MS with hot cams?

[vandor]

Hello,

I have an MS box that will eventually find it's way on my car. I've set up other programmable EFI systems before, but not MS.
Some of these systems have a hard time dealing with engines with hot street cams (one specific one: 260º degree duration at .050" clearance, 304º duration at running clearance, 84º overlap) and individual throttle bodies, even when switched to RPM based metering (eliminated the MAP sensor).
My question is, how well can MS be tuned with a naturally aspirated street engine running a hot cam and ITBs? I've talked to a few people, and at first they always say the car runs great, but later it turns our there are flat spots here and there, even after months of tuning.. To me the point of running FI is to get modern-car like driveability and also have performance.
Thank you,

Csaba

[Matt Cramer]

That is wild enough that you'd probably want alpha-N or a blend of alpha-N and MAP. But I don't see a problem with this. You will want to get this tuned on a steady state dyno to get all the low load spots - that should avoid the flat spots you're hearing about.

[vandor]

Hello,

Yes, definitely need alpha-N. There is no point in using a MAP sensor, as vacuum is only ~4 inHg at cruise, so there is too little vacuum difference between quarter throttle and full throttle to have enough mapping points.
I would not think of tuning without a dyno
Thanks for your input!

Csaba

[Matt Cramer]

Hello,

I would not think of tuning without a dyno

You'd be surprised at how many people do. Not the easiest way to get all the off-throttle points dialed in.