

[Power Surge]

right, i just used a vac leak because it too is unmetered air not seen by the maf when venting metered air is air that the maf saw didnt make it to the motor.

Yep, right on the money. A vaccum leak will cause the car to run lean, since it's air not seen by the MAF.

 

[adidas_kn]

I will be going with a draw through setup I believe. Unless I can figure out a good place to put The 90mm MAF in the cold side piping. I didn't want to have to deal with going from a 2.5" cold pipe to a 4" MAF then back down to a 2.5" cold pipe. not much room for those transitions. Do they even make a 2.5" to 4" silicone transition coupler? I would think it would be allot easier and propper to put the Bypass valve on the cold side up pipe in the engine bay and feed it directly back into the turbo inlet. Too bad the Tweecer wont support switching from a MAF setup to a MAP setup. Get rid of the whole MAF and use a GM based 3 bar MAP sensor like on my buddies boosted Accord.

 

[TT SHO PROJECT]

Then do us a favor... keep your schooling and your knowledge to yourself. If you want to goober up your own backyard project go ahead, but please don't don't give advice to people who want to learn the right way to do things.

dude get a life man... try to learn something ok? i dont missinform ppl... i just know what works and what has been proven by years and years of use... talk to tool man if i recal he vents his and his maf is before the turbo... tool man knows his stuff... dont talk smack just cuz yer jellus... theres no point to this convo.. i didnt run a speed shop cuz i didnt know what i was talking about... i ran one cuz i knew exactly what i was talking about. and yes my cars a "back yard project" thats cuz i am not gonna pay someone to do the work for me... i like to do everything my self.. theres more pride in doing the job your self and doing it right than to have someone else do it and mess something up and get stuck with a huge bill.

 

[TT SHO PROJECT]

lets see here im refering to turboed cars NOT blown cars... huge diffrence there... u cant vent mettered air on a blown car cuz the blowers still pushing air where as the turbo is Not. i too have onwed and ran a blown car before.... i tried to vent... big mistake pig rich ran like a$$... but on a turboed car its ok to do.

Sorry, but I have to agree, venting metered air to atmosphere is not the correct way to do it. If the car is tuned properly, there will be no issue of melting pistons. I seem to recall that when it goes pig rich like that the computer quits learning KAM values and the extra fuel will destory the catalytic converters, neither of which is a good thing.

I've had the blower installed on my car for 2 years with 10 psi of boost and a pretty good tune. With over 15k hard driven miles, it still running like a top.

 

[Bringetto]

I will be going with a draw through setup I believe. Unless I can figure out a good place to put The 90mm MAF in the cold side piping. I didn't want to have to deal with going from a 2.5" cold pipe to a 4" MAF then back down to a 2.5" cold pipe. not much room for those transitions. Do they even make a 2.5" to 4" silicone transition coupler? I would think it would be allot easier and propper to put the Bypass valve on the cold side up pipe in the engine bay and feed it directly back into the turbo inlet. Too bad the Tweecer wont support switching from a MAF setup to a MAP setup. Get rid of the whole MAF and use a GM based 3 bar MAP sensor like on my buddies boosted Accord.

im working on it, trying to figure a way to make a map sensor work on a sho.. not for f/i, but for ITB's

Something like this

http://www.directignition.com/graphics/gallery/72dino.jpg

 

[TT SHO PROJECT]

yes, your right, blowing metered air isnt good, might as well have a massive vacuum leak.

In my future plans of a turbo setup the bov on the pressure side before the maf .

running the maf post turbo is good to do But you also run into tuneing problems... maf's dont like the rush of air being pushed threw them... there are Blow threw maf's but pro M nolonger makes them. when running the maf after the turbo or blower or what ever u may have the mafs signal is not a clean signal. thats why haveing the maf before the turbo or blower works much better for tuneing and reliability.

 

[TT SHO PROJECT]

I will be going with a draw through setup I believe. Unless I can figure out a good place to put The 90mm MAF in the cold side piping. I didn't want to have to deal with going from a 2.5" cold pipe to a 4" MAF then back down to a 2.5" cold pipe. not much room for those transitions. Do they even make a 2.5" to 4" silicone transition coupler? I would think it would be allot easier and propper to put the Bypass valve on the cold side up pipe in the engine bay and feed it directly back into the turbo inlet. Too bad the Tweecer wont support switching from a MAF setup to a MAP setup. Get rid of the whole MAF and use a GM based 3 bar MAP sensor like on my buddies boosted Accord.

