4.3 TBI Power Upgrade

[Tail_Gunner]

I'am very close to getting 60 mph, the boat is propped to the max and i am wondering if i upped my fuel pressure a bit and ran the right intake take manifold could i expect maybe a 50 hp increase. (mabe a littel timing change also)

I know this is kinda of a pie in the sky question, but does a 4.3 (2001 tbi volvo) benefit from improved breathing with such a simple method, or would a cam have to be included to get a decent gain.

Im kind of suspious about the exhaust manifold's being able to compliment the enhanced air flow, but maybe they might be able to scavenge enough to make it all work...............any thought's here?

 

[Bondo]

Re: 4.3 TBI Power Upgrade

TG,...... You've got that little 4.3l Strung Right Out There Now.......
Knocking on 60's Door is Quite a Feat with a 4.3l.....

I Don't Think that there's Another 50hp left In it,... Not without some Major Internal Surgery.......

Not only are you nearly At the Top of Induction Systems,.....
The Exhaust is going to be the Stumbling Block to further Hot Rodding it..... Thru-Hulls Won't make enough Difference Either..... True Headers Might,...
But I Doubt it......

You've basically got 2 Choices.........

Live with What you Have,.........
Or,......
Up-Grade to a 350, V8..............

 

[Tail_Gunner]

Re: 4.3 TBI Power Upgrade

I understand that, plz explain (if you will) how a cold exhaust wont scanvenge air flow? is the flow that bad (are the exhaust header that ruff) chit ive had to much wine to talk with reason, I find it hard to believe that @ 215hp that crank or cam is distressed, Most likely im not used to any mech tell me i cant do this,,,,,,aka im a Norweigan........

 

[Bondo]

Re: 4.3 TBI Power Upgrade

It isn't Hot, or Cold Exhaust,.........

It's about the Size of the runners,+ Where they Meet......

Marine Manifolds,+ Riser just Don't Flow Well.......Even Thru the Transom.....

They say Dry Stack Headers are the Best.........
I've never seen them listed for the 4.3l though............

 

[Reel Poor]

Re: 4.3 TBI Power Upgrade

Some of the performance exhaust manifolds advertise an average of 6-10 percent hp increase.

I don't know if many have v-6 manifolds. But you could gougle marine exhaust manifolds and possibly find a few.

IMCO
Stainless Marine
GIL Marine
Just to name a few. Probably pricey too. :%

 

[Tail_Gunner]

Re: 4.3 TBI Power Upgrade

Damm got a little excited there for a moment, i guess i knew those exhaust manifold's didnt look like they were built to flow for preformance. And thinking about it a little bit, Chev turbo charged there cyclone to get big hp, and they only got 265 if i remeber right.... Anyway's thank you for the solid advise.... Who need's 60 anyway's..:'(

 

[WillyBWright]

Re: 4.3 TBI Power Upgrade

Keep in mind that EFI's are built with very specific factors. Starting messing with this without compensating for that gets you a dead motor in a boat running Zero miles per hour. If you can't reprogram the computer, you're courting disaster.

 

[180shabah]

Re: 4.3 TBI Power Upgrade

A 4.3 can reliably produce 250-260hp in marine trim. However, as pointed out above you have some limitations to deal with. First, are your exhaust manifolds, I have seen tuned manifolds (not headers though) for 4.3's, but I don't remember where at the moment. Your larger limitation is your induction. There is not alot out there to "Hot Rod" your TBI. If you are serious about the power increase I would suggest dumping the TBI for an Edelbrock 4bbl and Intake along with a cam upgrade, just don't go too wild on the cam or you will create some major problems for yourself.

As a plus your TBI setup could be sold on Ebay to recover some cash.

However a better option would be to drop in a 350 V8, skip the 305 it is not worth the effort. Use aluminum exhaust manifolds and risers and it will not be any heavier than your current 4.3

 

[whywhyzed]

Re: 4.3 TBI Power Upgrade

If you're already propped to the max, you'll have to change drive ratios before adding more power, no?

 

[Bondo]

Re: 4.3 TBI Power Upgrade

If you're already propped to the max, you'll have to change drive ratios before adding more power, no?

Ayuh,...... In Theory atleast......

Over the last year or so,....... Eric Busted the Crankshaft in the 4.3l that we'd put into his Hy-Liner,....
Soo,... We dropped in a 350 we had laying around.....
With the 1.65/1 ratio in the Alpha, GenII,..... We ended up going to a 25" pitch with a Double Cup on it to get the RPMs manageable........
A SSteel Prop in 26" or so would be a Better Choice,.....
But,.... A SSteel Prop on a boat owned by Anybody from the Purcell Family is ASKING for Trouble........ I've Never seen folks do Soo much Dredging with their boats as These people.......
Bob,+ I usually have the props rebuild on the entire Fleet of the families boats,......
Every Year.......
Mom Purcell does better than the rest of the Clan,......
But,.... With 87 years of Practice,......
You'd Expect that........

Sooo,.......
Ayuh,... It Can Work,..... But you'll run Out of the standard Pitches, available in Standard Aluminum Props.............

 

[Tail_Gunner]

Re: 4.3 TBI Power Upgrade

Sometime's the old urge come's back to mod a motor a little bit, had i been able to to simply bolt on a manifold and up my fuel pressure and maybe bigger injector's or change the duration on how long they inject i might have pursued this,

But as Bondo has mentioned the exhaust will more than probably have to be modded as well and when you are that far, here come's a cam along with it, and who know's maybe gear's but unlikey.

That goes from a simple and inexpensive job to a major system change along with a lot of time and $$$. This season i intend to enjoy the boat and have some serious fun.

There are some good manifold's out there for tbi systems i believe there Eldebrock, but i would not ever loose my efi for a carb, it's just to easy and truly more flexible than carb's (just a opinion) As to timing, i work in a co. where there are @ least ten or 12 mech's that are full blown modder's and damm good one's. Noo i would not hook up a old lap top by my self and start plugging in new number's not even.

Working with Walleyhed i was able to get this boat to 56 mph so far using 3 blade stilletto's,trying to get to the next pitch increase drop's my rpm by 400-500 rpm indicating a big power to weight issue (or tourqe) and before jumping on the enertia prop idea i just posted to see how feasible it would be to beef this motor up a little to get the big gain i need here.

So for now im just going to sit on it..........:devil: well if i can sell the 22 pitch 4 blade, who know's maybe a 22- 23 enertia and 58 will be in my future, Thanks for all the input....

 

[andy1canada]

Re: 4.3 TBI Power Upgrade

Hey Gunner!

Canuck newbie here...

I just bought a boat that I'm going to repower. I'm leaning towards a 4.3 MPI.

The boat I bought is 19/ft. 3000/lbs. with a decent deep V hull. Seems to me you are getting great speed out of your 4.3.

How heavy is your boat (empty)?
How is it for yanking skiers out of the water?

Thanks for your time and trouble!


Remember: It is human nature to squeeze one's beer harder the closer he gets to 60 mph on the water, therein surfaces the terrible calamity of spilling more than one is drinking...

Terry Anderson

 

[Tail_Gunner]

Re: 4.3 TBI Power Upgrade

Im very happy with my motor good econ, it will pull skier's with ease tube's etc. The boat is a 186 -18' 6" wellcraft litte over 3200 lbs with a 20 degree v and a 8' beam, i was told by the dealer it was a fast boat for it's size and motor i guess he was right. There are some extremely savy guy's here you might want to start a new thread and get some opinon's.