Strip Poker 388

iTrader: (6)

What modifications have yall been doing these motors?? I am fixing to pull the motors to freshing and try to get more power .I figure around 650hp maybe ?I do not want to go with blower right know but the mods need to work with a blower

There has to be some racers that's done some stuff , I have [heard] of off set ground cranks ,longer rods,raised compression in the factory 2 classes. One racer said that Sterling had built some 740hp Factory 2 class motors back in 2001 when SBI did not tech motors.

I already know about the ecm,throttle body mod. What else is there?

What and which cam and with a bigger cam will it work with the reprogrammed ecm?

Some have said up the compression but if I add blowers next winter I do not want to change pistons and rebalanced the motors.wasted money

Also some have said to up grade to aluminum heads with the coated water jackets. But most of the heads I have seen they raise the exhaust port .500 so this will be a problem with the CMI headers lining up with the tail pipes?


Thanks


Rob

Airpacker

The edlebrock marine heads have stock port location. They come with inconel exhaust valves already so you just need to add keepers, retainers and springs to match your cam selection. Use good head bolts or studs. You can blue print the combustion chamber sizes to achieve a true 9.0 to 1 ratio as well. Mine were anywhere from a bout 8.4 to 8.8 to one before we did them. Use a 1.8 to one rocker arm for a little more lift and duration, add an adjustable fuel pressure regulater and you can make 570 hp with no ecm mods.

jdnca1

I've looked into this before. I thought about porting the heads or going to aluminum, cam change, and bumping the compression. Did NOT consider making it a stroker. I was trying to find ~125hp. What I learned is the biggest obsticle to overcome is the "highly restrictive" stock intake manifold. I talked with someone who's done the above mods and could only make another ~30hp due again to the intake. He then put on a single plane intake and 850 carb and picked up ~100 hp turning 5800.

FYI, the 500EFI makes ~520HP stock.

Strip Poker 388

iTrader: (6)

The motors have already been into so it has some stuff already like arp head bolt ,bigger oil cooler ,oil thermostat.bigger oil pan.the aremotive fuel pump,fram race style oil filter system..


Airpacker which fuel pres regulator you talking about??? . it already has the ASM on it and its not a very good way to go using parts on the old one . I would not mine a new design all together.


On the rocker arm I plan on buying new cam anyway so I would not need the 1.8 rocker arms. at 1.8 and higher i would think that would put more stress on the guild.


I don't think 570 is going to be enough??

Strip Poker 388

iTrader: (6)

If the Intake is so restrictive ?what happens when they put the Whipple blower to make the so called 828 hp they claim with other parts. I know its forced in but restriction is heat. Extrude hone it??prob not worth the dollars..


I plan on redoing the ECM's again when we Dyno the motors.

testdrv321

- The whipple forces the air in so the restrictions are in a sense reduced.

- I'd check with Lingenfelter, they have alot of similiar engines with bigger power.

- The HP500EFI is 500 crankshaft hp / 470 propshaft hp per Mercruiser

35/25

Does anyone know if the 500 EFI has changed in any way since it was first introduced (I believe the first model year was 1999 when both the carb version and the efi version were offered)? I am interested in a 1999 model boat with these engines and wondered if there is anything I should be aware of.
My present boat is a 1999 model with T-500HP carb motors and I experienced the imfamous valve spring problem typical of these engines. If I pursue this other boat with the EFI's, just want to know in advance what to lookout for.

Rich

bob_t

1999 and some early 2000 EFI's didn't have the additional mechanical fuel pump (the one driven by the raw water pump). Our 2000 500 EFI doesn't have the mech. fuel pump, just the electric. I called Merc Racing and they verified my serial number as an early 2000 and they said that some had the additional fuel pump (added to late 2000's). Supposed to help alleviate vapor lock that was experienced on the models without it. Also, 1999 and early 2000's may have the same Crane valve springs, not the "redesigned" comp cam valve springs. There appears to be no distinct, clear cut, "changeover" for the early 500 EFI. Looks like they used up the old carb motor "stock on-hand" until it was all gone.

splashandburn

Also, 1999 and early 2000's may have the same Crane valve springs, not the "redesigned" comp cam valve springs. There appears to be no distinct, clear cut, "changeover" for the early 500 EFI. Looks like they used up the old carb motor "stock on-hand" until it was all gone.[/QUOTE]


Does this mean that on later model motors (2001- 2002) you do not have the valve spring issue? I have a 2002 with 175 hours and am wondering if I need to replace the springs this winter or next. Is it still recommended that around the 200-250 hour mark this be done??

ISurvivedNMU

Merc says yes, you still have to change the springs..... They say, check your springs at 50 hours, then every 25 hours after that. Once you see a crack, you know when your driving style denotes them to be changed.

He went on to say racers need to change at 50, and more pleasure boaters will need it around 300.....

Personally, checking the springs, at least on a 500hp carb, sucks, cause you need to pull the risers and manafold.... Not sure on the efi... Sounds like to much BS... Change them around 200 and you know you wont loose seat preasure witch is what you need to keep you valve train happy in that motor.

I changed my crane springs over to comp at 110 hours.. they were three years old, and they looked like new, but all had lost about 30 pounds of seat preasure except 2. No cracks or any wear.

If you are changing your spring, put in titanium retainers to reduce the unsprung load on each valve... costs about 50 bucks extra....