endeavour32

So the boat I bought has had the Whipple 525 ecu upgrade done to them. Supposedly you get better midrange punch, and maybe 1 mph on the top end. HOWEVER, in return you have to run premium fuel. From what I can tell, they bumped up the timing in the mid and also added a couple of degrees on the top. So not knowing at all what the timing curve is like in this engine. I'm guessing that the top was set at 32 degrees from Merc and is now at 34, I don't understand the need for 91. This is a 8.74:1 CR engine. I've ran 34 degrees timing on 10.4:1 before with 91 and never had as issue at all. I've also ran 87 in a modified 420 with iron heads with 34 degrees timing and no issues. So I'm confused why this mod would require 91.

Ryan00TJ

525EFI Whipple PCM Upgrade???

endeavour32

I've read that post, but I would like to know what the actual curve is. That post just states that 8 degrees is added between 3000-4000 rpms, and a couple on top.

Ryan00TJ

I understand what your saying. I don't know the actual curve on the 525. If you could get ahold of Dustin @ Whipple, he could give you more info. FWIW I have their Stage 2 on my 496HO. It also requires 91. Stock timing was 28*. Stage 2 is 34* thru midrange and 32* at WOT. 9.0-1 on crap iron 496HO heads with a joke of a combustion chamber design. I have ran 89 marina e10 fuel since 2015.
I would think the 525 with lower compression and aluminum heads would be fine on 89.

endeavour32

I agree- I think that 89 will be just fine. I do want to find out what the curve is on this tune. I don't think Whipple will disclose that info, there is almost no info on this on there site. Even when Dustin and Raylar were arguing about the effectiveness of the 525 tune on a forum post, there were very few specific facts about it, other than the Merc tune is lazy and leaves 25 hp on the table.

endeavour32

I did find this, so it indeed looks like there is a nice improvement with this mod.