Clutching on a Boosted Apex Shockwave??

[acutah]

Last year I ran a MPI Stage 1 Blower. Stock weights loaded up with the heaviest rivets. Stock Secondary. It would pull about 10500 at 9000ft.

This year for the first half of the year I had still had the stage 1, and then I upgraded to the stage 2. At the first of winter I switched to Shockwave helix. I was told I could get those extra few hundred RPM's that I needed at elevation, and that I could back it down a bit at lower elevation (6500 ft) so I wouldn't bounce off the rev limiter. The result has been that I could only pull about 10,000 RPM at 9,000ft. even with it screwed all the way in. This is even now with a stage 2 blower. I was then told that my weights were too heavy. I lightened up the rivets and now I CAN achieve max RPM.

The problem is its not pulling the boost it is supposed too. MPI says they think my clutching is messed and I need to go back to what I had last year. They don't think my current setup is loading the motor enough. This seems to make sense to me. Especially since I have had nothing but problems since I added the shockwave. Just wondering what others are running and if this all makes sense.

Any input would be appreciated. I just want to get this licked before all the snow turns to mashed potatoes.

 

[julio]

helix

I had trouble when I put the shockwave helix in this year (turbo apex) I ended up takeing some fine sand paper to the ramps and then polishing them to make them smooth, helped alot. doesnt make any sense that you went to a bigger charger and cant pull the cluthcing you had with the smaller charger. You should need more weight to slow the motor down. I think I would look the charger system over and see if you are leaking any boost somewhere. julio

 

[upnover]

my thoughts

I had trouble when I put the shockwave helix in this year (turbo apex) I ended up takeing some fine sand paper to the ramps and then polishing them to make them smooth, helped alot. doesnt make any sense that you went to a bigger charger and cant pull the cluthcing you had with the smaller charger. You should need more weight to slow the motor down. I think I would look the charger system over and see if you are leaking any boost somewhere. julio

im no tuning wizard, but, i have a shockwave on my stage 2 nitro, the straight angle i have might not be the best angle (not so much angle but it isn't a ramped helix, could be an issue) for boost, guessing here. the angle i was told to favor is 1.5 to 2 turns out on the shockwave. and if it isn't, weight it so you are. i was told that just because your shockwave is adjustable doesn't mean the angle to get the rpm is a good angle for the engine. second. if you have your rpm and dont have the right boost, there can only be 2 problems, leaking boost, or MPI sent you the wrong pulleys which they have done lots to people. its impossible to compare your weight to other peoples, im running 4.5 gram rivits in stock weights in both the inner hole and the middle hole, empty in the tip. might seem like not too much weight but i also have a lighter primary spring and have tightened up the secondary spring as much as possible. so without the spring changes and a changing ramp angle on the helix who knows which weights i'd be at. I was told, get your fuel map right first (o2 sensor) then screw the helix out 2 turns, weight accordingly to desired rpm, then only should have to adjust .5 turns to keep rpm at elevation and snow conditions and this should keep the helix close to what the engine likes. dont know if this will help at all but mine pulls like a bulldog.