overboost in top gear..........

[gannon888]

a few months ago i posted a question regarding my car overboosting it top gear at around 4k revs. (1.5 bar recorded (set at 1.2))

 

i was told that im running my turbos at too higher boost for top speed, which i accepted was true.

 

since then i bought a trd bonnet where i can hear my enging much better and i noticed that my apexi bov leaks at the 4k rpm mark and doesnt really hold the boost after that (i can hear my bov trying to dump the air) and i also read that the apexi isnt really man enough for a tt supra.

 

so in conclusion does anyone think that because my apexi is leaking air (due to being a weak spring) that thats the reason why my car has been overboosting?

 

also my car doesnt seem to have as much power (probably due to the fact that ive knackered the bov)

 

any feedback would be greatly appreciated

 

cheers

 

martin

[Swampy442]

Think about it logically, if the blow off valve was leaking would it gain pressure? No it would lose pressure

 

Also if youre driving the car how do you know the bov is leaking? Theres alot of air lines and pipework under there...

[clapyohandz]

You get 1.5 bar steady ?

 

The apex and blitz bov's are notorious to leak indeed.

[Nic]

The boost pressure will always be greater the higher the gear you are in, as the engine is under more load ie. if you get 1.2bar in 2nd gear, in 6th gear you may see 1.5bar.

 

You will need to either regulate the boost pressure with your right foot or turn the boost controller down a little, however this will also reduce the boost pressure in lower gears. Alternatively you could use a boost controller that can map the boost settings against speed eg. Blitz iColor, HKS EVC, etc. this would allow you to peak at 1.2bar through all gears.

 

As already said, if your BOV is leaking it would reduce the boost pressure.