Michigan Boarder Engine Blueprint and Build

[WheelerWake]

490 lb-ft torque is big block territory. That means you won't have to run low pitch prop just get it out of the water with ballast. You also won't be buzzing the motor just cruising.

[Michigan boarder]

Yes, there was vid and pics, and get that all done soon. Had to work today, then do the yard in the pouring rain, now just took a break from watching the AMA's with the wife, tomorrow it's up at 3am and work work work. But I will get that stuff up before too long.

[Michigan boarder]

I must admit, I was a little worried with the time that it took...but as the saying goes...Good thinks happen to those that wait....

Sarge, very nice build and thanks for hanging in there...

John, i felt that smack talking comment `bout our (my) big blocks....

if you can realize those numbers and specs at the prop.....I WILL make the trip to barefoot your boat for sure....without the additional weight of the big block and those numbers, you should have a sweet set up!

my guess is you will top out at about 52.5-53.5 mph...hello gas station, but what the hell, you can always buy more gas....

you will want to look at a the prop I run on my echelon...we can lend you one in the spring to try one out...

Sounds good! And you can bring two buddies, we'll still have plenty of power.

Seriously, wasn't trying to smack talk the big blocks, just using it as a comparison. Pretty cool that the SBC can actually put that much power out. I'm going to be very careful with the flame arrestor (need AIR FLOW) and carb selection. Got all winter for that.

We know the hp ratings were 265 for the small block and 395 for the big block, does anyone know what the torque specs were for those two engines as they were equipped in 1994?

[JB-FOOT]

Sounds good! And you can bring two buddies, we'll still have plenty of power.

Seriously, wasn't trying to smack talk the big blocks, just using it as a comparison. Pretty cool that the SBC can actually put that much power out. I'm going to be very careful with the flame arrestor (need AIR FLOW) and carb selection. Got all winter for that.

We know the hp ratings were 265 for the small block and 395 for the big block, does anyone know what the torque specs were for those two engines as they were equipped in 1994?

john

it will be interesting to see where the secondaries "kick in" at...hopefully they are not just at 40-ish mile an hour as you may be footing and all of a sudden...get pulled over...that is the one thing that is nice about fuel injected vs. carbs, it is smoother with out that BaaawwWAAAAA..... of the secondaries kicking in while holding on to the rope....

But Oh how sweet the sound and feel at the throttle end of the BaaawwWAAAAA.....

[BoatFlyRide]

This is giving me inspiration to keep my current setup and rebuild it when the time comes!

[sgt1970-442]

well I would post the computer screen shot I took of the best pull but I can't seem to paste it from photobucket.

I can't even quote anybody. what has changed or what am I missing?

[shawndoggy]

well I would post the computer screen shot I took of the best pull but I can't seem to paste it from photobucket.

I can't even quote anybody. what has changed or what am I missing?

Site doesn't play nice with internet explorer. Try a different browser (safari, chrome, Firefox, etc).

[Michigan boarder]

Here's the 850cfm pull at 38 degrees BTDC:

[Michigan boarder]

Here's that big pull. This was really cool. We just moved the timing up to 38 from 36 on this one, running 93 octane fuel.

Edited November 24, 2014 by Michigan boarder

[MalibuNation]

I love this kind of stuff. Thanks John!!

[WheelerWake]

That torque curve is nice - big and flat. Never went sub 400 lbft.

Was the left/right A/F ratio difference instrumentation related, or is that what it is?

[John I.]

Cool.

[Woodski]

Excellent work, an absolutely awesome power curve matched perfectly for the application.

@sgt: well done and great combination of components, you knocked it out of the park & that looks like a perfect curve for a ski/wake/barefoot boat. John will be very happy with the results, although his arm sockets will complain a lot if the CFO does anything approaching a WOT take off. Sounds like the 850 carb is pretty sweet and efficient.

