Water Pumps for Crossovers?
 

I am thinking about installing crossovers on HP 525's EFI's to try and gain some HP by removing the standard circulating pump.Does anyone know if the 525 sea pumps will work all right without the circulating pumps or will a different sea pump be required. Also, what type of HP gains can be expected by doing away with the circulating pump. Any assistance from someone who has experience in this area would certainly be appreciated.

Re: Water Pumps for Crossovers?
 

I have had bad experience trying to run crossovers on non-blower motors. Major P.I.A. trying to dial in temps and water pressures. Multiple threads on this subject here in the past. My advice ... save your money and your motors. Don't waste your time ... it is not worth a few un-noticeable H.P.

Re: Water Pumps for Crossovers?
 

[QUOTE=VIPER7. Also, what type of HP gains can be expected by doing away with the circulating pump.[/QUOTE]

I agree. None that you will ever see w/o putting the motor on a dyno. And then very little.

Re: Water Pumps for Crossovers?
 

Maybe 12 To 15hp !!!!!!!

Re: Water Pumps for Crossovers?
 

Have to agree I would spend my time and money somewhere else on a N/A engine! Way too many issues with heat and pressure with no noticeable gains.

Re: Water Pumps for Crossovers?
 

I agree with everyone that there are much better places to look for power on an NA engine but if your determined to do it, Rex marine out of California has a poppet valve kit that actualy works and runs her at 160-170. I had to install one on a customers boat that came with a marine power engine with a crossover and the boat builder didn't leave any room in front of the engine for a circ pump. It had condensation problems becuase it was never getting over 80 degrees. I was suprised at how well the poppet valve sytem worked right out of the box.

Re: Water Pumps for Crossovers?
 

525EFI's have closed cooling. You cant remove the water circulating pump. It is what is circulating the coolant.

Re: Water Pumps for Crossovers?
 

Duh :D I don't know what the hell I was thinking

Re: Water Pumps for Crossovers?
 

I totally forgot closed cooling. Must be one of those senior moments. Thanks for the correction

Re: Water Pumps for Crossovers?
 

Appearantly the same thing I was. :rolleyes:

Re: Water Pumps for Crossovers?
 

So ...... remove the heat exchanger ... loose the weight .... 25,000 motor ..... :rolleyes:

Re: Water Pumps for Crossovers?
 

You can probably find .233 mph increase after much time and money just run with a 1/2 tank of gas for the same results.You will have a hard time getting your temp up to the level for the efi to work right. Unless you are supercharging leave it alone but the seawater pump will be fine no closed cooling and no circulation pump along with low temps you can get into hi water pressure problems. Lab your props and pick up a couple of mph for less bucks and better results. :evilb:

Re: Water Pumps for Crossovers?
 

I'm some what confused. With crossovers you talk about dialing in water pressures and temperatures yet all the manufacturers and dealers that sell these setups say bolt it on and ride. Now I realize they are the ones making money off of the sale . But whats the truth ? This has to be the MOST talked about subject on this forum. For the record I put a crossover on a carburated 454 Magnum and was not impressed and it was a top grade crossover

Re: Water Pumps for Crossovers?
 

you were not impressed ? explain ....

Re: Water Pumps for Crossovers?
 

Crossovers DON'T work if you want a thermostat out of the box!!
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I just went through the crossover ordeal myself...Finally got it working fine.
1. No thermostat = no temps, good water pressure = too cold running for an N/A motor.
2. Thermostat = good temps, high water pressure = blown hoses, head gaskets or intake gaskets.
===
Here's what works, if you want to run a thermostat:
1. Use a crossover with a bypass. You need the bypass for keeping the exhaust cool when the thermostat is closed.
2. Drill 2 to 4 3/16" holes in the thermostat inside the sealing lip. This allows air and steam to escape when the thermostat is closed, and allows some hot water to escape to the top of the thermostat. This also helps equalize the side to side temps somehow.
3. Use a pressure relief valve to control water pressure. The Mercury Racing part is a good one. It goes inline anywhere between the seawater pump and the crossover. A 1" dump goes overboard. Sorry, I don't have the P/N handy. They cost a little over $100, except at Bam, where they doubled the price for some reason recently.

Voila! A fully working crossover system with a thermostat..
Kent

Re: Water Pumps for Crossovers?
 

