525EFI Whipple PCM Upgrade???
 

Anyone done this 525EFI Stage 1 Performance Upgrade?

Looking for performance changes and opinions from some that have done this. Mid to larger twin engine boats. Hear it will wake them up in the mid range, looking for some real world, I spent the coin opinions.

Thanks.

We've done the upgrade on numerous 525's. The biggest gains are in the midrange. It gets about 8 deg of timing in the 3000-4000 rpm range. The timing curve of the 525 is extremely lazy. It's done that way to make it dummy proof. You can put the crappiest, piss water gas you can find and go shove the sticks through the dash and into the cabin and the engine will stay together. It's so lazy that the knock sensors aren't even functional. Every customer that we have done it for has seen a noticeable difference. There have been a few that have had some top end gains, but most gains are in the mid range. The biggest factor that we have found is the current propping. If you are propped for 5000-5100, you will see a noticeable diff in top end. Not to mention, you are leaving some on the table now. The 525's need to be propped right at the limiter (5400-5500) in order to get the most from them. The upgrade raises the limiter to anywhere from 5800-6000, depending on what you want. That engine will easily pull to 5700-5800 rpm. Not much need to go above that. It is and has been money well spent for us. I've never had a customer that wasn't happy with the upgrade.

One thing to consider. I WILL NOT do the PCM upgrade to a 525 that hasn't had the top end done. The stock springs have no business being turned that high. You are asking for trouble. As long as it has a good set of springs, do it. You won't regret it. Let me know if we can help.
Eddie

Does the guardian mode get raised to the new upper rpm limits. Can u use 89 octane still

We have done tunes for both 89 and 91. In order to get the most out of it, you have to run 91 octane. If you can only get 89 octane, we can still do a tune, but you will give up a little. We can't put as much timing in it through the mid range. Instead of adding almost 8 deg, we can only add 4-5 deg.
Eddie

Eddie, I heard the engine hours and hours at the rpm ranges are reset, any truth to that?

What can be done to the 500efi's to squeeze little more out of them?

The rpm history can be erased at any time with just a scan tool. When shopping for a boat and you have the ecm's scanned, you should always add up the run history hours to be sure that they are the same as the total hours.
It doesn't reset the total hours.
Eddie

First thing that needs to be done is to change the throttle body. That is what holds that engine back probably the most. There aren't really any gains with just tuning. About the only thing you can do is to raise the limiter. If you change the throttle body, you can take advantage of some tuning as well.
Eddie

Im due for a rebuild in the future, got 550hrs in salt water with the engines never opened up. Trying to gather info for when the time comes. What throttle body do you recommend?