700SCI Questions
 

Hello Guys,

Im just curious if anyone else has had this problem with the 700sci ? One of our customers chose this engine package with the nxt drive in one of our 30's and is complaining big time about the performance out of the hole! He claims that he can go WO throttle and the engine will not even rev for about 2 seconds, after that he says it revs very slow for about another 3 or so seconds and then it comes alive and is a monster. He says Mercury claims that there is a program in the computer that will not allow the motor to apply all of the horsepower from a dead standstill! He loves the boat but hates the performance out of the whole, any ideas how to correct the problem??

Have a pair of 700 SCi;s in a 38 Fountain. It does the same thing. I was told that it is because I am running such big pitch props. 16.5x39. Mine has to go into boost to brake the props loose to spin them to get on plane. We are also running 1.5 gears in #6 dry sump drives. You have to give it full throttle to get it to go into boost. Their is a lag time before it does. Have also tried to get the rpms off idle bring them up to about 1000,1200 then hit the throttle. It helps a little but their still is a lag time.

wonderful drive by wire technology. Its the tourque management software taking over. Once some of the tuners figure out how to crack the ecm's Id expect him to be very happy with those.

I have to agree that it is the torque management system. A Merc racing engineer came out to assist and certify my guys in the installation and he deemed it normal. Bottom line is the customer is bummed about it. He loves his new boat but claims he regrets the power train decision he made. We are running a 5 blade maximus , cnat recall the pitch at the moment but it is the one that performed the best overall. My customer tried a 4 Blade Bravo and he says it helped a little out of the hole but killed his top end. We have done 720's from Teague and they performed awesome! The 700sci is a beast and a hell of a motor but I think Merc needs to Torque management issue soon! P.S. The reason my customer chose the 700 is becuase he lives in Lake Tahoe and is at 6800 feet. The one cool thing is he only lost 2mph with the altitude chane from Phoenix to Tahoe!

I have another customer running twin 975's in one of our 34's and he is running about 116mph. Believe it or not he decided to go with XR Drives. He says the #6's rob way to much HP so they may be part of the problem along with the big props?

I´m not in the same power league as you guys, but my N/A 2006 525EFi in my 80 mph Outlaw feels exactly the same when I run a Maximus prop, and even with the labbed 28" Bravo, it seems like it takes a few seconds until things really come alive. I figured it is the nature of the camshaft.
However, in retrospect, it could be electronics protecting the drive from abuse. Not such an issue with my power package through an XR, but blower motors can give their drives hell.
The first time I rode in a 100+ mph boat, I was surprised how much work it was to get the thing up on plane. There really are no free lunches.......

I think the lag is just part of the torque management system, I wonder what they are protecting, the transmission, or the NXT drive. The 6's may take a little more horsepower to turn, but Ill take the reliability. The boat still runs 114 mph with twin 700's.

:party-smiley-048: Thats why we left when we did:D If we stayed it would have been really ugly, how was Worx band? We are not running from a standing start. Besides you know how hard that would be on those gearcases of yours.......oh thats right you already had problems.

I agree. Does anyone know which tranny they are using? I thought I read somewhere it was a Bam......which should take the 700 all day long hard out of the hole. Surely to god the NXT can take that?? The torque management would be great to have on some big hp bravo applications....especially if it is controlling the boost bypass valve on the Lysholms. The big bam tranny works great to 1200hp......you can blow one at will at 1400hp. And baby it in reverse. We had the motors set on 1200hp trying to get a 43nt off the trailer in a shallow ramp. Gigged it.....and KABOOM!!

Its not a transmission like Hueber, or Bam. The NXT transmission is a new piece. Im told it is a bigger version of the cone clutch set up in a bravo drive. Thats probably over simplified, but its not that big, and it runs Mercury Hi Pro. gear oil in it.

I'm willing to bet he'll regret that move. :(

Did the customer ever check it with a scan tool, see what the timing and manifold psi was when it felt low on power? The 700sci run very conservative timing down low, which I assume is for the tranny. I've been working on a boat that took the 700sci out, put a 598ci 1200hp engine in. Although it only idles at 750, it doesn't have a shift interupt in it and it bangs like you can't believe during shifting. I'm working on interupt to help it, but so far, everything has held up, although the drive has made handling extremely bad. Gonna try again this weekend, have the X dimension 3" higher than a Bravo, and now have gone to the 5 blade mercury cleaver (#6 prop). Its a Vbottom, and it just goes where it wants, very little steering control. That was with it only 2" higher than a bravo application. I'm actually thinkin it needs to go even higher, but thats not really feasible.

Btt

I'm sure they are just trying to save the driveline...because they never who is going to be running the boat...if you know what I mean...and probably the cam/head package to produce those H/P #'s may very well be laxed on the bottom end...can't have it all sometimes ! Rob

I have no lag with my engine. It's not a Merc 700, but it is a similar mechanical engine. So the difference will be the softwear.