@M-B: the "old" mill was 265 hp @ 4700 rpm and 350 ft-lbs @ 3200 rpm. You will need a different prop, your current one will make the boat feel like it has a rubber band for a prop-shaft. I run a lot of cup on mine and it works great, with more cubes and tons of torque you will probably also want some more pitch than say an Acme 515. Try a few (or learn how to tweak one) before you commit as you are treading new ground. J-B's comments on the secondaries is also very good, you might be able to move that with prop selection. Also, you will want a free breathing spark arrestor, one of a big block will work (Zenith is the manufacturer on the old Merc. BB's, J-B can confirm that). I wouldn't waste the $ on a K&N, you don't need the filtration they provide since you are running on water with little to no dust. A nice, free flowing exhaust will also help, you can make them pretty cheap, I am sure you have gone through Martin Archers thread, I think I commented on how I make mine also in that thread (4" dia tubes).

Per some of your comments, I think you long line barefoot. If yes, you will find your first ride very entertaining, you will have about half the amount of time to go from buttriding to standing...unless of course you like to ride on your butt at 40+ mph. The wind up from 2000-4000 is amazing, that is one thing you will really notice.

[Michigan boarder]

@Woodski: Thanks for the info on the old mil, that is good to know for comparison. Everyone that I brag the new numbers to asks me what the old numbers are. So if I pick up that 850 carb I'll be handling 140 more ft-lb torque.

Regarding the prop, yes, there will be a new prop for sure in the future. I think I'll hang on to the current 13x13 as a power prop in case I want to yank up my family of 5 all at once on wakeboards (would be pretty cool).

Steve was suggesting a 780 carb that he had in mind, so that needs to be considered too. I was starting to consider fuel injection but John (buddy of Steve's) said to be careful with that, but I can't remember exactly why. Do fuel injection systems come with exhaust O2 sensors? I need to think about what I'm spending - $700 for a new carb, or put $700 towards fuel injection, which is still like another $500 after that (the cost of a prop).

Once the engine is back in the boat I'll start measuring up what I can go with for a flame arrestor, since I'll know what kind of clearance I have from the engine cover. This is an easy one actually, simple for me to fab/modify as needed.

On the exhaust, the ETX's are 3.5" output, and the STE's are 3.5", so I'm just going with 3.5" exhaust throughout. I have new 3.5" wet exhaust tubes and fiberglass openings for the silencer that I will replace the old ones with, but I need the engine back in the boat first so I can make it fit right (angles, position, etc.).

On barefooting - I've tried long line unsuccessfully, but then JBFoot hooked me up with some better gear and that was when my boat problems started, so I've yet to give it a go. But I know this is the year for it!

[Michigan boarder]

That torque curve is nice - big and flat. Never went sub 400 lbft.

Was the left/right A/F ratio difference instrumentation related, or is that what it is?

That's a good question, maybe Steve can chime in on that.

[Michigan boarder]

This is giving me inspiration to keep my current setup and rebuild it when the time comes!

I agree. I was torn for a while with "Time to upgrade the boat?" when the engine failed, but I know that I'll just be spending that much more on a newer one, why bother when the current one does everything I need. I'm so glad Sgt (Steve) offered to help, it has turned a bad thing (engine failure) into that "new boat" feeling, no freaking way I'd ever sell this thing now.

[Woodski]

Steve was suggesting a 780 carb that he had in mind, so that needs to be considered too. I was starting to consider fuel injection but John (buddy of Steve's) said to be careful with that, but I can't remember exactly why. Do fuel injection systems come with exhaust O2 sensors? I need to think about what I'm spending - $700 for a new carb, or put $700 towards fuel injection, which is still like another $500 after that (the cost of a prop).

@ M-B: I agree with John, there is the potential for many gremlins when installing an FI system, particularly when doing so on a unique combination like yours. Yours would require a totally unique calibration along with specifically matched injectors to ensure the proper F-A ratio and appropriate fuel flow. The incremental gains FI offers over a well tuned carb (cold starts / improved fuel economy) will be offset by the cost, calibration requirements, potential poor results and lastly, most likely less power than with a good carb. It is not uncommon for a fuel injection system to deliver less power than a carb setup. The really nice thing about a carb is it is a "dumb" system, it does not need to know how much fuel to inject or when to do it, it simply provides fuel based on the air passing through the venturi's. I am not saying that fuel injection is a bad thing and if offered the choice, FI is the way to go, I am just saying that given the setup you have, priority on where to spend you hard earned $, time and resources, it is probably not a good investment. Yes, most or all the aftermarket FI systems I have seen come with O2 sensors, which of course you can't use. If you want to save some more $, there are several tricks you can do to your original carb to make it breath better and offer quicker throttle response. A good book by David Emanuel (Super Tuning and Modifying Carter Carburetors) details the steps to blueprinting the Weber carb.

