can a smogger 454 BBC engine have any power potential?

Discussion in 'Engine Combos and Dynometer Database' started by Grumpy, May 9, 2016.

  1. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    trust me when I say that with proper upgrades ANY physically functional 454 chevy can be modified to make an honest 400 hp PLUS and its generally easier to do than with your common 350 SBC starting point.
    well to start it would help a great deal if you posted the engine casting numbers and if you did a compression test to give us some idea what your working with, your compression ratio, head and block casting number and the intake would be very useful.
    I build a constant steam of big block chevy engines, but without knowing exactly the part numbers and condition of what your starting with, the car its going into, the transmission, rear gear ratio, compression ratio, and your intended use or expected performance your simply guessing and starting at a distinct disadvantage!
    yes most 454 engines can be improved noticeably, but theres a world of difference between, starting with a 270 hp 1974 corvette engine and a 450 hp 1970 chevelle engine as an example
    yes there are some versions that are FAR better than others, as to the basic components used, but even the basic low performance 454 has the potential to out perform most common 350 sbc engines, I see that many guys build!
    yes you'll need to clean up the heads, boost the compression ratio, change cams etc. but the end result is that the extra 100 cubic inches of displacement and the better head design has advantages, even the crappy peanut port heads in stock form flow similar numbers to the SBC vortec heads most guys think of as performance heads on a sbc.

    I know many of you guys would rather be skinned alive with a dull razor and power sander, dipped in alcohol and rolled in rock salt, rather than take the time and effort read links, and sub links, but for those willing to learn....
    Btw heres a tip learned through experience , if your 496 -540 displacement BBC combo includes an engine with at least 10:1 compression and a cam with at least 240 duration at .050 lift, and oval port heads, youll almost always find a single plane intake has some advantages over a dual plane intake.

    Last edited: Apr 12, 2019
  2. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    I'm posting this as a reminder that some articles you see in magazines and on-line,
    that you'll run across don,t paint a realistic picture in my opinion
    the first thing I noticed is the super convenient & extremely low prices they quote
    for the short block, and they basically ignored or got the needed machine work for free, compared to what you would normally need in my experience, and I would never re-use a timing chain that had obviously had thousands of miles of previous use.
    they also ignore the cost of things youll most likely need like fans, distributor cap, ignition wires spark plugs, hoses, a flex-plate or clutch, motor mounts ,water pump,pulleys, a new oil pump, all new bearings and a couple dozen other items that add to the cost to get the car running, your unlikely to find roller rockers for under $100 or for that mater lots of other listed prices for parts, the whole article is rather deceptive
    I doubt the engine will continue to run all that long with cast pistons if they keep hitting the engine with a dose of nitrous

    to be fair I know a guy that was given a running motor home that had a 454 chevy engine that had been in a car wreck, so yes once in a while you,ll see or hear about bargain deals, but you certainly can,t depend on or expect that.

    read through it and tell me what your thoughts are?

    454 Big-Block Budget Engine Build - Making Cents
    We Build A 700HP 454 For $2,403.
    Richard Holdener Jun 7, 2010
    [​IMG]View Full Gallery
    It seems a certainty that Chevy guys would rather eat dirt than drive a Ford, but not all Chevy guys agree about their choice of powerplant. The original small-block has a lot going for it, including power potential, minimal weight and even affordability. By comparison, the big-block takes a few giant steps up the performance ladder, but does so saddled with both additional weight and cost. There is no denying the power potential of a nasty Rat motor, but it is considerably larger, heavier and more expensive to build than a comparable mouse.

    In the past, big-block guys had to be serious about their need for power in order to overlook the mass and cost issues associated with building the Rat. The old adage that "speed costs money, how fast do you want to go" certainly applies here. Or does it? What if we told you there was a magical land where big-blocks and small-blocks were available for the exact same price? What if we further sweetened the deal with a serious weight reduction for the big-block with the addition of some aluminum cylinder heads? In one fell swoop we have all but eliminated the cost and weight penalties associated with building a fat-block Chevy. Interested? Read on!

    Where is the magical land where big-blocks roam free, ripe for the picking? The answer is your nearest wrecking yard. It seems that the wrecking yards label every method of motivation as simply "complete engine" and let it go at that. This means the complete big-block can be had for the same price as a small-block, V-6 or (God forbid) four-cylinder, econo-box motor. Lest you think that the boneyards are devoid of big-block Chevys, we snagged not one but two different big-blocks from our local Pick-a-Part (and found three more), so obviously they are still available (hint-stop looking for that LS6 Chevelle and check out the engine bays of full-size trucks).


    Most impressive was the fact that a complete BBC (meaning carb to oil pan and fan to flywheel) could be had for the bargain basement price of just $200, plus $40 core. This price can be reduced on special sale days where everything in the lot (including a complete BBC engine) is 50 percent off. Additional discounts can be had by purchasing a long-block (for $170) or a short-block (for $129). Since we planned on replacing the heads, cam and intake in our build up, we started with the basic short-block for a meager $85 ($45 plus core purchased on half-off sale weekend).

