4.3 performance upgrades

ric · **Posted:** Sun Aug 12, 2012 11:25 am

The other thread got me thinking, so I was going to start a post on 4.3 Vortec upgrades I'm cooking up. As you know my boat has the amazingly simple to made big horsepower 4.3GL. I do not tow, I just want something fun on the river.

As it stands right now:
Stock 4.3GL Vortec
Volvo Penta aluminum 23p prop.
190hp, 52mph top speed GPS'd.

Here's my plans,,,,please feel free to add what you've done or plan on doing

Stage 1:
KN "flame arrestor"
Tune/jet carb
Set ignition
23p stainless prop

Estimated HP should be around the 220 mark (same as GXi). The GL/GXi are identical engines with identical CFM carb/throttle bodies. The difference in 190 to 220hp is the GXi is tuned better and the GL is rough set so it's only 190, so they can charge more for EFI and tell people it's better (when all it does is cost more to fix)

Stage 2:
Edelbrock Performer vortec 4.3 4bbl intake manifold (which has the correct marine provisions)
Holley Marine performance 600cfm 4bbl carb with vacuum secondaries made for the 4.3
Mild performance marine camshaft with good mid range torque
MSD 6M-2L Marine ignition controller with rev limit

At this point HP should be in the 275 hp range, my goal. In a 19ft 2800lb boat with a speed designed hull this will be absolutely crazy. Reliability and performance will be 2nd to none. Cruising fuel consumption will be better then stock. Total cost will actually be fairly cheap due to selling of take-offs, under $1000.

Can't wait to start!

deafwish · **Posted:** Sun Aug 12, 2012 3:44 pm

I'm thinking your power outcomes are very optimistic & will keep an eye on this thread. :wink:

Tvega · **Posted:** Mon Aug 13, 2012 10:11 am

I will also keep an eye on your mods . I had intake manifold problems lately let me know what the part number is to the intake cause I'm looking for one also. :mrgreen:

ric · **Posted:** Mon Aug 13, 2012 10:15 am

Tvega wrote:

I will also keep an eye on your mods . I had intake manifold problems lately let me know what the part number is to the intake cause I'm looking for one also. :mrgreen:

http://www.edelbrock.com/automotive_new ... r-v6.shtml

neutron · **Posted:** Mon Aug 13, 2012 11:11 am

that HP estimate does sound a little hard to reach I would guess with all that you would gain 40 to 50 hp. which is still impressive
i would think a GXI has differnt heads/valve sizes and better fuel delivery with more controlled atomization of the air/fuel

ric · **Posted:** Mon Aug 13, 2012 12:12 pm

neutron wrote:

that HP estimate does sound a little hard to reach I would guess with all that you would gain 40 to 50 hp. which is still impressive
i would think a GXI has differnt heads/valve sizes and better fuel delivery with more controlled atomization of the air/fuel

Same exact engine. Volvo tunes the carbs for all situations (weather, altitude) so they're only 190hp. Since the FI self adjusts it's tuned tighter hence the 220hp. They're both capable of the same HP output, it's just if you go tighter on the carb and have it set for your location like 50ft above sea level here in FL and bring the boat to a lake where it's 1000ft above sea level... you'll have running issues. The fuel injection boat will not it will make it's own adjustments. A 600cfm vacuum secondary 4bbl is actually capable of better fuel consumption and acceleration over the 2bbl because it only will open the secondaries when needed by the engine, and while on the primary only it's like 250cfm air opening.

neutron · **Posted:** Mon Aug 13, 2012 12:29 pm

you will deffinitly get better fuel economy with a 4bbl, the front 2 bbls are way smaller than a 2bbl. so if you are easy on the throttle and dont open the secondaries it will be great on fuel.
an intake and carb is easy,but to put a camshaft in is way more work, do you have the room to pull the camshaft out without lifting the engine?

ric · **Posted:** Mon Aug 13, 2012 12:41 pm

The whole back half can be taken apart like a jigsaw puzzle so you have easy access to anything. No engine pulling needed.

Winter Sux · **Posted:** Mon Aug 13, 2012 6:29 pm

ric wrote:

neutron wrote:

that HP estimate does sound a little hard to reach I would guess with all that you would gain 40 to 50 hp. which is still impressive
i would think a GXI has differnt heads/valve sizes and better fuel delivery with more controlled atomization of the air/fuel

Same exact engine. Volvo tunes the carbs for all situations (weather, altitude) so they're only 190hp. Since the FI self adjusts it's tuned tighter hence the 220hp. They're both capable of the same HP output, it's just if you go tighter on the carb and have it set for your location like 50ft above sea level here in FL and bring the boat to a lake where it's 1000ft above sea level... you'll have running issues. The fuel injection boat will not it will make it's own adjustments. A 600cfm vacuum secondary 4bbl is actually capable of better fuel consumption and acceleration over the 2bbl because it only will open the secondaries when needed by the engine, and while on the primary only it's like 250cfm air opening.

What happened to that 275 HP from the first post? Just an inquiring mind wanting to know

ric · **Posted:** Mon Aug 13, 2012 6:40 pm

That is with 275. It's quite easy to do with a Vortec v6. Read any hot rodder forums, they love to modify these v6's and parts are EVERYWHERE.

Winter Sux · **Posted:** Mon Aug 13, 2012 7:43 pm

I thought you downgraded your expectations to 220 HP. Thats why I added the quote from you.

So you are saying 275 with your mods from the first post??????

NiagaraChillin · **Posted:** Mon Aug 13, 2012 7:53 pm

ric wrote:

It's quite easy to do with a Vortec v6.

+1 to that, shoot I've seen 400hp + coaxed outta those V-6's, depending on how deep your wallet is of course.

But, all that new HP ain't gonna matter if ya can't get your drive in the water...

ric · **Posted:** Mon Aug 13, 2012 7:59 pm

My expectations of 275 with cam, intake, carb are about right on with stock heads, heck maybe low. Look these things up, 400+ ain't that hard. I've seen em 450+ on 93 octane.

Winter Sux · **Posted:** Mon Aug 13, 2012 8:15 pm

I dont have to look it up Ric. Remember, I'm a licenced tech and work on these things all the time. When these guys get 275 out of them, they are using tweeked heads along with your mods or very close to yours. I know getting 400 out of them is possible but, these engines are VERY radical with a radical exhaust. Are you expecting 275 without tweeked heads and a dinosaur design of a water cooled marine exhaust?

neutron · **Posted:** Mon Aug 13, 2012 8:20 pm

right all that air and fuel getting sucked into the engine needs to come out, I would expect some free flowing exhaust in th emix as well

www.iFourWinns.com

4.3 performance upgrades

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