Fuel injection for 496

Automotive powered airboat discussion.
SHOOTER250
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Fuel injection for 496

Postby SHOOTER250 » Sat Jan 20, 2018 5:55 pm

Looking to switch from pro systems 850 to FI
on a 700 hp 496. Not looking for performance boost, trying to stop dieseling at shut down
Is anyone running FI if so what kind and pros and cons
Any advice would be appreciated

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Deano
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Re: Fuel injection for 496

Postby Deano » Sat Jan 20, 2018 7:34 pm

There is quite a bit of (what I perceived to be) good, usable information in this thread:
https://southernairboat.com/phpBB3/viewtopic.php?f=48&t=70926&p=683178
I guess how valuable it is to you depends on what you already do and don't know.
I found it to be enlightening, but I admittedly don't know much about that.

There is a lot of such information all over the board.
The [Search] function (above right) would likely yield volumes.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
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Aeon
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Re: Fuel injection for 496

Postby Aeon » Sat Jan 20, 2018 10:05 pm

For a 700hp motor you could do one of the holley hp setups with new intake, throttle body, injectors and you will need a new distributor and fuel pump and regulator with both pre and post pump filters. Your tank will need a place for the return line as well. This will run you a bit over 5k. Call holley and they can spec you out. The only thing that's hard for the diy guy is the two bungs on the headers for the o2 sensors. The rest is pretty much plug and play. The boat will idle and start like a dream and you can keep af ratios spot on.

Have you thought about taking it to a tuner that can get your idle purfect and air fuel mix right with what you have? Sometimes just a bit less rpm can fix it
17x8 Circle H powered by a TurnKey LS3, 2.55 ox box and 82" 3 blade JX

Aeon
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Re: Fuel injection for 496

Postby Aeon » Sat Jan 20, 2018 10:07 pm

https://www.summitracing.com/parts/hly-550-838
With dist, pump, regulator and injectors
17x8 Circle H powered by a TurnKey LS3, 2.55 ox box and 82" 3 blade JX

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Re: Fuel injection for 496

Postby ladyblackwater » Sat Jan 20, 2018 11:09 pm

I went to the Holley Hp Efi for the reason you are thinking about going to it. I will say after going to the Holley Efi you will NEVER want another carb again. It's a pretty simple system. The only thing you will need to add is 1 bung in header for O2 sensor, high pressure fuel pump and regulator. The best and easiest is the fuel filter regulator that GM uses. It should only cost you about $3500 to change it over and believe me you will be glad you did.
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Re: Fuel injection for 496

Postby loudmouse » Sun Jan 21, 2018 8:52 pm

The carb isn't causing the dieseling the tune of the engine is.
15' Alumitech deckover LSX TT Oxbox 84" JX 4-blade
Gas required Water optional :dontknow:
Built and Tuned by Me
14'X8' JW, Chevrolet 122CID LNF Turbo Engine, Ox box, 80" NGR 3 blade

Life is short, eat your dessert first! :downtown:

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Re: Fuel injection for 496

Postby ladyblackwater » Sun Jan 21, 2018 11:21 pm

Loudmouse believe me it's the crap fuel when are running. I had the number one carb guy is in the US. build me and tune a carb and still couldn't get it to run consistent because the fuel isn't consistent. When you are running big blades the rotating mass with the high temps of the cylinder from junk fuel it's going to diesel. You have to remember even when you turn the power off to the motor and the prop is still spinning then the carb is dumping fuel. That can not happen with injection because there is no way for the fuel to flow without power to the injectors. The only other way to make it work is to build the motor with less power so it can run on lower octane (grade) fuel.
Greater love hath no man, than to lay his life down for a friend.

Bitterly clinging to my guns and my religion!

