Like Tree0Likes

502 MPI Upgrades

Reply
Old 06-16-2002, 10:34 AM
  #1
Registered
Thread Starter
 
formula271's Avatar
 
Join Date: Aug 2001
Location: Oswego,New York
My Boats: 1999 Formula 271
Posts: 157
Default 502 MPI Upgrades

Has anybody done any upgrades to these 502 MPI motors? I have had my ecm reprogramed and changed to a K&N filter which gained me a little more power. What about changing and/or modifying the heads, cam or intake? If so what heads or cam do you guys think will be the best to go with? What kind of cost are these upgrades going to be? No, I don't want to Whipple it or procharge it. I'm just looking to make another 50 or so hp. What is the difference between the 500hp and the 502 MPI besides about 55 hp? Thanks for any constructive input.
formula271 is offline  
Reply With Quote
Old 06-16-2002, 12:21 PM
  #2
I hate the winter!!
Platinum Member
 
Vinny P's Avatar
 
Join Date: Jul 2001
Location: long island, new york
My Boats: 99 checkmate 259
Posts: 2,707
Default

I was kicking this same ideas around for a while. After hearing of a few horror stories of inproperly re-mapped E.C.U.'s I decided against it. Someone on this board sent me this link to an article that did just what you want to do. http://www.azspeed-marine.com/articles-1a.html It sounds great, really an easy thing to do. BUT, if a few guys here on OSO can give you some of their stories, you may think twice about it. If you can get a hold of DirtLawyer, he can tell you of his problems.
My answer to the need for a little more power was finding an HP500EFI. I should have it delivered in a few days. I am not expecting a BIG increase in speed, but it will give me the 85 horsepower that I wanted to get from my 454 Magnum. Also, if you were to sell your 502 and couple that money with what the upgrades would cost, you can probably find a used HP500 for the same money. That way you increase the value of your boat, those Blue motors are worth something at resale.
Vinny P is offline  
Reply With Quote
Old 06-16-2002, 05:27 PM
  #3
Registered
 
Join Date: Oct 2000
Location: Knoxville,TN, USA
My Boats: 1986 Cigarette
Posts: 361
Default 502 MPI upgrades

Upgrades are straightforward and work extremely well for this engine. These upgrades are well documented and are widely available from reliable and reputable engine builders. There are several people with lot's of history in successful 502 MPI upgrades. Cam, lifters, roller rockers with screw in studs added, valve upgrades, ECM reprogramming, exhaust, and minor head work are the most common things I've seen. Additionally a .005 bore with J&E pistons with improved ring operation is a nice addition.

My word of advice. Only do these things with dyno tuning. You are just guessing otherwise. ECM programming is best left to those with experience.

If you are serious about making these upgrades call Performance Marine in Oshkosh Wis. Ask for Rod. He can make these motors work very well.

Good luck.
deboatmon is offline  
Reply With Quote
Old 06-16-2002, 10:09 PM
  #4
I hate the winter!!
Platinum Member
 
Vinny P's Avatar
 
Join Date: Jul 2001
Location: long island, new york
My Boats: 99 checkmate 259
Posts: 2,707
Default

You are right boatmon. Re-mapping an ecu should only be done on a dyno. I don't see how companies out there can say that they can get it right by just talking to you on the phone for a few minutes. I just feel that by the time you count up how much it costs to upgrade an engine right, you can step up to a better Mercruiser motor where you know it is right.
Vinny P is offline  
Reply With Quote
Old 06-16-2002, 10:43 PM
  #5
Registered
 
Join Date: Oct 2000
Location: Knoxville,TN, USA
My Boats: 1986 Cigarette
Posts: 361
Default 502 MPI upgrades

I kind of agree Checkmate. But, there are tons of 502 MPI/EFI available and they share many of the good parts from the HP 500 series. There are good used 502 EFI's available for around 5K. I would say with the upgrades I stated, you could spend another $3-5000.00 and have a great performing motor. Personally, I like the fuel injection systems for idle characteristics and good mid range torque. Like you said, maybe getting a good used HP 500 is better. But, maybe not. Both are good motors.

