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Senior Master Technician
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Discussion Starter #1
Hows it goin, I recently rebuilt a 78 tahiti super tiger and installed a big block chevy I built for it, estimated around 500hp. I rebuilt the jet drive with an a impeller loader scoop with a place diverter and red insert cone. So far ive held it wide open for about 6 to 7 seconds and hit 63 MPH on a gps. I can spin the impeller to 5200 rpm constantly so my HP estimate is about right. The question is from your experience, how long should it take me, holding it wide open, to hit the max speed, and what should I be seeing for a max speed with this type of hull. Thanks.
 

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Senior Master Technician
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Discussion Starter #3
Damn I was hoping for around 65-70 MPH, I wonder if I put a droop snoot, shoe and rideplate if i can lift her fat ass out of the water. Before we rebuilt it she would run about 60 but take forever to get there. Now the acceleration is stupid compared to before. Funny how I only gained 3 MPH
 

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Administrator
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MPH is not generally the target with a jet. Being quick is their best attribute.
 

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Senior Master Technician
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Discussion Starter #7
OK, that would make sense due to the fact it feels like it pulls 2x as much as before. As I said above, do you think that a droop, rideplate, and shoe would make a difference? I'm used to the drag racing scene, im new to this water stuff.:confused:
 

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tintingsandiego
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I recently had my motor built by Bostick with a bit less HP than yours. He rebuilt my pump as well adding a 9 vain aggressor/straight snoot. While cruising now its about 2-300 rpm's less to be at same speed. I added a bolt on shoe/plate from Duane HTP which helped out more in top end for control and attitude. I never gps'd my boat before or after but definitely can tell its out of the hole faster, rides better and has picked up top speed. I feel all the add ons led to each giving a small improvement and in the end a big improvement over all.
 

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Resident Ford Nut
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10,075 Posts
If you run it at ski speed (3,000-3,200) for a few seconds then run it WOT for 8-10 seconds you're probably 98-99% done
 

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21' Bahner Sport
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125 Posts
Hows it goin, I recently rebuilt a 78 tahiti super tiger and installed a big block chevy I built for it, estimated around 500hp. I rebuilt the jet drive with an a impeller loader scoop with a place diverter and red insert cone. So far ive held it wide open for about 6 to 7 seconds and hit 63 MPH on a gps. I can spin the impeller to 5200 rpm constantly so my HP estimate is about right. The question is from your experience, how long should it take me, holding it wide open, to hit the max speed, and what should I be seeing for a max speed with this type of hull. Thanks.
Wow, your boat brings back a lot of memories, that was my very first boat that I bought myself. I had my engine built by Jim Pisciotta Racing and it had a few more ponies than you have and it ran 66=68 on a speedo, mind you that was way before GPS. I had a blast with it though and learned a lot about jets.That damn motor ripped the torque side of 1/4 stringer right out of the floor though. Luckily my Dad knows a lot about fiberglass and repair and we fixed it correctly. I sold it to a guy that loved it, so all good. Like the others have said, you are about right were you are going to be...

Just have fun and enjoy it
 

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That's running pretty good for a cruiser! Use the money you have to buy a smaller hull over pump parts. Then you can have a family boat and a runner!
 

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Hows it goin, I recently rebuilt a 78 tahiti super tiger and installed a big block chevy I built for it, estimated around 500hp. I rebuilt the jet drive with an a impeller loader scoop with a place diverter and red insert cone. So far ive held it wide open for about 6 to 7 seconds and hit 63 MPH on a gps. I can spin the impeller to 5200 rpm constantly so my HP estimate is about right. The question is from your experience, how long should it take me, holding it wide open, to hit the max speed, and what should I be seeing for a max speed with this type of hull. Thanks.
I played with a 1973 tahiti years ago and for shits and giggles went out and ran at an NJBA race at bluewater-Stock 454 with manifold, carb and headers. I won that race and the boat ran dead-nuts at 69.7 mph every pass. I will add I did alittle (on the trailer) bottom work on it to free it up a pinch. No droop jc stock pump no ride plate or diverter and that boat was all done in about 500 ft then it was light a smoke have a beer and go thru the traps about 8 or 10 seconds later. It was fun and surprised me how well it ran for a heavy ass boat!
 

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Yea, the Tahiti Super Tiger is not a cruiser. It is an 18 footer and is basically a splash of the 18 Southwind.
You said you are running an A impellor. Would maybe a little smaller impellor free up the engine for a few more rpms? Have you seen how free the hull is riding? Maybe you could need to get the hull to with less wetted surface. See if you can get some pics to see where the water is breaking, that will show you how free it is running.
In My Advantage, I should be pushing close to 700 hp, and am running a A2 impellor, and am only seeing around 4900- 5000. To say the least, I am very disappointed in performance, but I think I will need a smaller impellor to free up the engine. It caries the bow really well, but the speed and rpms are not what I think they should be.
 

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21' Bahner Sport
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125 Posts
I played with a 1973 tahiti years ago and for shits and giggles went out and ran at an NJBA race at bluewater-Stock 454 with manifold, carb and headers. I won that race and the boat ran dead-nuts at 69.7 mph every pass. I will add I did alittle (on the trailer) bottom work on it to free it up a pinch. No droop jc stock pump no ride plate or diverter and that boat was all done in about 500 ft then it was light a smoke have a beer and go thru the traps about 8 or 10 seconds later. It was fun and surprised me how well it ran for a heavy ass boat!
"was all done in about 500 ft then it was light a smoke have a beer and go thru the traps about 8 or 10 seconds later" :))THumbsUp
 

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78 Tahiti

Does your boat look like this? This is a 1978 Tahiti Low Profile As it sits with only intake and false floor removed it weighed 708lbs:))eek:)) Rides real nice, fun boat,:))THumbsUp
 

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Does your boat look like this? This is a 1978 Tahiti Low Profile As it sits with only intake and false floor removed it weighed 708lbs:))eek:)) Rides real nice, fun boat,:))THumbsUp
Exact same hull and it weighed in at just under 800 pounds,full floor, carpet and pump so I figure the weight would be about the same. I got rid of that boat along time ago but will say it was a good well built family boat that with a few improvements could see alot more. I would just address the bottom before re-rigging. They came out of the mold with a big hook at the transom and not so straight a keel! Doing that will add ???? mph! The one I played with had a stock hardin marine 454 that I added a c427x manifold, headers and an 850 holley list 4781. After the little bit of bottom work it really came to life! No pump work,ride plate, shoe, or diverter. Also remember that back in the early 70's boats the standard package 454 marine was a 425 h/p chevrolet!!!! Good luck with your'se!!
 

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John your Tahiti, which is the Tahiti Tiger, is the same exact hull as My Kona was. Only difference is that the Kona's had full stringers. The Op said to have the Super Tiger, which is basicly like the Southwind hull.
 
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