Getting closer, how fast will it go?

[EightSecV6]

Ive been putting my '99 259 Convincor back together with some mods for this year. The engine is fresh (now a 468) with 8:1 Ross pistons and stock rods/crank. The heads are the stock rect. port magnum heads, I cleaned up the bowls a little and put all new stainless valves in them and also installed 1.7 Lunati roller rockers. I installed a mild hydraulic roller I got from Crockett and I also now have long CMI long tubes. I used Fel-Pro MLS head gaskets and ARP bolts for reliability sake.The engine has a Whipple side mount that made about 6psi on the stock long block. I have a Bravo 1 with a 4 blade 28p.
Other mods for me over the winter:

-Fresh paint on the hull
-rebuilt and recovered interior side panels
-Hardin marine stainless sea strainer
-Hardin marine full flow thermostatically controlled oil/ps cooler
-offshore engine mounts
-Mototron 60# injectors
-Aeromotive fuel pump, regulator and braided hoses with a modified rail
-I removed th MEFI 3 and I am installing a FAST programmable unit
-MSD 6al2
-removed all stow compartments in engine area (makes A LOT of room)
-Removed and capped off the factory Y pipe and silent choice
-new Sterndrive Engineering trim cylinders
I still have the big job of assembling it all but I get closer everyday!

Will it hit 80 MPH on the GPS?????

 

[Big Red]

You need at least 550 to 600 hp to hit 80 in a boat your size and at least 650 plus foot pounds of torque. This is to me a good ball park figure Your prop might be a little big

You can drop hp but the torque numbers need to rize

 

[EightSecV6]

You need at least 550 to 600 hp to hit 80 in a boat your size and at least 650 plus foot pounds of torque. This is to me a good ball park figure Your prop might be a little big

You can drop hp but the torque numbers need to rize

I hope to get it out there soon! I think I'll be in the hp/tq range. The guy who I bought the boat from said they had it to 78 on the GPS once and it burned a valve with the stock Magnum and just the Whipple, I would love to see 80 but I'll take a RELIABLE 75

 

[ezstriper]

I think you may be close, but I doubt you will hit the 80 mark, I'm redoing my 251 with a simular setup with a weiand and a 489, going to play with the boost but @ 6psi you are going to be well over 10-1 comp. and in a boat with pump gas....going to be iffy to keep it out of detonation..probably what happened before. guess we can compair notes...in a couple of months for me anyway...good luck Rob

 

[safetynut]

enlighten me...

Curious why you decided on a 4-blade 28 P?

I don't know much about the props but I would think you'd want a 3-blade 25P or 23P? no?

I figured if you were looking for top end performance the 3-blade would get you their? Do I have this wrong or is there anotheer good reason for the 4-blade. (besides how cool they look, I really like the 4-blade look).

Just wondering...

 

[EightSecV6]

Curious why you decided on a 4-blade 28 P?

I don't know much about the props but I would think you'd want a 3-blade 25P or 23P? no?

I figured if you were looking for top end performance the 3-blade would get you their? Do I have this wrong or is there anotheer good reason for the 4-blade. (besides how cool they look, I really like the 4-blade look).

Just wondering...

That is what was on the boat when I got it. I have read a lot of posts about porpoising problems with the 259 hull. I have also read the 4 blade prop will help minimize this, maybe that is why it was on there, the previous owner said it would run up to about 5400 with that prop on it, I never got it that far.

EZ I am using the FAST engine management for tuning which imho is a major improvement over the stock MEFI3. I can tune it on the fly and keep it a little rich as well as pull timing as rpms and boost increases.

 

[Big Red]

Your on the right track with a four blade most Convincors are running a 4 blade not 3 blade. A very good start would be a bravo 24P 4 blade. I think you would need over 600hp to turn that 28p 5400. I am running 500-550 hp with 570 foot pounds of torque and turnning a 24p 5800. You are correct with porpoising I know most convincors if not all 23-30 have this problem. It takes place durning mid speeds just trim down and it will stop or leave your trim up and speed up and it will stop. I can make mine look like a basket ball going down the lake with a touch of the trim botton.

