Jet Boat Design flaw ?

[RH]

I'm new to the jet boat thang , bought a 1976 spectra 18 end of last summer 460 with a berk. JE runs like a top but here is my question and I would like your opinion . I have read many posts on regulating water pressure going through the block because it runs too high and low water temps during normal operation because they should be higher . I don't know my water pressure and my temp while out cursing is around 120 Deg. , my boat is stock . Why would so many jet boats be built without the builder addressing these problems ? I would consider both these issues to be a design flaw what's your opinion ?
Thanks RH

[1973 Hondo]

From what i understand, being told that is, on the berk it puts out over 200 psi from the pump to the motor,What i do know is the jacuzzi at max rpms only puts out 40 psi,or 200 gph . And that is a question everyone is asking my friend. And im sorry but the wj pump is the only one i know at this time..

[jet4fun]

you should read my reply on this thread (http://forums.***boat.net/ubb/ultimatebb.php?ubb=get_topic;f=11;t=002455) it should explain how to alleviate your problem (if you have one)...
as far as there being a design flaw... well thats a matter of opinion. most boats (boats other than jets) have to use a water pickup system and a water pump... the idea behind a jet boat is to use water pressure from the jet rather than using a water pump, in other words a much simpler and reliable setup. as i've stated in my post on that link, once you have a correct setup you should have no problems......
BTW, the other way to plumb the system is to have a brass gate valve right where the water comes in from the jet, and adjust this gate valve at idle to hold the motor at about 180-200 degrees... you should NEVER have any kind of valve or restrictor on the outlet line going overboard this is when you will run into some serious problems because you are restricting the water trying to exit the motor

[Tahiti Tiger Mark]

I have a 455 olds with a berkeley jet, I had the low temp thing last year but then I bought the Thermostat housing from CP Performance. now my temp runs between 160 and 200 where it should be. Problem with running too cool is lost performance, the oil and motor doesn't get hot enough to evaporate the water moisture inside the motor also which is not good. The housing is cheap and worth the money to protect your investment.

[RH]

Thanks for the opinions keep them comming , I understand the problems and the solutions but my point is why , if these are problems , why did the builders not address them and solve them . If the boats were sold with problems in my mind they would be defective . RH

[Jbb]

jet4fun:
you should read my reply on this thread (http://forums.***boat.net/ubb/ultimatebb.php?ubb=get_topic;f=11;t=002455) it should explain how to alleviate your problem (if you have one)...
as far as there being a design flaw... well thats a matter of opinion. most boats (boats other than jets) have to use a water pickup system and a water pump... the idea behind a jet boat is to use water pressure from the jet rather than using a water pump, in other words a much simpler and reliable setup. as i've stated in my post on that link, once you have a correct setup you should have no problems......
BTW, the other way to plumb the system is to have a brass gate valve right where the water comes in from the jet, and adjust this gate valve at idle to hold the motor at about 180-200 degrees... you should NEVER have any kind of valve or restrictor on the outlet line going overboard this is when you will run into some serious problems because you are restricting the water trying to exit the motor Exactly ...there is no simpler system than having a firehose at your disposal...I have a valve at the inlet and I have set it once ...As I run boost on a 8.75 to 1 engine I prefer to run a little cooler anyway...keeps detonation away...I would rather have to regulate the constant flow down than worry about not getting enough out of the rubber impellored pumps!
[ April 11, 2003, 06:31 PM: Message edited by: JETBOAT BRIAN ]

[Tom Brown]

I'm not so sure, Brian. I think the rubber impeller is the way to go.

[Jbb]

Brown...You starting with me again....?.... :D

[Squirtcha?]

I don't know RH. My setup is as simple as they come and it works just fine. My temp at idle is 150-160 degrees and around 120 while underway. I've never had a problem with water in the oil and my motor performs just fine. Outlet water from the pump is valved and I run the ol' Bassett T valve for headers. I did valve the dump water but I never touch it. Just run it wide open all the time. These guys are probably all correct when they say you should run a pressure regulator, but I'm not gonna mess with it. It's been running just fine for going on 6 years now. If it aint broke..............
http://jetboat.homestead.com/files/P1010010t.jpg

[Wet Dream]

I wouldn't consider it a design flaw, but more of a slight challenge that any jetboater should be able to remedy, specific to their application. :D

[Tom Brown]

I think the biggest design flaw with jet boats is putting the prop inside a shroud. :D
Sorry, I had to...
I'd like to point out that it's important to keep some pressure in the cooling system. The pressure will keep the water from boiling in the jacket closest to the cylinders. If that happens, you will get flash insulation and have a normal looking water temperature but your cylinders will egg all to shit.
I'm sure the valve on the cold side of the engine is fine but I'd make sure there was 10-15 pounds in the block, if it were me.

[jet4fun]

RH:
if these are problems , why did the builders not address them and solve them . If the boats were sold with problems in my mind they would be defective . RH like i said, a matter of opinion... if its set up right from the start then there should be no problems...... would you call a v-drive defective because you have to periodically change the rubber impeller, would you call an outdrive defective because if anything clogs the pickup the motor overheats, would you call a car defective because you have to change the oil every 3-5K miles :confused:

[RH]

Jet4fun , your talking apples to oranges . I mean if I bought a new 1976 Spectra 18 off the show room floor and the motor never ran at the ideal temp. for maximum performance because it did not have a thermostat and the cooling systems pressure was so high that it was blowing out gaskets because it was not regulated that boat in my opinion would be defective , it was not set up right from the start . You are talking about maintenance and part failure . Why didn't Spectra and every other boat builder install the thermostat and the regulator , it would have been a cheap fix for a better performing and longer lasting motor . RH

[Super D]

I agree, RH. It always perplexed me why they'd sell a pefectly good boat with a little grenade in it waiting to go off. Especially if you're new to jets (like I was before going back to a prop) - you'd never even know this was an issue until too late! :confused:

[Squirtcha?]

RH
Personally, I think you're putting too much stock in "the motor running at the proper temperature". When I took my last motor out of my boat, it was the original from 1976. The crank had never been turned and the cylinders were all in perfect shape. No scoring, not even egg shaped. I coulda probably run that motor for another 27 years without doing anything to it, had I not wanted some more power from it. Granted, it was a low compression stock motor, but the cooling system was setup exactly the same way it is now and max temperature I ever saw on the gage was 160. If there are any horsepower gains to be had by running your motor at 200 degrees, I'm betting they're negligible. As far as longevity is concerned, I'll be happy as all getout if this motor lasts half as long as the last one did.
[ April 11, 2003, 11:09 PM: Message edited by: Squirtcha? ]

[Cas]

I have a little different take on this. I ran a 455 Olds for 11 years without any problems like I'm hearing so many are having. I never blew out gaskets, didn't overheat, none of it....heck, I didn't even have a gate valve on it for the first 5 years. I think a lot of people are making a big thing out of nothing mostly because of the idea that hotter is better.
I'd rather run the engine a little cooler so the oil doesn't overheat.

[LVjetboy]

Wow Steve, you're up late.
If anyone's read Rex's link to the cooling thread bible, you know I'm there. I've played with quite a few cooling systems. Here's some thoughts:
Is cooling temperature more important than oil temperature? I'm thinking not.
Does a cooling system for a 375 hp engine work just as well for an 875 hp system? Why should one system fit all? Personally, I think the stock system flow rate is too low at idle and too high at full throttle...leading to a lot of controversy.
Why assume a jet product offered new by Spectra or anyone else for that matter is the best design and completely free of problems? Consider the market and resources devoted to jet boat "design and engineering" if you could call it that. Not nearly that of Detroit, but look at all their defects. How much effort from us consumers to get Detroit to "address" their defects? Even though those defects well known?
Lots of ideas floating around about "don't ever do this" or "don't ever do that." But my last engine survived gate valve inlet regulated, ball valve inlet regulated, cold running temps and hot running temps, many a Nos run, ball valve and Rex thermostat regulated, water injected headers, milkshake from time to time, monkeying with pressure gages and experiments with water pressure from 15 psi to 35+ psi, sucking a rock and running the water dry.
All that and never a pressure regulator to speak of. On and on for 11 years of jet boating. BBC 454 engine just torn apart and guess what? Looks nearly new according to DNE. Very little wear. Same as Squirtcha's comments.
So in the end apparently many designs and running temps work fine. But I'm always looking for the best design and not just what works fine. So you'll see a lot of posts from me on this subject...looking for that best system the jet boat mfg's don't care to spend the time or money designing.
And I'll still measure the pressure drop across my big block to solve that mystery once and for-all.
jer
[ April 12, 2003, 03:05 AM: Message edited by: LVjetboy ]

