Upgrading Power on 5.7 300hp

[lg260ss]

Re: Upgrading Power on 5.7 300hp

I have a horizon edition.

If i drop my tim tabs all the way down then yes the boat remains level, but the acceleration time is increased as well, more drag to overcome.

I havent changed anything yet, i used Compcams to find the Marine cam. They have three, mild good and wild. I took the good cam for lift is only 0.500. I am well aware of the coil bind and will upgrade the valve springs to LS9 with Ti retainers. They are good till 0.55 lift and the seat pressure isnt too high.

I will stay with the stock cam timing chain.

I understand the engine is at high loads all the time, but you all have to remember, to much fuel is just as bad as too little. I am running 95 octane fuel and i change the oil, plugs and filters at the beginnin of every season. I barely put on 20hrs a season, and i use synthetic oil and KN oil filter.

I chose the 218/224 for the cam mimiced the LS7 cam. That cam had great bottom end torque, but i think it was because of the wide lsa. We have narrow LSA. i need an LSA, Lobe seperation angle, greater than 115, then i will make more bottom end torque.

FYI, This is a 2009 VP, there is no need to change the platinum spark plugs every year, especially at 20 hrs a season. Engine oil and gear lube should be changed at the end of each season before layup. And once again, the stock 5.7 VP with DP drive should be more than capable of pulling up a skier easily. My brother is 6'5" and 300 lbs and I used to pull him up on a wakeboard with this same boat/engine package all the time. Four winns hulls have an extended planing surface and are known for effortless planing. You still have yet to tell us if your drive is down all the way, check it visually to assure it is in the full down position before the hole shot.

 

[Scott Danforth]

Re: Upgrading Power on 5.7 300hp

If i drop my tim tabs all the way down then yes the boat remains level, but the acceleration time is increased as well, more drag to overcome.

leave your trim tabs up. trim the drive all the way down. trimming your tabs all the way down is like putting on the brakes. you obviously do not know how to use trim tabs

I havent changed anything yet, i used Compcams to find the Marine cam. They have three, mild good and wild. I took the good cam for lift is only 0.500. I am well aware of the coil bind and will upgrade the valve springs to LS9 with Ti retainers. They are good till 0.55 lift and the seat pressure isnt too high.

Remember. this is an EFI motor. if you change anything in the motor, you have to reprogram the ECM otherwise it will not run right if it runs at all.

I understand the engine is at high loads all the time, but you all have to remember, to much fuel is just as bad as too little. I am running 95 octane fuel and i change the oil, plugs and filters at the beginnin of every season. I barely put on 20hrs a season, and i use synthetic oil and KN oil filter.

No need to change the plugs every year. Also, running 95 octane fuel may be a waste (depending on which Octane scale), the motor is designed to run on 87 octane (R+M / 2)

I chose the 218/224 for the cam mimiced the LS7 cam. That cam had great bottom end torque, but i think it was because of the wide lsa. We have narrow LSA. i need an LSA, Lobe seperation angle, greater than 115, then i will make more bottom end torque.

It sounds like the cam specs from the Extreme Marine XM270HR 08-417-8 - Xtreme Marine

Not a bad cam, however absolutely useless without reprogramming.

the long and the short of it. From your posts it sounds like you are not operating the boat properly.

For a hole shot (also to pull skier out of water). Trim tabs up, drive all the way down to between 0 degrees and -3 degrees. Mash the trottle. As the boat comes up, you may have to trim up to about 2 or 3 degrees on the drive. If you have a bunch of people on one side of the boat and there is a list. use the trim tabs to adjust the list.

If your motor is in good tune, not suffering from any fuel system restriction (such as loose paint in the fuel cell) the boat should explode out of the water with F5 props and 4 people on board.

Now if your not happy with the boat and you still want to do a cam change, I would also pull the block and put in a stroker kit since you have to reprogram the ECM anyway. Might as well go all in.

 

[MikDee]

Re: Upgrading Power on 5.7 300hp

IMO, Why are you using 93 octane? 87, & 89 octane are fast flash, & burn off fuel, 93 octane is slower igniting, longer burn off fuel. Unless you have 10:1x1 compression, and or advanced static timing, or a faster advance kit in the distributor, you don't need the extra octane. You really don't want either of these conditions in a boat anyway. I feel you're wasting your money on unburned gas, and lugging your engine unnecessarily with 93 octane. Yeah, I understand your engine is set up to pack the cylinders with fuel with the work done to it, but you want to burn most, if not all of it as quickly as possible, and higher octane is not the answer. It's like having a race car with 2:73 desert gearing! Once you get to 100mph you'll start to feel it, below that I suspect it would be a slug. I think you should try 87, or 89 octane gas and see if you get an improvement in your hole shot, and overall running.

