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

[rbchristian2]

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

UPDATE:
I installed the Quadrajet on the boat today and just to remind everyone it is a 2002 Four Winns 190 Horizon with a 5.0 GL.

My experience was a little different with the throttle linkage as it wasn't hooked up to the 2V spot and the 4V holes wouldn't work. So no biggie I had to drill two holes and when I go back tomorrow it will be ready to rock and roll.

Also the vacuum line for the Holley is 3/8 where the Quadrajet was 1/4 so I had to get a reducer and a 4" piece of hose. and the last difference was the stock bolt for the Flame Arrester wasn't long enough, again, no biggie. I just stopped on the way home and got a 12" piece of threaded rod and I am going to make a bolt tomorrow.

Besides that it was a direct bolt on for my application. I did start the boat and once the new water seperator was filled up and the fuel bowls it started right up and sounded great. I didn't drive the boat today as the linkage wasn't right and I couldn't secure the Flame arrestor on the carb. I will post after my drive tomorrow (weather permitting) and let you know the results.

Thanks again for all the help!

 

[ramster]

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

When I installed the Q-jet on my stock 5.0 it was actually from a 4.3 LX (E-Bay) I think the jetting was a tiny bit on the lean side but it ran good and I think I saw better fuel economy at cruise speeds. That jetting stock was 66 primary jets and 40 rods, and the secondary rods I changed to the DH's to give some more fuel at WOT.

 

[craze1cars]

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

Thanks for coming back and updating. Almost missed it since the last board change and thread moves.

PS: I would be interested in what your compressed gap measurement was with the 1.6 rockers on both the the intake and exhaust valves that proved you didn't have a binding issue. thx

Which compressed gap are you asking measurement of? Between the coils of the spring? Between pushrod and side of pushrod hole? Between piston and valve? I don't even know what spec would be on either of those first 2 measurments even if I did measure it...I didn't.

I essentially just installed them and hand-rotated the engine while watching the full swing. At full lift there is still a small gap between coils of the springs, so it's not coil-binding. And there was a visible gap between the pushrod hole and the pushrod, I'd guess 1/32"? Again I didn't measure. All I was concerned with was that springs didn't bind and rods didn't rub, and neither occurs. And I disassembled 3 times after test runs with the various combinations...all was clean and nothing showed signs of touching at max RPMS either.

But maybe you're asking about squish clearance between piston TDC and valve? I'm sure there is a recommended miniminum for that, but frankly I didn't check...I just did the math. My factory Volvo cam has a spec max lift of 0.283 on the exhast side. So with 1.6's it will lift the exhaust valve 0.4528. Intake is a bit less. I have consulted several sources that say a Vortec head will easily handle lift of 0.46 or even more...plus a buddy of mine built a Vortec for his truck with 1.6's on similar cam lift...50,000 miles of towing and he also has no problems. So I wasn't worried about it and I just went on faith with the math alone, plus obviously the visual check of rods and springs.

All I can say is I've spun it up to 5,200 rpms several times. It's quiet and running fine...nothing has self-destructed or shown any signs of touching. Sorry I have no measurements to share to put a number to my clearance....

 

[John_S]

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

The clearance between the bottom of the valve retainer and the top of the valve-guide seal. But, you answered the question, with the cam specs. I thought the volvo cam had more lift, which would have put you over when you used 1.6 on the exhausts.

BTW, I don't believe rotating would have found the issue, unless it was severe. I think it would wipe out the valve seals first, but don't know for sure.

 

[craze1cars]

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

Yeah I didn't check that clearance...I just did the math and figured it was good. I will certainly report back someday if something self-destructs!

Thanks.

 

[rbchristian2]

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

When you had it on your stock 5.0GL, did you have the Quadrajet set up stock out of the box to see your 2-3 MPH difference? I am doing this tomorrow (weather permitting) so it is set for Memorial Day weekend. Did you notice any gas mileage difference either way? Anything else you remember?

This is the most informative thread and very detailed thanks to you,craze1cars and mikeneal (if I am forgetting someone, sorry!). Thanks!

UPDATE:
After installing the carb and being disappointed with how it ran I put the old carb back on... BUT I still wondered why I only had 4200 RPM's... So I started digging... I am assuming this is a reverse rotation engine, which I didn't know and the timing (from the previous owner) was actually retarded 3 degrees. According to my timing gun (for a standard engine) it would appear to be advanced actually was not. So After I put it back to 10 degrees advanced initial timing (89 octane) the motor ran much better. So I decided to put the quadrajet back on.........