Now you have the right idea! there are things that let you run a gm map inplace of teh ford maf...(i forget what its called) this is the best way to run with a turbo... screw the maf lol.... if i had a lil extra cash to burn id go that rout ditching the maf all together.

 

[TT SHO PROJECT]

im working on it, trying to figure a way to make a map sensor work on a sho.. not for f/i, but for ITB's

fyi there is a product out there that lets you do this exact same thing without running a stand alone.

 

[Bringetto]

well, dont keep it to yourself, please do tell

 

[Power Surge]

running the maf post turbo is good to do But you also run into tuneing problems... maf's dont like the rush of air being pushed threw them... there are Blow threw maf's but pro M nolonger makes them. when running the maf after the turbo or blower or what ever u may have the mafs signal is not a clean signal. thats why haveing the maf before the turbo or blower works much better for tuneing and reliability.

Dude, please get a clue, you have NO idea what you are talking about, regardless of whether you think you do or not.

I will be going with a draw through setup I believe. Unless I can figure out a good place to put The 90mm MAF in the cold side piping. I didn't want to have to deal with going from a 2.5" cold pipe to a 4" MAF then back down to a 2.5" cold pipe. not much room for those transitions. Do they even make a 2.5" to 4" silicone transition coupler? I would think it would be allot easier and propper to put the Bypass valve on the cold side up pipe in the engine bay and feed it directly back into the turbo inlet.

Blow through MAF setups are the desired method for both blower and turbo cars. Naturally, it's dependant on packaging, proper setup, and your tuner knowing what he's doing. The other nice thing, is that when a MAF is under pressure, it doesn't have to be as large as if you are trying to draw through it. So if you run your MAF blow through, you don't need a 90mm housing.

If I were building your car, I would use an 80mm Lightning MAF, with smooth transisions on both sides. Then, use an extender on it (like a MAFia) to get the needed voltage range for your power level. The nice thing about the MAFia is it has 7 settings, so you can readjust it as you add more power to the car and don't need another MAF. Then simply run a blowoff between the turbo and the MAF and vent to atmosphere.

This is how I'll be doing the turbo setup on my SHO when the time comes.

 

[twr]

I deleted my response... this thread is getting way off topic, no reason to keep it going like this.

By to the topic.

If you are going to do a draw through MAF setup, my opinion would be, get the largest bypass valve you can get. It is also my opinion and experience that a draw through MAF is easier to tune. Although my car runs good using the MAF in a blow through configuration, my A/F ratio is not repeatable. I'm guessing you are going with a tweeker, so as long as you have the transfer function for your MAF, use what ever MAF you want.

 

[yamahaSHO]

im doing this by the book.... if you have the maf before the turbo and vent.... u vent mettered air inbetween shifts this also hepls to cool down the pistons... this IS the right way.... im not here to fight over stupid **** i know my stuff been doing this my whole life... if you want hot pistons and melted parts fine you do it your way.. i didnt goto school for this for Nothing!

If you're venting metered air, you are verly likely to run rich, which *could* give you cooler pistons (not likley off throttle), but at the same time wash oil off of the cylinder walls, and **** your cats (if you run them). This is definitely NOT the right way of doing things and wouldn't be considered text book. A good tune will give you "cool" pistons and venting metered air is not under the consideration of a good tune. When you let off the throttle, the mixture SHOULD be leaning out to the point that it shuts off the injectors. With the injectors shutting off as they should, you won't get any cooler than that with the car constantly running.

You car stalls because it is rich when you BOV vents boost that has been metered. Generally, in this situation, since you're running relatively low boost, your tuning is off because it shouldn't stall. Both Terry and I vented metered air with our SC's so much that the EEC crashed, but the car never stopped running. IIRC, Tim is venting metered air without stalling.

Yep, right on the money. A vaccum leak will cause the car to run lean, since it's air not seen by the MAF.

