Can a 572ci make 850hp na? under 6000rpm
05-25-2006, 10:38 AM
#61
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Re: Can a 572ci make 850hp na? under 6000rpm
Looks like you've done good. Congrats.
Has anyone noticed that 5900rpm HP peak keeps showing up on most HR cams on BBC's?
Has anyone noticed that 5900rpm HP peak keeps showing up on most HR cams on BBC's?
05-26-2006, 11:34 AM
#62
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Re: Can a 572ci make 850hp na? under 6000rpm
WE have run 4 sets of sticks and you could bet on peck HP @ 5800- 5900 I'm sure it would be 5850 if this dyno captured @ 50 rpm increments 
05-26-2006, 02:49 PM
#64
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Re: Can a 572ci make 850hp na? under 6000rpm
Yes, 5900 has turned out to be a magical #.
Reasons:
Hyd rollers are heavy
BBC valvetrain is heavy
To turn higher rpm we need more spring pressure.
Unfortunately the higher spring psi leads to hyd lifter collapse and instability.
Run lower spring psi and valve spring run into instability.
So, kind of weird, huh, going either way with spring psi will put you right in this same rpm limit.
So, if a hydr roller profile is designed to make power over this rpm, why install it if we are rpm limited to this 5900 ? We are making a narrower rpm band by raising the lower limits but still stuck at the high limits.
Morel has been doing a bunch of testing on this. RMBuilder was a part of some of this. They , Morel, now have a few different lifter designs as of this year to combat this rpm issue that all HR rollers face. One is actually Marine Specific.
Anyway - I wanted to mention all of this because dyno sheets do give information - usually more than what is noticed. This is the power of the information age - comparing many things against each other and discovering info that would make no sense until you place it against many others.
================================
Summary: Just because the peak hp on a motor is say 5900rpm, does not mean that the camshaft profile is determining this.
Hope this helps.
Reasons:
Hyd rollers are heavy
BBC valvetrain is heavy
To turn higher rpm we need more spring pressure.
Unfortunately the higher spring psi leads to hyd lifter collapse and instability.
Run lower spring psi and valve spring run into instability.
So, kind of weird, huh, going either way with spring psi will put you right in this same rpm limit.
So, if a hydr roller profile is designed to make power over this rpm, why install it if we are rpm limited to this 5900 ? We are making a narrower rpm band by raising the lower limits but still stuck at the high limits.
Morel has been doing a bunch of testing on this. RMBuilder was a part of some of this. They , Morel, now have a few different lifter designs as of this year to combat this rpm issue that all HR rollers face. One is actually Marine Specific.
Anyway - I wanted to mention all of this because dyno sheets do give information - usually more than what is noticed. This is the power of the information age - comparing many things against each other and discovering info that would make no sense until you place it against many others.
================================
Summary: Just because the peak hp on a motor is say 5900rpm, does not mean that the camshaft profile is determining this.
Hope this helps.
Last edited by SB; 05-26-2006 at 02:51 PM.
05-26-2006, 04:21 PM
#65
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Re: Can a 572ci make 850hp na? under 6000rpm
try lighter valve gear and stiffer pushrods, last hyd roller I ran I used morel lifters, got 6300 with no sign of float, curious to see how long they last in boat at 6000. Also set springs close to coil bind. Last season I was having some harmonic issues at 5500, this year I ran power up to 6+, funny thing on dyno the motor really calmed down at 6000, without spin tron I am just speculating . gg
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