[RH]

I am Ford and sell thousands of 460's to boat builders , if there is a performance lose do to cooler than I recommend engine temp's , Its going to piss me off because my engine will receive the blame and not the boat builder .
Next question , What is the difference between engine temp and oil temp , do they differ that much ? RH

[HavasuBarney]

Jet Boat design flaw? :D :D
Come on now, you had to know this thread has been calling my name, loudly!
Let's see, where to begin. How about the idea that you have put a car motor INSIDE your boat!
Then you have that jet which should be pointing at your feet or perhaps the small of your back while you sip some ice cold brews or even some wine with a tub full of hotties! Let's not even mention that you have huge holes in your boat and suck water into it in order to move.
Design flaw.... ya think?
It sounds like the temp might be a little hot for my liking too. I'm not much of one to enjoy a tempid 104 degrees, but some thing around 110, I can sit in there and sweat untill my toes are shriveled! :D
Hot tub car boats.... design flaw...? :D :D
No, you guys have given me purpose on the internet!
All in good fun though guys! :)

[old rigger]

RH:
Why didn't Spectra and every other boat builder install the thermostat and the regulator , it would have been a cheap fix for a better performing and longer lasting motor . RH RH,
from 1972 to when I quit building boats in the mid 90s, I've never worked at a shop that didn't install a gate valve in a pump, and that includes, Tahiti, Hawaiian, Rogers, Advantage, Howard and Warlock. Well, throw Warlock off the list, they didn't do any jets. Even in the 60's when my dad started at Tahiti, they were standard. If the owners took them off for some reason, that's another story. My guess is that your Spectra came from the shop with one whan it was new.
I've never had any problem dialing in the right temp with a valve in place but I really like the looks of those thermostat housings that Rex or who ever sells. I've never had the need for one, but they seem to be a great idea.

[AZKC]

Thanks for stopping by HB, Allways a pleasure :D
Hows your purple boat doin :cool:
KC

[HavasuBarney]

AZKC:
Thanks for stopping by HB, Allways a pleasure :D
Hows your purple boat doin :cool:
KC :D
I always check in with this forum because you guys are the true hot boaters IMO. You guys work on your own boats have have a similar mindset to myself, always looking to better your boats.
I love you guys! :)
I even really like what I know about jets, I just don't know much in that department. Same with motors, just never done any of that stuff.
Please never take my teasing to heart, it is all in good fun, except you Chet! :)
The purple boat is in a holding pattern at the moment, too busy with other customer's boats and the little time I'm not working, I'm tring to be on the water.
Any way, I like hangin with you guys and hope we can share some tips, cold ones and a few laughs as time goes on!
Take care buds!

[RH]

I here ya HB those jets feel real good after a full day of yard work and weed whacken with my 2-stroke , smoke belching , high pitched ear piercing , high polluting little WEED WHACKER !
Hey maybe you can help me out , this thing is really loosing power it barley spins the little string thingy , You do work with LAWN and GARDEN equipment right ? RH

[RH]

Old Rigger
Where was the valve located , was it mounted or just placed inline ? Do you recall how the boat builders did the nonskid was it some kind of epoxy with sand ? Thanks RH

[bp]