Well the verdict is I went from 48 on the two barrel to 52 with the quadrajet and that was on very rough water yesterday (Memorial Day) so it might have another Mph or so. The acceleration was slightly improved and the boat feels great.

The cost was $295 carb (http://www.i-5automotive.com/marine/) , under $30 for the fittings (summitracing.com), $10 for fuel line from West Marine. All under $350 and a noticeable difference... So if I put a stainless on the boat I might pick up another 3 MPH and now I have a 55+ Mph boat, respectable in my mind. I know Craze1Cars, you have a stingray which is an unbelievable boat with speed for what it is, but mine is a little heavier and I am happy with the gain... THANK YOU FOR ALL OF YOUR INPUT AND HELP!!!!!!!!!!! If anyone is considering the upgrade, it is a no brainer.

 

[craze1cars]

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

Glad it worked out for ya! Sounds like you got similar modest gains as most of us who have done this simple carb swap.

I am a little confused about your "reverse rotation" comment...I could be wrong...someone correct me if I am. But I am fairly certain that all Volvo, Mercruiser, etc I/O V8 engines rotate clockwise (as you are staring at the front/pulley side of the engine). In my mind this is considered standard rotation...not reverse. Same direction it rotates in my pickup truck anyway...

Nice little diagram: http://www.propowermarine.com/faq-rotate.htm

So a normal timing light will work on all these motors just the same as it would on any short block Chevy in a pickup truck or whatever...

Regardless, thanks for updating with your results! Enjoy the summer...

 

[rbchristian2]

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

Glad it worked out for ya! Sounds like you got similar modest gains as most of us who have done this simple carb swap.

I am a little confused about your "reverse rotation" comment...I could be wrong...someone correct me if I am. But I am fairly certain that all Volvo, Mercruiser, etc I/O V8 engines rotate clockwise (as you are staring at the front/pulley side of the engine). In my mind this is considered standard rotation...not reverse. Same direction it rotates in my pickup truck anyway...

Nice little diagram: http://www.propowermarine.com/faq-rotate.htm

So a normal timing light will work on all these motors just the same as it would on any short block Chevy in a pickup truck or whatever...

Regardless, thanks for updating with your results! Enjoy the summer...

I guess I was confused myself. Number one is on the front right of the motor where most of them as I know are front left. I am a ford guy but I have a lot of chevy friends. When I advance my timing light, it went the opposite direction of the distributor so if I were to believe one it is definitely the distributor, it doesn't lie. Maybe mine was built on a Monday or a Friday but it runs GREAT... Now I am going to be testing props.

Thanks again for the help!

 

[jdskidawg]

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

all this is amazing info two questions do you think this would work on a mercruiser 5.0 ? i am in the planning stage of doing the 4bbl upgrade gathering all the parts and what not. Not real familiar with cams. would the same roller rocker set up would work on a mercruiser as well. like you, not real into doing HUGE upgrades and spending a bunch of money! just want to make what i have the best it can be! sitting at 6000Ft above sea level i lose a lot of pony's and i want to fine tune the motor to get some of that back
any info you have to offer would be greatly appreciated

also what gears do you have in your outdrive?

 

[rbchristian2]

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

all this is amazing info two questions do you think this would work on a mercruiser 5.0 ? i am in the planning stage of doing the 4bbl upgrade gathering all the parts and what not. Not real familiar with cams. would the same roller rocker set up would work on a mercruiser as well. like you, not real into doing HUGE upgrades and spending a bunch of money! just want to make what i have the best it can be! sitting at 6000Ft above sea level i lose a lot of pony's and i want to fine tune the motor to get some of that back
any info you have to offer would be greatly appreciated

also what gears do you have in your outdrive?

I am going to leave the specifics to someone that knows more about mercruisers than I do, but I believe the Merc's have a two barrel manifold so that ups the cost... I am sure you can do a search and find a lot of people doing this on Merc. Volvo's were harder to find, but after doing it I don't know why more people don't do it...

 

[craze1cars]

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

all this is amazing info two questions do you think this would work on a mercruiser 5.0 ? i am in the planning stage of doing the 4bbl upgrade gathering all the parts and what not. Not real familiar with cams. would the same roller rocker set up would work on a mercruiser as well. like you, not real into doing HUGE upgrades and spending a bunch of money! just want to make what i have the best it can be! sitting at 6000Ft above sea level i lose a lot of pony's and i want to fine tune the motor to get some of that back
any info you have to offer would be greatly appreciated

also what gears do you have in your outdrive?