Under boost, a vacuum leak is no longer a vacuum leak (when boost is present), it is now a boost leak and can cause the car to run rich because it vents metered air.

lets see here im refering to turboed cars NOT blown cars... huge diffrence there... u cant vent mettered air on a blown car cuz the blowers still pushing air where as the turbo is Not. i too have onwed and ran a blown car before.... i tried to vent... big mistake pig rich ran like a$$... but on a turboed car its ok to do.

I agree that the SC still keeps pushing air through when the engine spinning, however, if properly recirculated, it can be done. Although much harder than a turbo because of the amount of constant air....


I will have to agree with Terry. If you want a draw through MAF, get a large BOV and recirculate it. A draw through is MUCH easier to tune as Terry stated. If he comes up with a good way to move the TB into the fender, I may go that route too. Just like Terry, my AFR's were not repeatable. I would let Chris take the car out and he would come back and say your tune is off, I hit 14 or 15:1 at WOT, but when we drove it next, it was 11:1.

 

[TT SHO PROJECT]

If you're venting metered air, you are verly likely to run rich, which *could* give you cooler pistons (not likley off throttle), but at the same time wash oil off of the cylinder walls, and **** your cats (if you run them). This is definitely NOT the right way of doing things and wouldn't be considered text book. A good tune will give you "cool" pistons and venting metered air is not under the consideration of a good tune. When you let off the throttle, the mixture SHOULD be leaning out to the point that it shuts off the injectors. With the injectors shutting off as they should, you won't get any cooler than that with the car constantly running.

You car stalls because it is rich when you BOV vents boost that has been metered. Generally, in this situation, since you're running relatively low boost, your tuning is off because it shouldn't stall. Both Terry and I vented metered air with our SC's so much that the EEC crashed, but the car never stopped running. IIRC, Tim is venting metered air without stalling.



Under boost, a vacuum leak is no longer a vacuum leak (when boost is present), it is now a boost leak and can cause the car to run rich because it vents metered air.



I agree that the SC still keeps pushing air through when the engine spinning, however, if properly recirculated, it can be done. Although much harder than a turbo because of the amount of constant air....

i know that if you recirculate the air instead of venting it should work much better but then u dont get the cool sound but yeah wheni said my car stalls thats cuz i launch under full boost if i have to stop real fast and the motors only at 2500rpm when i vent that full boost be it 8psi or 10psi thats just too much venting at such a low rpm for the car to recover..

 

[adidas_kn]

Okay then I wil go ahaead and buy the Godzilla BOV/Bypass valve. I thought it would be too big but maybe not. I def want the draw through setup due to ease of install and less crazy transitions. I like the whole 4" turbo inlet to a silicone adapter, to a 4"id 6" long pipe with a fitting for the BOV to vent into, to a 4" 90 degree silicone bend to the 90mm MAF then to the filter. Pretty straight forward.

Well there it is. Big as h3ll. Looks nice though.

 

[Toolman]

If you plan to put your MAF on the inlet side of the turbo, then you need a bypass valve that recirculates the bypassed air back into the airstream. This is because the MAF has already registered that air and added fuel to compensate for it. If you don't put that air back into the airstream, the car will run like crap.

So the theory goes. In reality, the original turbo SHO, driven from east coast to west coast and all points between, day in and day out, and making 400whp in a seconds notice, ran with a vented to atmosphere BOV (AND an FMU which made things even worse). No problems.

If you put your MAF in the turbo ducting as a blow-through setup, and then put the bypass/blowoff between the turbo and the MAF (i.e. before the MAF), then you can use a blowoff and vent to atmosphere because the MAF hasn't read that air yet.

Make sure get the right valve for what you need. A bypass and a blowoff DO the same thing, by a blowoff valve won't have a provision to attach a hose if you need to bypass the air.

Also, a lot of BOV's come with attachements that allow them to work as a bypass. My TiAl 50mm does not, but that is okay with me.

 

[adidas_kn]

I ordered the Turbonetics Godzilla BOV/Bypass valve. I also ordered a1' section of 4" SS pipe that a return can be welded to. This will be on the inlet of the Turbo. I also bought all the T-Bolt clamps and silicone connectors I will need. I will end up mocking up my intercooler piping using the 2.5" mandrel steel pipes and straight sections I have in my tool closet. After they are welded I will have them powder coated for looks and protection.