imDementeD

iTrader: (7)

im trying to learn as much as possible about running na-t.
now i want to just use an SAFC since my power goals are low.
i also want to keep the stock MAF.
Now we all know about the stalling issues while running and Na-t and usually the fix is either to have the BOV recirculated.

now this is what i dont understand..why would you even run a bov if your just going to recirculate it?..

i have tried searching this on club na-t/supra forums but its really hard to search with such common words being used so i get a 1000 threads that have absolutely nothing to do with this question

so any knowledgeable people here want to chime in
(this question was asked by me on clubna-t in a thread but the forum is practically dead so im being impatient for an answer)

romycha1

iTrader: (3)

Because the MAF has already compensated the fuel for the air that the BOV vents.... If it vents into the atmosphere, your engine will run rich since it's spitting more fuel in. If you recirculate the air, it will eventually use it.

imDementeD

iTrader: (7)

yea i understand that..but wouldnt it just be best to not run a BOV..i dont understand how it will relieve pressure if it just circulates it back into the piping? am i missing something here??



also i know theres mixed opinions on this..but cant you just run without a bov and have no issues using stock maf? or has anyone tried this?

Kira X

iTrader: (24)

I'd run the blow off valve just for the sound alone as stupid as that may seem.

BartleDoo

iTrader: (1)

The pressurized air is recirculated into the low pressure piping (where the turbo sucks in air). Technically speaking, if you recirculate then it is a bypass/diverter valve. You need this or your turbo will be destroyed by reverse pressure waves when you lift throttle. If you need more info on boosting, just google it and you will find more than you could ever need.

good2go

iTrader: (6)

A blow off valve prevents compressor surge, you MUST have it or bad things WILL happen. Usually they just vent to the atmosphere, but you could also recirulate it back into the intake IN FRONT of the compressor. I think you're mistake is assuming it would just recirc back into the compressed side of the intake, ie. AFTER the compressor.

here's a quick read for you:

http://en.wikipedia.org/wiki/Blowoff_valve

eliteskill

iTrader: (8)

Most serious ppl put it on for function. The sound is a bonus. However it's annoying sometimes too so mines recirculated so it's not so loud. I only hear it on cold mornings/nights.

imDementeD

iTrader: (7)

i understand how turbo works..i did a LOT of reading on not running a bov and what i found was no hard evidence that compressor surge actually destroying anything
a thousand people say no bov will work without any damage another thousand say it will
but no evidence to support either case other then joe somebody saying hes been boosting 20psi for 3 years and the turbo is still fine without a bov.


but good2go you're right i did assume it would go back into the compressor side which is what i didnt understand the point thanks for clearing that part up for me

T4-Teg

iTrader: (2)

Compressor surge will not damage anything when boost levels are lower than ~10psi on small turbos. Look at all the production turbo cars in the 80's - 90's that dont even have BOV/Bypass valves from the factory. Those turbos and engines have been proven to last well past 100k miles.

Now if your slapping a 60+MM turbo onto your SC, then YES you need a BOV/bypass valve, even only running 10psi. 10psi from a large turbo is much more boost than 10psi from a tiny turbo that comes stock on cars.

TheRonTom3

iTrader: (5)

Compressor surge has been a hard fought topic in the last few years. Many people say its the worst thing in the world for a turbo and will destroy it in no time. Others beleive that it is a good way to have better response.

I personally think from the research i did on it while I had my 240 that yeah on cheap china turbos it will eat them up, but on a high quality name brand set up it shouldnt significantly shorten the units life. It definitely will shorten the life of the unit but you'll easily get a few years out of it before you need a rebuild and most built cars need other things rebuilt in that time frame anyway

BartleDoo

iTrader: (1)

What cars don't use bypass valves?

Where is this information from?

And who NA-T's with a tiny turbo?

BartleDoo

iTrader: (1)

How does it increase response? Under acceleration the turbine is spinning one direction. When you close the throttle plate, the air being sent from the turbo to the intake manifold hits that throttle plate. Then, it travels the opposite direction and hits the compressor wheel causing the rotation speed to be rapidly decreased. You have exhaust gases spinning the turbo shaft one way, and pressurized air trying to spin it the other way. That doesn't seem like it would increase response to me.

LexusFTW

iTrader: (7)

Buick GNs don't have bypass valves.

good2go

iTrader: (6)

Agreed... and I should think that pretty makes not running a BOV a moot point then.

imDementeD

iTrader: (7)

i dont have a tiny turbo but its not huge by any means and only plan to run 9psi for quite a while..

one other thing to through in the mix..with an auto car the bov isn't needed between shifts correct? since the throttle is still open.

i do understand that it should in theory harm a turbo..but has anyone or company really put it to the test to see what kind of damage it will do and over a period of time how much time it'll take off the life of it? and what is a life expectancy of a turbo anyway??