Besides, you are going to spend some time dialing in the prop first...

[Falko]

I had very good success with an Edelbrock marine series carb. I ran a 680 on a 5.7 small block with good success. Never dynoed it so no numbers. But the boat (a 21.5' I/O with 4 blade prop) would scrape 62 mph (GPS). Other mods to that engine were a performer manifold and full Mallory marine ignition. Ran nice.

[JB-FOOT]

@ M-B: I agree with John, there is the potential for many gremlins when installing an FI system, particularly when doing so on a unique combination like yours. Yours would require a totally unique calibration along with specifically matched injectors to ensure the proper F-A ratio and appropriate fuel flow. The incremental gains FI offers over a well tuned carb (cold starts / improved fuel economy) will be offset by the cost, calibration requirements, potential poor results and lastly, most likely less power than with a good carb. It is not uncommon for a fuel injection system to deliver less power than a carb setup. The really nice thing about a carb is it is a "dumb" system, it does not need to know how much fuel to inject or when to do it, it simply provides fuel based on the air passing through the venturi's. I am not saying that fuel injection is a bad thing and if offered the choice, FI is the way to go, I am just saying that given the setup you have, priority on where to spend you hard earned $, time and resources, it is probably not a good investment. Yes, most or all the aftermarket FI systems I have seen come with O2 sensors, which of course you can't use. If you want to save some more $, there are several tricks you can do to your original carb to make it breath better and offer quicker throttle response. A good book by David Emanuel (Super Tuning and Modifying Carter Carburetors) details the steps to blueprinting the Weber carb.

Besides, you are going to spend some time dialing in the prop first...

Exactly, Props, Props, and more Props for testing.....but I may be able to narrow down that search for John since I have already done the same with the same hull....

[martinarcher]

Exactly, Props, Props, and more Props for testing.....but I may be able to narrow down that search for John since I have already done the same with the same hull....

Right on....he's got a great place to start since I know your pretty darn picky about boat performance and just the man I would want testing my new prop combo.

[Woodski]

@J-B Foot: what prop(s) do you run on your Echy? I recall you posted some info, not sure where to look...

[JB-FOOT]

@J-B Foot: what prop(s) do you run on your Echy? I recall you posted some info, not sure where to look...

Yes, I have to find that., I listed different props and rpms and speed....now. just where is that....

[MalibuNation]

You could use this as a start:
http://www.themalibucrew.com/forums/index.php?/page/props.html

[WheelerWake]

I had very good success with an Edelbrock marine series carb. I ran a 680 on a 5.7 small block with good success. Never dynoed it so no numbers. But the boat (a 21.5' I/O with 4 blade prop) would scrape 62 mph (GPS). Other mods to that engine were a performer manifold and full Mallory marine ignition. Ran nice.

This is a big advantage that I/O's over inboards, being able to "trim it up" probably gives about 10 mph.

[WheelerWake]

Prop selection on my setup has been backwards from what I expected. I have a home-brew stoker 350/383 also (mine has mefi though). We run ~2500 lbs ballast + ~1500 people, gear, fuel, etc.

I've tried 2 props, a 14x16 and a 14x18 (have a 1.5:1 v-drive). Wide open, from a stop, both stall at about 3900 rpm. I'll bet mine has a similar torque curve to yours, starts heading south around this rpm (looking at the graph's on the "just a little fyi" thread.

The interesting thing is, the 16" pitch prop takes 8 seconds to get to 20 mph with ballast, while the 18" is quicker at 6 seconds. I believe this is because the engine is able to spin them both to 3900 rpm "stalled" and the 18" pushes more water at this rpm.

I obviously run the 18, the 16 is my spare.

I've recently acquired a 14x20 but won't be able to test it until next season.