Boxes
 

What do they mean when they talk about boxes on an engine?
Or boxes in general and motors? What are boxes?

We are talking about extension boxes. They are used to create a setback for the outdrive. The most common extension box for a B1 drive has a 12" setback, but 7" are very common as well. They can be had as straight or with lift. Usually the boxes with lift has a 3" lift. Latham, IMCO, Stellings and others are makers of extension boxes.

Boxes on a Baja

Another closeup shot of boxes on a Baja

What do they do for performance on a boat?

Thanks

jj

Great pictures. I now know what they look like. How do they help in performance

They fool the boat basically into thinking it's 12" longer changing the leverage point that the drive has and allowing the boat to run at less trim angle. In some instances like mine it actually raised the X dimension by 1" installing the Imco Neutral box. If you install anything other than a 7" Latham or 12" Imco Neutral or Stellings adjustablel box. Which basically leaves the Imco -3 box you have to raise your engine which in most instances creates ALOT of work.

Thank you for explaining it to me. It doesn't sound like something I will be doing. My first priority this spring is the hydraulic steering, then the msd box or rev limiter ( dyno testing the engine) so I don't over rev the engine and blow it up when the the outdrive comes out of the water.

Thank you again for explaining it to me

jj

I would really like to know the exact horse power the boat has

Irish. It is not in most instances BUT ALL INTANCES A LOT OF FRIGGIN' WORK:lolhit::evilb:

I you want to fly your boat, you need to throttle it. A rev limiter won't save your motor or outdrive.

over reving the engine
 

I won't be doing it on purpose , but some times you do come out of the water, I don't do it intentionally. There is no rev limiter on it. When original owner put the procharger on it. He (his marina) couldn't get it adjusted correctly, ( what ever he ment by it) So he left it off. The owner told me if the prop comes out of the water it will over rev (raise the rpms to high) the engine because of the power in the boat. People on this chat line told me i need a rev limitor or a msd box on the egine to prevent over reving the rpms and blowing the engine. This is all new stuff to me. What is your opinion on what i presented top you

The issue is not so much whether or not you do it on purpose. When you leave the water, the motor will rev very suddently and therefore the rev limiter is not fast enough. It does help you a bit, but when you run in conditions where you might leave the water, you need to be on the stick. It will also be very hard on your outdrive if the prop speed is not matched to the re-entry speed. The fine art of throttling a boat is not something you'll learn in a day, give it time.

msd box thank you
 

Question will a msd box help the situation? ( I talked to a racing shop that works on high performace boats and he said that a persons reaction time is not fast enough to prevent damage, that a msd box would be a good safety device to prevent any unwanted damage)

Will a persons hands on a throttle be quick enough to prevent damage from occuring?



How do you match prop speed back into the water?


I see a ton of pictures with people taking the whole boat out of the water. Don't they take a chance every time?

I usually drive with one hand on the wheel and one on the gas at high speeds. Lake erie is known for being choppie.(i feel more in control when one hand is on the throttle at all times at hight speeds)

I appreciate any help in this department. I am very new to this. Your suggestions will help me save money and make a better decision on how to handel the situation this spring.

Basicly when i feel the boat start to come out of the water or feel it come out or anticipate it because of large waves back off on the throttle before it happens.

thank you
jj

If you are ready for it, you should be quick enough. Yes, the rev limiter will help as well, just don't rely on it alone. The way I do things, I NEVER take my hand off the throttle, other than a brief moment to push tab buttons ect. Now how to match prop speed. It is not that easy to explain and difficult to do. Techniques can vary as well. When the boat leaves the water it loses speed, how much depends on various factors from boat and setup itself to weather, waves, load, the angle of which the boat leaves the water and re-enters the water ect. I tend to pull back so the rpms get below but somewhat close to where they were, when the prop was in the water. Then it's very much a feel thing of how fast and when you start to apply throttle so that the rpms are matched to the speed you enter the water with. Re-entry angle and other variables are there too. Next time you watch offshore racing, try and listen to how the motors rev. Sometimes when a boat is really hauling with a good throttle man, you can hear how close the rpms match when the boat left the water and entered the water. it kinda gives you an idea about the reaction times as well.

