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restored82
Newbie Joined: October-11-2006 Location: Canada Status: Offline Points: 37 |
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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 |
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Jus Fishin
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Brian,
I'm sure Joe or someone else will be by to answer regarding gains but I can answer the trans question. No problem with the Velvet. They are common on big blocks with lots more HP and will handle it. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21115 |
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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. |
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restored82
Newbie Joined: October-11-2006 Location: Canada Status: Offline Points: 37 |
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Thanks for the response and sharing your knowledge. Would the above mentioned changes run well on mid range or super fuel?Any idea as to the compression ratio adding the gt40p heads? Thanks Brian
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Jus Fishin
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peter1234
Grand Poobah Joined: February-03-2008 Location: United States Status: Offline Points: 2756 |
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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
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former skylark owner now a formula but I cant let this place go
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21115 |
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P's net ~9.5:1, no problem with 89 octane.
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restored82
Newbie Joined: October-11-2006 Location: Canada Status: Offline Points: 37 |
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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?
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Jus Fishin
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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They are direct bolt on but you must have the head bolt thru holes drilled out for 1/2" . The heads were used on 5.0 Explorers and Mountaineers and 5.0's used 7/16" head bolts.
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restored82
Newbie Joined: October-11-2006 Location: Canada Status: Offline Points: 37 |
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Nice thank you
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Jus Fishin
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63 Skier
Grand Poobah Joined: October-06-2006 Location: Concord, NH Status: Offline Points: 4234 |
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Brian, post some pics of your boat if you get a chance, would like to see it.
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'63 American Skier - '98 Sport Nautique
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Donald80SN
Grand Poobah Joined: January-12-2009 Location: Denver, NC Status: Offline Points: 3888 |
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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.
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1980 Ski Nautique SOLD Back to Cypress Gardens
2002 Sport Nautique, GT-40, FCT2, Cover Sports, Tower Bimini, Inc., Wet Sounds Audio System, Star Gazer Wake Edition S. 1968 Ski Nautique, Project. |
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john b
Grand Poobah Joined: July-06-2011 Location: lake Sweeny Status: Offline Points: 3236 |
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I just finished investigating GT40P heads for my engine. I found that tri-state cylinder head is able to provide rebuilt GT40P cylinder heads complete with springs and a 3 angle valve job, good for .550 lift for $598.00 + shipping, usually around $50 for the pair. They will also build them for your specific needs depending on the cam and rocker style you want and they usually ship in about 3 days from receiving payment . Talk to Sean about your needs.
812-421-0095 1712 Read Street Evansville, IN 47710 A lot of people seem to be satisfied with their products and they seem very knowledgeable. They are also a Flotec dealer and build a lot of Ford heads. |
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1970 Mustang "Theseus' paradox"
If everyone else is doing it, you're too late! |
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restored82
Newbie Joined: October-11-2006 Location: Canada Status: Offline Points: 37 |
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Thank John and Donald for the above information.Much appreciated
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Jus Fishin
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Donald80SN
Grand Poobah Joined: January-12-2009 Location: Denver, NC Status: Offline Points: 3888 |
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Yes, Tri-State was the other name that I could not remember.
Thanks John. |
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1980 Ski Nautique SOLD Back to Cypress Gardens
2002 Sport Nautique, GT-40, FCT2, Cover Sports, Tower Bimini, Inc., Wet Sounds Audio System, Star Gazer Wake Edition S. 1968 Ski Nautique, Project. |
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restored82
Newbie Joined: October-11-2006 Location: Canada Status: Offline Points: 37 |
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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
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Jus Fishin
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john b
Grand Poobah Joined: July-06-2011 Location: lake Sweeny Status: Offline Points: 3236 |
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I am not qualified to answer that question. I am only listed as a Grand Poobah because of the number of questions I have asked of others on the site. I am not an expert by any stretch of the definition.
I have read that some believe that the 2.02 valves breathe a bit better, but reduce the charge velocity a bit at low rpm resulting in a slight loss of torque at the low end. I haven't seen any data to support this, but it does not seem beyond the realm of possibility. Someone more qualified may chime in or you could consult with Sean at Tristate since they have much experience with these heads. Cheers |
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1970 Mustang "Theseus' paradox"
If everyone else is doing it, you're too late! |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21115 |
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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)!
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restored82
Newbie Joined: October-11-2006 Location: Canada Status: Offline Points: 37 |
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Being that both versions of these heads are readily available which is considered the better choice. I have asked this before does an H pipe benefit marine applications. Has anyone tried using one and could they share any results.
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Jus Fishin
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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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
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john b
Grand Poobah Joined: July-06-2011 Location: lake Sweeny Status: Offline Points: 3236 |
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The GT40P heads are available with 2.02 or 1.90s. The 2.02s require machining the combustion chambers for clearance and flow. The car guys believe the 2.02 are a waste of money because the heads are not capable of flowing the volume the valves will handle. A company called Powerheadd will do the conversion and I believe Tristate will as well. As far as cars it is far better to order a pair of AFR 165s than to waste your money on 1970s iron unless you want to squeak out a few more hp while scoring points for originality at the car show.
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1970 Mustang "Theseus' paradox"
If everyone else is doing it, you're too late! |
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