Top end

Hello Joe: So what sort of horsepower gain would be gained from adding the gt40 heads ,intake[performer] and roller rockers? The other question would be ,what impact such an addition would have on the velvet drive 1:1 transmission?Another question is would an H pipe in the exhaust net any benefit.? I always ran them in my exhaust systems in muscle car days with noticeable gains. How would the above modifications impact the ski ability of the boat?

   I much appreciate your input and that of all others who spoke up.The you tube hot rod ski boat videos were sweet. Hearing a rumbling cam in a sweet SN rev up   and was awesome. It would be even cooler to see from an along side perspective. All ready located some heads online . Thanks again

No problem with the velvet but big blocks use the 72c/10-18 (small blocks use the 71c/10-17).

Figure 300ish with the aforementioned upgrades. Figure upper 40's in a 2001. You want gt40p heads, not gt40. The latter is fine but they have larger chambers and flow incrementally less.

This upgrade and the associated gains has been pretty well covered here. Feel free to search and bring yourself up to speed.

the top end is something that as stated above gets a little hairy with some hulls at speed. bearing in mind the costs per mph gained I would opt for the hole shot and time to get to 50 . nothing more fun than a zero to 50 run

Thanks again. The next question which comes to mind. Being that the combustion chambers are of a smaller size. Are the gt40p heads a direct bolt on or are there any clearance issues created between valves and pistons which could require machining?

Nice thank you

Do a site search for GT40P and you will find two companies that the CCFan guys use. I believe that one is Clearwater Cylinder Head in Florida. I think I got that right and there was one more. These two companies can provide you a rebuild product at a good price. The heads have been checked for cracks and have had new valves and springs installed. Someone will chime in a tell the other one or correct me on both. I believe both are in Florida.

Thank John and Donald for the above information.Much appreciated

Hi John : Thanks again for your help. Would you consider Tri state version with the 202 intakes and 60 cc combustion chamber the best choice. Seems to me 620 is a good price for these heads. Thanks so much for sharing

I suspect it's all goodness for our boats, John. Pretty hard to hurt low end power with all the prop slip we get. We're finding that big cams and single plane intakes work just fine. Slightly larger valves won't be noticed (in a bad way)!

Just so you know they are not 2.02's,but not that that makes any difference. Here are some spec's I had found a few years ago on a number of different Ford heads. As to a H pipe,kind of difficult to put one in a boat with the stringers in the way certainly can't work around them easily. The exhaust is already 3" per side and shorter than a car anyway and might not cool being enclosed and minimal water flow. I feel that you think you are going get huge gains with what your planning but in reality it will be minimal in these design of boats. With one person on board, my 69 16 ft Mustang while accelerating great,will top out the same as my stock 95 21 ft Super Sport