A ? about tighter heads

[silverbullet02]

Its all good, I do want to re-ring it with new pistons. I did a compression check today with a good gauge, all between 136-139

I don't think I'd touch it with those numbers.

 

[whipper]

James, what was your temp before and after cut heads while pulling a skiier??

130-135ish. No real difference just never did like running 25-30 mph in warm water. When the water is colder spring and fall no problem but the kids dont want to in the cool water anyway. Ive stopped skiing and tubing behind the gs for two years now. I figure if I ever went with one of the new type motors I will pull again. My Friends all have real ski boats so when were with them they use them. i take the moms and dads all for joy rides to off set fuel usage.:beer: Really i think the ideal ski engine would be a 250xs or a new Evinrude for water sports. Pull like a mule and never worry about heat issues.

You need a 22-23 pitch prop to pull properly and Im just not into that unless I can spin my motor to 8000++.:very happy

Im pretty sure the head temps haven't goten to wild compared to stock. There is a little bit more pull out of the hole with smaller props like 25-28 pitch. But your not going to notice a whole lot unless you add more mods to help with breathing and more fuel. Its more of a starting point to other ideas you may have for future mods I feel. i wouldnt just do the heads on a stock motor without a plan for more revs from an acu or svs one day. If you want more quikness raise the revs with the stock heads then do the heads. Thats what i did also. I went a year with the Brucato unit with 7500rpm limiter. Then I went heads. heads are under 200 to do. I really dont think you can hurt anthing going 34cc. You have outstanding compression right now for a 225pm so maybe look at raising your existing box or an acu to 7500? Its sweet running 26 pitch props to 90. Much more fun than a 28 to 90.:beer:

 

[whipper]

Like Silver bullet said great Comp already. I just wanted to add. I did mine out of necessity. Because I boat at higher altitudes I lost around 5-7 psi from sea level. Me and Jay figured out one day with a formula he found that by going 33cc heads I could capture back some of what I lost. it worked great for my situation. I was at 123-125 and the 33cc heads bumped me to low 130,s. Thats around normal. Yours is great!! I would look at raising your limiter before I did anything. Promaxes can handle 7000-7200 no problem at all. Lots of guys running low 7,s everyday with these motors. Billy has run 8000 with no probs.:gasp So 7500 and prop to 7200-7300 and it will make the ski prop scream when your just runnen without a prop change. Or your limited to 70-75mph with a 24 with a stock box.

 

[xb03]

James, my limiter is set at 7500. Man I bet a 260 up there feels like a promax here at sea level lmao.

 

[whipper]

James, my limiter is set at 7500. Man I bet a 260 up there feels like a promax here at sea level lmao.

Hmmm good question? Wish I new:big grin

Probably a 260 still would feel stronger up hear. The heads and air can get them back to normal.

I have more holes in my cowl to bring in more air. Ive removed the filter on the Starboard side of the motor to let more air in there and that also cleaned up the lines to the vst on top. Heads and adjusted brucato acu to not be to lean because of this. Fattened up fuel curve, 7500 rpm also.

When Brian and i tested some OK props on lake Murry in SC when while breaking in the motor 2 up hit 90. Both of us over 200lbs. Back home after seat time i could barly get to 90 by my self. Went to a lake closer to sea level and hit 96 mph with a 30.

Thats when I started doing the little things. Ive seen 94 and change a few time since up hear with a good prop and great weather. Motors getting on now and can see 91-92 on good days with even better props.:big grin

Im sure a 260 would see 100 any time any place. 2500 ft or less above sea level. up to 106 the closer to sea level ya go. Pretty big differences in top speed with a 27 pitch prop.

I sure would have LOVED to try my motor at sea level a couple of years ago with a good 28 or 30. im sure I would have been knocking on the century door pretty closely?

Moving the seat side ways also made around 1 mph difference. Less counter steer and counter weight. With low fuel and 30-40lbs less in the port side you can feel the difference at speed and see it on the gps.

 

[90 5.0]

my pmax went boom at 420 something hours....

i think an injector quit though #6 went lean.

I had check comp recetly before the death and they were 136-138 on all 6...

my heads are cut a little, not much

 

[whipper]

cowl holes so it can breath. Just my own little experiment. i also ditched the water seperator beside the intake to open up that side. The water seperator blocks the starboard opening and the fuel lines didnt help much there either. The holes i drilled in the top of the cowl are angled toward the sides on the inside. i sprayed a hose at the holes and checked were the water went inside to make sure I the angles dint digest toward the intakes incase of rain. i Also have plugs for them incase it does. The 10 or so little holes at the bottom of the cowl really helped with acceleration. The top holes made a big differance in how I reached top speed I feel. I richened up my oil a touch also because of the 1000 or so hours. Its been a real great motor.

 

[whipper]

James, my limiter is set at 7500. Man I bet a 260 up there feels like a promax here at sea level lmao.

I raced a STV RR with a 260 and waxed him in the half mile to 90 mph with a 26 offShore on the limitter at 7500.:beer: If we had more lake he would have beat me because he can do 110 pretty easy.:shock: