My jet boat goes 85+ mph with about 100 hp less than that..., cast crank, H-beam rods. BBF.
Also, it's much more than just the engine's power output.
LO
how much hp on a 2 bolt BBC???
I have a short block BBC 454 on the motor stand bored .60 over, fully ballanced with a cast crank, stock re-worked/shot peened rods. crank journals have been line honed, all ARP bolts including main cap studs.
My motor guy says 650 no problem on that bottom end and he knows what hes talkin bout but I figured id throw it out there and see if anyone had some advice.
Heres my question. I have a 74 rogers and would like to see 85-90 mph outta it. It does a solid 70 with the motor i have in it now (425-450 hp est.) Ive already had the pump redone and set up for it except for maybe an impellar change, just wondering if 650 hp would get me there (85-90 mph) or if it would be worth investing in a steel crank, some new rods and have the caps splayed if id need more hp.
Any oppinions would be great!!
My motor guy says 650 no problem on that bottom end and he knows what hes talkin bout but I figured id throw it out there and see if anyone had some advice.
Heres my question. I have a 74 rogers and would like to see 85-90 mph outta it. It does a solid 70 with the motor i have in it now (425-450 hp est.) Ive already had the pump redone and set up for it except for maybe an impellar change, just wondering if 650 hp would get me there (85-90 mph) or if it would be worth investing in a steel crank, some new rods and have the caps splayed if id need more hp.
Any oppinions would be great!!
1 - 20 of 27 Posts
Also, it's much more than just the engine's power output.
LO
I think you should paint it...
Your motor guy is right, and you can run more power on that cast iron crank than people will give them credit for.
The killer of them is the torsional harmonics of high RPM, so, according to my motor guys, do your best to keep it spinning under 6,000RPM. For an A-cut impeller, that takes a ballpark of 650 to 700HP, so don't cut the impeller too small and build the motor accordingly for good mid-RPM torque.
Good bolts in the stock rods are also worth a lot more than they get credit for. With good ARP bolts in them, the 3/8"ers may well be on par with the stock "racing performance" rods with those monsterous 7/16" Boron Steel Aloy bolts the factory uses. Same rods, bigger bolts and closer inspection.
The killer of them is the torsional harmonics of high RPM, so, according to my motor guys, do your best to keep it spinning under 6,000RPM. For an A-cut impeller, that takes a ballpark of 650 to 700HP, so don't cut the impeller too small and build the motor accordingly for good mid-RPM torque.
Good bolts in the stock rods are also worth a lot more than they get credit for. With good ARP bolts in them, the 3/8"ers may well be on par with the stock "racing performance" rods with those monsterous 7/16" Boron Steel Aloy bolts the factory uses. Same rods, bigger bolts and closer inspection.
paper weight!! im talkin heavy layup, 3 people in the boat and an ice chest full of beverages.My jet boat goes 85+ mph with about 100 hp less than that..., cast crank, H-beam rods. BBF.
Also, it's much more than just the engine's power output.
LO
I think you should park the pretty boat for awhile and get back to your roots bud!!!I think you should paint it...
What Rogers hull is this? Pretty sure there is a nasty little black one that ran better than that number with less power...
Two Bolt main Motors are very strong , run it ! Tom
We ran an Injected Fuel motor on 100% nitro that was a 2 bolt in our dragster for atleast 4 years and never hurt it. Then we put it in a sand dragster on 85% nitro and a 250 shot of nitrous and never hurt it. That was all with a gm steal crank. The factory stuff is alot stronger than people give it credit. I would run it with plenty of comfidence.
I think you should park the pretty boat for awhile and get back to your roots bud!!!
I'm working on it bud...I think we need to take a run down to Lost Lake and Aha and see what guys are running these days.
better than 90 with 650 or better than 70 with 450?What Rogers hull is this? Pretty sure there is a nasty little black one that ran better than that number with less power...
im down down for aha on sat! waters gonna be horible in parker anyway.I'm working on it bud...I think we need to take a run down to Lost Lake and Aha and see what guys are running these days.
i like what im hearing all but mr. 85 plus with 350 h.p. maybe a 300 merc on the back of a stoker or baker.... yeah the bottom of my boat could use some work but c'mon now. and with a ford?
You have to take a lot of peoples responses with a grain of salt. It takes a lot of HP to make a jetboat go...This isn't your first rodeo GRoper
dosent mean i cant call em on it! all in gd fun!You have to take a lot of peoples responses with a grain of salt. It takes a lot of HP to make a jetboat go...This isn't your first rodeo GRoper
i like what im hearing all but mr. 85 plus with 350 h.p. maybe a 300 merc on the back of a stoker or baker.... yeah the bottom of my boat could use some work but c'mon now. and with a ford?
I think he meant, 85mph with 100hp less than your 650hp motor.
Darrell.
Also, in the "user how-to" section is a thread on having a machine shop covert your 2-bolt main to a 4-bolt setup, if you so desire, and it isn't horridly expensive.i like what im hearing all but mr. 85 plus with 350 h.p. maybe a 300 merc on the back of a stoker or baker.... yeah the bottom of my boat could use some work but c'mon now. and with a ford?
The core magazine article is 1/2 dozen years old or so, the quote then from the shop that showed it was $300. Figure inflation for yourself.
It DOES require a factory 4-bolt rear main cap, just for alignment and spacing setup on the mill, but the cap can be a loaner as the original cap to the block is used.
2 bolt block
have a 2 bolt main cast crank in mine no problems yet .i installed a girdle on the mains to make it a little tighter and have the rev limiter set at 6000
have a 2 bolt main cast crank in mine no problems yet .i installed a girdle on the mains to make it a little tighter and have the rev limiter set at 6000
tw bolters are pretty strong. I wouldnt worry about it at all until you start to add some serious power-adders...use some quality hardware though...ARP studs are nice
we have a 2 bolt main studded that sees 6500 all the time.there is no stock stuff in there though.
it makes around 725hp according to the impeller charts.
they are very tough imo.
stock crank is fine imo for what you are wanting
deviltravis
it makes around 725hp according to the impeller charts.
they are very tough imo.
stock crank is fine imo for what you are wanting
deviltravis1 - 20 of 27 Posts
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