Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

[deafwish]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

This would still be one of the best Volvo specific 4BBL threads on-line, which is why I'm bumping this back up!
I have a 1997 5.7GLPLKR (215HP) in my Four Winns Horizon RS 180 and am considering this upgrade.
My Volvo is a pre vortec block (12 bolt 2BBL manifold) and I have Hi-Tek stainless exhaust manifolds.
Solas 21p Amita 4 blade prop spinning at 4450RPM (range of 4200 - 4600).
I've scored a cast iron spreadbore manifold (was off an old Corvette) and am wondering whether this 4BBL upgrade is worthwhile on a pre Vortec engine?
All I'd now need is a Holley 4175 and throttle bracket to get this working, which should be <$500.
Any advice before I spend time & money?

 

[Walt T]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

That carburetor should be fine, it's a good choice although I would probably use a 625. The bigger the primary bore the less low end torque you will have. This is why Rochesters are popular. At any rate, I would not use that manifold. I like the Edelbrock 26014.

To answer your question, It might give you 1-2 mph top speed. Maybe 5 mph with that small boat. The Four Winns is a deep V though. Any HP gained will be at top rpms since you're making more cfm available. However, if the motor doesn't need it it wont use it. The vacuum secondaries may not even open. Do the math, at 4600 rpm your engine needs about 390 cfm, well below what that carb can supply. The engine will not use more than that unless you use forced induction. However, it will certainly look nice, might be fun for you to install, and if you don't mind spending the money and adapting hardware heck, go for it! Who knows, might prove me wrong. Wouldn't be the first time.

 

[old islander]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Those stock GM 4BRL manifolds are not realy great for making power. If your motor lives around 5000rpm or less you would be much better off with an aluminum manifold like the Edelbrock performer. It will make power in that RPM range, and give you a much bigger boost in your low end torque. But with a stock cam like walt said, it still wont be much.

 

[Bondo]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

This would still be one of the best Volvo specific 4BBL threads on-line, which is why I'm bumping this back up!
I have a 1997 5.7GLPLKR (215HP) in my Four Winns Horizon RS 180 and am considering this upgrade.
My Volvo is a pre vortec block (12 bolt 2BBL manifold) and I have Hi-Tek stainless exhaust manifolds.
Solas 21p Amita 4 blade prop spinning at 4450RPM (range of 4200 - 4600).
I've scored a cast iron spreadbore manifold (was off an old Corvette) and am wondering whether this 4BBL upgrade is worthwhile on a pre Vortec engine?
All I'd now need is a Holley 4175 and throttle bracket to get this working, which should be <$500.
Any advice before I spend time & money?

Ayuh,.... Welcome Aboard,.... Generally speakin', goin' from a 2bbl carb to a 4bbl carb will get ya 'bout 20hp,...

 

[deafwish]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Thanks for the responses, fellas.
I know these older SBC's are a different kettle of fish when compared to the Vortec blocks, which is why I'm asking...
This is a salt water boat & I'm hesitant to use anything aluminium.
The marine Edelbrock alloy manifold will cost a fortune down here & I won't spend that sort of money for this project.
Another school of thought would be to buy a marine grind cam, lifters, push rods and valve springs while retaining the current Holley 2300 (500CFM) 2BBL?
A flat tappet cam package will only set me back $350, excluding labour...
These are the cam' spec's (part number is 1666):

http://www.crowcams.com.au/media/catalogues/15.0 SB all.pdf

Will a cam upgrade show a reasonable gain, given my compression ratio is only 9.11:1?
Will the Holley 2300 flow sufficient fuel/ air?

 

[Walt T]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

You already have a marine cam and I would not use that carburetor. If you're thinking of cam and staying with the 2bbl dont bother, it's a waste of money. It's actually all a waste of money since any gains will only be seen at high rpms and even then they will be very small gains and you won't be happy with the cost/benefit. The only way to get real gain is to turn a higher pitch prop at the same engine rpm. That takes substantial HP and torque gains. One way is to use Vortec heads, cam, and manifold with a 4 bbl carb but if you thought the aluminum manifold was expensive then the Vortec will be way out of your reach. Then there is still no guarantee you can turn a higher pitch prop. The other way is to build an engine from the bottom up and swap them out. It simply is not going to happen just swapping cams and carburetors. If it were that easy boats would come from the factory like that.

 

[deafwish]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Thanks for the honest response, Walt.
I'll keep the engine as is and enjoy it for now...
To go on a brief tangent, would swapping the Amita 4 for a stainless HR Titan net me similar performance results to the engine work I had previously discussed?

 

[aerobat]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

a friend had to replace a cracked intake manifold on a mercruiser 5.7 and bought a weiand manifold because the dealer promised him supersonic cruise with this. we tried to merry it with the rochester quadrajet and it ended in a nightmare. the carb bracket and the manifold simply does not want to work with a quadrajet for whatever reason, the engine bogs , sputters and does not run well at all , even with careful idle mixture adjusting.

saying that i,m sceptic with such modifications

 

[Walt T]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

We will need more specifics to help with prop recommendations. Pitch, diameter, number of blades, current wide open throttle rpm and top speed.

 

[deafwish]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

We will need more specifics to help with prop recommendations. Pitch, diameter, number of blades, current wide open throttle rpm and top speed.

Solas Amita, 4 blade, 14x21, 4450RPM (trimmed) at 49mph.
I can PM you if we prefer to keep this thread about carb' upgrades?! :facepalm:

 

[Walt T]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

You could try a 3 blade which has less drag in the water and might get you to 50 but there is less "bite" on the water for pulling out of the hole and towing skiiers. Lots of folks use 3 blades though and your boat isn't all that big. If you can try one from a local prop shop might be worth a shot but I wouldn't expect much. PM me all you like.

 

[Tail_Gunner]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

You already have a marine cam and I would not use that carburetor. If you're thinking of cam and staying with the 2bbl dont bother, it's a waste of money. It's actually all a waste of money since any gains will only be seen at high rpms and even then they will be very small gains and you won't be happy with the cost/benefit. The only way to get real gain is to turn a higher pitch prop at the same engine rpm. That takes substantial HP and torque gains. One way is to use Vortec heads, cam, and manifold with a 4 bbl carb but if you thought the aluminum manifold was expensive then the Vortec will be way out of your reach. Then there is still no guarantee you can turn a higher pitch prop. The other way is to build an engine from the bottom up and swap them out. It simply is not going to happen just swapping cams and carburetors. If it were that easy boats would come from the factory like that.

That pretty much sums up the game..Just dropping true vortec heads and a 4 barrel should net about 70 hp gain..You have the intake off its another hour to bolt on new heads..Id bet if you did a search you find a good set of heads for 3-400 there has to be ton of old boat stuff out there.

Ohh back to carb's: http://forum.grumpysperformance.com/viewtopic.php?f=55&t=3052&p=8056&hilit=+Vortec+heads#p8056

 

[deafwish]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Bolted on a 3 blade VP 14.3 X 21P prop today & got a resonable increase in top end with my existing setup (2bbl).
Cracked 53 mph at 4800 rpm.
I'll report back once I fit the spreadbore manifold and Holley 4175.
My Volvo Penta rpm range is up to 4400-4600. Is it worth upgrading anything (valve springs?) if I continue with <5000 RPM?

 

[NHGuy]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

It's ok to rev it a little high. If the valvetrain can't take it the motor will fall down at the higher rpms. It can't break anything. What happens is the valves bounce as they close which causes the motor to slow down from lost compression. Some folks assume the valves float, but they don't. There's enough valve spring force to keep the lifters on the cam lobes when they are open. But as the valves close the lifters are going toward the cam's base circle. At that part of the cycle the valve spring force is lower and when the valve is closing fast the factory spring can't keep the valve from bouncing as it hits the seat.
If it can make 5000 rpm or more go to the next prop pitch.
Your motor won't do anything bad if you over rev it. I have run my pre vortec 5.7 to 5200 or 5300 a couple of times when testing props.
Valve springs would stop this, but so would a taller prop. And the nice thing about a prop is it's easy to change and it can make the engine seem to be less frantic because it turns a little slower for a given boat speed.

 

[Tail_Gunner]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

This would still be one of the best Volvo specific 4BBL threads on-line, which is why I'm bumping this back up!
I have a 1997 5.7GLPLKR (215HP) in my Four Winns Horizon RS 180 and am considering this upgrade.
My Volvo is a pre vortec block (12 bolt 2BBL manifold) and I have Hi-Tek stainless exhaust manifolds.
Solas 21p Amita 4 blade prop spinning at 4450RPM (range of 4200 - 4600).
I've scored a cast iron spreadbore manifold (was off an old Corvette) and am wondering whether this 4BBL upgrade is worthwhile on a pre Vortec engine?
All I'd now need is a Holley 4175 and throttle bracket to get this working, which should be <$500.
Any advice before I spend time & money?

OK i will be the first to admit i love to tinker....but your dead on arrival with non vortec heads...they flow air. Bolt what you like ontop or on the bottom....even in the middle your dead. Now bolt on some vortec's they actually bolt will flow air...now the game's afoot.... bolt on some springs that will allow cam lift and control seat pressure the games on...now push push in a cam with duration and lift.....again flow's air..games on. As to intake's and carb's without the afore mentioned item's there earing's on a pig.....a bit sharp angled but it is what it is. Do all those mods then bolt on a carb and intake....get the correct metering rod's for your altitude and play well in the sun

 

[deafwish]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

I have what I deem to be a realistic goal of having a 50 knot (57.5 mph) boat.
Sorry to be sounding like an amateur, but am I kidding myself in proceeding with this simple 4bbl upgrade for my goal?

 

[Walt T]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Yes. As mentioned several times by several frozen boaters who are finally thawing out good god it was cold last week. My dog was afraid to lift his leg, heck I would have been too. Anyway as mentioned by frozen boaters a simple carb won't do much but Vortec is the best bang for your buck. Save your money, buy a set of Vortec heads off Craigslist or "Midnight Auto Supply" (Neighbors car), buy a nice Vortec intake, nice carb, and enjoy the ride. I believe that will get you a good top end gain and preserve low end punch.

53 mph at 4800 rpm is pretty darn good! I'd say perfect actually. You can certainly try a manifold and carb. You can always sell them when you go to Vortec but I doubt you'll get much for the manifold since most performance SBC's are Vortec. As a couple of famous bodybuilders once said "Believe me now and listen to me later"... It is better to under carburate than it is to over-carburate. As I said, your motor will not use any more air than it needs. I can almost guarantee a 4bbl at this point will not net you anymore top speed and may actually hurt performance. Trust me, 53 mph is nothing to sneeze at. It cost me a lot of money, time, blood, sweat, and beer to get my boat to that speed.

I have to ask, why the name "Deafwish"? I ask because I have bilateral cochlear implants.

 

[deafwish]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Thank you again for all the advice fellas - I appreciate it.
I deal with a number of performance workshops & will consider a set of Vortec heads/ manifold/ carb for a winter project.

Walt T - I'm an audio nut that used to compete in car audio 'Sound Off' competitions. No disrespect intended to anyone with a hearing disability.

 

[Lou C]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

I know that on the older 4.3s they were rated at 175 hp with the 2bbl and 205 with the 4 bbl. Mine with the 4bbl you feel a definite surge in power as you pass 4,000 rpm

 

[Walt T]

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

Re: How much HP would be gained adding 4bbl to 5.0L Volvo GL Vortec?

None taken DW. I was hearing before I lost it. Still am an audiophile, all my cars have sound systems in them. Music is different now and the learning curve just keeps going. I'm fortunate is the way I look at it. Most people in my situation cant enjoy music. Engine noises were pretty easy to relearn but I cannot set valve lash by ear. Not yet anyway.