Wild conversion thougt
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=1892
Printed Date: November-22-2024 at 8:19pm
Topic: Wild conversion thougt
Posted By: keuka1
Subject: Wild conversion thougt
Date Posted: June-17-2005 at 9:41am
What do you all think about changing a 1986 351 from carb to fuel injection? Worth it cost wise and/or perfomance wise?
Thanks
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Replies:
Posted By: GottaSki
Date Posted: June-17-2005 at 11:17am
I recommend spending the money on heads, a fresh carb and hot ignition.
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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Posted By: Nautique2001
Date Posted: June-17-2005 at 11:44am
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I have a 1986, SN 2001, with 351. I wouldn't covert over if I were you. The engine starts and runs smooth when everything is tuned right. The only advantage to FI to me would be the initial start up. If your boat is like mine, you don't need to give it gas to start it again when it's warm. That's my opinion.
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Posted By: Jim_In_Houston
Date Posted: June-17-2005 at 11:53am
Gottaski is right on! Good advice.
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Happy owner of a '66 and a '68 Mustang
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Posted By: David F
Date Posted: June-17-2005 at 1:13pm
Keuka1:
Not a crazy thought...I almost went that route with my '77 Martinique so the wife would feel more comfortable taking the boat out by herself. She has never been too comfortable starting the cold engine and getting if off the trailer due to the initial high idle caused by the choke. And then if she blipped the throttle to release the high idle it might die on her....
So, the only real retrofit EFI option is Holley's TBI setup. I think it runs about $1500.00. In fact it is basically the same unit that PCM used in '94 and '95. A few years ago, Skidim stated in their catalog that would soon offer a EFI retrofit kit...they never did. I wonder why?
There is someone who has posted here in the past who is attempting to craft an automotive Ford MPI unit to his engine, but he has not updated us on the progress or success/failure. The biggest challenge most of us saw to this project was incorporating the O2 sensor so that the automotive ECM would produce a proper enrichment map and not go open loop on the O2 sensor. To my knowledge, no marine EFI engine has an O2 sensor.
Good luck.
Follow-up: I think you want to look for the Holley part # 700-52. This is the 4-bbl version for small engines rated between 255-400 HP.
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Posted By: workky
Date Posted: June-17-2005 at 10:22pm
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I have a holley projection unit on my 1984 2001.Runs great.It's very easy to start.I never really checked the GPH,dont really have to,seems to get good fuel consumption
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Posted By: Jim_In_Houston
Date Posted: June-17-2005 at 10:40pm
Show me somebody that gets good fuel consumption and I'll show you somebody that leaves their boat parked.
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Happy owner of a '66 and a '68 Mustang
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Posted By: GottaSki
Date Posted: June-19-2005 at 4:29pm
workky, tell us more..
I had heard the projection was fine for baja-runner wanabbees that go up and down the lake at WOT, but not so good for throttle-response junkies like us...did you make it work?
My experience is the fuel mix is not the limiting factor on the Windsor engines.
Why did you switch? Would it be fruitless without your better gt40 heads? Would you do it again?
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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Posted By: axlr8or
Date Posted: June-19-2005 at 8:55pm
Hello Keuka1.
The changeover sounds like a great idea, and I've thought of it, also. I wanted to use a multiport fi engine from a Dodge truck in the barracuda. The requirements for programming a custom computer for this purpose is relatively small, and the pic 12f676 chip and related components are extremely cheap (The mcu 'computer chip' is about 3 dollars. (the expense is research and writing the program)
BUT, most people have 'heard' of FI, but really don't understand its advantages.
1. Cold start (yeah, everyone knows that)
2. Auto 'dialability' (automatic tuning)
3. Improved fuel efficiency (more on that in a moment)
4. Reliability
Understand that a properly tuned carbuerated engine will produce as much horsepower as its FI alternative. It will not do this as efficiently. The actual benefit of FI is in the 'MultiPort' configuration and concerns cylinder washout. Advanced cam timing, inductance, and simultaneous exhaust/intake valve layover purges and moves more air through the cylinder (removes more exhaust out and brings in more fresh air). This is great in multiport, because it then injects fuel at the end of this cycle, and right on time. In a carbuerated engine the system works much the same, but the only air the cylinder can get has already been fuel enriched. So, out goes fuel into the exhaust system during the valve layover. The net effect is the same, just with fuel being wasted.
The TBI unit works similar to the carbuerated model. TBI was a 'hold em off' stage so manufacturers had time to perfect the multiport system. They got to use all of the old tek for intakes and spark n' stuff.
My biggest reason for the same idea is fuel economy. 210 HP (not really) in a boat of this weight with its hull configuration throws fuel in to the lake.
But anyway, if you wanna do the conversion for the 'neato factor' by all means. I wish I had the time to throw at it. For practicality sake, though, best advice was already given by 'Gottaski'. Your money and gas will go much farther with his suggestion.
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