Mercruiser engine block is no different than Volvo's, but I have no idea what year motor you are asking about...my 1999 is a Vortec, if yours is a few years older that has potential to changes things with regards to specific roller rockers that need to be purchased because yours may have entirely different heads from the pre-Vortecs (generically speaking pre-1996), etc. And the older heads don't breath as easily, and therefore will see less gain from a 4bbl conversion because the motors can't pull the added CFM of a 4bbl anyway...even my Vortec 5.0 barely breathes enough to gain anything from a 4bbl, but it gains a few. Overall Mercruisers are far more difficult to convert to 4bbl than Volvos. Off the top of my head you'll definitely need a different manifold, different flame arrestor, more difficult linkage setup, likely a more difficult fuel line setup, obviously a carb, etc. Frankly if I had a Mercuiser I wouldn't have bothered with this 4 bbl upgrade....too much $$$ for the modest gain IMO...but everyone has different levels of what they think is too much. Roller rockers alone won't gain you anything noticable, only the 4bbl upgrade will...barely. If I had a 5.0 Mercruiser I'd go an entirely different direction and find myself a used 5.7 out of a pickup and transfer all the marine parts to it...including the factory 2 bbl setup you have now and just forget the 4bbl idea. It would run fine, be relatively easy, be more cost effective, and give you more HP gain. There are hundreds of other topics out there about that popular 5.0 to 5.7 conversion. The only reason I did this 4bbl upgrade to my Volvo 5.0 is becuase I got it done for $500-ish, which I thought was OK for a 25-ish HP gain. Could have kept it at $350ish if I didnt' spend the extra $150 on the rocker arms...which are barely worth it at all...probably 3 hp from those? But methinks you'll be spending a grand or two easily I think to do all the same to a Mercruiser, but I suppose that all depends on how stingy you are with buying parts. A used 5.7 might cost the same and get you 40 or 50 HP gain and substantially more torque for hole-shot.

Overall I'd suggest you start a separate topic or find some Mercuiser guys (they're EVERYWHERE) who have done the 4bbl conversion and/or the 5.0 to 5.7 conversion. Talking too much about it on this thread here will only add to confusion...this has been a 100% Volvo topic up unil now...and Volvo guys doing this conversion are hard to find. You'll have LOTS of company on the Mercruiser side. Despite sharing engine blocks, the two brands are substantially different with regards to their bolt-ons.

My Volvo has 1.60 gears. Good luck in your project!

 

[John_S]

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

all this is amazing info do you think this would work on a mercruiser 5.0 ?

Post your own thread for clarity. There are plenty of people that have done this to their mercruisers, even though you do have the added expense of an intake manifold, that can help you with details.

 

[awalkertx]

Dead thread revive... and I apologize if it should've stayed dead and me start another thread...

I've got a 1997 Cobalt 200 with Volvo Penta 5.7GL PLKD motor and DP-S 1 out-drive... Counted the intake bolts and it's a first gen SBC. Obviously the Vortec is a superior head design and as such a better power plant, but given that mine's a 350 should a 4bbl swap be something to undertake? I have no desire to swap engines (or heads) at this time because the engine (and boat) have less than 400 hours on it. Please don't chastise... boating will happen again soon!

I've looked at the specifications for the 5.7GL vs the 5.7GS and see a 215HP v. 250HP for the two. I have the shop manuals, which includes both power plants, but it only shows that the GS has a 4V carburetor vice the 2 on the GL. I have googled far and wide for any other differences between the two engines and really can't come up with anything other than carb and hp rating.

Boat fires right up, but it's sat so long rather than rebuild the carburetor maybe go the route of a factory rebuilt Holley 4175? Looking at the parts catalog for my 5.7 liter engines model "LK" it looks as though the intake is shared between the GL and GS.... I'm assuming Volvo used a common one with an adapter like they did with the Vortec motors.

Looking at the parts manual the GS calls for a P/N 3855279-0 Carburetor assembly... as far as I can tell, that's a Holley 4175 based on my googling. Carb has never been rebuilt, everything on the boat is factory (except for fluids and impeller).

Thanks for any input, but I'd sure like to go from 215HP to 250HP!

 

[GA_Boater]

Dead thread revive... and I apologize if it should've stayed dead and me start another thread...

Issue the apology.

Closed.