mac temp.

[julianconde]

thats what im about to do ill let you know how it works andy..

julian

 

[k&b guy]

thank you Andy.

CARTER

 

[LarryConrad]

I run my Mac with the water cooled head, water restricted at the outlet. if the water temps are cold as in the spring no water at all. I tried the buggy head turned down in diameter and reduced to three fins with very inconsistent results, and went back to the water head. .006 head clearance, 60-70% nitro, Irwin muffled or Silver Bullet HP,Geraghty modded carb.My Mac doesn't wake up till it starts building heat,at least 200Fthe airhead over cooled it Started out with the engine on a TS-2,Nice cowl and radio box, the rest of the boat is junk. Next hull was XTR-21 Leecraft, very fast but dicey in the turns. Currently residing on a Powersurge Nemesis, Fast and predictable. My back up Mac is setup to go on a Lynx if I ever get back to running tunnels again, I'm just having too much fun running outriggers and sport hydros.

 

[k&b guy]

thanks for the info larry. i can`t reach 200 degrees (still trying) in the winter. over 100 degrees in the summer. no problem then. too windy to run this week. curious to see if the gasket will cut down on the lower heat sink problem.

CARTER

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[Tim_Duggan]

Carter,

I got good results using a gasket with my MAC O/B and also used a finned air cooled head with 3 fins. I used a back cut X637, SPP O/B pipe, 50% nitro, 1L plugs.

 

[k&b guy]

glad to hear the gasket helped. thanks Tim.

CARTER

 

[HTV Boats]

i remember reading a while back where someone was going to make a insulator out of g-10, 1/32" for between the powerhead/lower unit. never heard how it turned out. i made a gasket 1/32" out of regular gasket material. oil,water,gas,solvent resistant. haven`t tried it yet. am i wasting my time with gasket material?. input appreciated.

CARTER

I am not sure your loosing a great percentage of the heat down the lower unit though a simple insulator could not hurt. The main source of heat is the head, upper cylinder and out the exhaust. The front half of the crankcase is basically cooled by the air & fuel induction through the carb and intake of mass quantities of air. If your looking to retain created heat the hottest part is the exhaust. I have had success powdercoating pipes and maybe the carbon fiber pipe retains heat also though the choice of volumes and shapes are better in aluminum. Not a big selection of CF pipes for OB's. Inboard pipes are better shielded by cowls and hulls where OB pipes just hang out in air and water spray. I have also wrapped pipes with some success but I prefer powdercoat.

Mic