Boost Spike

[PMJ]

Originally Posted by Blue70SS

Thanks Ted... just ordered a .30 and a .35 to experiment with for the 1/4 mile. It looked like the smallest was .30 for Mikuni.

I haven't heard of this issue on a Maggie? Are you having the problem. I fixed mine by slowing down the throttle and changing the fuel injectors during the initial drop in pressure...seems to be working great.

[Blue70SS]

Originally Posted by PMJ

I haven't heard of this issue on a Maggie? Are you having the problem. I fixed mine by slowing down the throttle and changing the fuel injectors during the initial drop in pressure...seems to be working great.

Not a boost spike, but I'm having a lot of timing pulled after of each shift at WOT for about .4-.5 seconds (sometimes ~ .3 sec) - which is also about how long it's taking for boost to hit max. It also could be boost is taking longer due to the timing. We've ruled out knock, burst knock, and torque management, but might be a hidden problem with the Nick Williams 102mm TB. We're not letting it go into test mode (so limp mode can't occur in theory), but the ECM might be reacting still. Plus I drilled out the orifice on the drivers valve cover to allow my RX Monster Catch can to work better for my current boost levels vs blow by pressure. It's only a theory of mine at this point, but the Maggie has 3 vacuum inlets on the drivers side - the center one is being used by the bypass valve. The other 2 are flowing a lot more with the valve cover orifice to the catch can being drilled out to 1/4", so the vacuum to the Maggie bypass might be slightly reduced during shifts at high rpm and while the engine is still venting. The tune was adjusted for the unmetered air already.

However, I was interested in how to hold boost during shifts - like the ZL1 is able to do. Powershifting to hold boost seems too risky to me - with how quick rpm can climb already.

[PMJ]

Originally Posted by Blue70SS

Not a boost spike, but I'm having a lot of timing pulled after of each shift at WOT for about .4-.5 seconds (sometimes ~ .3 sec) - which is also about how long it's taking for boost to hit max. It also could be boost is taking longer due to the timing. We've ruled out knock, burst knock, and torque management, but might be a hidden problem with the Nick Williams 102mm TB. We're not letting it go into test mode (so limp mode can't occur in theory), but the ECM might be reacting still. Plus I drilled out the orifice on the drivers valve cover to allow my RX Monster Catch can to work better for my current boost levels vs blow by pressure. It's only a theory of mine at this point, but the Maggie has 3 vacuum inlets on the drivers side - the center one is being used by the bypass valve. The other 2 are flowing a lot more with the valve cover orifice to the catch can being drilled out to 1/4", so the vacuum to the Maggie bypass might be slightly reduced during shifts at high rpm and while the engine is still venting. The tune was adjusted for the unmetered air already.

However, I was interested in how to hold boost during shifts - like the ZL1 is able to do. Powershifting to hold boost seems too risky to me - with how quick rpm can climb already.

Hmmm, you seem to be having the opposite problem I saw where boost was too fast. I don't think the jet is going to help. I see your theory of holding the bypass open, but it will still slow down opening after it starts to close. That recommendation was to slow down the bypass valve so boost ramped up slower...

I logged my friends Maggie last time I was at the track. I'll have to take a look at it when I get back home this weekend.