On another note, why is your customer concerned with the hole shot??? If the boat gets on plane, thats all that should matter. he isn't hurting anything or stressing anything out with a soft hole shot. Why people hit WOT before on plane to me is just stupid and purposly abusing the equipment. These aren't drag boats.....

Check out this video, if you haven't already seen it. There is CERTAINLY lag before the boost comes up, built into the software. Otherwise, this guy would have left his drives on the bottom of the ocean. These are Merc 600's. What an idiot, by the way!
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Thats what I mean, idiots like that. Drive mechanics must LOVE those guys.

twin 700's 40 pitch props no lag. 33 Eliminator.

In some boats, when they have such large props, and low rpm ranges, they may need some extra torque down low, but like you said, with drivers like that, you can't always have the best of both worlds. I wonder if the 700sci equipped with #6 drives have a different program.

Dustin

Do you have # 6's or NXT's? By the way, I have a 33 as well.

By the looks of it he also has his K-Planes/Trim Tabs burried too!

NXT's. Yeah we actually know each other Dustin. Had a quad rotor motor.

Email me if you get a chance, [email protected]. Curious what rake and diameter prop your running. I just went to the #6 prop shaft and installed some 37 pitch, 18deg props with 1.21 gears.

Dustin

see post in prop section mercury CNC

Email me if you get a chance, I'll fill you in on what I found. I'm running a 33', dual 1200hp engines, Imco SCT drives, with their new lower. I'd send you a PM, but it's not available.

I'm not sure if this will help on anything other than a mercury #6 drive when spinning a large prop.

Without cavitation plate vent tubes we cant even get on plane.1.24 ratio #6 dry sumps 4 blade 37Px 17" Mercury cleavers methanol injected 565CI engines.

With vent tubes and very little throttle she spins right up to 5 grand and out of the water .
Again I cant say that it's not in the way Mercury has set up their 700s, but I cant imagine why they would program any intentional lag into their supercharged engines.
Good luck!

The lag time is programmed in because you can order a 600 with an XR drive. Also, maybe the transmission in the NXT can't handle a full throttle holeshot of the 700? Then again, I may be talking right out of my fat white a s s!

Still need a drive combo that wont break with the ilmors.

#6, or Arneson.


Darrell.

I have a buddy that test drove a deckboat with a 700NXT package First owner only had it a few months. He said it took forever to get on plane, due to the software holding the motors back. He didn't purchase for this reason. Said he couldn't imagine what it would be like getting on step with 8 people on board. I think Merc is being very conservative with the NXT to ensure no bad press in the beginning. I like the drives overall. It would be a perfect drive on my 28 Cat.. Two #6's would simply be too much weight hanging off the ass end on my boat.




Darrell.

I just ran one the other day (friend bought one, and I gave him about an hour of sh@# for not buying our stuff), and I saw that the boost was a bit low compared to throttle position below 3000rpm. Never tried 100%, but at 50%, at 2500rpm, it has 1psi of boost which is a bit low, especially for blower speed. Therefore, it's only logical that they have the bypass system open more there. But they don't offer the bypass position info on the data logs of the Rinda software. Maybe the merc laptop based program gives more data, has anybody checked into it?

Thanks,
Dustin

Curious if the 600SCI has the same issues? If you can get it with a XR, then I could certainly see it.

Here is a clip on the 600's you might find interesting.
http://www.youtube.com/watch?v=WWFi1SE2R7M

Went out last weekend in a 39 TG with 700SCIs. No issues getting on plane. Couldnt see any boost until 3800RPM. I thought it was a nice package.

700 Nxt
 

I just finished a 700 NXT upgrade on my 05 382. Photos are on the formula thread. I have no lag whatsoever. The 700's launch the boat on to plane. I never mash the sticks down anyway. These are not dragboats. 11,000 pounds. The NXT's have a ventilation port that releases the props with just a little throttle. I would imagine that a six would need a tube to release the props. On a deckboat i would guess there is a prop issue. Try a few before you walk away. They are really impressive in a 382. Dan from Team Archer marine did the install. I think the X dim is really critical to lift the large bullet out of the water. Also turning in was the "choice". My 2cents

What are your boost numbers when comming on plane? Maybe a newer program this year?

You would think they would have different cals for #6 with big trans, #6 with small trans, NXT with small trans, etc. I think some customers just don't see it because they don't drive it like the guy in the youtube video! I'm sure they all have similar cals.

Dustin

That video is exactly why Merc would detune there motor drive combo.

I took my boat out yesterday for the first time 08 39 with 700's NXT's.
The boat had no problems getting on plane. In fact this boat gets on plane faster than my 38 with 525's. There was no lag time. I was very happy with the way the boat got on plane.