efi limited?
07-26-2003, 12:18 PM
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efi limited?
My HP500efi seems lazy during the summer.(no air in the south)If I wanted to make 575-625hp should I go to a carb set-up?Ofcourse I mean after heads,raise c.r. to 9:1etc. Any ideas? Bob
07-26-2003, 12:27 PM
#2
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That's about your only choice...
It is pretty hard to modify an EFI engine without having a close relationship with an EFI computer programmer around. It is really a hit and miss proposition sending the computer away to have it reprogrammed for a
do-it-your-self engine builder. Many of the so-called EFI experts can't be trusted to deliver on their promises.
Sincerely,
Dennis Moore
do-it-your-self engine builder. Many of the so-called EFI experts can't be trusted to deliver on their promises.
Sincerely,
Dennis Moore
07-26-2003, 02:00 PM
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Sure you can....
You should have no problem making that kind of HP given the changes that you are planning on making (heads, cam, etc.). The Mercury Racing EFI system is more than adequate to handle that power level, provided you afford the fuel injection system the same consideration that you do the long block.
Your issue with performance in the south in hot summer months is not due to the limitations of the fuel injection system, it is the direct result of warm water temperatures, hot air temperatures, and high humidity. Whether you have a carburetor or EFI, if you can not get more or better air to the engines in the heat of the summer you will lose some performance. We made great strides with our boat to get more air in to improve breathing, but we still run summer and winter props to stay at maximum RPM - 30's in the summer and 32's in the winter (although this summer, the 32's are still the prop's of choice).
With respect to the ease of reprogramming or the trustworthyness of perspective EFI reprogrammers, Dennis Moore's comments unfairly (in my experience and opinion) paint a very few individuals with a very broad brush. You can and will run into all of the same issues with a bad (carbureted) engine shop and package as you will with an EFI program. You need to work with someone you trust and respect for anything to work.
My two cents.
Your issue with performance in the south in hot summer months is not due to the limitations of the fuel injection system, it is the direct result of warm water temperatures, hot air temperatures, and high humidity. Whether you have a carburetor or EFI, if you can not get more or better air to the engines in the heat of the summer you will lose some performance. We made great strides with our boat to get more air in to improve breathing, but we still run summer and winter props to stay at maximum RPM - 30's in the summer and 32's in the winter (although this summer, the 32's are still the prop's of choice).
With respect to the ease of reprogramming or the trustworthyness of perspective EFI reprogrammers, Dennis Moore's comments unfairly (in my experience and opinion) paint a very few individuals with a very broad brush. You can and will run into all of the same issues with a bad (carbureted) engine shop and package as you will with an EFI program. You need to work with someone you trust and respect for anything to work.
My two cents.
07-26-2003, 02:15 PM
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You are next door to to Precision Marine in Kenner La. He does a lot of EFI work. Did a good job of reprogramming my ECU on a 502 with headers.
www.precisionmarine-efi.com
www.precisionmarine-efi.com
07-26-2003, 02:33 PM
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Thanks guys.Padraig,I've been to Precision and your right.Mark & Billy are great.They know what there doing and take good care of there customers.My race car has three side drafts and I can do anything with them.I guess I'm just use to making changes when I want to.Boat runs great in the winter.Thanks for the comebacks. Bob
07-26-2003, 02:41 PM
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Much easier
A reprogrammer has an almost impossible job, tuning an engine that he doesn't have access to and can not be tested immediately after the changes have been made. It is really a crap shoot on his part and something that is hard to do without much customer and reprogrammer frustration. The only way he can reprogram your engines ECM accurately is by running your engine on his dyno or making changes to the ECM after a thorough, on the water, test session.
It is much easier to adjust ignition timing and rejet a carburetor than it is to find a man that can reprogram a computer for a particular engine/boat combination. It really becomes a hassle when every minor tuning change involves removing the ECM and mailing it off to the computer expert.
The only way that the AVERAGE GUY will ever be able to REALLY MAKE a MODIFIED Mercruiser EFI work as well as a carburetor, is when someone sells an affordable computer that replaces the standard GM MEFI ECM or Motorola PCM and can be reprogrammed in the boat, by the engine builder, as the boat is being tested. We are getting close, but not yet.
Sincerely
Dennis Moore
It is much easier to adjust ignition timing and rejet a carburetor than it is to find a man that can reprogram a computer for a particular engine/boat combination. It really becomes a hassle when every minor tuning change involves removing the ECM and mailing it off to the computer expert.
The only way that the AVERAGE GUY will ever be able to REALLY MAKE a MODIFIED Mercruiser EFI work as well as a carburetor, is when someone sells an affordable computer that replaces the standard GM MEFI ECM or Motorola PCM and can be reprogrammed in the boat, by the engine builder, as the boat is being tested. We are getting close, but not yet.
Sincerely
Dennis Moore
07-26-2003, 03:14 PM
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Dennis,
Precision Marine that is in his town is a great programmer. He has done hundreds of mods like Bob wants. They have a dyno there and have baselines for mods to the popular motors. Im sure he has done something in the past exactly like he wants. I spoke to him this spring and included in the dyno/program fee is an in water tune of the ecm to set the idle. I was building a clone of a 500EFI and he said 550-600 hp with mostly stock equipment is possible. With Dart Pro 1 heads and a raised compression ratio more is possible. In fact a local cat with twin 500EFI's modified by Precision with the Dart heads and other fuel system mods won the P-1 class in the SBI Worlds last November. Im still saving for the Darts.
ps: Picked up a copy of Trucking a couple of months ago while waiting at an airport.
Ron
Precision Marine that is in his town is a great programmer. He has done hundreds of mods like Bob wants. They have a dyno there and have baselines for mods to the popular motors. Im sure he has done something in the past exactly like he wants. I spoke to him this spring and included in the dyno/program fee is an in water tune of the ecm to set the idle. I was building a clone of a 500EFI and he said 550-600 hp with mostly stock equipment is possible. With Dart Pro 1 heads and a raised compression ratio more is possible. In fact a local cat with twin 500EFI's modified by Precision with the Dart heads and other fuel system mods won the P-1 class in the SBI Worlds last November. Im still saving for the Darts.
ps: Picked up a copy of Trucking a couple of months ago while waiting at an airport.
Ron
07-28-2003, 08:51 AM
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Ron,I'm saving for the Darts also.My plan is to do the engine and let Mark set it up on his dyno.Mark did tell me the HP was very sensentive to changes in the weather.I'm just programed from my car to be able to make changes any time I want to.Thanks everyone for getting back to me. Bob
