OK here's todays deal... just got the phone call on my engine fron the dyno shop . the 429 ford made 397 hp at 4750rpm my boat is a blueprinted hull glastron cvx 20 it has a Berkley 12JF pump with a Legand "B" alloy impeller... I also got the ultimate wear ring to complement the impeller along with a complete used (like new) bowl jetovator end of pump thingy. Any idea about a top speed and what to expect performance wise now that I have some soild numbers???
quig.
Is that one of the 20's with the pipes coming out of the deck? Hard to say how fast, we had a cvx 23 jet running right at 70 mph. A buddy of mine has a 20 Intimidator (wondering if that is what you have) stern drive pumping out a few horses and he is running 90.
Hi Quig,
Do you have "before" numbers for mph, rpm and (impeller cut...if changed) for your hull design? If so, I can give u a close estimate. If not, I have a guess, but would rather have your baseline.
Also, will they be giving you the complete dyno chart? I'm curious if 4750 is the peak and what hp would be at say, 5k?
jer
no ratso I have thru hull exhaust with the jet but I think the hull is the same can you tell me how the boat handles at speed??
hey Jer... that is exactly my problem... I bought this boat as a complete basket case it hasn't been in the water for 5-6 years so I can't give you any befor numbers... what I am trying to do is race the fast guys on the river . The fastest single engine boat will do just around 70 mph so I am hoping with what I have learned from you guys that I will be right there befor I start to tune everything in. As far as the sheet is concerned I am going to pick up the engine in the morning so I can give you a better feel for what it reads.Could you guess for me an approximate speed?? or what I might expect performance wise with this combo??
ok, my no-expert guess: 62-64 mph
That based on a healthy (400hp) 429, a straight medium-V 20' hull, and tight pump with trim.
I've heard of cvx-20's running upper 70's, so I think performance potential is there...but it may take some big hp.
Without a baseline, this is a total guess on my part. But I wouldn't be surprised if stock BB power drove your typical cvx-20 to high 50's. Let us know how it goes.
jer
Hey quig, I have been around a lot of cvx's over the years, 16's to 23's. LVjetboy is pretty damn close on numbers. I can talk to my friend tomorrow to see what he is pumping out, but it is a stern drive, usually a little faster than the jet, at least in stock trim. The boat gets a little hairy once it gets up in the 80's but we are going to do some bottom work on it next.
thanks Jer!! thanks Ratso!!
now using your "no expert" judgement what else can I do to raise the mph in my boat (I know this is hypothetical) but where else can I look for speed .If the same hull was seen doing 90 then do I need a lot more hp to push my boat up ( Iam putting a nitrous kit on the boat)but is there any "go fast tips you goodguys know that you could pass along????
quig.
I would have to agree. As you know I have a CVX 20 also, and I guess the HP at 400-425 and run right around 65-68 with a new (SPAM, Aggressor impeller)depending on the day. This year it will be getting a new ignition and a stealth manifold. Hope that will put me into the 70+ range.
Good luck and more pictures of the paint job please the color lay out looked killer! http://free.***boat.net/ubb/smile.gif
Jesse
Since this is just a SWAG (scientific wild assed guess) operation, my best estimate is that you will hit somewhere between 58-62 mph. In my experience, it takes a lot of HP and a light hull to hit anything over 75 mph. I'm talking about maybe 500+ hp at something like 5400 rpm in a low-profile hull. That glastron is a heavy hull, and will take very large doses of HP for incremental improvements in speed. The track to higher speeds is to have a carefully set up pump, ride plate, shoe, and hull.... Then keep adding HP and tuning the ride of the boat until you get what you want. Keep in mind what the intended purpose of the boat is, and keep your plans realistic. If you really want to go fast, you might consider a different style of hull.
My 2 cents
SteveM.
My guess is also in this range but probably 56-58
Originally posted by Jetmugg:
Since this is just a SWAG (scientific wild assed guess) operation, my best estimate is that you will hit somewhere between 58-62 mph. In my experience, it takes a lot of HP and a light hull to hit anything over 75 mph. I'm talking about maybe 500+ hp at something like 5400 rpm in a low-profile hull. That glastron is a heavy hull, and will take very large doses of HP for incremental improvements in speed. The track to higher speeds is to have a carefully set up pump, ride plate, shoe, and hull.... Then keep adding HP and tuning the ride of the boat until you get what you want. Keep in mind what the intended purpose of the boat is, and keep your plans realistic. If you really want to go fast, you might consider a different style of hull.
My 2 cents
SteveM.
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