95-98 5.7l types

[Shabah180]

What is the 5.7l lx efi gen+? I believe the only made this style in 97 or 98 and it supposedly was rated for 280hp ( also heard merc didnt have a way to rate hp back then so it was rumoured to be less)
Just curious, i bought a 98' mariah shabah 180 with 230 hrs, it was babied, the fella who owned it swapped the original 4.3 for a 5.7l and upgraded the outdrive to a bravo 3.
Merc had a bunch of different 5.7l set ups, 2 barrel, 4 barrel, efi, during the end of the 90's.
Has anyone had that 5.7 gen +? Is it a rare motor?

 

[alldodge]

Howdy

All manufactures had to rate HP at the prop before 1998, so a 280HP is a 280HP by NMMA standards. Being 280 EFI motor but would also mean it's 260 HP according to Merc manual. The next question I would have would be, is the 18 foot Shabah rated for that much HP. If it is not, then you will not be able to get it insured.

And no the 5.7 EFI is not rare, they are all over the place

 

[thumpar]

My 96 is an EFI 250hp. 96 was the switch over year to Vortec heads.

 

[NHGuy]

I have been trying to ascertain this stuff myself since my boat had a 1997 4 barrel 350 Mag when I got it. Since it was a repower I never trusted the 350 Mag label until this week when I removed it from the boat. Lo and behold there is a sticker on the flywheel cover that confirms the Mag.
What I'm leading up to is this. I think the LXi engines have the standard flat tappet cam and the Mags have the roller with more lift and duration for a few more ponies.
Since you have EFI you also get the advanced ignition Thunderbolt V. It is excellent, it seeks best timing whenever the throttle position or load changes. It constantly listens for spark knock and maximizes timing til it starts to ping then pulls out some advance.
Now here's the uncertain part. Mercruiser lists the Gen+ as having Aluminum intake, 9.4:1 Compression Ratio, valve lift of .431 Intake, .450 exhaust. Cam duration @ .050 is.294 intake, .307 exhaust. These values are all incrementally bigger that the normal Gen ! Small block 5.7 Mercruiser.
My guess is the engineers learned the engines could operate at those numbers and when they started to use them their was a natural need to identify the engines built this way, that's probably how they became the Gen+.
My 97 350 mag is apparently not gen +, it has a roller cam and an iron high rise intake with Thunderbolt V,.

 

[Shabah180]

I have been trying to ascertain this stuff myself since my boat had a 1997 4 barrel 350 Mag when I got it. Since it was a repower I never trusted the 350 Mag label until this week when I removed it from the boat. Lo and behold there is a sticker on the flywheel cover that confirms the Mag.
What I'm leading up to is this. I think the LXi engines have the standard flat tappet cam and the Mags have the roller with more lift and duration for a few more ponies.
Since you have EFI you also get the advanced ignition Thunderbolt V. It is excellent, it seeks best timing whenever the throttle position or load changes. It constantly listens for spark knock and maximizes timing til it starts to ping then pulls out some advance.
Now here's the uncertain part. Mercruiser lists the Gen+ as having Aluminum intake, 9.4:1 Compression Ratio, valve lift of .431 Intake, .450 exhaust. Cam duration @ .050 is.294 intake, .307 exhaust. These values are all incrementally bigger that the normal Gen ! Small block 5.7 Mercruiser.
My guess is the engineers learned the engines could operate at those numbers and when they started to use them their was a natural need to identify the engines built this way, that's probably how they became the Gen+.
My 97 350 mag is apparently not gen +, it has a roller cam and an iron high rise intake with Thunderbolt V,.

Yes, the boat belonged to an owner of rond's marine here where i live. We know him and has been a service tech ( an anal one) his whole life, he's retired now. The boat and motor have been very well taken care of. Id post pictures if i can figure out how to do it with a phone haha!

I have a 5.7l lx 4 barrel, pre vortech. I first bought a bayliner ( i know lol) with a 3.0 and got tired of the lack of power. Did a ton of reading in forums and online. Then found the mariah and jumped on it. No, the hull is rated for 190 ( on the plate) and it is insured, just had to pay a premium for it.
Seems like theres guys on these forums who are incredibly knowledgable.. Because i bought it at the end of the season, i havent had her in the water, pick it up next friday,
Do the 5.7's have a lot of pull? Strong motor?

 

[alldodge]

Guess I should have said you may not be able to get it insured. Glad you were able to do it.

The 5.7 is a stronger motor then the 4.3, basically a 4.3 is a 5.7 with two less cylinders.

You will be able to post pics after you have posted 3 times.

 

[Shabah180]

Guess I should have said you may not be able to get it insured. Glad you were able to do it.

The 5.7 is a stronger motor then the 4.3, basically a 4.3 is a 5.7 with two less cylinders.

You will be able to post pics after you have posted 3 times.

Thanks!!!

 

[Bondo]

that's probably how they became the Gen+.

Ayuh,.... Welcome Aboard Shabah,.....