RH:
I am Ford and sell thousands of 460's to boat builders , if there is a performance lose do to cooler than I recommend engine temp's , Its going to piss me off because my engine will receive the blame and not the boat builder .
Next question , What is the difference between engine temp and oil temp , do they differ that much ? RH well, try not to get toooo pissed. i've observed a number of engines thoroughly dyno tested, and one of the things that we watch is now the engine responds to reduced -water- temp. they always make more power at reduced -water- temp.
try not to think of -water- temp as -engine- temp. this is not a car. think about the system for a moment; the water is making a single pass from lake temp, through the engine, and out again. the objective of the water FLOW is heat transfer, engine to water. the water is not recirculating through a radiator. the oil temp is not going to even remotely be reflected by water temp, because the oil is staying in the engine, hopefully transfering heat to the cooling water.
also, think how it's plumbed. you have a discharge off the bowl, going through a mostly 3/8 ID line, supplying the engine. the water pressure establishes what the cooling flow rate will be through the line. pressure supplied by the berk (or jacuzzi, or panther, or whatever) will vary depending on rpm. my quikdata bowl pressure tap is 180 degrees from the cooling pressure tap, so it should be roughly the same. here are some pressures from last year. these are just ballpark figures, as other pumps may produce different results, but it still shows how variable the pressure can be:
1600rpm - 21lbs
2700rpm - 53lbs
3000rpm - 68lbs
4000rpm - 126lbs
5000rpm - 180lbs
now, there will be pressure drop through the supply line, and pressure drop accross the valve, or whatever else you have in the path to the engine .how much?? still waiting for jer to answer that one.
the bottom line for me is; if the water temp is 130-140, i'm getting good flow and heat is being transferred. cooler single pass water temps will result in better power, at least on my engine and the other engines i've seen on dyno's.. i don't like restrictions in the outlet that could impede flow. water exits at the top, so the water passages should be full. the only way you can get the water temp up is to reduce flow. but, that doesn't mean heat is being transferred any differently.

[Unchained]

I really didn't think the jet cooling system was all that hard to figure out. You just don't want to much or to little. Kinda like a car engine.
For the basic design flaw that has to be the outboard.
It's like someone finished the boat and threw it in the water and THEN SAID,
"Hey, we forgot the engine" :rolleyes:
"Well, just hang one on the back"
What's handy? :confused:
How about that one from the fishing boat? idea
OK that will do. pig_flyi

[LVjetboy]

RH,
Like bp says, oil and water temps for our engine's can be way different than cars. I didn't think so until I measured 265+ on the oil temp at full throttle with water temps running 80 degrees (inlet) and 170 outlet. A jet boats oil can get really hot, and when you back off to idle, all that heat wants to go up top.
jer

[old rigger]

RH:
Old Rigger
Where was the valve located , was it mounted or just placed inline ? Do you recall how the boat builders did the nonskid was it some kind of epoxy with sand ? Thanks RH Rh,
yes, the valves were/are mounted on the pump, where the inlet is. Just run an extension, 6 or 8 ", to clear the transom then mount your valve to that bib. That way you dont have to reach way back in the transom adapter to adjust the valve. I've even seen guys, once they get the setting right, take a little piece of chain and put it from the handle to the transom or something so the setting wouldn't change.
On that non-skid, you're exactly right. On boats like a Spectra, Tahiti or so on, it was done on the plug by sifting sand on wet paint, or gel. On the better boats, like the Howard (when he put a better looking deck on the Spectra 21 bottom) or Schiada, they used stuff like diving board non skid which came in a nice printed, more uniform looking pattern. Much nicer. That other stuff always reminded me of a liter box! It's easier to patch though, if you want to fill a hole.

[Havasu Hangin']

HavasuBarney:
I love you guys!I think someone has gotten a hold of Barney's password...either that, or he's drinkin' in the afternoons...
Maybe I should dig up a few quotes?

[HavasuBarney]

OK, well it's an S$M type love relationship, that all I got to say about that.
Quit stirring our loving pot here HH. :D

[Havasu Hangin']

HavasuBarney:
Quit stirring our loving pot here HH. :D I can't help but think of the "I have the fastest boat and all the women at the river want me...you jet guys are losers (http://forums.***boat.net/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=4;t=000731)" thread...
Telling me not to stir the pot? Hmmmm...someone has gotten a hold of Barney's password... http://www.planetsmilies.com/smilies/confused/confused17.gif