Offshoreonly.com - "Dyno Exploring the 502 EFI" from Hot Boat

Offshoreonly.com (https://www.offshoreonly.com/forums/)

- General Boating Discussion (https://www.offshoreonly.com/forums/general-boating-discussion-51/)

- - "Dyno Exploring the 502 EFI" from Hot Boat (https://www.offshoreonly.com/forums/general-boating-discussion/249451-dyno-exploring-502-efi-hot-boat.html)

"Dyno Exploring the 502 EFI" from Hot Boat

dbkski, if you'd like I could e-mail these to you in higher resolution and more printer friendly format. I thought this might be of interest to others here though. I'll do part two ASAP.

I remember that article, i think I remember that the old KE headers, (back then were PF Marine headers) were the best of the bunch. I'm installing SM manifolds on my 2000 502 EFI's right now. Good article.
Dean

Quote:

Originally Posted by Dean Ferry (Post 3351640)

Yup, good stuff. I'm posting it on request. Here is part 2:
http://i763.photobucket.com/albums/x...es360Large.jpg
http://i763.photobucket.com/albums/x...es361Large.jpg
http://i763.photobucket.com/albums/x...es362Large.jpg
http://i763.photobucket.com/albums/x...es363Large.jpg
http://i763.photobucket.com/albums/x...es364Large.jpg
http://i763.photobucket.com/albums/x...es365Large.jpg
http://i1123.photobucket.com/albums/...i_girls_37.jpg
:) :)

Nice find. I remember when Hot Boat magazine was the best one out there.

Nice article Carl. Thanks for posting

I studied the entire article and what they ended up with is very close to a 525 EFI. They installed CMI headers, modified and ported the intake, did the same to the throttle body and did a lot of head work. Then they installed a roller cam with specs nearly the same as a 525 cam. They ended up with 543 hp @ 5,400 RPM. That happens to be where the rev limiter starts to hit on a 525 and is where I run my 525 on the top end. I've often read that the 525 actually puts out closer to 540 hp. The project engine made 594 Lb-ft torque @ 4,000 RPM where the 525 specs at 570 Ft-lb torque @ 3,800 RPM. The project engine was held to just a slight compression increase of the stock 8.75:1 which is the same as the 525. They also confirmed that with the lower compression ratio the engine runs best on 87 octane fuel and lost power with 92 octane. I will always run 87 octane in my 525 from now on unless I'm topping off old fuel.

I did a few projects with Jeff Koerner back then in the early days of MEFI 1 very nice to work with. Marine efi has come a long way since then. Great power from that manifold mod still works today.