    With big-blocks available for such a minimal cash outlay, we decided a low-buck build was in order that simultaneously maximized power and minimized expenditure. Naturally we had to set official goals for each. In the power department, we decided that any decent big-block (even one starting out life in the wrecking yard) should produce a minimum of 500 hp. To this power output we decided to add a small shot of nitrous and reach for no less than 700 hp. While a 700hp big-block build is not ground breaking, reaching 700 hp for our self-imposed ceiling of $2,500 (including the engine) is considerably more impressive.

    To put this into proper perspective, check out the pricing on some of the big-block (or even small-block) crate motors online. You'd be hard pressed to find a BBC short-block for that price, let alone a long-block equipped with aluminum heads, a performance cam and high-rise intake (with nitrous no less). Heck, there are a lot of BBC cylinder heads that cost more than $2,500, but our plan was to secure a suitable (running) 454 truck engine, add the necessary (cost-conscious) performance components and test the whole mess on the engine dyno. Think of this build up as your own personal stimulus package.

    Our Gen-IV 454 pulled from a one-ton work truck was equipped with the desirable four-bolt block, but the reciprocating assembly was a combination of a cast crank, forged rods and cast pistons. Naturally, the lack of forged components worried us, especially the pistons, but we had full confidence in the stock crank at our intended power level. Given the lack of forged internals, every precaution had to be taken with regard to the tune, lest we blow our low bucker to smithereens.

    The factory pistons presented another problem in the form of piston-to-valve clearance. The low-compression, dish-top pistons featured valve reliefs designed for the 2.06/1.72 valve combination used on the factory (iron) peanut-port heads, not the larger 2.25/1.88 valve package in our Pro Comp heads. Knowing we needed a healthy cam to reach our goal of 500 hp with the low-compression 454, we mocked-up a pair of cams using the Pro Comp heads and factory pistons prior to assembling the motor. Since we did not have access to the Summit cam we planned to order for this build up, we did the next best thing. We tested P-to-V with a pair of Comp cams, one larger and one smaller than the cam we planned on purchasing from Summit. The smaller XE274H (flat-tappet) cam fit with a minimum P-to-V clearance of 0.115, while the larger XE284H cam snuck by with 0.065. This meant the Summit grind (0.540 lift, 238/248 duration) would easily fit. Running wilder cam timing (like the Comp XE284H or larger) would require use of the Isky valve-notching tool to add the necessary clearance.

    The next obstacle was ring seal. A visual inspection and leak down of the motor indicated that it had been run hot sometime in its long life. While we hoped to simply install the new cam, heads and intake on the used short-block, it looks like this particular motor required a bit more attention before final assembly. Due to our budget, new pistons were definitely out of the question, but we elected to install a cheap set of rings after a quick hone to break the glaze. To keep costs down, we honed the cylinders ourselves using a flexible ball hone. The only costs associated with this adventure were the new rings and a couple of cans of brake clean, engine degreaser and Chevy Orange spray paint.

    While we had the pistons out, we decided to scrape off the years of grease and paint the block. We also hit the tops of the factory pistons with a wire wheel to clean off the oil and carbon deposits (though this reduced our static compression). We wanted a nice, clean surface to minimize the chance of detonation once we hit the nitrous. When we had the block painted, the pistons cleaned and the new rings installed, we reassembled the short-block using the original bearings. Naturally, we'd strongly recommend a complete rebuild (using the stock crank), but this story is for those who accuse us of not speaking low-buck here at Super Chevy.

    The awaiting short-block received the hydraulic flat-tappet cam from Summit Racing (K-1303) using the stock timing chain. Again, we'd recommend replacing a high-mileage chain with a new double roller version, but sacrifices had to be made to appease the low-buck gods. The engine was assembled using the low-buck gasket set from Pro Comp with the exception of the head gaskets. We stepped up to a set of Fel Pro 1027 gaskets designed for the Gen-IV block. The complete gasket set from Pro Comp included head gaskets, but the gasket set was designed more for a stock rebuild than performance usage. With nitrous use, we felt better stepping up to the Fel Pro head gaskets (which offered improved cooling passages compared to the Pro Comp set).

    Though offered with full CNC porting, we selected a set of as-cast heads from Pro Comp for this low-budget build. The aluminum Pro Comp heads featured 320cc intake ports, a 2.25/1.88 stainless valve combination and flow numbers that easily eclipsed anything offered by the factory, especially our cast-iron, peanut-port heads. Wanting to maximize the power of our head selection, we set aside some of our budget for additional head work.

    In addition to surfacing the heads to bring the chambers down to 116cc to help improve the static compression ratio, we also enlisted the aide of Bryce Mulvey of Dr. J's Performance to fine-tune the as-cast heads with a performance valve job and minor bowl blending. Our relatively mild cam timing could not take full advantage of the high-lift airflow offered by a set of fully-ported CNC heads, but the mild head work offered by Dr. J's would yield big low-lift dividends on the as-cast heads. