Marginmn

iTrader: (1)

I was running 50 at around 3400 rpm. (These are GPS speeds, not speedo.) The midrange seemed good to me - about as good as before with the 30's, but not as good as when I had the 28's on it, but that would be expected going from 28's to 32's. Now it just keeps going after it hits 80 instead of hitting a wall. As for handling in the sloppy stuff, I have no idea because I have not run in any. But the boat is running higher in the water and that is why it can run faster. At the absolute top speed the boat is ROCK SOLID. Not even a hint of rocking or pitching or chine walking. It just runs straight and level.

I am speculating but I think that I will be able to run faster in the chop because when I tuck my nose in now I will be doing 80 instead of 70. I guess I'll find out in the fall.

As for your friends boat he may have gone too high with his X dimension. I have heard that if you go too high then you have a hard time getting on plane, and that it also kills midrange and top end handling. I wouldnt accept that just to get a few extra mph so I will probably keep mine where it is at.

What kind of HP and props is your friend running to get into the low 90"s?

aTX427

Congrats on the results - 86mph is stout for a side by side 38. I have been thinking about doing the same thing on my 2000 Lightning, but $$$ been holding up an expensive experiment. Is there any chance you could measure the distance from the bottom of the transom plate to the notch? that is the easiest way to determine where you are compared to everyone else. The xdim is somewhat difficult to get exact. You should be able to place a flat ruler behind the trim block to get a straight line measurement from the transom plate to the notch. Appreciate you.

Downtown42

I run lo-mid 30's h2o pressure when WOT.

Test report from factory shows 28-30 @ 4000
32-35 @ 5300....85mph

tomtbone1993

iTrader: (3)

interesting info............good thread

Marginmn

iTrader: (1)

John, regarding X dim - I'll try to get a measurment the next time I'm down at the lake. I put her up for the winter this weekend. Looks like we need to sort out that water pressure problem before we can do anymore testing. It pegged the water guage and blew a water hose off the last time I was out. I guess it's better to have to much rather than too little.

rclaws35

That's very interresting, I put -2 Imco's w/1.26 gears on my 2001 38 and boat was lazy but did pick up about 3 mph. I changed gears back to 1.50 and then the boat would not get on plane with 33 merc labs, so I bought some 32 - 5 blade Herrings. Boat would not get on plane at all then. I then bought 1" spacers and that helped, but was not great. Now I'm back to 2" spacers and 1.50 gears . Still does not get on plane to good but I can live with it. 33 pitch = 5800= 102 mph/ 32 - 5 blade Herrings =5300 = 100mph
Going to call Herring see about cutting down Dia. of prop.
GOOD LUCK!! $$$$$$

Marginmn

iTrader: (1)

I think 2001 is about when fountain started raising the X up. I assume your 38 is a lightning? What kind of power are you running to get it over 100 mph?

rclaws35

Somewhere between 850 and 900. The engines are 510, Brodix heads BDS 871 with 850 Holley's. 7 lbs of boost. Great engine combo.

Marginmn

iTrader: (1)

Sounds nice. Is the boat pretty stable at that speed? Have you had much trouble keeping your drives together?

rclaws35

The boat handles great. Only one problem with drives. One end cap got loose and cost me one cone clutch and one gear set. I'll try to post pictures.