 

[jimmbo]

Re: Upgrading Power on 5.7 300hp

A 24 ft boat with a 5.7 is going to take its time getting up on plane. Even with it under propped 4 inches it not going to be a ball fire.
Being an engine controlled by a computer your mod options are limited. I recalled reading that engine uses 1.6 ratio rocker instead of the standard 1.5, making for slightly more valve lift and a slight increase in effective duration. Swapping back to the 1.5s would shorten the duration, moving the torque curve slightly lower in the rpm range. The lower lift might help the bottom end ever so slightly. Changing the cam is like buying a pig in a poke. Who ever is helping with the selection had better know his stuff. Grinds for boats are different than for cars, and even what the boats' intended use had better be understood by the grinder. Again the ECM is going to throw it overseeing in to the picture. I know some will no prob, reprogram the ECM. Hope whoever does the reprogram knows what they are doing and the engine is doing.
If it were my 24 footer and I like it I would consider supercharging or swapping to a 7.4

 

[Tail_Gunner]

Re: Upgrading Power on 5.7 300hp

Be aware that retuning a modified 5.7 with a cam swap is very simple if it is a mefi. $200 will get you a tune and by very competent tuner..One can tune his own for about 600 if you can read do some math.

 

[MikDee]

Re: Upgrading Power on 5.7 300hp

A quote from Whitfield oil co.



"Some racers and/or tuners think that they need a slow burning gasoline to make good horsepower. This is far form the truth. What we need is a good fast burn gasoline to be able to complete the burn in the time available. An added benefit is that less spark timing is required with a fast burn gasoline. The reason is that peak cylinder pressure occurs sooner with a fast burn gasoline. Too soon is not good, so the spark timing can be slightly reduced to take advantage of the fast burn, still allowing peak power to occur at the correct crankshaft position.

Keep in mind that at 6000 RPM, each spark plug fires 50 times per second. At this rate, there is very little time to draw the intake charge into the cylinder, compress it, burn it, expand it, and exhaust it. A good fast burn gasoline is very important in making as much horsepower as possible at this engine speed. The most horsepower is developed when the gasoline is burned completely."
That's why I said all you need is 89 octane!

 

[Tail_Gunner]

Re: Upgrading Power on 5.7 300hp

In short to the above marine engine's are archaic...however they are very well designed to survive a wet exhaust enviroment. Actually boats's are meant to have fun watch the kids scream or the girl friends... wives what ever.....now this thread is about the nerd crowd....how can we tinker it to to our delight....Once a wise old Oracle said go boating and live the dream..keep it simple and have fun. That old boy was wise beyond his time...keep it simple and have fun..

 

[Walt T]

Re: Upgrading Power on 5.7 300hp

Even if he gets the ecm programmed for the new cam the difference aint gonna do a dang thing. Its still gonna be slow if not worse out of the hole. Maybe a very very slight possibility of 1-2 mph gain at top end, but I don't think so. Not worth the money. The rest of the motor is not designed to take advantage of the cam.

 

[Naf]

Re: Upgrading Power on 5.7 300hp

I use this octane of fuel in all my engines, from 2t to my monster 415ci race car engine.

I like the controlled burn of the higher octane, additionally its a purer cleaner mix. Where i am the 90 octane is rubbish and filthy.

One more note i forgot to mention, i am using the boat in sea water, i thoroughly flush the motor after every use. I feel the extra buoyancy is causin the boat to misbehave...

If i find a correct cam for my rpm range then i would see a proper acceleration and engine performance. Dynojet makes a piggy back to help alter the fuel. Another issue is i am rich, i should be 14.0 idle 13.3-13.8 cruisin and 12.0-12.2 at wot. If i was supercharged then 11.5-11.8 at wot...

Who makes sc for our engines? That would be the best cheat

 

[Scott Danforth]

Re: Upgrading Power on 5.7 300hp

magnuson makes a great supercharger, however back to your fuel. the motor's EFI tune is not using your 95 octane. put good old 87 or even 89 octane back in there and you will pick up some power.

If anything, salt water will help you get out of the hole faster.

I still think your not using the tabs and trim properly.

 

[Walt T]

Re: Upgrading Power on 5.7 300hp

Good luck Naf. You're ignoring all the good advice from seasoned veterans here. Its your money.

 

[Maclin]

Re: Upgrading Power on 5.7 300hp

I worked at a refinery. Basically all the gasoline from the initial refining is the same, octane enhancing is the last thing that happens.

 

[Naf]

Re: Upgrading Power on 5.7 300hp

I will try half a tank of low octane fuel, if it perks up the acceleration, then great. If not i will return back to my 95 octane, and try to curve the fuel slightly.

Another issue i have had with this boat is even with -5 trim the bow pops up uncontrollably. Empty with just one passenger in 1-2 foot swells and it feels like i am in open waters. I installed a hydrofoil fin, it worked great till it bent the bracket. didnt install the middle two screws at the suggestion of my dealer here.

