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I'm in the mid 70's I want 80mph+...ideas?

safetynut

safetynut

Member
Hey Fella's,

I've got a 2000 Checkmate 235 Persuader (454 EFI/w/Bravo 1). I'm in the mid 70's right now running a Mirage Prop and trimmed out. The engine is basicly stock with thru hull exhaust but I really want to run in the Low 80mph range.

Any ideas for increasing top end (without opening the engine and taking drastic measures)? The engine only has 100 hours and I really don't want to open it up.

I've heard about "lab created props" but don't know anything about them. I also considered Lenco Trim Tabs but was told they won't increase top end speed. I also thought about K&N air filter or some other means of better air flow in hopes of more horsepower?

Any ideas? Anyone with a similar boat Convincor, Peersuader, etc... with proven results?

:welcome:
 
Cheap Speed

First I would change the air intake to a K&N set up . Then go on ebay and find some Stainless Marine , EMI , CMI high flow headers, you will gain a little!
I would add a Land&Sea stern jack that will give you about 3mph. I know Imco made them too just an extension that pushes your prop into the clean water. But air flow in and exhaust out will be the easiest and cheapest first moves.:banana:
A whipple or Procharger SuperCharger would be the easiest way to 80s!
 
This type of topic has been hashed out a bunch of times, and the answer, much to the chagrin of the original poster has been how much do you want to spend? You will not see any gain with an air intake, you might see a mph or so with an exhaust (generally an exhaust upgrade is used for other hipo upgrades with bigger cams that need better exhausts to keep water from being sucked back into the motor). A labbed prop might be your ticket, but there is at least one guy on here who has a 142 blower on his older Covincor or Senator and picked up some real decent speed on an otherwise stock motor. Although to use that type of blower would require you to lose your EFI. I think that would be your ticket to cheap speed, and you wouldnt have to "open up the motor," other than swapping an intake manifold. It would require some carb tuning, and there is some serious knowledge here to steer you in the right direction as far as that goes, or you could get one from Nickerson. It is my belief (ie not necessarily fact) that the EFI will be the real hinderance to cheap, easy speed in your case.
 
One more thing, and this is a word of caution from an experienced hand. Your boat is already doing mid 70's which is faster than 95% of all other boats you will ever come into contact with. So what if your boat does 80mph, it will get you nothing but bragging rights, and it might get real expensive to get there. Do you think you will have $5,000 more fun if you spend $5,000 to pick up a few mph? I spent $14,000 just on my motor and other incidentals, and yeah its much faster, and yeah I feel much more confident in pushing the motor at hi rpm for longer periods, but I wouldn't say that I am having $14,000 worth more fun than I was having before. Not only that, its a never ending process. Some guys on this board have twice that and more in their powerplants, and everyone (myself included) are talking about what we are going to buy for next season. So just prepare yourself for what may result if you get the speed bug, because things can get out of hand ($$$) quick when you are dealing with boats. But I will tell you, nothing beats the smile on my face when I start my boat and hear that rowdy idle!!
 
try this. trim down and sit 4 head in the back seat. i wont race somebody unless i can take their passengers. might not work in your rig, but it does in mine. rooster tails look pretty off the back, but flat and steady is control. more weight same trim, gets me more speed with solid control, w/3 blade 24 chopper. same way using 4 blade cleaver, 5 more mph and control i could fall asleep at the wheel at 75k. it happens so fast that the gps dont catch up, but im doing it in conditions sometimes that my friends aint looking at it and i sure aint. seen 79 once before it blew in the floor. my enchanter dont like flat water. doing this w/a 2.5 handgrenade
 
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i know you people think im a fool and dont try to tell me i aint. but in reality im a normal redneck. ill quit my after hours sh** talking and get serious with anyone who wants to check out those rigs ive posted. those aint no homemade crap capt morg thought up at 5 am. weve got these boats and id like to talk to someone or everybody, get serious about it, and get some help and ideas and suggestions as to what a redneck fool can do with this Mirage 28 im getting ready to build as smilemaker3. ide like to know if you all have even seen it. i know you saw that baby tunnel. i aint no liar or deceiver. and ide like to pay my dues for the year if you all will allow me, and ill quit the bs and get serious, and let you guys watch what this fool will do anyway, with or without. but ide sure like to be serious and learn more. im getting ready to fly big, and i cant wait for the days that i used to dread. small craft advisories. coming summer, those will be the only days i can go in the mirage. ill have a boat for every condition. who would like to meet the real me, not captainmorgan.
 
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how long did it do 80? seconds, minutes, hours? my tunnel did it for 120$ in 10 minutes. if your a millionaire, can i go for a ride with you?
 
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captainmorgan said:
i know you people think im a fool and dont try to tell me i aint. but in reality im a normal redneck. ill quit my after hours sh** talking and get serious with anyone who wants to check out those rigs ive posted. those aint no homemade crap capt morg thought up at 5 am. weve got these boats and id like to talk to someone or everybody, get serious about it, and get some help and ideas and suggestions as to what a redneck fool can do with this Mirage 28 im getting ready to build as smilemaker3. ide like to know if you all have even seen it. i know you saw that baby tunnel. i aint no liar or deceiver. and ide like to pay my dues for the year if you all will allow me, and ill quit the bs and get serious, and let you guys watch what this fool will do anyway, with or without. but ide sure like to be serious and learn more. im getting ready to fly big, and i cant wait for the days that i used to dread. small craft advisories. coming summer, those will be the only days i can go in the mirage. ill have a boat for every condition. who would like to meet the real me, not captainmorgan.
Click to expand...
OK.........................
 
oh forgot, said we had a boat for every condition. what if we aint drunK?
we could go 80 all day. ill shut up, but us fools aint quittin, aint slowin down, and aint nobody stoppin us. its too much fun beating money with junk.
 
