how to make more h.p.out of 502 mag?

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02-16-2009 | 10:33 PM

#11

KAAMA

Registered

Joined: Oct 2000

Posts: 4,541

Likes: 107

From: Western Michigan

Quote:

Originally Posted by jeffswav

If you are planning on keeping the boat and adding further upgrades later. If you are do the exhaust first then do other mods later. It will only yeild you about 1 or 2 mph but exhaust is needed for cam upgrades. I use EMI with long stainless risers.

That's a great idea! A better breathing aftermarket exhaust system is what you really need FIRST when doing mods/upgrades.

02-18-2009 | 06:11 AM

#12

GLH

Platinum Member

Joined: Dec 2002

Posts: 15,270

Likes: 21

From: Burlington, VT

Quote:

Originally Posted by RichardCranium572

Whipplecharge it

"Run some boost through that biatch"

That is the first answer I saw when I got on OSO years ago and it still works today!

02-18-2009 | 07:21 AM

#13

TylerCrockett

Michigan Mad Man

Joined: Feb 2003

Posts: 1,172

Likes: 2

From: Ruby, Mi

I have a kit on my website we have been doing for over 9 years that picks almost 100 HP and 100 # of torque. crockettmarineengines.com

02-18-2009 | 01:20 PM

#14

rssteiny

Registered

Joined: Jul 2002

Posts: 2,233

Likes: 1

From: pa

i have a set of gils off my hp500s i might sell as well as a set of heads ,the heads need refreshed also a pr of cams as i am refreshing and powering up, my heads and cams and exhaust will get you where you want to be and more.

pm me if intrested

Last edited by rssteiny; 02-18-2009 at 01:23 PM.

02-18-2009 | 05:55 PM

#15

formula 382 sr-1

Registered

Joined: Dec 2006

Posts: 2,494

Likes: 1

From: Chesapeake Bay

Quote:

Originally Posted by ricric

hello fellow boaters,how can i "bolt on" more horsepower to my stock merc 502 mag (1997 model).? already thinking of relatively inexpensive gil exhuast-any thoughts?what else for quick add-ons?trying to acheive around 450-475 hp range without serious modification.thank you:

I have a set of hp500 heads that have bigger valves then what you have . The mag came with 2.190 intake & the hp500 came with 2.250, they will help you get you where you want to be.

02-20-2009 | 01:44 AM

#16

CB-BLR

Chris

Joined: Sep 2005

Posts: 1,426

Likes: 1

From: Snohomish, WA

call Bob Maderia aka RMBuilder at 585-654-8583

Chris

09-20-2021 | 06:27 PM

#17

Clemat

Registered

Joined: Mar 2021

Posts: 3

Likes: 0

Fountain lightning build

Quote:

Originally Posted by ctuck0659

I'm in the middle of rebuilding my 502's to around 500 h.p. using the set-up recommended by Mark Boos at Precision Marine. There's no real short-cuts or single component upgrade- you're either "all-in" or you're wasting your money. I'll have close to 10K invested in 2 engines when all is said and done, and that's with used Gil's

I have a 1998 35 lightning and lost a motor the other night. I’m about to pull both of them out and have them both rebuild just to be safe, what’s your build sheet to be around 500hp?

09-20-2021 | 08:03 PM

#18

Griff

Charter Member # 55

Joined: Oct 2000

Posts: 20,272

Likes: 2,513

From: Omaha/LOTO

Quote:

Originally Posted by Clemat

I have a 1998 35 lightning and lost a motor the other night. I’m about to pull both of them out and have them both rebuild just to be safe, what’s your build sheet to be around 500hp?

This is a 12 year old thread, so I doubt you'll get a response from him.

Here is a 502MPI build thread 502 MPI upgrade results