Hey everyone. I just recently purchased an evo 8. The car had a few aftermarket mods on it when I bought it, such as a 3" exhaust, cai, a recirculating greddy type s bov, and an ecu reflash from dynoflash.

I took the car to the track the other day and it seems like something is wrong. With a 1.8 second 60' time, the car only did a 13.6 @ 97mph. I've noticed that although the needle on the boost gauge stays calm and pegged @ 20 psi until about 6k rmp, from 6k rpm to 7k rmp it starts to violently shake and back down a little bit to around 17-18psi. Does this sound like a boost leak to you guys?

Also, I have heard that the greddy type s bov is notorious for leaking around 15psi. Anyone have any knowledge/experience with this?

And, if this is a boost leak, would this alone be be enough to create such pittiful track times/trap speeds?

 

i'm assuming its a mechanical boost gauge? If so , it could simply be that the car or wherever its mounted to is getting a vibration at that point and shaking the needle in the gauge. Do you know how to make a pressure tester?

 

No, but I've been reading up on it because it looks like that's my next step. It's weird because it feels like the torque is there, but the horsepower at top end seems to be lagging. Oh, and yes, it's a mechanical boost gauge.

 

I'll try to post a pic of mine, you'll need about a foot of 2in pvc pipe, a 2 in cap, and a 2 in 45 degree elbow. I bought an on off valve and an air hose fitting so i can turn it on and off with the airhose attatched while i let air in or stop the flow. Just have someone in the car watching your boost gauge and when its a few pounds above what you normally boost stop and listen for leaks.

 

I am having the same problem right now. I can pull a 1.70 60', then end up running a 12.3 on with more mods, about 3 tenths higher than it should. I did see on a log on my run that boost was tapering off, and my mech boost gauge is not picking it up as far as I can see. Just do a boost leak test and find out for sure.

 

This is what it should look like. The rubber coupling comes with the band clamps already. This will attach right to your turbo compressor housing.

 

Whoa, sorry its humungous...

 

If you want to buy a nice boost leak tester check these out:

http://siliconeintakes.com/tester.htm

I'm not sure if we need 2.5 or 3" right off hand.

 

to go straight to the turbo its 2 in. i believe the intake would be 2.5 in. I like those too, but for less than or equal to that i prefer to have the on/off valve rather than having to keep putting the hose on and off.

 

Thanks for all the help guys. I am going to try that boost leak tester next week. But first, I am going to try swapping bovs...i think its my old greddy type s that is causing the leak. I say this because I know a few people that have experienced leakage on this valve at boost levels over 17psi. This is exactly where my leak is going down to...from 20-21 to around 17-18psi, and it doesnt drop any further. Plus, I hate the damn whistle sound of that greddy valve.

 

Im going to try the boost leak tester unit and see if i can find the leak that makes my boost gauge needle shake at idle.