My 525 builds
 

I just finished my 525 upgrades and will be hitting the dyno in next day or two. Here is what we put together and will be interesting on what they will do with stock Merc injection. Goodwin Competition took short blocks bored .030 and stroked to 540ci with 9-2-1 compression all the best american forged components. Stock 525 cams with johnson lifters. Tyler Crockett machined a bigger throttle body blade and intake opening, flowed injectors, machined pro max 317cc full cnc heads to work with closed cooling and headers, reprogrammed computer's. Goodwin is going to dyno with wet CMI's and all accessories. My guess is 620ish HP and high 6's on TQ. What you guys think? I have heard over and over the Mercury Racing intakes will hold motors back. https://cimg6.ibsrv.net/gimg/www.off...4c146d502a.jpg
https://cimg0.ibsrv.net/gimg/www.off...0db26d881b.jpg
https://cimg2.ibsrv.net/gimg/www.off...fd6bde5e0d.jpg

looks awesome interested in the outcome

I think your hp estimate will be pretty close. Stock 525EFI's dyno at around 560hp at the crank.

Will that run on 89 octane?

why are you not increasing the injector size ?? or did I miss that

Should be ok on 89 octane. Stock is 8.7.1 so did not increase compression a lot and full CNC chambers should help also but still all depends on the tune. No did not increase injector size. Tyler has built a bunch of these and did not recommend it to me but guess we will see how it performs on dyno. Will post results.

I built 540's with 500 EFI intakes, AFR 305 heads, custom hydro roller and 60# or 65# injectors and they made 625 hp 650 trq........Id be surprised if you get you # without more fuel and cam, and yes the plenum is restrictive..... good luck...B Smith build mine

That's pretty big jump in injector size. Do you remember fuel pressure you where running? I know if fuel system is up to it and fuel maps pulse widths ect you can flow a lot more fuel then the 43lbs that mercury markets injectors at 42ish psi. I originally did not want to spend the money and time to dyno but glad I did now. I did weld AFR gauges in tail pipes so should know if anything changes when we get them into the boat.

Will your Dyno numbers be in full marine trim with wet exhaust?

Yes running full wet cmi's with tail pipes and all accessories.