RX7_warrior

Hi ppl I need your help, I was fiting my greedy airnix intake (stock twin turbo setup) and for some reason I had to shorten the pipe that was going to the ABV...Well suprice suprice i found a metal item looking like a restrictor.

Bad news i have slightly cut part of it.

Is it suppose to be there a restrictor ?

RX7_warrior

Bump any help guys ?

I need to know if the pipe connecting ypipe with ABV has any restriction inside ? I try to upload a pic but something goes wrong ...

billyboy

There's no restrictor for the air bypass valve aka BOV.

Only bits of metal are the nipple at the Y pipe, probably 15mm long and at either end of the valve itself. If you can't manage to attach a pic, photobucket or similar?

RX7_warrior

I have uploaded the pictures here :

http://i1149.photobucket.com/albums/...psqhqmzwbe.jpg

I have asked a lot of friends if they had such thing inside the hose connecting y pipe to ABV and everyone said no. I also searched the documention of MAZDA but they dont have anything related.

So my suspicion is that the previous owner from Japan placed that metal thing there but i cannot answer the why?

As far as I can understand the subject placing a restriction at that place increases the pressure that the BOV holds, but this does not affect the functioning of the BOV since it vents boost once we let off the gas with vaccum applied on the small niple on top of the BOV by the Intake Extension Manifold.

So what is the point of creating more pressure within the ypipe ...wouldn't that lead to surge if too much air is given to the turbo's, what would have happened if I had a full exchaust ????

Please correct me if I am wrong I am just speaking out loud my thoughts

billyboy

Can't see a hole at all, so not even a restrictor - unless microscopic. Have you tested the valve?

Some people do run with the whole line removed and capped at the Y pipe. If you want to read more, there should be "no bov" threads here and elsewhere, search Rice Racing as author I'd suggest!

The spring does tend to get lazy over time on these from the heat, so they don't hold pressure as well after a few years. I haven't seen the diaphragm leak on one, but the nearby charge control in particular does perforate, maybe that's the case with yours...and they've done that for registration purposes...which can prove to be a stumbling block in Japan for non-stock cars.

cr-rex

iTrader: (114)

definitely odd. i cant think of any reason a person would do that. its not supposed to be there. go ahead and reconnect the bov without that installed if you have any of that stock rubber hose left after cutting that part off.

RX7_warrior

BillyBoy you are correct there is no hole at all so we shouldn't be calling it a restrictor. However, when switching gears the car was making the whoosh sound so the bov was venting air to atmosphere. This means that the air from the ypipe found a way to bypass that metal thing. For definitely not all the air within the ypipe vented out.

I have read RICE RACING opinion for no BOV but i don't agree to apply that logic on a non race car.

Before two months i have posted the following thread : https://www.rx7club.com/3rd-generati...oblem-1104128/

At that time with everything fixed on the car I couldn't understand why during turbo's transition I has hearing one of the turbo's fluttering. Now if i put all the pieces together, it make sense. Once i have fixed my boost problems the air pressure within the turbos was higher than expected (more than the turbo map (primary turbo)) because during gear transition instead of venting out the boost my car was keeping the pressure within.

Therefore during turbo transition the primary turbo had actually more pressurised air than necessary (7psi if I remember correct needed for opening the port to the 2 turbo), so during transition of turbos (actually few moments before opening the gate for the second turbo to engage) I was hearing the primary turbo fluttering aka surging.

I am going to run the car today to verify the above theory. But I truly believe that running the car with out BOV affects the lifetime of your turbo's and in our case with the rotary engines a broken turbo may as well end up destroying your engine.

billyboy

You might be hearing something other than the bov if the blockage was upstream of it....pretty much impossible to function as it is.

I'd describe the noise as a bit of a chirp, chirp when they're not fitted....the fully sik crowd over here often delete them, usually in SR20 powered nissans - trying for female attention....maybe! The charge relief valve is the other thing you might be hearing, it will make a steady drone without the airbox when running mostly on the primary, when the car is boosting on both, then back off it functions exactly as a bov.

I'd wonder if the car has been subject to an intake smoke test in Japan - and someone forgot to remove it - as another possibility. The valves and throttle shaft in particular on these things tend to leak a bit.