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Discussion Starter #1
Was wondering if you think an 871 is enough blower for a 586" blower moter. 8.8:1, it has fully ported pro1 345's, two 1150's done by pro systems, bullet cam .750 lift cant remember duration exacly but like [email protected] 050, lee intercooler. my problem is i cant get the rpms. took it out today 5900 at 5psi of boost. Use to run 6200 w 8psi of boost. boat has an agressor A. am i dreaming to think this thing should make 1100 to 1200 hp and i should see 6600 to 6800 rpms? My builder sid i should see about 6800 to 7000 rpm with an A cut.
 

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AKA Blownjet 468
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something just don't sound right. my little old 468 w/ an agressor A (they
say is comp. to a berk AA) would turn 6400-6600 all day long with a 12-71
at I think 2% over , making 16lbs boost /of coarse 116oct. fuel. what
lobe I ran was a custom grind, but baby compared to yours- 112lc, 655/678 lift , 268/272 @.050 but it ran EXTREMELY WELL! turn up the
boost, put some good gas in it, and see what it it will do!
 

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also i am 2.2% over to run that 5 psi of boost. would i be better off with a 14-71?
My question is what happened to change the RPM and boost level, a 14-71 might be a better match for 586 CI especially if you have a dry sump and crank trigger set up :)hand
 

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AKA Blownjet 468
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and yes, you would be better off with a bigger blower, with that amount
of cubes
 

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Discussion Starter #6
i changed pulleys. Before i ran 42 on top and 49 on bottom and today i ran 45 on top and 46 on bottom. Granted before was four years ago. should i still run the intercooler with a 14 71?
 

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Whoa, whoa. What is all this about a 14-71. Is this a pump gas deal. I assume it is or you would be running the blower harder than that. Why the hell would you go to a 14-71? Just to slow it down to a crawl so it leaked more. He is already running the 8-71 butt slow.
Your at damn near 9 to 1 compression, and 5lbs of boost, your creeping up on the limits of pump gas now. I don't know your timing, but you MIGHT be able to get away with 5% on the blower, but its edgey.
I have no idea how much power it takes to turn your impellor. I wouldn't know a A from a AA if it hit me in the head. But that piece is cammed and headed for way more boost than 5lbs. When you run a motor a 5lbs, you almost have to treat it like its N/A. Too much head, too much cam.
Take the same piece, throw some 116 in the tank, crank 32 degrees in the dizzy, push the blower up to 20-22% over with 16lbs of boost and bring a change of underwear.

The thing wants to run 7000+ It just can't do it with the boost pressure. Its all miss matched. It will never run right till it sees at least 12 lbs.
But on pump gas, you'll be picking piston pieces out of the pan in less than 5 mins.

If your engine builder knew you were going to run this on pump, go kick his ass!



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Discussion Starter #8
ok gn 7, yesterday i was running a 110/91 50-50 mix. Timing was set at 28 degrees. All i have access to is 110. Do you think I will be ok at 32 degrres and 12 psi of boost with 110 octane? With an A it would take around 1050 1100hp to turn 7000rpm the same hp to turn my impellor 6600-6700. Also without changing major components what kind of hp could i make on pump gas? I am willing to change pistons cam etc, but i would like to keep block, heads blower etc. What components should i change and to what to maximixe hp on pump gas? Can i make a 1000-1100hp on pump gas with the roots setup? Thanks guys.
 

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Whoa, whoa. What is all this about a 14-71. Is this a pump gas deal. I assume it is or you would be running the blower harder than that. Why the hell would you go to a 14-71? Just to slow it down to a crawl so it leaked more. He is already running the 8-71 butt slow.
Your at damn near 9 to 1 compression, and 5lbs of boost, your creeping up on the limits of pump gas now. I don't know your timing, but you MIGHT be able to get away with 5% on the blower, but its edgey.
I have no idea how much power it takes to turn your impellor. I wouldn't know a A from a AA if it hit me in the head. But that piece is cammed and headed for way more boost than 5lbs. When you run a motor a 5lbs, you almost have to treat it like its N/A. Too much head, too much cam.
Take the same piece, throw some 116 in the tank, crank 32 degrees in the dizzy, push the blower up to 20-22% over with 16lbs of boost and bring a change of underwear.

The thing wants to run 7000+ It just can't do it with the boost pressure. Its all miss matched. It will never run right till it sees at least 12 lbs.
But on pump gas, you'll be picking piston pieces out of the pan in less than 5 mins.

If your engine builder knew you were going to run this on pump, go kick his ass!
X2 GN-7 knows best ! My maybe was if you ran E- 85 or alky
 

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Discussion Starter #11
ok i cant get back out for a couple weeks but im gonna run 42 up top and 50 on bottom for 19percent over on 110 at 32 degrees and see what it'll do. or should i step the overdrive up more?
 