 

[EightSecV6]

Your on the right track with a four blade most Convincors are running a 4 blade not 3 blade. A very good start would be a bravo 24P 4 blade. I think you would need over 600hp to turn that 28p 5400. I am running 500-550 hp with 570 foot pounds of torque and turnning a 24p 5800. You are correct with porpoising I know most convincors if not all 23-30 have this problem. It takes place durning mid speeds just trim down and it will stop or leave your trim up and speed up and it will stop. I can make mine look like a basket ball going down the lake with a touch of the trim botton.

I can hardly wait to get this thing back together, I just finished up the long block tonight. I could make my boat porpoise like you said but I could also eliminate it with the trim tabs and leave the drive alone.
I dont think 600hp is out of the question with my combo but time will tell. I have spent a TON of money on this thing in 6 mos and I aint buying a new prop, if it doesnt work out, I'll just go slow!!!!!!

 

[Big Red]

I would not buy a new prop either. Like you said try what you got first. Then borrow one to try if you need to.

 

[winter]

I have to agree on the compression/boost/fuel issue. 8psi CR is about middle of the road for a blower, but 6psi isn't a whole lot. Be very careful of detonation, you may not even hear it. I'd say this... have two props and two pulleys at your disposal. For a fun day out with family/friends, prop it and boost it low. Just yourself and a fearless friend, running light, prop high and boost it up. Also tank-up with brand-name fuel, hi-test of course. No ****z, Wawa, no-name stuff, just the good fuel.

 

[EightSecV6]

Engine is about ready to set in, I test fitted the CMI headers with the side mount Whipple and much to my surprise I had a 1/4" clearance! Lousy cell phone pic but here it is!!

 

[boatn70]

Looks fun

my 242, dynoed at 558 crank hp so i figured 500 at the prop, ran a 23 3 blade for 72-73 mph. then came a procharger, 5psi, intercooled....runs 80-83 gps now. pretty safe, i havent had any detonation issues. im sure your used to that with the TRs youve been running. I estimated at 5psi i was somewhere like 650-675hp at the prop to go 82ish. BTW, this was with 28 stock bravo, best for handling as said before.
I have mine set up to turn up to 5800rpm so i really like the 26 bravo. i can come out of the hole easier and spin it up for some speed when needed, acceleration is outstanding!!
just remember to be easy on your drive outa the hole!!

Hey, i may be calling you regarding a TR if i pick one up. looking at something thats all stock right now.

keep us posted

b70

check out "Kevins second pass" this was 558hp and 23 pitch, 73mph ... hangs out there real good!!

http://www.fullmooninjune.info/home/moviepage.html

 

[EightSecV6]

my 242, dynoed at 558 crank hp so i figured 500 at the prop, ran a 23 3 blade for 72-73 mph. then came a procharger, 5psi, intercooled....runs 80-83 gps now. pretty safe, i havent had any detonation issues. im sure your used to that with the TRs youve been running. I estimated at 5psi i was somewhere like 650-675hp at the prop to go 82ish. BTW, this was with 28 stock bravo, best for handling as said before.
I have mine set up to turn up to 5800rpm so i really like the 26 bravo. i can come out of the hole easier and spin it up for some speed when needed, acceleration is outstanding!!
just remember to be easy on your drive outa the hole!!

Hey, i may be calling you regarding a TR if i pick one up. looking at something thats all stock right now.

keep us posted

b70

check out "Kevins second pass" this was 558hp and 23 pitch, 73mph ... hangs out there real good!!

http://www.fullmooninjune.info/home/moviepage.html

I plan to set it in next week and start wiring/rigging. I still have a ton of work to do and summer is coming fast!!!