Evinrude XP150 Question...

[SlimDaddy]

I have an Xp 150 rude on a 87' Stratos 179V. Currently the set-up is pushing it to 65.4 mph gps:D with a 6" jackplate,Boyesen reeds,and exhaust relief holes in the mid. The jets were fattened up .001 when the reeds were installed. I'm turning 5500 r's with a 24" pitch 4 blade. Do you guys think I would gain anything from raising the compression from stock with this set up? :confused:

[dynobo]

Your speeds are pretty good with that setup. Your slip % is about 2% so I would guess that your tach is probably off a wee bit. What compression #'s do you have now? You would probably gain on the bottom end and mid-range with the increased compression but, I wouldn't expect too much on the top side. With the speeds you are recording, you are probably turning in the 6000-6200 rpm range now. You might want to step up to a 25p or 26p prop. 140lbs of squeeze or more and you will definitely have to run the 93 octane.

[SlimDaddy]

Thanks Dynobo. My tach has acted strange sometimes like a bad connection or something I'll check into it. As far as the fuel goes I always run high octane pre-mix with Klotz(no VRO) since the vro cost me some cash before.If I went to a 25p or 26p should I stick with the 4 blade or try a 3 blade since it's pretty much a slug out-of-tha-hole?

[Lockjaw]

On my GT175 I picked up about 4 mph with the good heads, but I don't think that would work on your engine.

Try a renegade. I have a 25p one, and really like it. A raker would probably have better acceleration.

[EMDSAPMGR]

It is worth while to change your heads. There are a number of stock 149 cubic inch crossflow heads which will improve your performance. In this order of desirability, 76 200 (320644, 645), 79 235 (323872, 873,) 79 200 (323456, 457.) Some of the later XP engines came with heads that had an extra .040 lip added to the head face to stand it away from the block and lower compression. Don't know if your heads have this, but it can be machined off. You will need to rejet with any of these heads and if your engine is a 30 degree timing advance, you should reduce it. The renegades have more bow lift and may work well to lift your hull out of the water, increasing speed.

[SlimDaddy]

Thanks for all of the input guys. All of your ideas are greatly appreciated.

Thanks,
SlimDaddy