BOV installation details

[lotusman]

I have a '89 non-SE and want the added, immediate oomph with the BOV. I looked through the Installation of the BOV, the hard one, on the Espritfactfile and need some questions answered.

HKS recommended the SSQV valve, (part no. 1421-SA001) rather than the Red Racing Valve installed. Why should I use the Red valve?

They also recommended that I use the manifold rail system for the vacuum source, like the "Easy" installation procedure as it will have more continuous vacuum. Is there any benefit in using the intake manifold vacuum source given in the procedure?

Also recirculating back to the air filter box will result in maintaining the air fuel ratio and not riching up the mixture after the MAP has already computed for the air. Also, I am not a fan of the, "Pffpt". The SSQV valve shown does not have an exit port for the return hose. Is there more than one SSQV appropriate?

Is the BOV functional for a non-charge cooled car? It bothers me when I lift off the gas and see the boost gage bouncing, stall and need to spool up the turbo again.

I also can only get to about 0.6 bar max. Is that the best I can do with the car or will new chips allow that to go higher?

Do I need the installation Flange recommended by HKS? No mention was made in the procedure.

I hope there is someone who has done the hard installation and can tell me their results.

[5150Neo]

Yes, I did the hard install. I used a Greddy type S valve and piped the released air back to the air box. To prevent the released air from damaging the K&N filter when rentering the air box I installed a 45 degree elbow to direct the air away from the filter. Sorry, but I am not familar with HKS products. The Greddy valve is almost identical to the one in the instructions for the "hard" install. I mounted it in the same fashion as in the instructions but be very careful when cutting the hole in the plenum. Make sure you have enough room to get a consistant seal for the base of the valve and at the same time enough room for the two mounting bolts. The vaccume line in the instructions seemed to me to be unnessary. Instead I ran the line to a "T" on the end of the vaccume rail as it is done in the "easier" install instructions. The Greddy valve spring is quite stiff but my desired setting is with the spring adjustment screw set almost all the way out allowing the spring to sit in its most relaxed state. This setting was perfect, the valve only opens between 3/4 and WOT (Wide Open Throttle) as it should. My installation is on a 91 model with an upgraded computer. Regardless of model year, a BOV will help prolong the life of the turbo.

Cheers

John

[5150Neo]

Oh yes! The reason I used the Vac rail is because it supplies vaccume from all four cylinders. The "hard" instructions show the vaccume being tapped from only one intake runner.