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Discussion Starter #13
One last question gn. on race gas and at 12-14 psi of boost is the intercooler doing that much or just restricting boost. I just have a lot more pulley options w out the intercooler w the pulleys i have. but if it is helping to make power or helping to prevent detonation even w race fuel than i am ok with it if it is killing a couple psi of boost. It is a lee intercooler.
 

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It helping. With the setup your talking about running, I would be leary of any more than maybe 28* timing with out the cooler. Your compression/boost is pretty close to what I run most of the races. Its reliable at that setup. If you were running the drags, you might be able to take out the chiller and leave the same OD ratio. You never really said what it is you do with this boat. recreational, or drags, or....? With the pump gas set up I was assuming it is a recreational boat. If so, leave the chiller.



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For the amount of air you need with those heads and cam you need a bigger blower. Once you get to a point of airflow with a given size blower, spinning it faster will only make more heat, and that gives a false high boost reading, but no more power. I run a similar setup with a stripped 14-71 and superchiller at 12 lbs. on a 565 on 87 to 91 pump gas depending on air temp. Discharge air is much cooler than with the 8-71 at 8 lbs. I found I could drop the overdrive from 28% to 12% and make more boost too. TIMINATOR
 

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cam .750 lift cant remember duration exacly but like [email protected] 050,

OK thats a insane big cam for what you are trying to do. 290 deg at .050 ??? and running 6 lbs /pump gas?? ummm try like 275 at .050,32 deg timing 100llav gas and 12-14 lbs boost.
remember you want to spin the blower at 15-20+ %, so to big is not good as well as 2 small. I think a well set up 10-71 at 20% od would work quite well on this.


yeah and tim's correct over 22% or therebouts its a fine line between od,boost,heat and power
 

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Discussion Starter #17
I really appreciate all the help guys. GN, Right now i am just trying to get the motor to make hp (like my own personal drag racing). I will leave the cooler on it run on 110 at 32 degrees and 19% over and see what it will do. Quick cp i have a buddy at the airport so av gas is a strong possibility for recreational use. What final compression can i get away with on 100? I wont leave it at 19% over when using it recreationally. I am just frustrated. I have had this thing at two different builders and shame shit no power. First builder smaller cam, heads not ported, 8:1 compression and 8psi and same story 6-6200. Next builder ports the heads tells me i need more cam same story. He tells me 1200hp at 10 psi and good gas so in his defense thats what i will try we will see I am pretty sceptical. I have thrown a lot of money at this thing and been disappointed. Tminator i am very interested in your setup. Whats the static? What kind of hp you making? I wanna make 1000-1100hp on pump gas. Can you pm me your number so we can talk bout your setup? I obviously need help. Heck maybe you can build it? I have a lot of nice components.
 

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Discussion Starter #18
One thing to keep in mind guys is this thing was built almost 5 years ago. But I literally only have like 3-4 trips on this thing since my second build. i got a divorce early 07 so this thing has been sitting since fall 06. I remember i was running 8 psi of boost but couldnt remember my pulley ratio. When i dragged it out of the garage a month ago it had a 49 on bottom and 42 on top. But i cant remember if i ran it like this or stepped the pulleys up and ran out of season. The thing that made me think i didnt run it like this was it was making 10psi of boost on the trailer when timing it when i revved it to 5k. So i just bought a 45 and 46 and ran it like that to see and got s whopping 5 psi. I went with the intention of bringing and swapping the pulleys i had on it, but I forgot them at home like a dumbass.
 

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For the amount of air you need with those heads and cam you need a bigger blower. Once you get to a point of airflow with a given size blower, spinning it faster will only make more heat, and that gives a false high boost reading, but no more power. I run a similar setup with a stripped 14-71 and superchiller at 12 lbs. on a 565 on 87 to 91 pump gas depending on air temp. Discharge air is much cooler than with the 8-71 at 8 lbs. I found I could drop the overdrive from 28% to 12% and make more boost too. TIMINATOR
Not a single word on compression ration here. Guess thats a mute point in blower motors once you jump to a 14-71. :D So you run 12 lbs of boost on a 9 to 1 motor using pump gas. Your pretty good feat considering the final compression ratio is around 16 to 1, and 12.5 is about the upper limit for pump gas. He can hardly deal with the boost he can make now, and you think a 14 is the answer?

sam805, run what you have and see if it does what you want.



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Discussion Starter #20
Thats why I asked what his static was. Will run it GN. GN do you think it would be smart to do a piston swap over winter? Bring it down to 7.5 or 8:1 and make more boost? And hopefully make more power.
 
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