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need a HP figure for a 521 build

28322 Views 39 Replies 10 Participants Last post by  customblackbird
hello all, new to the forum... this is actually my first post/thread.

Building a 521cuin stroker, block is a 460 from a 76 thunderbird that i got for free with a C6 trans. engine was complete, i bored it .030" and purchased a stroker kit to make it a 521. i just purchased the cam etc and i wanna see what you guys think itll put out.

heres the engine specs.
10.5:1 compression, flat top pistons.
lunati voodoo cam #61605, 241/249 at .050, .582/.600 lift and a 110 lobe
(hyd flat tappet)
Going with the procomp 290/300cc aluminum heads (budget)
weiand stealth intake
900cfm carb
timing will be whatever it likes... gona upgrade the stocker distributer to prob a procomp billet HEI and 8mm wires.

trans will most likely be the C6 with a 2500 stall and 3.55 rear gears.

what do you guys think this will put out HP/Tq wise? oh did i mention im throwing this into my 87 firebird :) (which had a 480hp 383 but was stolen with less than 3000miles on it!)
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I understand budgets but I would stay away from the Pro-comp distributor a couple members have had nothing but problems with them. The heads are not very popular but my guess would be 580-600 depending on your tuning ability.
I haven't dealt directly with the pro comp stuff but have heard a lot of people being dissapointed. I have a set of the jon kaase scj heads on my 532 prostreet motor and they have done real well for me and from what I have seen on here Lem has a really good price on them. Also I have talked to Lem and he is a super guy.

In short if you can save a few extra buck and get a better set of heads like the scj's. That is just my recomendation.
I take it he already has the heads and the pistons are for stock location valve angles.

Alot of people don't like the Pro-comps but if that is what is in your budget right now thats fine I think the combo looks decent should be very responsive. You can always upgrade to a TFS Street later on when budget permits. Like I said I think 600 hp is realistic.
well im still in the air about the heads... i have a set of the D3VE heads that were stock but from what i hear they arent too great with power. I do not have the heads yet. the rotating assembly just finished balancing and just shipped about 2 hrs ago from CNC motorsports. this is what ive got so far.

D1VE block, bored .030, stock deck height.
rotating kit on the way: internal balance and should be 10.5:1 with 95cc combustion chambers. internal balance assembly. pistons are flat top mahle powerpacks forged with 13:1 compression but with larger 95cc heads it should be down to 10.5:1.

ESP-104604300 Ford 460/521/532 Stroker Eagle Cast Steel Crankshaft - 4.300" Stroke, Internal Balance 1

CRS67003D BB Chevy & Ford 6.700" Eagle "ESP" 3-D H Beam Connecting Rods 1

BBF450390F03 Mahle PowerPak Flat Top Piston Set, Big Block Ford 4.390 bore, 4.300 stroke, 6.700 rod, 13.0:1 1

FP-460A-SFI BB Ford 460 SFI Flex Plate 164 tooth - Internal Balance -

just purchased this yesterday from summit:

61605 lunati voodoo cam/lifter kit, 241/249, .582/.600 110lobe
cloyes double roller timing chain
professional products internal balanced balancer (neutral)

Ive already got a melling high volume pump/driveshaft, a ford racing rear sump conversion kit, ARP main studs, ARP cam/flexplate/engine kit (going to use stock head bolts tho) i also have a procomp high flow aluminum water pump. all together i should have a completed short block ready to go.

What i need help with is the top end! heads/intake/carb/distributer. but all on a budget. i want to make 600-650hp. 650 would be better (gotta beat my bros 68 vette with a 509 merlin :) )

what do you guys suggest? for heads/intake/carb/distributer.
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im trying not to spend an insane amount on this combo... but i want aluminum heads bc of the weight factor. I do all the work myself... making motor mounts for this thing to fit in my 87 firebird was a PITA! i had to raise the motor up bc my idler arm was contacting the front of the oil pan where the pump is! Then i had to push the engine back about 3.5" so the crank/pulley clears the front sway bar/radiator lol. im gona have to mod the firewall and relocate the gas pedal too.

being that the motor is heavy and my car is rather light, i want the motor to be as light as possible esp that its being raised up from the Kmemeber.

what are the thoughts of the ford racing cobra jet heads?

but the small chambers is gona kill my compression and i want to be able to run 93 octane pump gas.
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Yeah that is gonna hurt with the 93 octane. I have dish pistons in my 533 setup. Here is a link to carcrafts 557 pro comp build. It may help give you and idea of the power u can expect. Of course they are running more cubes and a roller cam. So have to just compare and see what you think. Just trying to help.