I am that conservative republican your momma warned you about!

loudmouse
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Re: Fuel injection for 496

Postby loudmouse » Mon Jan 22, 2018 6:39 am

I have a 572BBC with a 2.38 box and 4 blade NGR no dieseling. A 406SBC with 2.3 belt box 3 blade NGR no dieseling. I don't care who built the carb If your engine is dieseling then it's in the tune. Tuning is what I do and every engine that is done the problems have magically disappeared while continuing to run the same pump gas as always. Tuning an engine is alot more than just the carb though. Low timing and lean mixture most of the time is what causes the run on after the key is switched off. Most carb builders spec carbs for engines in a automobile which doesn't present the load that airboat engines experience. Think about how many drag cars you have every heard diesel? None and they have the same engines and same carbs. It's all in the tune
15' Alumitech deckover LSX TT Oxbox 84" JX 4-blade
Gas required Water optional :dontknow:
Built and Tuned by Me
14'X8' JW, Chevrolet 122CID LNF Turbo Engine, Ox box, 80" NGR 3 blade

Life is short, eat your dessert first! :downtown:

SWAMPHUNTER45
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Re: Fuel injection for 496

Postby SWAMPHUNTER45 » Mon Jan 22, 2018 7:45 am

Allowing the tops of the pistons to cool prior to turning off the ignition can also help to alleviate some of the run on. Generally as a rule we allow the engine about 20 to 30 seconds to come down then cut the fuel pump prior to killing the power.

I had experienced some run on over the summer and Mr Branch lowered my idle slightly and leaned my idle circuit about a 1/4 turn.

Long stroke engines build a high level of vacuum and in turn pull fuel easier than a short stroke build. I think a good carb man reading your plugs and pipes could get you fixed up.

SWAMPHUNTER45
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Re: Fuel injection for 496

Postby SWAMPHUNTER45 » Mon Jan 22, 2018 9:18 am

Black water $3500 to change over is that correct I thought it was cheaper ?

loudmouse
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Re: Fuel injection for 496

Postby loudmouse » Mon Jan 22, 2018 10:32 am

A couple hundred to tune it in would be money well spent. Easier Cranking, better throttle response, more power, smoother running and no dieseling. It's a no brainer. Now that's not saying that efi is bad jus that it also has to be tuned correctly for a proper running engine. Good luck whichever route you take.
15' Alumitech deckover LSX TT Oxbox 84" JX 4-blade
Gas required Water optional :dontknow:
Built and Tuned by Me
14'X8' JW, Chevrolet 122CID LNF Turbo Engine, Ox box, 80" NGR 3 blade

Life is short, eat your dessert first! :downtown:

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Re: Fuel injection for 496

Postby ladyblackwater » Mon Jan 22, 2018 9:14 pm

Loudmouse I've been right where you are at with carbs and said I would NEVER go to EFI but I've learned my lesson that on an Airboat the only way you to go is EFI. Believe me Ed Mac knows what he is doing when it comes to tuning a carb. He travels all over just to tune peoples carbs for weather change at race tracks. I'm not saying it can't be done but it sure isn't worth the headache when EFI gives you so much more tune ability. The only way you could ever get a carb to perform the best on an Airboat is to have a dyno that hooks up to the complete set-up. No one has that, that I know of anyway. With the EFI I can tune it at every rpm while I'm running the boat under a load. You can't get any better tune than that.You can do what Swamphunter said with letting it idle for a few before you shut it down. I don't have that option with what I do because I'm on and off the key over 30 times in a 2 hour wind.
Last edited by ladyblackwater on Tue Jan 23, 2018 1:09 am, edited 1 time in total.
Greater love hath no man, than to lay his life down for a friend.

Bitterly clinging to my guns and my religion!

I am that conservative republican your momma warned you about!

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Re: Fuel injection for 496

Postby ladyblackwater » Mon Jan 22, 2018 9:18 pm

Swamphunter for everything to change over to EFI was right about $3500 and that's turn key. I also bought new headers because I needed the O2 bung anyway and had the headers built to match the motor. Now the $3500 doesn't include the touch screen digital dash I bought but that isn't something you have to have. It was just something that made my life easier.
Greater love hath no man, than to lay his life down for a friend.

Bitterly clinging to my guns and my religion!

I am that conservative republican your momma warned you about!

SWAMPHUNTER45
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Re: Fuel injection for 496

Postby SWAMPHUNTER45 » Mon Jan 22, 2018 11:01 pm

Gotcha

Starting a new engine and Branch thru out the idea of fuel injection but an extra $3500 is a bit over the budget.

