Ateco 500efi upgrade
#21
Registered
Joined: Jan 2004
Posts: 4,480
Likes: 43
From: Tennessee
Unless you do all the things like Offshoredrillin is describing you probably are not going to see 600HP from a 500efi that will live and certainly not from a 502EFI (MPI) engine intake manifold and throttlebody!
Eddie Young knows and he has the experience to back that up too.
Just my experienced and work based two cents!
Best Regards,
Ray @ Raylar
Eddie Young knows and he has the experience to back that up too.
Just my experienced and work based two cents!
Best Regards,
Ray @ Raylar
#22
Banned
Joined: Mar 2002
Posts: 2,103
Likes: 3
From: michigan
My engine started out as a 500 EFI. Bored and stroked to 540, AFR heads, Bob Maderra custom cam, stock untouched intake with the Tyler Crockett top mount throttle body kit. Aeromotive 1000 fuel pump and 55lb injectors. Assembled and dyno'd by Mark at M.E.R Performance 693hp at 6000rpm. Jeff Wurl
#24
Registered
Joined: Nov 2005
Posts: 107
Likes: 0
From: New Castle, DE
Correct fuel system is a must. My new engine blew with only 19 hours running time. My fuel system was upgraded but still had low and inconsistent fuel pressure. The builder installed fuel pump was replaced and I now have consistent fuel pressure. The builder returned the fuel pump to the manufacture for testing (?) and I am waiting to hear the results.
#25
Banned
Joined: Sep 2007
Posts: 12,849
Likes: 3
From: Frankfort,ill
Correct fuel system is a must. My new engine blew with only 19 hours running time. My fuel system was upgraded but still had low and inconsistent fuel pressure. The builder installed fuel pump was replaced and I now have consistent fuel pressure. The builder returned the fuel pump to the manufacture for testing (?) and I am waiting to hear the results.
#27
Banned
Joined: Mar 2002
Posts: 2,103
Likes: 3
From: michigan
You are not pull much over 600 HP with a stock "untouched" intake.... that is both upper and lower without magic voodoo nobody else can get. I would still like to see your sheets thats with both corrected and uncorrected numbers.
#28
Registered

Joined: Feb 2006
Posts: 519
Likes: 15
#29
Registered
Joined: Jan 2004
Posts: 2,777
Likes: 12
From: San Diego, California
On our Raylar HP675efi upgraded HP525efi we went to 540 inches also, our CNC program and valve and spring upgrades on the stock Mercury/Edelbrock heads, bigger injectors AND serious rework and new plenum on the stock Merc Racing manifold and got to 675HP at 5600 rpms.
So with good AFR heads, and a better air delivery thru Tyler's throttle body/top manifold kit and Mark's good build, I think 693HP at the higher 6000rpm is possible, especially with the bigger cam duration it might take.
We just kinda engineered our offering for the 675HP max., we think the Bravo XR in average use can take and at 5600 rpm rev-limit where we feel the engine will live for 400-700 hours without valve train life issues. We try and build design and build for endurance not biggest HP numbers. Most performance boaters in TODAY'S economy cannot afford nor want to redo their engines every two - three years!
In any event , nice results, good job and I hope that engine runs forever!
Best Regards,
Ray @ Raylar
So with good AFR heads, and a better air delivery thru Tyler's throttle body/top manifold kit and Mark's good build, I think 693HP at the higher 6000rpm is possible, especially with the bigger cam duration it might take.
We just kinda engineered our offering for the 675HP max., we think the Bravo XR in average use can take and at 5600 rpm rev-limit where we feel the engine will live for 400-700 hours without valve train life issues. We try and build design and build for endurance not biggest HP numbers. Most performance boaters in TODAY'S economy cannot afford nor want to redo their engines every two - three years!
In any event , nice results, good job and I hope that engine runs forever!
Best Regards,
Ray @ Raylar
#30
Registered
Joined: May 2007
Posts: 61
Likes: 0
From: east greenville pa.
I can't post the sheet but it was 598hp@ 5200 and 659tq @ 3800.
The heads flowed [email protected] minor porting.I have a Arizona Speed ramjet intake on it.I can look up the specs for the cam.Any questions feel free to ask.
The heads flowed [email protected] minor porting.I have a Arizona Speed ramjet intake on it.I can look up the specs for the cam.Any questions feel free to ask.


