Boost into the crankcase is bad
06-08-2006, 11:58 PM
#44
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Well I just put mine on and WOW I think i had so much boost that my pvc valve was leaking by bad. Say I'm reading 17psi but I was only getting 13 psi that was useful. I took the S out for a drive today and I think I'm getting all 17psi now! Lets just say that I don't even get very good traction till the end of fourth!!!! That's never happened in 80 degree weather before 
Taking it to get re-dynoed this week....402 just didn't sound like enough lol....
Taking it to get re-dynoed this week....402 just didn't sound like enough lol....
06-09-2006, 06:04 AM
#45
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Originally Posted by fperra,Jun 8 2006, 07:02 PM
Wrong. Since the crank vent creates a partial vacuum in the crank case, there is still flow from the crank to the vacuum source. And the vacuum source is the intake manifold. You are just not pulling fresh air through as in the stock system, but you are pulling all the bad stuff out.
If you don't want the vacuum in the crank case then just use a better PCV valve or use only one of the crank vent valves.
If you don't want the vacuum in the crank case then just use a better PCV valve or use only one of the crank vent valves.
And i never said i dont want the vacuum in the crank case, all i said was that i dont want to take out an important function of the pcv valve(having all that "dirty air" replaced w/ fresh air) just for the sake of having vacuum. cars have been running fine the way the stock set up works.. And i haven't seen conclusive proof that vacuum would greatly help in making a car run safer, or stronger.. Boost in the crankcase i know is bad, hence the crankvent in the back would prevent that. imo, i think it would be best to just have a breather up front, and the krank vent in the back. That way you are preventing boost from entering the valve cover, and at the same time letting the pcv system do what its designed to do, it wont be seing boost so it should function like normal. my .02
06-09-2006, 07:30 AM
#46
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[QUOTE=Harpoon,Jun 3 2006, 12:49 PM] Okay, since Sideways got this back up again, let's talk technical.
Comptech recommends the Krank Vent for the '04, '05 and '06 cars, but not necessarily for the previous models.
Comptech recommends the Krank Vent for the '04, '05 and '06 cars, but not necessarily for the previous models.
06-09-2006, 07:46 AM
#47
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Originally Posted by gary_phd,Jun 9 2006, 08:30 AM
I "introduced" the Kranvents to Comptech. I had some issues with my blower, and brought my car to their facility. In the process of trying to diagnose the issue, they tested the amount of pressure in the blower and crankcase with and without my Krankvents installed. What they found was that boost was entering the crankcase, and by the third run dyno run, I was getting FULL boost in the crankcase and blower. Mind you, the pcv on my car only had 5000 mile on it. I installed the Krankvents almost immediately after installing my SC (@5000 mi).
Without the Krankvent system, I achieved only ~ 270 ish whp (can't remember off hand). This was when boost was bypassing the pcv. With just the Krankvent at the PCV, ~ 285 whp. Then, with both installed at the pcv and breather, I hit 305 whp.
Aside from the power gains, you do not want any boost inside the blower because of the design of the gaskets (inner and outer) at the shaft. This increases the chance of the gaskets blowing, and eventually leaking.
As a result, they opined that the AP2 pcv design may be weaker, and that they were going to recommend the Krankvents - at least to one at the pcv - to prevent boost from entering the crankcase.
I've got over 36k on my car, SC installed around 5k, with Krankvents installed around 5500k.
Without the Krankvent system, I achieved only ~ 270 ish whp (can't remember off hand). This was when boost was bypassing the pcv. With just the Krankvent at the PCV, ~ 285 whp. Then, with both installed at the pcv and breather, I hit 305 whp.
Aside from the power gains, you do not want any boost inside the blower because of the design of the gaskets (inner and outer) at the shaft. This increases the chance of the gaskets blowing, and eventually leaking.
As a result, they opined that the AP2 pcv design may be weaker, and that they were going to recommend the Krankvents - at least to one at the pcv - to prevent boost from entering the crankcase.
I've got over 36k on my car, SC installed around 5k, with Krankvents installed around 5500k.
06-09-2006, 10:51 AM
#49
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wow, big difference. I'll be dyno'ng my car soon, so i'll probably try out the different combinations and post the dyno sheets on here.. just waiting on the krankvents.. One thing about the boost loss, whether you have a krank vent in the front or not, it shouldn' t matter as long as you have the krank vent in the pcv tube. I'm guessing that extra jump in power(285-305) is coming from that extra vacuum that every1 is talking about by hookin up the front krank vent to flow outwardly? I'm still a lil weary on bypassing the stock system just to get more power, but that is a big increase.. Just curious, is that 305 @ stock boost levels?
06-09-2006, 11:01 AM
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The front vent flows outwardly anyways. Everytime you step in the throttle you open the throttle body and air is pulled out of the crank case into the intake. The Krank vent is just making sure that it only flows INTO the intake and not into the crankcase