I would say save your money and pop for a set of TFS heads over the procomps. I would also do a roller cam but thats just me I guess. It may take you longer to build because of budget, but I think you will be happier in the long run.

just my .02 :)
Just make sure that the heads you get will match up with the valve reliefs in the pistons you already have.
not gona do a roller cam... sure they make more power but they cost alot to retrofit... i already ordered the cam so its down to the heads/intake/carb/ distributer.

i thought about starting with the procomps as a bare casting and working with them there. but from what i hear the TFS heads are pretty awsome. how much power would i be looking at with the cam i have, the cubes i have and the TFS heads with the weiland stealth intake?

im not sure how to get the compression down tho... the pistons are flat top so i have to see about the valve reliefs, dont the TFS heads have small chambers?
Just make sure that the heads you get will match up with the valve reliefs in the pistons you already have.
what differences are there between the heads/valves that they change enough to watch the valve reliefs in the pistons.

the pistons are mahle 450390F03 pistons, doesnt say anything about the valve reliefs being different. are the TFS heads different with the valves then stock?
A460, P-51's and SCJ have non traditional valve locations. The TFS Streets (Powerport 290's) have traditional valve layout. The streets are nice heads I just bought a set this spring very happy with the quality. The Pro-comps are known to have crappy valvejobs when buying factory assembled units. Scotty Johnston aka TheMadPorter and I believe Randy Malik aka RMCompRandy sell heads that they bought bare and assembled, they would be a good source if you decide to go that route. The Pro-comps are not a race head by a long way so don't expect wonders from them.
If you want to run pump gas with your existing shortblock, the Pro-Comps or Edelbrocks with 95cc chambers are where it's at.
I have built and dyno'ed almost that exact combination except it was a 466 and the heads were "bowl ported".
It made a tick under 500 horsepower. Tried for many pulls to get it above 500 but, 498, (I think), was the best we could get.
Add about 40 horsepower for the larger 521 and you'll be right around 540 horsepower if it's tuned close.
ok thanks guys. Ive been doing alot of research about the heads and i was actuually looking into the edelbrocks due to the 95cc combustion size. Due to the flat tops im limited to the heads im able to run so my only decision is the edelbrocks/procomps.

I can get the procomps bare for like 420-500$ a head, and the cheapest ive seen the edelbrocks bare for are like 700$ a head. How well do the edelbrocks perform over the procomps? or would it be better to get the cheaper procomps and port them a bit?

whats the best/cheapest place to get bare heads from? jegs sells procomps, and of course ebay. Edelbrocks ive seen on summit etc.

rmcomprandy... what combo was it that u dyno'd? is it the cam or the heads thats holding me back. i figured with the 10.5:1 compression, and decend heads with the lunati cam having decent duration that i would be making more than 540hp... thats kinda low in my book. most 460 builds i see with procomp heads make around 600hp. so is it the cam or the heads thats keeping me below the 600hp mark?
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If you're planning to build the heads from bare castings, be prepared to size the guides, do a valvejob, blend the bowls, etc. Bare heads are NOT a plug and play deal, you can't just drop the parts in and go.

Edelbrock's complete assembled heads are one of the highest quality, best finished offerings available. No bowl blending or other work needed. Just bolt em on and go. The same can't be said for Pro-Comp.
What he is saying in a real nice way is that if you buy bare Procomps and do them right that the Edelbrocks will probably cost you less.

Any of the vendors on this sight will hook you up. From my experience they all are competive in price, and if you buy cheaper, then, your getting cheaper not just less expensive.
For your 600 horsepower goal;
with those heads you'll need more cam,
with that cam you'll need better heads

Just remember - the more horsepower you gain at the top with camshaft, you'll lose twice as much torque at the bottom - the more horsepower you gain at the top with better cylinder heads you'll only lose about 1.2 times the torque at the bottom of what you'll gain in horsepower at the top.

How narrow of a power band can you get away with...?
also just a quick question about the cam on a 460... im used to chevy rollers but im gona be running the lunati hyd flat tappet 61605, and i got the ARP pro series cam bolt/washer kit. Now originally the stock cam had a mechanical fuel pump cup/thing that bolted on the front of the cam. Im not using a mechanical fuel pump so do i have to put that fuel pump lobe back on?
thanks guys, the edelbrocks look to be like 700$ for a bare head so 1400 for a pair of bare heads, vs worked over procomps with some porting for 1200, 200$ isnt alot but it would pay for my weland stealth intake lol, the procomps i was referring to was the ones that RMcomprandy sells that are worked over etc. this car will be mainely street driven which means most of my driving will be below 4500 but i get alil aggressive on the street. which is why i will prob be going with a 2500 stall vs a 3000-3500 stall which would be better suited for the track.

rmcomprandy... having alittle trouble understanding what your saying. basically the lunati cam i have ill need better heads? personally i dnt want to rev this thing beyond 6000-6500... and any of those shifts would be at the track (which will be limited use) so id like my power range around where my cam is, 2500-6500 is what the cam is rated to in a 460 but my 521 will cause the operating range to drop a good bit. so peak power could be like 5500. I just want this thing to be fun on the street but still hang at the track. so what do you recomend and wat kinda powerband would i be looking at with the cam i have and either the worked over procomps or the edelbrocks?

thanks alot for the help guys
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