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454 MAG on roids budget minded build-looking for any suggestions...

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  • 1 Post By Baja Rooster
  • 2 Post By articfriends

454 MAG on roids budget minded build-looking for any suggestions...

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Old 07-12-2018, 04:02 PM
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Default 454 MAG on roids budget minded build-looking for any suggestions...

I am putting together a pair of budget minded gen 6 454 mag based engines with a bunch of stuff I have laying around and looking to see if anyone has any suggestions, input from similar builds…. I am not looking to be the fastest guy around, these are being built to repower a 38’ boat with 460s in it currently. Plan to pick up a little speed and build these the way I want them.

Stock 454 mag long block with 088 heads-have
Crane 731 cams and associated hardware-have 1 engine worth
Comp cams high energy roller rockers-don’t have
SSM manifolds with +6” risers-have
Edelbrock air gap dual plan manifold-don’t have
HP500 oil thermostats and coolers-have thermostats, maybe 1 cooler
I have or have access to 750, 800 and 850 carbs so I have choices there-also considering a few EFI options
Thunderbolt ignition with 24 degree modules-have
Serpentine setups-have

Mated to bravo drives with full to helm latham steering


Things I have considered is piston swap to a higher dome or milling the heads to bump compression a bit. The piston swap I am not sure is worth it considering I will not need to do any machine work on the short blocks as it sits. If I start walking down that road I would likely scrap the entire rotating assembly and go to a scat 9000 cast crank, scat rods and forged dome pistons which totally defeats the budget built 454 mags so a, trying to stay away from that and keep at least 5k in my pocket lol.
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Old 07-12-2018, 05:24 PM
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Mag pistons? 13.5 domes? 9:1 with 119 heads. 10:1 is max for marine-iron heads. The extra point is worth 2%. A LOT more than 2% extra dinero. Pistons are good? Not all detonation-pitted? Paid for and already on the rods? A lot of heads are 113 also. I cc heads with a 4 buck Walmart flavor shooter. 25cc syringe for injecting gravy into meat...or injecting water into combustion chambers. And there us a .027 composite GM head gasket that is worth about half a point free. That .610 lift is just in the lift range of the stock dogbone roller lifters. An aftermarket long travel lifter will be more budget-friendly than any tie-bar lifter you would dare run.

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Old 07-12-2018, 08:45 PM
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Yes stock pistons and they are all in good shape. The engines are broke down and getting alm new rings, bearings... I think my biggest thing right now is if the 731 cam is enough for the engine and if the dual plane is the right choice. I'm hopeful that I can get close to the 500hp mark, I may be day dreaming on that but I think it should be close. In the past i have built several L29 gen 6 cast internal engines with pretty much the same build and they were sitting at 450hp but fell on their faces at 5k. Those motors ran amazing though and had power all the way through the power band but couldn't breathe after 5k which is why I am looking at the 088 heads on this build. One thing I could also do is use the L29 large ovals with the mag short blocks but I'm worried that the compression would be too high for pump friendly fuel. Another thing i should mention is I don't want to go too high on compression because we may end up in places that dont sell high octane fuel. We have been talking Bahamas lately so I dont want to get stuck somewhere over fuel issues because I went to high on compression
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Old 07-12-2018, 10:56 PM
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That airgap is a really great manifold for what you’re trying to do. You can read here at the end where a single plane only gave up a ton of torque with no gains on top.
Get More Power from a Chevrolet Performance ZZ502 Crate Engine

That 731 cam oughta be about right for you as well - not really worth reinventing the system for it. Better heads may be a good way to go and usually more cost effective than salvaging what you have.
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Old 07-15-2018, 05:44 AM
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Originally Posted by Baja Rooster View Post
That airgap is a really great manifold for what you’re trying to do. You can read here at the end where a single plane only gave up a ton of torque with no gains on top.
Get More Power from a Chevrolet Performance ZZ502 Crate Engine

That 731 cam oughta be about right for you as well - not really worth reinventing the system for it. Better heads may be a good way to go and usually more cost effective than salvaging what you have.
We recently saw this on my dyno, a friend bought a zz502, did some repairs, got rid of the intake then brought it to me to dyno w a vic jr on it. The afrs cyl to cyl were screwed and when we put a zz502 dual plane back on it we saw 40+ft lbs tq gain AND a hp gain in the rpm band it actually ran
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