As for the flame arrestor/ECM upgrades, I've not heard any really strong user support. How about you ?
deboatmon is offline  
Reply With Quote
Old 06-17-2002, 09:34 AM
  #6
hauling ass-a
Guest
 
Posts: n/a
Default

Was just wondering, what horror stories are you talking about? I 'am running a arizona speed ecu and really have had no problems at all! Please fill me in dirty lawyer.
 
Reply With Quote
Old 06-17-2002, 09:52 AM
  #7
hauling ass-a
Guest
 
Posts: n/a
Default

Was just wondering, what horror stories are you talking about? I 'am running a arizona speed ecu and really have had no problems at all! Please fill me in dirty lawyer.
 
Reply With Quote
Old 06-17-2002, 12:14 PM
  #8
Registered
 
Cattitude's Avatar
 
Join Date: Jun 2001
Location: Tulsa, OK, Grand, Beaver, LOTO
My Boats: '97 Scarb Thunder, '06 Formula 330ss for sale
Posts: 1,213
Default It's all in fesibility and expectations

Lot's of options- spend a grand on ECU and flame arrestor for a GPS digit or two, Whipples on the other end. The middle ground may be viable if you are going to freshen the motor anyway. Otherwise you are spending on labor and goodies almost as much as a whipple for about 1/3 of the gain.

The HP500 swap is viable if you can cut the right deals, does add nicely to eye candy and resale.

Good luck!
Cattitude is offline  
Reply With Quote
Old 06-17-2002, 08:10 PM
  #9
I hate the winter!!
Platinum Member
 
Vinny P's Avatar
 
Join Date: Jul 2001
Location: long island, new york
My Boats: 99 checkmate 259
Posts: 2,707
Default

Hauling-ass:

Is that motor you are running stock or modified? I was considering doing a little work, such as heads, valves,cam, bumping the compression just a bit. With this in mind, enter e.c.u re-mapping. I can get the motor to make a little more power with no real trouble, but all of this hinges on the re-mapped e.c.u. I personnaly don't see how someone half way across the country can do the right job by just asking you a few questions on the phone. Every motor I have ever built always requires some tuning. Most importantly MIXTURE. In a carb, no problem screw in another jet, or power valve. What do you do with EFI? Do you send the ecu back a few more times until it is right? I didn't feel like getting involved with that. What really made my mind up is when I called a company that does ecu re-mapping and asked what they do to the program to make power in stock motors, they told me that they lean out the mixture, and increase timing advance. So I asked him how does ADVANCING the timing, and leaning out the mixture bring you more top end power? He told me that is how motors would react to that kind of change. SO, I laughed in his face and hung up the phone. Now maybe I spoke to someone who usually cleans the bathrooms and was walking by the phone when it rang, I really don't know. In any case, I stick with my original thoughts, a modified motor should only have the ecu re-mapped on a dyno, where conditions could be properly monitored and the ecu can be set up according to the data.
Vinny P is offline  
Reply With Quote
Old 06-18-2002, 08:51 AM
  #10
hauling ass-a
Guest
 
Posts: n/a
Default

my motor is a 502 and it is stock. After talking with a few people about this issue I have come up with a conclusion about the ecu re-mapping. With my motor I did not re-map to gain top speed, I was told this change would only effect the low end and midrange. I have had no problems at all, my midrang was the biggest improvment! After talking with arizona speed they told me mercruiser loads up their lower end and has a little less timing advance. If you are looking to gain major improvements on the top end this would be a waste of money. I actually bought my re-mapper ecu of the classifed section of oso. I figured for $400 I got another ecu reprogrammed from arizona and if it didn't work I would have a spare to compare it with. Efi motors are fun to try and get big power without doing all kinds of mods. Personally if I knew I was going to keep this boat for 5 more years I would have whipple charged it!!!!! I still think you can't beat the whipple!!!
 
Reply With Quote
Reply

Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Jean-Claude
General Q & A
2
05-26-2007 06:07 AM
gferdon
General Q & A
8
01-11-2004 05:23 PM
hauling ass-a
General Q & A
4
09-12-2003 09:49 AM



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 05:39 PM.


Copyright 2011 OffShoreOnly. All rights reserved.