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Jason Finser
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Re: Fuel injection for 496

Postby Jason Finser » Tue Jan 23, 2018 1:01 am

I have seen EFI engines dieseling as well. (No idea how it happens on EFI, but I have seen it)

Oddly enough when I personally had a dieseling issue with my carbed BBC 502 it was a combination of 2 issues. My throttle wasn't closing all the way. Not enough to notice an increased idle, but just enough to allow it to diesel, and adjusting the distributor/timing 1/2 degree one way or the other would stop it, or allow it to happen. It took a while going back and forth trying to get it just right.

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One Eyed Gator
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Re: Fuel injection for 496

Postby One Eyed Gator » Tue Jan 23, 2018 3:51 pm

Swamp Look at the FItech they have some interesting stuff that might fit your needs.

I am sure in total the EFI system is expensive, Holley HP is around 1750.00 just to get started and if you need customer service your really in trouble.

SWAMPHUNTER45
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Re: Fuel injection for 496

Postby SWAMPHUNTER45 » Tue Jan 23, 2018 4:41 pm

Yea Mr. Branch was pushing me saying this next build would be a prime FI candidate. It seems complex to this old school mind as I would need new fuel pump set up with a return and the wiring then adding bungs etc.

A 950cfm annular just seems so much more simple to me Mike!

One Eyed Gator
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Re: Fuel injection for 496

Postby One Eyed Gator » Wed Jan 24, 2018 7:01 am

The FI tech has TB system that work with your dist and would sit on top of you intake.

I know you like to research check it out, fairly inexpensive as well.

It has taken along time for me to move towards EFI still running a carb myself But i do have everything I need to go efi except ecm and TBSS intake on my next motor.

And I like the annular boosters seems to help with throttle response. I am sure your motor will be a beast.

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Re: Fuel injection for 496

Postby loudmouse » Wed Jan 24, 2018 8:37 am

Ladyblackwater, while EFI is better a carb can be tuned to run absolutely perfect and crank easy. The only issues that I see with them is if ur boat sits alot moisture will condensate in the bowls and cause the engine to miss. That's why I recommend cranking them at least every 2 weeks and allow the engine to warm up to 180° before shutting it off. Otherwise you will need to clear the bowls of the water b4 she will run right. Not as bad in summer months as winter but still occurs when we are having alot of rain.
15' Alumitech deckover LSX TT Oxbox 84" JX 4-blade
Gas required Water optional :dontknow:
Built and Tuned by Me
14'X8' JW, Chevrolet 122CID LNF Turbo Engine, Ox box, 80" NGR 3 blade

Life is short, eat your dessert first! :downtown:

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Deano
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Re: Fuel injection for 496

Postby Deano » Wed Jan 24, 2018 1:02 pm

SWAMPHUNTER45 wrote: . . It seems complex to this old school mind as I would need new fuel pump set up with a return and the wiring then adding bungs etc. . .

Reading that, I can't help but point out that you never miss a chance to imply I'm a low tech caveman (and I maybe I am). :wink:

I got a pile of rusty junk in the corner. If I win the lottery tonight, I'll race you to fire an EFI Caddy; you'll have the head start. 8)

Come on Swampy . . . get off that wallet !! . . :D
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan

SWAMPHUNTER45
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Re: Fuel injection for 496

Postby SWAMPHUNTER45 » Wed Jan 24, 2018 2:14 pm

Just ordered a hand built 950cfm annular

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Deano
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Re: Fuel injection for 496

Postby Deano » Thu Jan 25, 2018 8:40 am

Just as well . . . I'm sorry to say I the bets off, at least 'til Saturday night. :lol:
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
- Carl Sagan

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F0zzy2
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Re: Fuel injection for 496

Postby F0zzy2 » Sun Feb 11, 2018 10:05 pm

https://www.summitracing.com/parts/fif-30008
https://www.summitracing.com/parts/aei-18688
I put the mean street on my 580 for about $1500 and am pretty happy with it. Easy to tune, no more dieseling but no real increase in fuel efficiency. I ran it all last year with no problems. My only complaint is I would like to plug it into a digital dash but FI tech is not compatible so your stuck with their small controller screen.
18X8 Silverdollar- 580 BBC- CH-4 2.67 ratio - 4 84" S Series Blade


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