upgrading 5.0Fi for more power. General question on upgrade

[jwhinerman]

Hello,<br /><br />I have a 95 Four Winns Sundowner with a Volvo Penta 5.0Fi SX cobra. I know that this is basically a ford 302 engine, and I was looking for a little more performance. One thing I was looking at was swapping the rocker arms with 1.7 roller type which came oe on 93 mustang cobras. There are a lot of guys with mustangs who use these to gain some more lift and a light more duration from their cams. It should give you a little more cam lift for a little more power.<br /><br />Has anyone done anything like this, and is there any reason why the same type of mod in a car would hurt the performance of the boat?

 

[rodbolt]

Re: upgrading 5.0Fi for more power. General question on upgrade

hello <br /> be aware that more lift and duration creates more overlap. more overlap creates water in the exhaust proplems and volvo already has enough of those.

 

[rabidfish]

Re: upgrading 5.0Fi for more power. General question on upgrade

Even more importantly, changing the way the engine flows air & fuel (exhaust) creates different characteristics for the engine that the ECM is not calibrated to accept. It's quite possible that your engine may not even run. This scenario is not limited to Volvo. Mercruiser and OMC all have the same issues. If you need more power, you may need a complete engine(to stay with EFI) Also, dont forget that idle quality has a direct influence on your ability to shift properly. Think about this issue before you're heading into a dock "HOT"!

 

[jwhinerman]

Re: upgrading 5.0Fi for more power. General question on upgrade

The rocker arms would only have a minimal effect on the duration, but pick up about .030 lift. As far as the engine running, I find it hard to beleive that a .030 increase in lift will cause any idle problems, not to mention the ecm should be able to make any adjustments that it may need.

 

[Bondo]

Re: upgrading 5.0Fi for more power. General question on upgrade

The rocker arms would only have a minimal effect on the duration, but pick up about .030 lift. As far as the engine running, I find it hard to beleive that a .030 increase in lift will cause any idle problems, not to mention the ecm should be able to make any adjustments that it may need.

I think it'll "only have a minimal effect" on AnyThing.......<br />You'll Never Feel it.......<br />You'll Never See it.......<br /><br />In other words.....<br />You're Wasting your Time,+ Money............

 

[MGallik]

Re: upgrading 5.0Fi for more power. General question on upgrade

More overlap also decreases cylinder pressure at lower rpm's. If you do notice anything below 4000 rpm, it may be LESS POWER. You'd have to compensate with more advance which could cause pinging and engine damage.<br /><br />What you want to do wouldn't be that extreme, but as said above, it's not worth the effort.

 

[jwhinerman]

Re: upgrading 5.0Fi for more power. General question on upgrade

Well, May be I will try it , and switch back if I have to. I have the set of rockers from a mustang that I parted out, so It was worth a try. You did bring up another point though about the timing. I am told that a lot of boaters bump the timing up on these engines. Any idea what is "safe"?

 

[MGallik]

Re: upgrading 5.0Fi for more power. General question on upgrade

It won't make enough of a difference for you to worry about the timing. Thats just an example of some things to consider when modifying an engine.<br /><br />You stand to gain 3 to 5 horse power tops, most likely not even that. As Bondo said, you won't feel it.......<br /><br />You asked if anyone has done something like this. I'm a Chevy guy so I'll use that as an example.<br /><br />The stock rockers are called 1.5. they are actually 1.45.<br /><br />If you set the cam timing at 110 degrees atdc AND use 1.6 rockers you can gain 5 to 10 hp in the 350cid small block. On the 305 sb I would expect 3 to 7 hp tops.<br /><br />Is your mod worth the work, cost, and trouble?

 

[jimmythekid]

Re: upgrading 5.0Fi for more power. General question on upgrade

there is no substitute for cubic inches IMHO

 

[Bondo]

Re: upgrading 5.0Fi for more power. General question on upgrade

You're dealing with a Computer Controlled Engine........<br /><br />The Computer will bring the Timing Back Down, all by Itself.....<br /><br />Another Bad Idea........<br />

is there any reason why the same type of mod in a car would hurt the performance of the boat?

Ayuh..........<br />Lots of Reasons.... Depending on Which Mod. you're talking about.........<br /><br />Look, It Sounds like you've got a really Nice Late-Model Boat.............<br />Just go out,+ Enjoy it......<br />There's No Hidden HorsePower to be Found.......<br /><br />Any of the mod.s you've mentioned Require that the engine can Breathe............<br /><br />NOTHING you can do on the Intake-side is going to Do Any Good,<br />Till you go to a set of Headers,+ Thru-Hull Exhausts.............<br /><br />Standard Factory Exhaust IS the Choke-Point on a boat engine..........<br />That's the 1st Thing that Has to be Fixed.............<br /><br />Good Luck..............

