Modifying a 502EFI
09-16-2002 | 12:16 PM
#1
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From: Baton Rouge, LA
Modifying a 502EFI
I touched on this in another thread but will start a new one also.
I am planning on modifying my 502 EFI in my 27 Fountain for more power this winter. The boat has 70 hours on it now. I am not interested in supercharging so lets not go there. I am planning on keeping the original EFI system but modifying it to support the added power. This is my main concern, the EFI. I have no idea how far from the original engine paremters I can go. Anyone with any experience with this please offer your experience and opinion.
This is what I plan to do. My goal is to have somewhere between 550 and 600 hp at the flywheel.
K&N flame arrester (already have)
CMI exhaust, either the elbow tops and retain stock Corsa diverters or the new HP525EFI style with Teauge switchable tips if needed.
Head work, keeping the original heads with a mild port job and milling to bring the compression ratio up to around 9.4 to 1. Adjustable roller rockers and valve springs to match new cam.
Camshaft, change cam to something that makes more power and allows me to retain the EFI and use the less expensive CMI E-Tops with the Corsa diverters if possible. Any recomendations? I will call several Cam manufacturers to get their picks based on the engine and use.
EFI mods, adjustable regulator and reprogrammed ECU to suit new engine. Any other mods needed such as throttle body, injectors, plenum spacers or work?
Who to use for the EFI programming and set up?
Does anyone out there have a proven combination similar to this? If so what kind of power did it produce?
Whats your opinion Dennis? Your advice has been very helpful in the past.
Ron
I am planning on modifying my 502 EFI in my 27 Fountain for more power this winter. The boat has 70 hours on it now. I am not interested in supercharging so lets not go there. I am planning on keeping the original EFI system but modifying it to support the added power. This is my main concern, the EFI. I have no idea how far from the original engine paremters I can go. Anyone with any experience with this please offer your experience and opinion.
This is what I plan to do. My goal is to have somewhere between 550 and 600 hp at the flywheel.
K&N flame arrester (already have)
CMI exhaust, either the elbow tops and retain stock Corsa diverters or the new HP525EFI style with Teauge switchable tips if needed.
Head work, keeping the original heads with a mild port job and milling to bring the compression ratio up to around 9.4 to 1. Adjustable roller rockers and valve springs to match new cam.
Camshaft, change cam to something that makes more power and allows me to retain the EFI and use the less expensive CMI E-Tops with the Corsa diverters if possible. Any recomendations? I will call several Cam manufacturers to get their picks based on the engine and use.
EFI mods, adjustable regulator and reprogrammed ECU to suit new engine. Any other mods needed such as throttle body, injectors, plenum spacers or work?
Who to use for the EFI programming and set up?
Does anyone out there have a proven combination similar to this? If so what kind of power did it produce?
Whats your opinion Dennis? Your advice has been very helpful in the past.
Ron
09-16-2002 | 03:12 PM
#2
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Joined: Apr 2001
Posts: 313
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From: Charleston, WV
Corsa told me they don't reccomend over 500 hp on thier diverted system. I changed to Gil 4" wet exhaust and K&N flame arresters, started bumping the rev limiter. Changed 28p to 30p Bravo 1 props. Been smiling ever since.
09-16-2002 | 03:23 PM
#3
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I think the best place to start is with Arizona Speed and Marine.
Don't take everything they say as the gospel truth but you can learn a lot from them! Always remember that their first priority is to make money! (like any good business) That being said, I think that they have the most experience with modifying Merc EFI engines.
Give them a call and ask them about engine packages, if you follow the package that they recommend then they will know exactly how to program your computer. If you deviate from there suggestions it could be a frustrating ordeal getting the computer right on.
Hope this helps!
Sincerely
Dennis Moore
Don't take everything they say as the gospel truth but you can learn a lot from them! Always remember that their first priority is to make money! (like any good business) That being said, I think that they have the most experience with modifying Merc EFI engines.
Give them a call and ask them about engine packages, if you follow the package that they recommend then they will know exactly how to program your computer. If you deviate from there suggestions it could be a frustrating ordeal getting the computer right on.
Hope this helps!
Sincerely
Dennis Moore
09-16-2002 | 04:01 PM
#4
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Posts: 1,070
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From: Baton Rouge, LA
I am not planning on using ASM. I have read a few horror stories about them on this board plus they are too far away. If you read their ads you would think they were the best place to go for this stuff. Business is business though. There are two local companies around here that do EFI programming. Precision Marine and Total Performance and Marine and they both have dyno facilities.
I was just trying to get the opinion of people on this board before I talked to a local guy. You know try to find out what I really need to do as opposed to what a business wants to sell me. I think that is the key to making my project work the way I want it to.
Anyone else? I know many people have this engine in their boats and Im sure some have modified it.
Ron
I was just trying to get the opinion of people on this board before I talked to a local guy. You know try to find out what I really need to do as opposed to what a business wants to sell me. I think that is the key to making my project work the way I want it to.
Anyone else? I know many people have this engine in their boats and Im sure some have modified it.
Ron
