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Killer 401 |
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WesternRed 
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5799 |
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 Posted: May/21/2022 at 6:53pm |
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Have you run it without that funny looking hair dryer attached?
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I've finally given up drinking for good...........now I only drink for evil.
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Trader
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Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881 |
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Posted: May/21/2022 at 7:24pm |
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Agree to try without the supercharger. Should be 454 HP @ 6400 without it.
John, it may be that you need the 1050 CFM with the supercharger. Just not getting the fuel for the air at pressure. Did the dyno show a sharp drop in the AF mixture at peak? You'll get it sorted, just a little time.
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Gench
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Joined: Oct/09/2021 Location: Boulder CO ish Status: Offline Points: 182 |
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Posted: May/21/2022 at 9:52pm |
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I’ve been reading and reading on building a motor, including supercharged. I’ve never built one, just to preface my comment; that said, from what I’ve read and believe to understand… those heads flow too good for that much overlap. Clearly I could be wrong based on my none experience. The 16 degrees of overlap will bleed off boost. Closing the intake so late, bleeds boost. That makes the supercharger work harder, creating more heat. It seems a 224 duration cam @ 110 lsa with only 4 degrees of overlap, plenty to clear the chamber. Supercharger creates more exhaust flow so scavenging should be more efficient, unlike turbo that slows exhaust.
Again, looking to understand vs challenge. Thanks
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Rebel Machine
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Joined: Jul/03/2007 Location: Western Il Status: Offline Points: 5122 |
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Posted: May/22/2022 at 6:42am |
Here's my cam card just for comparison. Mine is also Torqstorm equipped. Made 578 HP and 603 TQ. -Steve-  Edited by Rebel Machine - May/22/2022 at 6:44am |
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Trader
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Joined: May/15/2018 Location: Ontario Status: Offline Points: 6881 |
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Posted: May/22/2022 at 7:56am |
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I wonder about the QF carburetor. They did send you an 850 blow through and not an 850 draw through right? They look exactly the same but easily mixed up. Don't believe the camshaft is poorly chosen. Typical Camshaft specs of a SBC 406 CI:"A crank driven supercharger on a similar engine would have a vaguely similar cam
centrifugal supercharger cam, 240/248 @.050" tappet lift .635"/.630" with 1.6/1.6 rocker arms 113 lobe center, installed at 110 intake center line" |
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AMoCoLite
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Joined: Dec/23/2015 Location: North Texas Status: Offline Points: 441 |
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Posted: May/22/2022 at 8:49am |
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I’m not an engine builder by any stretch...but I’d like to see the dyno curve of one of the pulls...do you have one to share?
Thanks!
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WhatISit
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Joined: Aug/07/2017 Location: Phoenix, AZ Status: Offline Points: 0 |
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Posted: May/22/2022 at 11:07am |
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What are you using for a boost controller? Have you verified it’s building pressure?
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jcisworthy
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Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805 |
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Posted: May/22/2022 at 11:20am |
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I will get back with info tomorrow. I am going to check some things and make sure something stupid isn't going on
The reason I think something is up is because 400 on the motor is way off what I was expecting. I built a similar engine with full ported iron heads, 10:1 compression, essentially the same cam only hydraulic flat tappet, ported torker, 4.210 bore 401 and it made 556 hp and I think low 500's tq I used the same flat tappet hydraulic cam in similar 401 to this engine with same heads intake, fitech 1200 hp unit, but it was a paxton centrifugal similar boost with these heads and intake, 6psi and it made over 700 hp and high sixes tq
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Specializing in dyno services, engine building, and cylinder head porting
rbjracing.com Phone Number 518-915-3203 |
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Gench
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Joined: Oct/09/2021 Location: Boulder CO ish Status: Offline Points: 182 |
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Posted: May/22/2022 at 11:32am |
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My understanding- cam overlap is the 5th cycle of the camshaft. It’s purpose, exhaust scavenging. Boost requires minimal overlap as it’s pressurized vs atmospheric.
Late closing intake - causes a hammering effect on air helping achieve a greater VE at higher RPM. Can piston compression motion create buffeting in the air flow of the system as the intake valve is still open? Not sure but I can’t think of a value add. Again, looking to understand, this is a topic I’ve been deep diving on for quite some time. Plan to torqstrom eventually. Thanks
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Gench
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Joined: Oct/09/2021 Location: Boulder CO ish Status: Offline Points: 182 |
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Posted: May/22/2022 at 12:00pm |
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jcisworthy - hope you figure it out, frustrating. It’s certainly not the cam causing down power so I don’t mean to distract.
If it’s a roller vs flat tapper cam thing, maybe your cam profile and boost you need even more valve spring?
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jcisworthy wrote: