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

[craze1cars]

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

If you would like to stay with the Holley family of carburetors (bolt on replacement for the 500 CFM 2 BBL). Holley has an 0-80555C (4175) spread bore Quadrajet replacement. I have never seen this carb used in marine applications but it offers the same tune-ability as regular square hole Holleys and is offered in a 650 CFM vacuum secondary. If your Vortec intake manifold is the stock cast iron unit that's found on some Mercruiser, Yamaha & OMC, you will be limited on which flange pattern to bolt up to and the spread bore to square bore might lead to some clearance / linkage geometry problems.

Thanks. I'm aware of the 4175...I mentioned it up above in post #8 (I know this all gets wordy and an awful lot to read...) as that was the very carb utilized by the only other person I have found on iboats who has done this mod to a 99 Volvo 5.0. He hasn't responded to my PM yet so not sure if he's still around...

I seem to have a LOT of options to work with on clearance and linkage adjustments...there's a huge plate bolted behind the carb with holes drilled all over it where my cables come in, so I can move that linkage around pretty much to wherever I want or need to in order to get the right angles. So my first impression is that I won't have a problem there.

So it looks like the million dollar question is I need to look at my manifold first to confirm what I have for bolt pattern. I'm a little surprised someone here doesn't know for sure what these 99 Volvo GL's were equipped with...but I guess I'll have to just dig out the wrenches to find out for myself.

 

[83Evinrude]

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

So y'all MIGHT have to follow this thread until Octoberish if you really want to see my results.

I'm not in a hurry either, but very interested since our boats have the same power/gearing and are similar size and layout/usage.

56.2 mph gps, 4,570 rpms, 21p 4 blade stainless Solas Titan HR-4.

Last summer ours ran 53mph (GPS) at 4800rpm on a 21p 3 blade aluminum. I now have a 20p 4 blade stainless Stiletto Bay Pro II that I have yet to run however.

 

[ECVCHAMP]

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

I'm not in a hurry either, but very interested since our boats have the same power/gearing and are similar size and layout/usage.



Last summer ours ran 53mph (GPS) at 4800rpm on a 21p 3 blade aluminum. I now have a 20p 4 blade stainless Stiletto Bay Pro II that I have yet to run however.

I can wait as well, can't touch it untill March(factory warr.)
Mine runs 53mph @4800rpms with factory 14.5x19P 3 blade
Just put on a Michigan 14 3/8x 18P stainless 4 blade lost about 3mph. gained quite a bit on the take off(seat of the pants memory method)

 

[craze1cars]

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

Last summer ours ran 53mph (GPS) at 4800rpm on a 21p 3 blade aluminum. I now have a 20p 4 blade stainless Stiletto Bay Pro II that I have yet to run however.

I'd be interested in your results on that Stilletto. Ironically that is the the EXACT prop I was intending to replace mine with, if I were to elect option #1 in my very first post above. Of course we currently have 2 drastically different props...your 3 blade alum vs my 4 blade stainless...so not sure it would tell me much.

But I'd still be very interested in how that works for you. Thanks.

 

[83Evinrude]

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

I'd be interested in your results on that Stilletto. Ironically that is the the EXACT prop I was intending to replace mine with, if I were to elect option #1 in my very first post above.

Personal issues and the weather has kept me from testing it so far, but I'm hoping to fix that this weekend.

I think the main reason our motors came with the 2bbl is because it gives greater incentive to sell the injected motor when the horsepower difference is 50hp. I think a 4bbl carb version could have easily been produced at 250-260hp but then the $2000 or so premium your paying for fuel injection only comes with quicker and easier starts and a bit better economy but not 50 extra hp.

I like the simplicity of the carburetor since I can easily work on it myself and parts are cheap, but I would also like the extra hp.

 

[Mischief Managed]

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

I think the main reason our motors came with the 2bbl is because it gives greater incentive to sell the injected motor when the horsepower difference is 50hp. I think a 4bbl carb version could have easily been produced at 250-260hp but then the $2000 or so premium your paying for fuel injection only comes with quicker and easier starts and a bit better economy but not 50 extra hp.

I agree.

I also want to point out that when a carburetor is rated for a specific CFM, it's done so at a specific vacuum. Even though a 305 cubic inch engine can only draw in 441 cubic feet of air per minute at 5000 RPM and 100% VE, that does not mean it can't use a 600 CFM carb more effectively than a 500 CFM carb. If the engine still has some manifold vacuum at WOT, it can likely make more power with a bigger carb.

 

[craze1cars]

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

Pic's worth 1,000 words I suppose. I popped the carb up to see what the manifold looked like. 2 Pics below...one of current setup mostly assembled with 2bbl Holley carb. 2nd is of the manifold.

So it's now confirmed this Volvo piece is definitley a spread-bore manifold, with only 1 bolt pattern (5 5/8" x 4 9/32") so it won't accept a square bore carb without adding an adaptor plate. Best I can tell my spread-bore choices are very limited...Quadrajets, ONE Holley (4175 650cfm), and maybe some Carter Thermoquads (were these made in marine versions?? I dunno)

But if there is nothing to lose by using the $30-ish square-to-spread adaptor plates that both Holley and Edelbrock sell, it opens up the entire world of square bore carbs to me...and many more choices, especially in the 600 cfm range which I think would be best for this small motor. I'm still REALLY leaning hard toward the Holley 4160, if only because is is a DIRECT bolt-on with the fuel line location, linkage, and everything else I already have, plus I have a jetting kit and a bunch of other parts for Holleys. Their 4175 spread-bore appears to have fuel input from a different direction...and I'm not sure about the linkage situation.

Is anyone aware of these adaptor plates being a bad idea from a performance perspective when put on a spread-bore manifold? Or are they perfectly fine in that aspect? Thanks.

 

[mikeneal]

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

I did the swap about a year ago. (1999 5.0GL)
I used the holley 4175 spreadbore and bolted it to OEM manifold. I made a AN type stainless fuel line, my linkage is not applicable because I have perfect pass. (speed control for wakeboarding). Overall I am very pleased with results, bottom end is slightly better (smaller primarys and more top end. I had some issues getting it dialed in, in fact I thought that I had defective carb at first and was too lean at low throttle settings even with brass changes. Even mailed it back to holley and they flow bench tested it and it was perfect. I then repeated the exact same plug reading deal with stock 2 barrle carb and plugs looked exactly the same. Found out it was the newer ethanol fuel and my old school plug reading techniques. (was not too lean) Bottom line, jetting without an O2 sensor is tougher then used too be. So I left it slightly too rich and has been good for about 150 hours.
Anymore questions feel free to ask.

 

[craze1cars]

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

Hey! Thanks for chiming in. I actually sent you a PM about this because I found your old post.

Any thoughts on how much you actually gained? Remember your RPM increase or anything like that? Did you need to reprop?

And guess what...I have Perfectpass too! You can see their cable in my first pic of my current carb. But I don't see how that would impact the linkage much...please share if it does.

So basically you just needed to come up with a fuel line and that was about it? I'd love to hear your jetting if you have it documented somewhere, just to give me a starting point. My apologies if I'm asking too much...I understand it was a while back.

Thanks again.

 

[dannyual767]

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

.....56.2 mph gps, 4,570 rpms, 21p 4 blade stainless Solas Titan HR-4. Perfectly jetted factory 2bbl, full fresh ignition tune-up with all new parts and timing set. 502 hours. Speed & RPMS obtained from Perfectpass Stargazer gauge.

When I read this, I was wondering what the heck kinda boat was getting those speeds. And then I read:

And in case anyone is wondering, the boat in question is a 1999 Stingray 200LX bowrider.

And it all became perfectly clear! I've got a 2004 Stingray 200LX with the 5.0GL Volvo and I've seen 56.5 mph on gps with a 21" pitch prop. These are some fast boats.

I too have thought about adding a 4bbl carb to the engine but I was thinking about going with an Edelbrock Vortec Performer aluminum manifold.

 

[John_S]

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

Pic's worth 1,000 words I suppose. I popped the carb up to see what the manifold looked like. 2 Pics below...one of current setup mostly assembled with 2bbl Holley carb. 2nd is of the manifold.

So it's now confirmed this Volvo piece is definitley a spread-bore manifold, with only 1 bolt pattern (5 5/8" x 4 9/32") so it won't accept a square bore carb without adding an adaptor plate. Best I can tell my spread-bore choices are very limited...Quadrajets, ONE Holley (4175 650cfm), and maybe some Carter Thermoquads (were these made in marine versions?? I dunno)

But if there is nothing to lose by using the $30-ish square-to-spread adaptor plates that both Holley and Edelbrock sell, it opens up the entire world of square bore carbs to me...and many more choices, especially in the 600 cfm range which I think would be best for this small motor. I'm still REALLY leaning hard toward the Holley 4160, if only because is is a DIRECT bolt-on with the fuel line location, linkage, and everything else I already have, plus I have a jetting kit and a bunch of other parts for Holleys. Their 4175 spread-bore appears to have fuel input from a different direction...and I'm not sure about the linkage situation.

Is anyone aware of these adaptor plates being a bad idea from a performance perspective when put on a spread-bore manifold? Or are they perfectly fine in that aspect? Thanks.

I would not use the adapter plate. Most people say they detract some, but have seen reports that say no impact. But, you seem to be a Holley guy, so just go with the 650 spreadbore. The 650 will not be too much for your engine. Those 2ndaries will only open to what your engine can use. If you have to, there is a spring kit to adjust when and how they open. I'd bet stock will be fine. The small primaries will be a benefit for the main waterports use, start, stop, hard acceleration to get on plane.

Also, given that the manifold is spreadbore only and volvo has always used Holleys, that the 650 is what they have done testing with and probably used before only having EFI/MPI. The q-jet was long dead before the vortec heads came out. They designed around a spreadbore for some reason. It wasn't because they had allot of manifolds laying around, like Merc. when they went to webers and used adapters.

If you are going to do this, i see no reason to go Holley squarebore. The fuel line is peanuts. Should not weigh in the critical decision path.

 

[craze1cars]

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

Thanks again John. If mikeneal is able to find me the jetting he ended up using with the 4175, which now seems to be running good on the same 1999 Volvo 5.0L I will be using, it will also be very easy for me to at least get a solid baseline to start with to fine-jet from there. It's looking like this is probably going to be my "easy" route.

 

[dannyual767]

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

When it comes to the adapter plate issue, I'm with imported_John_S. I don't have any experience with them but I do remember a decent bit of talk about them in my earlier hot rod days and my OPINION is that the adapters will cost some power. Just my opinion.

I bring up the Edelbrock Performer Vortec again: http://www.summitracing.com/parts/EDL-2116/?rtype=10

Not only would you probably gain a few extra hp from the manifold but you'd save the money from not having to source a spreadbore carb due to Edelbrock's dual bolt pattern.

I'm a member of the Stingray boat owner's forum and I remember someone saying that they used one with success on their 5.0 Volvo.

 

[John_S]

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

When it comes to the adapter plate issue, I'm with imported_John_S. I don't have any experience with them but I do remember a decent bit of talk about them in my earlier hot rod days and my OPINION is that the adapters will cost some power. Just my opinion.

I bring up the Edelbrock Performer Vortec again: http://www.summitracing.com/parts/EDL-2116/?rtype=10

Not only would you probably gain a few extra hp from the manifold but you'd save the money from not having to source a spreadbore carb due to Edelbrock's dual bolt pattern.

I'm a member of the Stingray boat owner's forum and I remember someone saying that they used one with success on their 5.0 Volvo.

Dan, the volvo intake in the picture, looks to be the equivelent as far as runner and plenum heigth with a performer. From pics its hard to tell, but see nothing that would tell me the performer is better. I like the cross hatch under the carb in the volvo. The performer is smooth, but the Edelbrock rpm has similiar crosshatch. With rich running boat carbs and allot of pumping on the throttle, will cause gas pooling. The cross hatch helps contain it and have a chance to mix with air, instead of just running down into the cylinders.

If you want a performer, I'll trade you even for a volvo.

 

[craze1cars]

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

Well....believe it or not, with a quick email to a few hot-rodding buddies in the business, I may have a lead on a used 4175 for dirt cheap that I can rebuild. Friend-of-a-friend situation where he KNOWS for an absolute fact there is one laying around unused on a wrecked boat that he'd part with, but he's unsure what the actual price will be and wants to confirm it is 100% complete. I will know more in about a day...that would be totally sweet if the planets align like that. We shall see.

I'd like to go back to the fuel line question. Would a generic stainless/braided kit sorta like this be OK?
http://www.holley.com/26-207.asp

If course I'm choking on the $120+ price tag on these kits depending on where I buy it...a bit more than pennies...

If not, or if someone has a more economical alternative, what do I need to be looking for and considering to make sure my fuel line is properly marine rated for safety? Suggested product and sales location would be appreciated.

Unlike many car guys who do these hotrodding conversions on boats, I genuinely DO want to do this CORRECTLY and by the book.

 

[John_S]

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

Are you sure the existing fuel line will not work? It looks to me to be using a flexible fuel line. The line is coming in on the side of the 4175 inlet and will not have to cross the manifold. You might have to use a tubing bender to open up the bend on the last section of the rigid piece.

Or call the guy that has the carb. You probably want the fuel line, too.

 

[craze1cars]

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

That thought crossed my mind too...that I might be able to use the existing fuel line since it is flexible and it appears I will be moving the carb inlet closer to the fuel pump (it has electric fuel pump, mounted high on the front of the motor). I fully intend to explore that idea before buying anything. Need to get a carb in hand first and see how things line up.

I had NOT considered asking for the fuel line off the donor boat. Another good idea...I'll have to keep that in mind. Not even sure what kind of boat/motor it is on, all I know is it was a GM motor of some type...friend couldn't remember exactly. If it's a mechanical fuel pump setup, it might be completely different from what I need, but maybe not...

Not sure yet if that's even available, so I'm just waiting to see where this goes until I hear back from my buddy after he gets home late tongiht.

 

[craze1cars]

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

When it comes to the adapter plate issue, I'm with imported_John_S. I don't have any experience with them but I do remember a decent bit of talk about them in my earlier hot rod days and my OPINION is that the adapters will cost some power. Just my opinion.

I bring up the Edelbrock Performer Vortec again: http://www.summitracing.com/parts/EDL-2116/?rtype=10

Not only would you probably gain a few extra hp from the manifold but you'd save the money from not having to source a spreadbore carb due to Edelbrock's dual bolt pattern.

I'm a member of the Stingray boat owner's forum and I remember someone saying that they used one with success on their 5.0 Volvo.

Thanks for your input...I'm not ignoring you and I appreciate the thoughts very much.

Frankly, like John, I'm not convinced either that this Volvo manifold is a bad one in any way in terms of performance...so I'll leave on the one I already have. Heck, I'm not even convinced I'll see a notable HP increase yet with even just the carb swap...I'm no stranger to attempting mods and finding myself right back where I started...this is a risk all tuners and hot-rodders take. And manifolds cost $$$$ and add to the risk. I think it is pretty clear how cheaply I'm trying to get this done LOL!

 

[John_S]

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

Heck, I'm not even convinced I'll see a notable HP increase yet with even just the carb swap...I'm no stranger to attempting mods and finding myself right back where I started...this is a risk all tuners and hot-rodders take.

Translation: Deep down in his heart, he knows he going to do it!

 

[craze1cars]

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

Just a point of conversation and interest...continuing the manifold discussion. Not sure how long this will be viewable, but this ebayer is selling my exact manifold, and it has a few decent pictures that shows the design a bit better than my pics did:
http://cgi.ebay.com/ebaymotors/Merc...6165083QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

Part # is 3856270. In searching at Volvo Penta Store, it appears this exact same manifold has been in use on pretty much EVERY single 5.0L and 5.7L vortec motor, carb'd and TBI injected, from 1996-ish thru 2006-ish.

Is this one better or worse for this application than the Edelbrock offerings? I have no idea. I suppose aluminum would be nice if only to remove a little bit of stern weight. All I know for sure is that I will not buy or test one. I will be running stock Volvo manifold.

In my model year range, the options for the 5.0 were either 220hp 2bbl carb, or 250hp 2bbl TBI. I will be curious if a 4bbl carb can be set on my manifold to produce about the same HP as the 2bbl TBI did. How will I figure this out? I won't. I'm too durn cheap to pay for dyno time on a stupid runabout, so I'm just gonna drive my boat really really fast until I run out of lake. Then I'll guess.

So what is my point in writing this particular post? I don't have a point.