I believe you'll find the "Gen.+" means it's got Vortec heads,.....

 

[1979 Quartermasters]

Welcome. I have a 5.7 in a 20ft Searay and it pulls plenty good. I was looking to build mine to 400hp (just for fun), but the parts coming from the US were too expensive due to low Canadian dollar. Mabe next year. Looks like we may be in the water early this year.

Ken

 

[Shabah180]

Thank you bondo! Do you guys know if the the 95' carbbed has a computer? Or is it only the efi's? I read somewhere you can have a ddt scan and it tells you the actual hrs on the motor, right from the motor itself. And i noticed a small bit of corrosion on the b3 lower where the prop meets the unit. Its not equipped with a mercathode system, but does have magnesium anodes for freshwater application.
Is the corrosion on the b3 at this spot inevitable?
The rest of the drive is spotless, but ive seen pictures of drives, not properly protected, and it can get ugly fast. Theres a science behind it all, this boat will only see water when its used it wont just sit for a mth.

Sorry if im jumping around with questions, haha! But it takes a while to get the knowledge you guys have. Its not just a drop the boat in the water and go!! Theres a lot more to it than that!!!

Thanks again guys!

 

[Shabah180]

Welcome. I have a 5.7 in a 20ft Searay and it pulls plenty good. I was looking to build mine to 400hp (just for fun), but the parts coming from the US were too expensive due to low Canadian dollar. Mabe next year. Looks like we may be in the water early this year.


Ken

So there is mods for the mercruiser! Theres a site on facebook called powerboat swap shop. Those guys and their offshore rigs are crazy! Haha! Blown up 454's
Making ridiculous hp. I just went on there to see about parts etc but this site looks more promising for what id want.
Are you running an alpha on the searay?

 

[thumpar]

I have been trying to ascertain this stuff myself since my boat had a 1997 4 barrel 350 Mag when I got it. Since it was a repower I never trusted the 350 Mag label until this week when I removed it from the boat. Lo and behold there is a sticker on the flywheel cover that confirms the Mag.
What I'm leading up to is this. I think the LXi engines have the standard flat tappet cam and the Mags have the roller with more lift and duration for a few more ponies.
Since you have EFI you also get the advanced ignition Thunderbolt V. It is excellent, it seeks best timing whenever the throttle position or load changes. It constantly listens for spark knock and maximizes timing til it starts to ping then pulls out some advance.
Now here's the uncertain part. Mercruiser lists the Gen+ as having Aluminum intake, 9.4:1 Compression Ratio, valve lift of .431 Intake, .450 exhaust. Cam duration @ .050 is.294 intake, .307 exhaust. These values are all incrementally bigger that the normal Gen ! Small block 5.7 Mercruiser.
My guess is the engineers learned the engines could operate at those numbers and when they started to use them their was a natural need to identify the engines built this way, that's probably how they became the Gen+.
My 97 350 mag is apparently not gen +, it has a roller cam and an iron high rise intake with Thunderbolt V,.

The EFI motors ran MEFI then and then went to the 555 later. Thunderbolt was used on carb motors.

 

[1979 Quartermasters]

Are you running an alpha on the searay?

I'm running Alpha I Gen II. I'm aware they are only rated for 300hp, but if you don't do WOT hole shots, I understand they can be quite reliable at 400hp.

Ken

 

[alldodge]

If your going to keep it in the water and plugged in you need a working Mercathode, without it you drive will not last.

 

[Shabah180]

The EFI motors ran MEFI then and then went to the 555 later. Thunderbolt was used on carb motors.

What the top end for speed running light on a calm day in the crownline? Mid 50's? I guess it depends what your propped for, ive heard guys changing props frequently depending on the plans for the water that weekend!! Lol

 

[thumpar]

What the top end for speed running light on a calm day in the crownline? Mid 50's? I guess it depends what your propped for, ive heard guys changing props frequently depending on the plans for the water that weekend!! Lol

I have never GPSed it. The speedo says upper 40's but I usually run with 5-8 people and lots of gear. Some day I will get it out on glass with me and a helper with a lighter load to see what it will do. I have never checked the specs on the prop. It is the one that came on it and is stainless. The WOT RPM is around 4600 so I just left it alone.

 

[NHGuy]

Well the 93 thru 97 efi, which I referenced, shows a built in knock sensor & spark control in it's electronic flowchart...so it's gotta be integral to the efi.

 

[Shabah180]

No Title

If your going to keep it in the water and plugged in you need a working Mercathode, without it you drive will not last.

So the drive wont experience any electrolisis or galvanic corrosion if the battery is taken out?

 

[thumpar]

The 5.7l EFI started in 1996 and yes there is a knock sensor. It is where the drain plug would go on the block on the starboard side.

 

[thumpar]

So the drive wont experience any electrolisis or galvanic corrosion if the battery is taken out?

Are you sure it doesn't have a mercathode? I thought is was standard on the Bravo. On mine the mercathode "box" is in the box with the serial numbers on it at the top of the engine.