When I say I was not Impressed I mean I used a thermostat with the holes drilled in it by the supplier also it was the right degree thermostat. It also has a bypass. I noticed a slightly elevated engine temp.And what seemed to be excess steam from the exhaust. Everything else on engine is OK ,riser gaskets, Impeller ect.I have a hard time believing that by removing a circ. pump it increases water pressure ,with all the restrictions in the cooling system . If water pressure is a issue with these systems why don't the manufacturers offer relief valve kits with the systems. I am under the impression the steam could be coming from the fact that without a circ.pump to build pressure in the block steam pockets form.Again this doesn't appear to be as cut and dry a modification as the manufacturers make it out to be or is it

Re: Water Pumps for Crossovers?
 

Thats pretty much what ever one realizes ....I don't think you can claim better performance ..My 454's had em when I bought the boat ...First thing I did was loose a sea pump and cooked a motor ....If I had a Circulating pump it might have saved the motor by buying me more time. My Merc Mechanic went nuts when he saw them ...I spent alot of $$ converting both motors back over. Water Temp and Oil Pressure alarms had also been removed .... I learned ALOT fast ...($$$$) . It is doable because there are alot of em out there ....but you need to really know what your doing and what to keep tabs on ... Main thing for me is the Clean and cool look .....most will not admit that .... Would I go back ? I might ....but you definitely roll the dice when you do .... I still have mine ...... on the Shelf ..... :cool:

Re: Water Pumps for Crossovers?
 

I went to Crossovers with no bypass, no thermostats on stock 330's. Then installed Oil Temp Thermostats to get some oil heat, with larger (racing) oil coolers. Had heat issues with stbd. motor for water and oil after 10 min WOT. No debris or impeller vanes loose, new seawater pumps did not fix issue of "tired" motor. Drilled 6-1/4" inch holes in Thermos and reinstalled. 10 min WOT now gives 110-120 Water and 190-200 oil. Fuel level and traffic in channel limited longer run.

Re: Water Pumps for Crossovers?
 

88FOUNT33 .. key to your app is 110-120 water temp .... to me that is TOO cool ....motor shoul be min 150 .... my .02

what temps you run just cruising or slow speed zones ? Motor need to be hot enough to disscourage condensation ...maybe you need to have less holes in Thermo ? This is typical results I have seen ... not being consistant across operating range ...

Re: Water Pumps for Crossovers?
 

I forgot to mention that if you are running a crossover, you should run a water pressure gauge. This will also tell you if the seawater pump is getting weak. I am running a Gaffrig mechanical with the nylon tube in the block.

I ran the thermostat without the relief valve at first. The water pressure gauge was PEGGED at beyond 35psi at 2,500rpm! It then blew off the hose at the crossover.
A fellow on the 'other' board had his engine milkshake on the dyno from this. Others have had this happen, too.

I believe that the four large holes that 88Fount33 is running likely has the same affect as the bypass. It would be very interesting to see what the water pressure is on that motor....

If you look at how a stock setup works, they just don't have water pressure issues. With a crossover and a closed thermostat, the seawater pump is basically deadheaded. And the thermostat restricts flow, increasing water pressure even when it is open.
Kent

Re: Water Pumps for Crossovers?
 

Mudball with all do respect to your post Please explain how removing a circ. pump increases water pressure .

Re: Water Pumps for Crossovers?
 

Here is an explanation from a fellow on the 'other' forum. It's the best verbal description I have seen of the stock system...

'Quote':
9) The sea water pump feeds water into the factory t-stat housing by means of the large inlet on the right. I takes a right turn to the back and then at the back it u-turns back up the left to the front. In the back there are a few holes to let some of this water raise up into the chamber that the water outlets to the exhaust are. This chamber is also where the t-stat (when open) feeds into. Yup, two chambers - well thought out I must say. Okay, back to the front - the cool water then enters the very large outlet that connects to the hose that goes to the recirculating pump. The rec. pump is a real pump, therefore it is drawing water from this area - the significance is that it is reducing pressure here since it is pulling, not pushing here. Remember, the t-stat housing also bleeds some water thru to the exhaust which is open to the atmosphere and thus water psi reduces here also. Ahhh, so this is why this system has lower psi than the others! Yes, sir. Smart engineering!