So i installed trim tabs. they didnt measure properly so the trim tabs are 9 degrees up and installed them at 0, basically straight with the hull.

I have been hit with plenty of issues and no return on my investments.

I can try and cure my trim tab angle issue, but it opens the door for corrosion and possible breakage. I could use grade 5 Ti bolts with a button head but i do not know how it will react with the pressure of the water pounding down on it.

I know my engine should give me more power from down low. Its a V8 with vortec heads and a marine style L31 intake. I had the TB ported and i openned the air passageway with a Kn filter, added Lithium marine batts, extra ground wires, and racing 100mm ignition wires.

I have stainless marine exhaust, but havent installed them for i dont have the time to sit on top of my mechanics and make sure they torque every bolt correctly and install the hoses correctly.

One of the Corsa baffles broke, so i have to wait till corsa quote me for a repair kit.

I am sorry if it doesnt sound like i am not listenin, its just there is other noise clouding my mind

The F5 behaved the exact same why but they suffered on top end, that being said says there is an issue with something, Fuel, exhaust back pressure, something.

With exhaust pointed down through the gear i should have more torque at low rpm, but with the side exits open i should gain top end HP. tried both ways and with no success of quicker holeshot accelerations...

 

[Walt T]

Re: Upgrading Power on 5.7 300hp

Oh I see, You didn't install hydraulic tabs. I assumed that. For a 24 footer the fixed tabs are not recommended but can sometimes help. You definitely should try hydraulic tabs.

Absolutely none of the "improvements" you spoke of will make an iota of difference. It's obviously not a fuel problem. I would say maybe verify throttle plates are opening fully but your top end performance numbers say they are.

If you could post a video of what your boat does so we can actually see what is happening perhaps that will help.

 

[MikDee]

Re: Upgrading Power on 5.7 300hp

How's your timing? You should at least check your timing to see if it on spec. statically. Then if you happen to have, beg, borrow, or steal an advance timing light, you could check it through the RPM range. I would also pull the plugs, if they're wet, or covered with soot,, you're too rich. IMO, platinum plugs are not my 1st choice for performance, durability, yes. I personally really like the AC M43R, I think that's the right # ? Or, a compatible heat range AC with these features. It has a huge center electrode that seems to provide a nice fat spark. IMO, those fixed trim tabs do nothing for you, just leave them as is.


One more thing, how are your exhaust flaps? If they're broken off, & blocking the exhaust that could be the problem?

 

[jimmbo]

Re: Upgrading Power on 5.7 300hp

You say you had the TB ported. Explain please. The K&N filter might be a USCG violation. Noise maker(side or rear vented) Exhaust is not going to make any difference on a 5.7, except annoy the neighbours. It will not yield any torque differences and at most 2 or 3 horsepower

 

[Walt T]

Re: Upgrading Power on 5.7 300hp

Throttle bodies can be ported so they're larger and smoother thereby allowing more cfm. It's pointless however, given that the thing already supplies more cfm than the engine can use. This mod is only used on engines that are run at rpms that require the extra cfm which most boats never do. It's the same with cam and valve mods. Its all meant to improve breathing at high rpms which is where most high performance motors are run. Higher lift/ short duration cams do help at lower rpms, but not all that much. If you're gonna do all these mods that help increase high rpm power, then put a smaller pitch prop on it so it can reach 6500 rpm and actually use all that junk you paid for. Or maybe install a clutch or a 4000 rpm torque converter. Boy wouldn't that be something. Grenading drives left and right.

We still don't know what the gear ratio is. This is critical, but his prop sizes and speeds suggest it's right on.

 

[Scott Danforth]

Re: Upgrading Power on 5.7 300hp

Walt, you forgot to mention that any mod to an EFI engine requires a re-tune of the ECM

Im willing to bet the porting of the throttle body messed up the low RPM air flow to the motor and the ECM isnt fueling properly.

the ECM is still running speed density, so if you change anything that may affect the fuel and spark mapping, you have to let the ECM know.

 

[Walt T]

Re: Upgrading Power on 5.7 300hp

Good point Scott. Larger intake ports will lower vacuum signal at idle which then affects MAP signal which then affects EFI giving the fuel ratios he mentions earlier. It is commonly known that larger primary intake bores will lower off idle response and torque rise will begin at higher rpms than with smaller primaries which give much crisper throttle response, then give way to the secondaries once the rpms climb to where they are needed. On a TBI there's just the two large primaries so coupled with stock cam, ecm, timing, it's just another brick in the wall he's building.

 

[jimmbo]

Re: Upgrading Power on 5.7 300hp

So when one ports a TB, I assume they have to install bigger throttle plates?