 

[f_inscreenname]

Re: upgrading 5.0Fi for more power. General question on upgrade

Bondo; “NOTHING you can do on the Intake-side is going to Do Any Good,<br />Till you go to a set of Headers,+ Thru-Hull Exhausts.............<br /><br />Standard Factory Exhaust IS the Choke-Point on a boat engine..........<br />That's the 1st Thing that Has to be Fixed.............”<br /><br />This http://www.shopcranecams.com/powcamlifkit.html and a set of thru hull exhaust would help but there is no cheap fixes. They get what they can out of these motors from the factory. I remember the last 4.3 liter 6 cylinder I had with it's Fuel injection and computer was a better motor then the 350’s we built as teenagers.

 

[snapperbait]

Re: upgrading 5.0Fi for more power. General question on upgrade

Jwhinerman...<br />Speed density EC4 don't take kind to modifications, and there are no performance proms for Ford EC4 speed density ecm's that I know of... <br /><br />Only way to make any more power with Ford EFI is to go with mass air, and that is'nt kosher in a marine engine compartment...<br /><br /> For all intents and purposes, you're stuck with what ya got...

 

[spzavicar]

Re: upgrading 5.0Fi for more power. General question on upgrade

I think that you would be fine adding the rockers and as far as the timing bump, if you do it correctly by unplugging the TFI module the computer should not reset the timing back down. Adding thru-hull exhaust would be the biggest bang (and expense) for you.

 

[Don S]

Re: upgrading 5.0Fi for more power. General question on upgrade

as far as the timing bump, if you do it correctly by unplugging the TFI module the computer should not reset the timing back down.

There is absolutly NOTHING you can do on the Volvo ECM's to change the timing. They are not programable, rewritable, or anything else.<br /><br />Doing anything that will increase valve overlap is also increasing water intake into the cylinder.<br /><br />And to all the auto mechanics ....... Marine is different from Automotive, and until you understand how wet exhaust is used, and how that water gets into the engine,you can really destroy an engine in a very short amount of time. So be careful with your suggestions. Some people may not know the difference.

 

[NYMINUTE]

Re: upgrading 5.0Fi for more power. General question on upgrade

Originally posted by jimmythekid:<br /> there is no substitute for cubic inches IMHO

100% agreed. Where in Bradenton are you?

 

[JasonB]

Re: upgrading 5.0Fi for more power. General question on upgrade

I have a carbes 302 in my 19' 'tron. Great engine. I have successfulley upped the power of mine when I rebuilt it BUT mine started life at 188hp with a 2bbl carb. Yours is rated for 235-240 I think. I don't think you are going to get any significant improvements from mods like rocker arms. I know someone who did same to their carbed 302 (94 model OMC) and I think he said they looked pretty, but didn't help. Not long after, the engine went poof. As others have said, that engine is very reliabe as it is and at best you might gain 10hp at WOT. 10hp MIGHT get you 1-2mph. It takes torque to spin a prop and that 302 is making about all the grunt reasonable already while keeping reliability intact. Be happy, some of us would love to have FI on our 302's.<br /><br />There is a company that makes stainless manifolds for the 302, but they are about $1400 a pair last time I checked..... They are supposed to flow much better and save 100+ lbs of weight.<br /><br />Your time/energy may be better server in cleaning the bottom, shedding weight from the boat, tune-up, etc. Maybe a set of tabs, smart or power might help.

 

[jwhinerman]

Re: upgrading 5.0Fi for more power. General question on upgrade

So, <br />If you advance the distributor, it will not advance the timing?????<br /><br />Anyway, the 5.0fi gets me to a top speed of about 55, which is pretty good for the inland lakes that I play in, not to mention it is a somehwhat deep cuddy, which has some weight to it. It is always nice to have a little more power though. <br /><br />On other item I also have in the garage is a 1/2" phenolic spacer that goes betwen the upper and lower intake. It is supposed to stop the heat transfer, and increase torque a little bit. Can't hurt to try that out, correct?<br /><br />John

 

[Don S]

Re: upgrading 5.0Fi for more power. General question on upgrade

So, <br />If you advance the distributor, it will not advance the timing?????

Any amount you change the base timing will also change the full advance timing an equal amount. so all your are doing is moving the complete advance curve to a different location, not just changing part of it.<br /><br />

On other item I also have in the garage is a 1/2" phenolic spacer that goes betwen the upper and lower intake. It is supposed to stop the heat transfer, and increase torque a little bit. Can't hurt to try that out, correct?

There shouldn't be enough heat build up in a marine engine to require anything like that, and who knows what will happen to when you add those and not change the ECM. But give it a try, all it can cost you is an engine.<br /><br />You should do something that will help, like the exhaust that was mentioned earlier, or put a DP lower on the drive, that would help. As has been said already the engine is pushing max that the manufactures can get out of it and still keep it a reliable engine.