Blow Off Valve

[93turbomr2]

I AM KINDA OF NEW TO THE WORLD OF MR2'S.I HAVE HAD SEVERAL TURBO CARS IN THE PAST(3000GT VR4,300ZX,SUPRA, & RX7)ALL WITH AFTERMARKET BOV.I RECENTLY PURCHASED A BONE STOCK 1993 TOYOTA MR2 TURBO.THE ONLY MOD THAT I HAVE MADE AT ALL IS A TURBOXS BOV.I DID THIS BEFORE DISCOVERING THIS SITE,BUT NOW I HAVE BEEN READING QUITE A BIT ON HERE AND HAVE SEEN THAT MOST AGREE THAT THE AFTERMARKET BOV IS ACTUALLY A DOWNGRADE FROM THE FACTORY.THE ONLY THING IS THAT I HAVE SEEN NO ADVERSE AFFECTS FROM THIS BOV.THE CAR SEEMS TO IDLE FINE AND I HAVE REALLY NOT NOTICED A DIFFERENCE IN THE THROTTLE RESPONSE.AS FAR AS GAS MILEAGE I AM NOT SURE CAUSE I DONT DRIVE THE CAR BUT ONCE TO TWICE A WEEK SO I HAVE NOT REALLY PAID CLOSE ATTENTION.SO THAT BEING SAID HOW WOULD I KNOW IF THIS BOV IS CAUSING ME A LACK OF PERFORMANCE,THROTTLE RESPONSE OR GAS MILEAGE.BECAUSE I CAN NOT REALLY NOTICE ANY DIFFERENCE OTHER THAN THE SOUND.I REALLY LIKE THE SOUND AND HAVE ALREADY SPENT THE MONEY.ANY ANSWERS WOULD BE MUCH APPRECIATED.

[Piddy]

First take off your Caps Lock....


Then try and get a hold of a stock BPV. With all recirulation pipes... and see how the car runs. I guarantee it will run better. Mine runs better just adding the recirulation pipes onto the stock bov instead of venting to the atmosphere. Not to mention... you are loosing the bypass feature... and killing your gas mileage.

[JekylandHyde]

Originally posted by 93turbomr2
HOW WOULD I KNOW IF THIS BOV IS CAUSING ME A LACK OF PERFORMANCE

Have someone follow you and describe the black smoke coming out of your exhaust whenever you shift at full throttle.


Many people run aftermarket valves, enjoy the noise and accept the loss of gas mileage. I did it for years myself. As I got more into racing and into the actually performance of the car, I became a purest and I prefer to make things run as best as I can.

The OEM is the best valve you can have.

Aftermarkets with a spring (like yours) are the worse.
They will never respond as fast as the OEM valve or as accurately.
The OEM valve is extremely sensitive which is what makes for great on/off throttle transitions and gets you back into the power quicker.

[93turbomr2]

As i said in the original thread the car was bone stock when i got it.Which would include a factory blowoff valve with all stock connections.I am not saying that you are wrong about this ishcoleobo.Alll that I am saying is that I have not noticed any ill effects.

[93turbomr2]

So JekylandHyde would you say the major disadvantage of this valve on my car is gas mileage decrease?

[JekylandHyde]

No, that is just one disadvantage (and you are actually losing gas mileage in two ways with that valve).

The design of the valve you have is based on a SPRING.
Their are two problems with springs:
1. They will never respond as fast as the OEM air-based design.
2. They have a a limited range of ideal performance.

Given enough boost pressure, the spring "strength" will fail and the valve will open (i.e. leak).
If you add spring tension (adjust the valve) to rectify this, you will end up having to tight to open under partial boost conditions. This is not ideal for a street car.

The OEM valve's design is based on air. It uses bosot against itself so it always performs optimially, regardless of boost pressure. The more boost you run, the stronger it holds shut and it will still perform properly at low boost or partial boost.

I could easily demostrate the OEM valve "wubbing/farting" at partial throttle as it constantly/quickly switches from on to off.
It's right where you need it when you need it.

It just lacks the "cool sound".