skopi55

Will the -2 Shorties give the same results on a 2001 35' Twin Step w/ 500 efi's? I am going to have to give this some thought. I also thought that unless you were running 90, you would loose mph. I am right at that barrier at 88mph.

Thanks for the help.

carney

I think He was saying that he went from sport masters to imco. when doing this the imco flows so much water you must dump water over board to keep the water pressure off the heads. Imco has a kit to do this.

Marginmn

Just got back from Lake Cumberland Marine. The tech guys up there think that I may not have a water pressure problem since I am running 525's which have closed cooling - so the pressure won't be going thru the engine at all. They have had some Outerlimits that also show huge pressure but on closed cooling systems it may not be an issue. I am going to check with Mercury tomorrow.

CustomRyder, the polished lowers look great. However, for anyone running in salt water Imco said they will lose that polished look really fast and look like crap unless you are constantly polishing them, so go with the satin finish if you are running in salt water.

A couple things to consider. I was running standard length Sportmaster lowers. I have heard that they can run as much as 2 -3 Mph slower than standard length XR lowers. The big water intakes and the longer skeg slow you down. So if you are already running XR lowers you may not see as much gain as I did going to IMCO shorties.

Also, I am not sure about which year Fountain started really jacking their X dimensions up, but if you are running a 2001 or newer boat then you might already be running a high X and not gain much of any benefit by trying shorties. But for those of us with 2000 or older Fountains where the drives are buried in the water then I have no doubt that they will help. The higher X the newer boats are running would explain why the newer 35 EX's with 496's are running almost as fast as the older 35's with 500's. You just need to call the factory with your Vin# and ask them where your X dimension was located. They should have all that in their records. If it's already in the 18+ range then you may not see the gains that I have.

As far as my X dimension is concerned, I was told by Jeff Harris when he picked up the boat last winter to take it back to NC that I was running a 16 1/2 X dimension, which is much deeper than fountain is currently shipping from the factory. I was told that they are now running 19+ on most of their newer boats, and that they can do so now because the newer Merc props are so much better at getting boats on plane.

They wanted to raise my X up 3 inches by installing my 525's higher in the boat but I choose to only go up 1 inch. My reasoning for doing this was (after doing some research) that raising the engines up that far would have a negative effect on the boats center of gravity and it wouldn't handle as well in turns - something that is very important to me. So I choose to do just one inch with higher engine mounting, and then after testing that set up try to pick up the other two inches with shorties. As for the sportmasters, the longer skegs are great in rough water, but in this particular application they really slowed me down. When I bought the engines the drives came with them new and in a sealed box. I thought they were regular XR's.

So, if my rigger is correct, I am currently running a 19 1/2 inch X. One thing of interest. When I called Imco to report the impressive results, and that I was happy with how quickly I jumped on plane, the Imco tech rep told me that I would benefit from a -3 shortie, reasoning that if I jumped on plane so quickly that I should go higher for maxx performance on the top end.

The only comparison I have to the regular XR lowers would be the two 38 fevers that LCM has swapped out 500 carbs for 575's. Both of those boats (A 99 model and a 2000) were running sub 80 with the 500's and ran 86-87 when the 575's were installed. So I'm running less HP and going just as fast with the shorties. The 2000 model that I drove with the XR's and 575 was scary chine-walking at 87. My 2000 was rock solid at 86 with the Imco's, but then so were my sportmasters at top speed. The Bullet on those drives rock compared to the rounded XR's.

Tomorrow it's suppose to be 70 here, so after work I'll head out and do some more testing. I've always wanted a 100 mph boat so during the off-season I am going to consider ways to get her closer to that mark.

One sub-100 but but super reliable option I'm looking at would be the 625 Ilmores. I could be in the mid 90's and not breaking drives with that package. Some of the speed pick up would be from the increased HP, and some from the fact that they weigh around 600 lbs lighter than a pair of 525's. No matter how fast, it's never enough

dykstra

congrats

candyman35

Congratulations!

I am interested in what merc says about the pressure. They thought 40 was OK for my 454's. Temp was all they were worried about with mine. I don't think 35 with the closed cooling would be a problem. As long as you are not blowing off hoses you should be fine. If you want to make sure of this I would ask the question in the racers section. I'm sure the F2 guys will have the correct answer for you.

BTW is you see another killer deal on 525's let me know.....please.

Dan

Marginmn

Thanks Dan,

If I go with new engines then I will be looking to move my 525's. One was brand new when installed this July and now has just 38 hours. The other had 50 ish hours on it when I bought it. I had new valve springs put on it just in case and had it put on the dyno to make sure it was perfect. It was. It now has 38 hours more.

I'd be willing to sell the pair for 35K if I get new power. Not a bad deal considering just one new 525 nearly goes for that retail.

Ran-Dom 32

I have a feeling that many 95 - 00 Fountain owners will be looking into -2 lowers.

pullmytrigger

congrats on the gains Marg!......its good to see some real gains after a bunch of exhaustive research and $$.......which as we all know is not a given with a boat

Marginmn

Well I called Mercury racing and they suggest that I keep the water pressue below 30 psi. They say running to much pressure over time will create hot spots on the heat exchangers. They offer a pressure relief valve. I'm looking into it.

LPBoater

Marginmn

How is th mid range - Friend of mine put them on his 38 fever and it also picked up top end, but in the mid range the slip was high and at 3500-4000 RPM struggles to run 50. Once it locks up it runs low 90's top end. Also noticed the rough water handling in the sloppy stuff was compromised. Have you experienced any of this?

LP