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ok, i even threw it in the trash, being it was empty. dont get mad at me, cause your creek is froze up. i went out yesterday just to help fix some peoples heat on a little island in the bay, and those dollar general face taboggans and sunglasses make people think im a fool for risking my life this time of year. but really pete, the surface ice in the ramp helps scrape the brant geese feathers blood and guts off the bottom of my smilemakers, because theres always a few in the herd who cant decide whether to fly or dive. and worse of all, the ones that misjudge the speed of the boat, and decide to fly when im too close. didnt take but one floor full of shattered glass to figure out installing a plexiglass windsheild. we love swapping drivers to see who can get their limit first. my friend said i made my boat sound like a popcorn popper, and one guy petted one in flight, and we are supporters of p.e.t.a. too. we feed the hungry few fish left in the creek, and fatten up those crabs that slipped thru the dredge. i will agree with that keyboard statement. i need to go mix me a drink...
 
Well, Whatever......anyways, back to speed...sober speed. If you're in the mid 70's now and you want to get to 80's, I don't think you'll do it with just basic add ons, (like prop, intake, or even headers) I would look around for somekind of a supercharger setup. One like Pete mentioned would work (142 or 177) but I, myself would prefer to keep the fuel injection if I could. A carb. is easier to make go faster if you're gonna tear the engine down and completely redo it, but that's not what you want and I wouldn't either.
A supercharger/procharger would work great. They sit off to the side ,like an alternator or something, and will give you more than enough power to get into the 80's, but It's gonna cost ya, I'm guessing 4-6grand., but I've never checked into it. They make ones that are made to work with completly stock engines like yours.
 
I would leave it alone and ride. Speed is nothing but a pain in the ass. If you want to go fast sell your boat and buy a cat hull. Unless you want to spend a crap load of money. Because adding that huffer is going to cut the life of your engine in half. We all like speed but I am about sick of dealing with everything that it causes. I am at the point now where I just like a good sounding cam and exhaust. The faster you go the more your going to beat your boat all to pieces.
 
In response to Charlie's comment on the blowers, don't forget computer tuning and injector swaps would also be necessary, further complicating and jacking up the price tag some more. Also, if you don't have it already, it sounds like you are in hydraulic steering territory, and you would definately be there with a blower. If you like the sound of a loud big block, a dry exhaust, or something that is close to 3/4 dry would probably make you smile, for a lot less $$ than a blower, but you likely wouldn't see much if any speed, and maybe see some tickets from the noise police.
 
This is a direct quote from Charlie (bigsbetter) from Sep. 2006 -- I think its the hot ticket for quick and easy speed, and Charlie can comment on reliability, care, and feeding etc.

"1988 251 Convincor Stock 454 with Wieand 177 supercharger running 4.5 lbs. boost. Timing is set at 28 degrees total. Holley 800 cfm carb. Stock everything else. If the blower is adding 125-150 horsepower as it's sopposed to then I'm around 450-475HP. Best speed numbers are 69.7 down river on GPS. I'm running a 26 Bravo 1 prop @ 4500 rpm. It runs about 3 mph slower with my 28 Hydromotive @ 4250rpm. Still expiermenting with props... and waiting for the cooler weather to get it over 70mph. The supercharger has gained me 12-13 mph. at a cost of $1900.00."
 
Charlie-I assume you are not running an intercooler on your blower, have you ever considered or looked into methanol injection? I know the Turbo Regal guys swear by it, and while it would let you turn up the boost and timing for more power, it would also be a great bit of insurance for super hot days or the occasional batch of bad gas...The majority of systems run certain types of cheap windshield washer fluid....
 
Safety Nut,
I just checked around online, and looked at ATI and Whipple setups. They both make intercooled setups, but the Whipple looks like it would be the easier deal as far as packaging. Also, it comes with a reprogrammed ECU. Also, the Whipples have far greater low end boost capability as compared to a centrifigal unit. Additionally, the Whipple, at least according to their comments, does not add height or forward width to the overall package. If I had the $$$, thats where I'd send it.
 
Yep, I absolutley love my blower!. It has caused me no problems at all. I don't think I'm even getting 4.5 lbs of boost like I stated before. I think it's only 3.5-4. I measured it 1 time and I think it was closer to about 4lbs. Anyway, it's perfectly reliable. All I do is put 91-93 octane in it and thats it. (well I do raise that hatch at the beach and act like I'm working on it just so people will come over and look).:drool:

PETE, I never thought about the methonal injection. I didn't know I could do something like that! I think I've heard about the winshield washer stuff on diesels. I'm gonna have to check into that or YOU can tell me more! It's like anybody else, should I leave it alone or try to go faster? Sure I want to go faster, but should I sacrifice the reliability.
 
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