Tips on solving a drop in MAP at WOT?

For discussing B&G MS-I/MS-II set-up and tuning of fuel parameters (including idle valves, etc.).
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SkinnyG
MegaSquirt Newbie
Posts: 5
Joined: Sun Nov 30, 2008 2:14 pm

Tips on solving a drop in MAP at WOT?

Post by SkinnyG »

10kPa drop between 6000 and 7000rpm.

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4AGE running MSIIv3.0 2.89, GSXR ITB's and EDIS-4

Engine also doesn't "feel" as strong in the top end as it did with the factory ECU and plenum intake, or the screaming from the ITB's just scares me into shifting.

O2 seems to read happy, I do not hear or feel any missfire or knock.

I could measure this with the MAP sensor on datalogs, or even with the MAP sensor disconnected (and running Alpha-N), calculating horsepower in MegaLogViewer also shows this dip.

Any tips on where I should be looking??

Thanks.
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Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: Tips on solving a drop in MAP at WOT?

Post by Matt Cramer »

I wonder if it's a standing wave effect of some sort that's not good for the MAP. Trying different length intake trumpets or runners may help.
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SkinnyG
MegaSquirt Newbie
Posts: 5
Joined: Sun Nov 30, 2008 2:14 pm

Re: Tips on solving a drop in MAP at WOT?

Post by SkinnyG »

I cut about 1-1/2" off the trumpets, and ended up with this, a 1.4kPa improvement. To go much shorter, I'd have modify the intake quite a bit. I could try longer.....

Image
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SkinnyG
MegaSquirt Newbie
Posts: 5
Joined: Sun Nov 30, 2008 2:14 pm

Re: Tips on solving a drop in MAP at WOT?

Post by SkinnyG »

No, wait. Found the same 1.4kPa difference in the morning's datalog, using the original trumpets.
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