tictakman

iTrader: (6)

When I had a local tuner tune my car we didnt have any problems with holding boost and that was at 8lbs. The system doesnt peak then drop off at all, just hits 3 lbs and holds. Thats why I dont know about it bleeding off like u guys are saying.

I have a stock 04' Z06 cam that I can throw in and test out but I would like to try the smaller pulley since it would require less work up front. Then if it hits 3 still, i can go look at the cam next for the big job. haha

Z

NoGo

iTrader: (2)

I use a regular Napa belt....nothing fancy. I went through several different makes when I first put the system together and liked the price of the NAPA belts.

I now run a 3.1 pulley and don't have slip problems with the SDCE system. The car has run 20k+ this way making consistent power for the last 6 years on the same belt.

I did a lot of testing on tensioner setups back in '03, '04; spending probably close to 2k on **** that didn't work.... So, I tell everyone not to make the same mistake that I made and just skip to a spring tensioned setup.

NoGo

iTrader: (2)

So are you saying the car once made 8 psi with this same supercharger setup. But now, for some unkown reason is at 3 psi.

If so, then don't change the cam.

I had a car (not LS1) a year or so ago that collapsed the inlet filter and was making practically no boost as a result.

Could be something as simple as a leak in your boost gauge line.

tictakman

iTrader: (6)

sorry if i am confusing you guys.

I have had quite a few setups on this car, na, front mount turbo, rear mount turbo, now the sc.

I had the car tuned with the rear mount turbo setup for 8lbs of boost. I didnt have a problem then with any boost bleeding off through the dyno tune or on the street. I then changed the setup to this procharger and w the 3.85 pulley im only seeing the 3 lbs.

I do have a filter right on the front of the sc due to the amount of room i have to play with but i dont think it would be causing a 5lbs decrease in psi. I wanted to try it without a filter but i dont want to get anything into the sc and decrease the life of it at all.

Z

NoGo

iTrader: (2)

Oh....that's different. The cam could be contributing then.

01boydws6

iTrader: (19)

I really think the cam is where your loosing boost. I made 11lbs with a 3.6" pulley on a 6-rib setup and now see about 9 to 10#s with my 3.85. I did the chevy chad mod. I am stock cubes. and the rest of my mods are in my sig.

tictakman

iTrader: (6)

ok, ill dig into that next weekend then,

I just dont understand why I didnt see it with the turbo then, why just the procharger?... can anyone elaborate on that?

Z

NoGo

iTrader: (2)

The speed of the turbo is variable, limited only by how much exhaust gas you bypass around the turbo with the waste gate. Your turbo will spool to a target inlet pressure as controlled by the waste gate.....which is why your inlet pressure is connected to the waste gate actuator. A turbo may only need to spool to 80k to reach the target boost pressure, or it may need to spool to 110k, but it will increase its speed until the target boost is met.

A supercharger on the other hand has a fixed speed dictated by the speed of the motor. Boost is dictated by how much back pressure you apply against the supercharger.

tictakman

iTrader: (6)

Wanted to update the thread, I ordered a boost cam from Bob @ Brute. Ill hopefully be installing it in a week or so then ill report back some findings to hopefully complete the thread.

Thanks again,

Zak

tictakman

iTrader: (6)

Ok guys back with an update. I installed the Brutespeed Boost cam and also pinned the crank. I took her out for a test drive today and I am still hitting 3lbs and holding steady. The cam seemed to help the pick up but it still only hits 3 lbs. Im hoping to hear Bob's input because he wanted me to buy his costly cam! just kidding... haha

-my buddy sent me a 3.4 pulley to try that as an option, so i would be going from a 3.85 to a 3.4 with a 6" crank pulley just to rule that out....

-what about totally removing my bov out of the system to see if that is contributing. I have ran it with a tight setting and also disconnected without any change.

-I also think it could by my intake, currently its a mushroom style due to spacing but I dont think that would rob 5 or 6 lbs of boost.

Set up is below if this could help out. Again, 2004 ZO6 engine w supporting valve train for Brute Boost cam, Nick William 90mm, MAF tuned, AIT being used...

rjparth

As my buddy frequently reminds me, it's all about the science and the math. When you pressure tested did you do it with and without the engine in the mix? In other words, keep the TB connected and pressurize from your charge tube where the supercharger connects. That will tell you if you have a PCV valve leak or EGR gasket leak, etc. Also, find the compressor formula spreadsheet for your supercharger so you can calculate impeller RPM based on crank pulley size, S/C pulley size and engine RPM. That will answer your pulley size question. With those two steps you'll know for sure that you're foundation is solid. Also remember that boost is a measure of restriction, not volume. You can flow the same CFM into the same engine and show different boost based on cam, headers, etc. because these variables affect restriction.

tictakman

iTrader: (6)

Out at the pool..but...I did pressure test the system connected to the engine and running the air hose closest to the sc. That held about1 bar so that's good. I'll have to check the charts ur talking about...

rjparth

No excuse, I typed my whole message and this one from the beach on my iPhone! Yea, you have to know the math behind your supercharger to determine the optimal pulley combo without stressing the supercharger. Boost gauges are great, but it's hard to see them on the street at 6k rpm. I was shocked as hell to see 8.5 psi on mine on the dyno.

Bob@BruteSpeed

iTrader: (16)

I'd next take the inlet side off and make one run, that way you can either rule it out or have found the problem. Bob

NoGo

iTrader: (2)

Another possible area to be loosing power is with the pully system. If you are slipping alot you won't be making much boost.

Make sure your pullies are alligned and something hasn't shifted.

tictakman

iTrader: (6)

Ill try a run with the intake hat off and see what happens, i just didnt want sand to get into the unit.

The pullies look like they are pretty straight right now. I had an initial issue of the crank pulley walking out so that chewed up the belt right from the start. Im going to look into Chevychad's mod as well as Asters for better belt wrap.

Ill let oyu know how the intake pans out later today.

Z

tictakman

iTrader: (6)

Next update, I took the mushroom filter off and produced about the same result but I think my gauge hit 4 lbs instead of 3.

Im going to take my extra stand off to a machine shop and have them mill down the diameter to run another idler pulley (chevychad mod) for the extra belt wrap.

Tomorrow I can swap out the 8 rib pulley (3.4) and see what that produces for psi in the mean time while I wait for the standoff to get milled.

Z

tictakman

iTrader: (6)

Next update, I took the mushroom filter off and produced about the same result but I think my gauge hit 4 lbs instead of 3.

Im going to take my extra stand off to a machine shop and have them mill down the diameter to run another idler pulley (chevychad mod) for the extra belt wrap.

Tomorrow I can swap out the 8 rib pulley (3.4) and see what that produces for psi in the mean time while I wait for the standoff to get milled.

Z

danameisoj

iTrader: (2)

figure this issue out already lol.. im wanting to do a similar setup on my ls1 fd lol

car is sick man . good luck getting it squared away.

tictakman

iTrader: (6)

I wasnt able to test anything today because of rain. I did find a machine shop for the idler pulley mod which is supposed to be done Friday. I did however rig up my intake piping to rule out the intercooler, ill test this tomorrow.