Nordicflame

iTrader: (4)

Has anyone come up with a good system for crankcase evacuation?
I’m thinking of adding a puke tank and was wondering if anyone has come up with anything better.
I currently run a 5/8 hose from each of my valve covers to the air horn on the SC.
PC now only uses an air horn and no conical filter as they once did.
Problem is that when the throttle blades get slammed shut the supercharger actually pushes the air back out the air horn and when it does, it sprays any oil in the hoses right out into the compartment.
Just Curious,
Dave

bobby daniels

I've got several customers that drill and tap a hose fittings in the line from the blower to the motor after the inner cooler and runs
it to one valve cover and has a breather in the other cover and it works well for them

Valley Boy

Use the 90 degree PVC valve that the BBC trucks use in both valve covers and reduce the hose size to 3/8" and you will cure your problem. Worked like a champ for me and provides all the evacuation that you will need for up to a 502 w/PC.


Valley Boy

tomcat

Hi Dave:

I don't know the answer, but your post makes me want to ask why none of the marine guys seem to run a bypass or anti-surge valve on their Procharger or other centrifugal when all the race cars use them. Back in the day when we were fooling around with turbos, compressor surge was considered a bad thing.

When you slam the throttles shut, that air is coming back out with all the energy you used to put it in there in the first place. This has to be hard on impellers and gears. I've heard Vortech say you don't need them under 10 psi, and Procharger say they don't need them because their impellers and gears are so tough.

For you guys that have had to rebuild your compressors, what goes bad on them? Do you think that compressor surge is a factor?

The reason I'm asking is that I'm seriously considering selling my intercoolers with bypass valves as standard equipment. It just makes sense that this would make things last longer.

NEVRENUFF

Hi Guys,

i have been pondering this very question myself and have decided to buy a couple of "puke" tanks and run the valve cover vents to them.

I have a 454 MAG with a Procharger (carb) and the kit instructs you to hook them up to the compressor intake horn as you said. I ran mine that way last year and found that I was getting some oil accumulation (maybe 1/2 an ounce every 30 hours or so) in the carb box. i'm running the stock valve covers and just figured that the normal blow-by was pushing oil mist through the lines. There is surely a reduced pressure zone at the inlet of the compressor and so I figured that the combination of the blow-by and reduced pressure at the compressor inlet resulted in the oil accumulation.

i'm not sure if this creates problems (power loss ) but the one concern i do have is the efficiency of the intercooler. That oil coating/accumulation in the core will reduce heat transfer by some amount I'm sure!

So, thats why i am going the puke tank route. JEG's has some nice light weight plastic ones with the norman sized breather vent filters and a drain valve on the bottom.

i have also wondered if my engine has excessive blow-by. It was freshened up by a reputable guy just prior to the procharger. i do know that the piston clearances are healthy. Anyone else noticed any oil accumulation?

Tom, on the bypass valves, I can see why they might be a good idea. I have also however been concerned about back loading the compressor gears when pulling back hard on the throttle. It makes some pretty nasty noise when you do that and I don't know if you heard it when we were at the dyno, but the belt squeeled every time Dean yanked back on the throttle. I noticed it when i first installed the kit and was running the motor without the back seat in the boat. The compressor belt was on but the discharge was not hooked up. Man did it sound bad when I'd rev the motor and then pull back hard on the throttle. For this reason, I don't suddenly slam the throttle back unless absolutely necessary.

My point being that while it might be hard on the compressor blades, maybe there is an offsetting benefit by loading up the compressor to help it deccelerate and minimize wear and tear on the gears. Just a thought.

I'd be inclined to skip the extra moving parts ($$). It also simplifies the issues with flame arrestors if you know what i mean. I need to get back to you on my I/C project. Been busy at work.

Paul

tomcat

Paul:

I didn't notice that noise, but if the belt is squealing I would say the compressor has put the brakes on while the engine and belt are still at high RPM. This has to be hard on the gears. Yes it is an extra cost, but I think I will leave room to mount one if people want it. The air dumped by the valve does not contain fuel, but to be safe it should be routed out of the engine compartment with a hose.

Nordicflame

iTrader: (4)

Tom,
I have been looking into a bypass that is attached to the intake manifold via a vacuum line.
When it senses vacuum, it opens. Zero vacuum to boost and it remains closed. I believe I've heard that some guys have mounted these on the intercooler for convienence.
I haven't done anything because I'm not sure if it would really do anything
Along with the gears, I still believe that a good amount of the blower noise at idle is from the harmonics of the impeller blades when the opposing flows collide. I believe that this would be somewhat reduced by the use of a bypass.

It would certainly help the noise when you slam the throttle shut after revving it in neutral.

Dave

NEVRENUFF

Dave and Tom,

Just a clarification. When I first noticed the belt slipping during rapid decceleration, was with the discharge side of the compressor disconnected so I don't think the belt slippage is due to the back pressure as much as it is due to the inertia of the rotating elements in the compressor. Once the flow is stopped (closed carb plates), the compressor unloads doesn't it? I'm sure there is a momentary increase but I'd expect that it is much like any other centrifugal pump where load increases with air flow. Are you sure that yanking back on the throttle does not unload the blades? This would exacerbate the back loading of the gear train. I saw a thread on this issue a while back but lost track of it. What was the consensus?

Another consideration is that the belt wrap over the compressor pulley (and tensioner) is designed to transmit more power in the driven direction. Therefore it takes much less load to slip the belt when the compressor is trying to drive the motor. Maybe that is why it slips? Another inherent overload protector for the gear train I guess. Either way, I'd be surprised if the belt is slipping due to the throttle plates closing. Just my .02

The concern with the bypass exhaust and flame arestors was mainly from a back firing condition. I always assumed that the flame arrestors were to protect from backfires igniting a potentially fume rich engine compartment. Either way, piping the outlet out of the engine compartment covers you.

Paul

rayseaeddie

if you're using the original valve covers than they are equipped with a great internal oil baffle in the valve covers. this allows you to install regular K&N breathers as they make a small 5/8 version that push right in. the only down side depending on your boat is you may smell some fumes at idle,but,the bilge blower will take care of that. forget the hoses to the intake boot. forget the bypass to,it hasn't been a problem in low boost marine applications.

mcollinstn

Why can't we weld a 1/2" diameter tube into our CMI's tailpipes and connect to the breather hoses? Tube at 45 or 60 degrees so the exhaust flow pulls the vapors out.

PCV valves on both of them would prevent anything coming back "in".

anybody doing this?