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Performance upgrades for 43L

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rinkernut

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"I read the electronic ugnitio

"I read the electronic ugnition upgrades, great info and many thanks to those that shared the info.
Here is info on my boat. 86 Rinker 18' 4.3L V-6 with OMC sterndrive.
I have a question. I want to increase the horsepower in my V-6 to around 250HP using a smooth idle mild cam and larger carb, and possibly rework the heads.

My question is will the drive unit handle the extra horsepower? According to the OMC manual I have it states the drive unit on my boat (matching part number) was used for V-6 and V-8 applications. Iknow the V-8's probably produced around 190HP, but that doesn't come close to 250HP, but I'm still wondering if this can be done without destroying the drive unit. Anyone have experience with performance upgrades?"
 
"That same drive is used for t

"That same drive is used for the 5.7's (probably 250 hp at the crank, 230 at the prop) except the gear ratio would be different in the top end so you would have to re gear it or change out the upper."
 
"Sounds like a V8 might be mor

"Sounds like a V8 might be more to your liking. 225HP is do-able on a carbed 4.3, but 250 not really possible. Remember, it's only turning 4600 rpm, and 4.3 just isn't enough displacement for any more than 225HP. If you put it in a Camaro and let it rev to 6,000 rpm then sure you get more power, but not in a boat.
A smooth idle mild cam? not sure what cam you are referring to, but I'm sure a stock marine cam makes the same or more HP than any "mild" automobile/truck cam. And with marine, you need a certain lobe overlap to make sure the cylinders don't suck in exhaust water at idle. "
 
"Thanks for the info guys. I

"Thanks for the info guys. I appreciate your expertise. I think I am going to try to squeeze everything out of the V-6. Any good upgrades or tweeks you guys know of to do that? How big should I go on the carb? It has a 2 bar. on it now. It runs great, but I am a speed demon so I want more power...LOL"
 
"Hi William,I put an edelbrock

"Hi William,I put an edelbrock intake manifold and a 4bbl carb on my 3.8 chev,and it made a big difference on top end.The engine now runs about 4500 rpm at wot with a 21p prop.The old 2bbl carb was tired so I did the swap,well worth it.Also with the new carb with the electric choke it starts right away and runs perfect."
 
"like Dan, I put a 4BBL on my

"like Dan, I put a 4BBL on my 3.8 - bought a used quadrajet and cast intake from an OMC 5.0 (smallest cfm unit I could find) and rebuilt it. $200 investment made a big difference. I would forget the "squeezing everything out" concept myself.
Funny thing about my 3.8 is I put Pertronix on it, and there is no Pertronix kit compatible with the 3.8...found out since that every spark is 12 degrees off... I don't know how it runs so nice, but it does...
happy.gif
"
 
"Thanks again! Got any part n

"Thanks again! Got any part numbers for the intake and carb for the 4.3L? Does anyone have the part numbers for the updated ESA module and petronix ignition system for the 4.3L? I looked on their websites, but they need the OEM part numbers and other information I have no idea how to get.

Budget is about $1000.00

I get about 40MPH out of it now and thats with 5 people on board and running 93 octane fuel. I think with the ignition, intake and carb upgrades it should do pretty good. I'll also try the 21 pitch prop. Its got the stock aluminum prop on it now. Thanks again for all the input. I'll keep you all posted on how it goes."
 
I SWAPED FROM A ALUMINUM TO A

I SWAPED FROM A ALUMINUM TO A STAINLES SAME PITCH A COUPLE OF YEARS AGO AND IT MADE A BIG DIFFRENCE IN HOLE SHOT AND PULLING SKIERS I WAS TOLD IT WAS BECAUSE THE ALUMINUM WOULD FLEX AND CHANGE PITCH
DEWAYNE G.
 
"for $1000 you could do the ed

"for $1000 you could do the edelbrock carb and intake and probably get a used stainless prop. You'll have an honest 205HP and it will be a very noticeable gain. I would predict 44-47 mph top speed.
The intake I used is a GM 14095286 which is for a quadrajet, but I don't think it fits 4.3's with balance shafts - it only fits early 4.3's. the ESA is 123-9898P, not sure which ignitor is for a 4.3, but if it's the 1563 you need, I have an extra (I also have an extra 123-9898P ESA). I also have a highrise cast iron 4.3 intake off the Chevy Astro...I didn't use it because I was unsure of clearance under my engine cover but it is a trick looking manifold albeit heavy. Geez, I also have another OMC quadrajet...I should build another one..."
 
"I have a 1990 18' Marada

"I have a 1990 18' Marada with 4.3 Cobra drive. This past winter I upgraded with a set of Vortec heads, Edelbrock Performer intake and 4bbl carb. I have also added the Pertronix igniter. Originally 160 hp at prop now should be around 205-210 I think. There is a noticable increase in mid range power and top end. Low end is decent. I recently bought a SS 21" 4 blade prop with some rake and cup. With just me aboard I can turn it 4500 RPMs and run 52 MPH. (GPS confirmed) Since my normal load is 4-6 adults and pulling skiers/tubes , I bought the same prop in a 19". Two people aboard I can slightly over-rev (4700-4800) and still run 50 mph. This morning I opened it up with 6 adults aboard. It turned 4600 and ran an honest 45-46 MPH so the 19" suits my needs a little better. I have the 21" for sale on Ebay if you are interested."
 
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