Here is a good vid of one of the best in the bizz. Johnny Tomlinson

http://www.youtube.com/watch?v=fIjwfwfeRAU

Brian Forehand also does a very nice job here.

http://www.youtube.com/watch?v=ZIu-G7reKvw

thank you for the info and y tube
 

I too usually keep my hand on the throttle unless i am moving the trim tams or out drive trim. I do get the jest of what you are saying about the prop speed. When I get the rev limiter or msd box put on the boat, I won't just rely on them, I will rely on my self. I have not gotten used to the engine sound yet. I have only had the boat one season, alot to get used to and learn. Thank you for your help. I am not intentionally going to take the boat out of the water at high speeds. Usually when the boat leaves the water it is around 40 -45 mph. And it is not intentional,

thank you for your knowledge and information

jj

If and when you break a drive, you'll want a rev limiter;)
..unless you have psychic abilities and are able to
foresee these cataclysms and pull back before they happen;)

Over the years, I've had 4 drives let go and the rev limiter
beat my throttle arm every time:D

thanks for the insite
 

Thank you for your opinion, I plan on getting one put on the boat, People also told me to put a msd box on it . Which is better? What should i put on it a msd box on it or a rev limiter?

Rev limiters are a safty for the motor.... they are a great thing to have, UNLESS its a fuel cut and you are boosted haha.

Take a look at Merc's ITS (Intergrated Transom System) it has 7" of setback and steering built in. Kill two birds with one stone. I saw some used ones in the classifieds not too long ago.
http://www.mercuryracing.com/accesso...nsomsystem.php

Very cool stuff, have not seen that before. I bet its not cheap.

I think as far as cost goes, if you bought a box and steering seperate, the price would be similar. I have ITS on my boat. I bought it used so I'm not positive of the original cost.

rev limiter
 

Are saying that if your engine is boosted rev limiters are no good? I have a procharger on my 502, I know that if your fuel pump breaks you can blow your engine becasue if you run out of gas you can over heat an engine witht he procharger and blow the engine, The original owner put a second fuel pump on it, incase the one built on to the engine fails. so the boat runs with 2 fuel pumps at all times

thanks for the site
 

I checked it out alittle. It look like a great set up. I have to really go thru it.

the system
 

How do you like the system?

I like it....the steering is great, and it cleans up the transom. The less holes you have to drill in your transom, the better off you are.

As far as the performance of the box, that's hard to say. I seem to be running around the same speeds as the same hull / power without a box. The boat runs good in rough or flat water so I'm happy.

Yes, on the 502 mag, the rev limiter is a fuel cut, not a spark/timing cut. it will lean out a motor with a quickness...

but we are talking about the STOCK rev limiter. if you have a MSD ignition rev limiter thats differnt.

ive got a imco box and raised x-dimension on my 24 with dual sterreing coming off the box and about 700 hp from a whippled 496 the boat performs awesome but ive never had the boat in very rough water

The problem with redundant anything where they both run at the same time and the engine will run the same on only one is that You won't know that one is dead untill they both are.

Since i have a procharger on the boat, I will be definitly going with the msd box, as back up incase I leave the water with the boat. The boat came with the procharger, but the owner couldn't get the timing with the rev limiter so he never put it on. But since you said it is a fuel cut then the engine would still blow up. So I guess it happened for a reason. So now I know to get a msd box instead of a rev limiter. If I get a msd box , I shouldn't need a rev limiter correct? Becasue it won't help in my situation.

My 24 ft has a 24 degree dead rise so it rides good in rough water, i am very happy with the performance. Lake erie is usually on the rough side. So I need all the help I can get with that lake

I wonder if there is a way to put an alarm on it, so if one of the fuel pumps fail, I will know. Or if there is a way to kill the procharger and the engine. So it won't over heat and blow up. I do monitor the fuel the whole time I am running the engine. I don't know if i will be able to save it in time. If they did fail.

I think the MSD ingnition obx has a built in adjustable reev limiter. thats what you want. niot a fuel cut one.

Thanks for the informations. That is what people tell me, to go with the msd box. I guess i will have a busy summer at the race shop I am going to. I can't wait to get it dyno so I know the exact horse power in that boat. The original owner thought 620hp or it might even be 700hp. Becasue he put the charger on it , and a better manifold and a couple of extra things. The second owner ( who i bought it from) knew nothing about the boat except how to put gas in it. He did nothing to the baot except drive it 6 times.
So I am trying to learn as much as possible about it now. I am not a motor guy, so everytihn is very new and trying to find people in the area to assist me is difficult. I have a real good mechanice that can take care of normal but stuff, but this new area of high performance is new to him, but he is willing to learn on my behalf. So I found a race shop that builds engines for race cars for 30 years and he also works on 24ft to 40 ft high performance boats, with big horse power. So I think I am in good shape and have everything covered, just need to find sa good upholstry guy and body guy. But a good friend of mine ownes a body shop and he is pretty good with stuff and he owns a 34ft sea ray cabin cruiser. thank you again