Whew! getting long? Yup! Not like I really like to type vs talk but many will read this, so let's go further.

The water get's pulled in thru the rec. pump and then get's pushed thru the block, heads, etc. So, what if the t-stat is closed ? Ahhh, the water slows down, almost stops, and farther back the water is going into the upper chamber of the t-stat housing and out the exhaust. Remember?

It's really an ingenious system.
'End quote'

Re: Water Pumps for Crossovers?
 

Mudball you type well but let me ask you this if all this water pressure exist in the block why would steam pockets develop .All this water pressure should collapse steam pockets . Also if water pressure is such an issue ,Why doesnt REX or STAINLESS MARINE orEDDIE MARINE address it.

Re: Water Pumps for Crossovers?
 

Hi Codered:

First of all, let me say that I am NOT a guru on this subject! I just know what I have been through recently trying to get this crossover to work, and what others have also been through.
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When I ordered my EMI crossover, I specifically asked them about any problems. They said there were none. It even came with a thermostat with one little 1/8" hole in it.
To answer your question, I have no idea why those suppliers don't know about the thermostat/pressure problem, other than most crossovers are used in blower applications where they are the only option (no room for a circ pump). I don't know of any blower motors running thermostats. Many run the restrictor washers, though...These bump the water pressure.
With nothing in there, the water pressure is very low. I never saw much over 10psi at WOT with nothing in there.
===
I also don't know about any steam pocket problems. I don't believe that at least I have that problem. After a romp, my head temps are close to each other and vary little from front to back.
My Merc relief valve limits pressure to 25psi.
Kent

Re: Water Pumps for Crossovers?
 

I might add, it is interesting to see the relief valve open! When the thermostat is closed, it shoots (more like pulses) water about six+ feet out the side of the boat!! It looks like a SUPER bilge pump working!! When the thermostat is open, it stills lets water out, but not nearly as much.
Kent

Re: Water Pumps for Crossovers?
 

Mudball I appreciate your time and insight on the crossover situation.I still see much confusion and mis -information by the manufacturers on this subject

Re: Water Pumps for Crossovers?
 

Merc runs a thermostat on their 575sci blower motor. I don't know if Merc runs them on their bigger blower motors. When the water is cold in the winter I avoid WOT on my 575 because of high water pressure in the 30-35 range. If I ever change the thermostat I think I'll drill some holes in it to see if that helps.

Re: Water Pumps for Crossovers?
 

The holes drilles in the t-stats are not for pressure relief, they are to bleed the air out of the motor while the stat is closed. Just think, how much water can you shoot thru a hole smaller than a straw? ;)

Been there done that. Never go back. Like Mudball stated, the best way is a separate pressure relief valve before the crossover.

Re: Water Pumps for Crossovers?
 

zahndok, your t-stat already has a little hole in it.

The marine t-stats have the hole to bleed air out.
Steam pockets form if you aren't running the correct headgaskets and/or a marine stat (or holes drilled in a non marine stat). Basically trapped air. Block pressure collapse steam pockets? Well, yes and no. If you are at a hot spot, your hot pocket of air can "breed" more air out of the water. Have you never heard of a steam engine? They ran on steam at 150 to 200 psi. Block pressure should never go over 20 or so. Not enough to collapse all steam pockets in some applications. If you can give the trapped air a place to go, then the resultant water that replaces it will cool the hot spot and the steam pocket is gone. Take a look at some drag intakes. Little pipe threaded ports over the rear water passages. That's for a steam line that you run to the main water crossover in the intake.

Re: Water Pumps for Crossovers?
 

guys i removed a recirculating pump from my 502 & experienced dramatic shifts in temperature with a stock thermostat. after doing some research i drilled a couple small holes in the thermostat & my problem vanished. my engine now ran at 140-150 all the time after warm up. a recirculation pump won't suck water past a failed raw water
pump. you need a water pressure gauge regardless whether you runa recirc pump or not. the holes in a thermostat with a crossover system allow the system to maintain a constant temp, without the dramatic temerature swings you would get without the holes. crossovers work great & eliminate an automotive component that is prone to failure. i didn't see any real gain in speed with a crossover but i was very happy with the reliability & simplicity of the modification.