bluewheelz

I almost forgot to mention that my air filter was dirty and at WOT there must have been a slight vacuum in the blower intake, causing the bypass to open. We moved the bypass valve line from that intake port before the blower to a line in the intake manifold. Doing this provides vacuum to open the bypass valve, but also puts pressure on the diaphragm to hold the bypass closed better when under boost.

Nuclear Endless

iTrader: (4)

Hopefully it all comes together.

Welcome to PT.net from Plano TX
Hopefully I'll see your SS around!

Gadgetized

iTrader: (9)

The bypass is designed to be hooked before the valve, not into the pressure side of the intake. The bypass is used to help out with cruising by opening up and letting air bypass the supercharger. I don't know for sure if the diaphragm will like the pressure and heat coming after the supercharger. It might not cause problems, but it was not designed to be hooked there.

The more I think about this I would assume you would have problems at part throttle with tuning. I would think that your tune would constantly be trying to go past the 105kpa area at part throttle. It could be fine at WOT. Who knows, maybe I'm wrong. Just a thought.

Gadgetized

iTrader: (9)

Also what are your total mods? People sometimes confuse boost with power, when it is basically a restriction of the air going into the engine. A supercharger on a 4.8 will make more boost than that same setup on a 6.0 given they have the same mods. The more mods you do(depending on the mod) will allow more air in and out, and creating less boost. Even though you have less boost you will have the same or more power. What I am getting at is if your heads, cam, manifolds, and exhaust system are causing more restriction, then the boost may climb as the RPM's climb.

bluewheelz

The only other mods are gutted cats, magnaflow muffler and Volant intake box and filter. Stock cam, heads, and exhaust manifolds. I am starting to think that kbracing96 is correct that the motor is using the supercharged air down low and as the motor gets less efficient up top, the pressure builds.

We made several passes at the end of the day, paying particular attention to the boost level at different RPMs. The boost level (with the bypass tied closed and with no wire tie on it) stayed around 3-3.5 lbs all the way up to 5000 RPMs, then quickly climbs to 5-6 lbs at the top. I am convinced that we have checked everything at this point. I guess it's time to pulley down, which from what I have read is going to be a total pain in the _ss. Another option is to install an overdrive balancer, but there's not much room between the water pump and balancer and it doesn't appear that the little room will give me the boost level I want (6-8 lbs down low)

I'm not going to quit now. I am ordering a PLX boost and PLX air/fuel gauge tomorrow so I can keep an eye on everything and I'm going to start the process of finding a way to drop the pulley size down. Anyone with experience here, please give me your advice. I am open to suggestions.

Thanks, guys.

Gadgetized

iTrader: (9)

Can a 1 bar even accurately measure boost? I didn't even think it could read into boost levels.

kbracing96

iTrader: (26)

The math says that it will make 6.8psi before any pumping losses with those pulleys on a 6l. The 8" IW pulley will fit, I had one on my KB blower setup, but it will only add about 2-3 psi or so. Rule of thumb, 1/4" on the balance adds about 1psi, 1/8" off the compressor adds about 1 psi.

On a 1 Bar MAP setup, the MAF is doing the fuel calculations vs air flow in boost till it's maxed at 512 gram/sec. Then its running blind off the last row of the VE table.

TIM Z

iTrader: (12)

I might have missed it but where are you getting your boost reading from??

I tapped my lower tub for a boost reference.

I saw about 4.5 to 5 psi If i remember correctly with the stock 3.3 pulley , at that time i was cam only 6.0 , no headers.

I had my snout machined for interchangeable pullies.

Remember this kit came with a pulley for a stock 5.3, so you cant complain about having low boost on a 6.0 stock or with mods.

Also you should get an HD tensioner from Leftcoast Joe., Pin your crank if ya havent already, and get dayco 100mm idler pulleys to help the belt stay tight, works great for me.
All you need is to pulley down , then the fun starts.

bluewheelz

I'm using the "factory" intake boost side tap that came on the unit. I have my MAP and Kenne Bell sensors on the same line. I have checked the line and there aren't any leaks.

When you state that you were getting 4.5 to 5 lbs, at what RPM did you get that pressure? I get about 3 to 3.5 until I hit about 5000 RPMs, then it climbs to 5 lbs. Like I said above, it makes a lot of sense that I am using up all of the air until the motor get's inefficient, then it climbs. But I keep hearing that with a stock internals 6.0 that I should have about 6 lbs.

I already pinned the crank, so the balancer isn't spinning. I am going to look for the idler pullies to get a better wrap around the SC pulley just to make sure. Is 100mm the best size for maximum wrap?

bluewheelz

Still waiting on my PLX gauges. I am about to order a 2.85 pulley (I think) and remove the supercharger and have it machined down to accept the pulley. TimZ (and everyone else who has machined the supercharger), do you have a measurement of what the completed snout diameter is after machining? How much clearance did you leave for further pulley drops? I am hoping that a 2.85 will do it. I don't want to order the pulley until I get the gauge and verify the pressure one last time, but I want to be prepared to run with it as soon as I get the gauges installed.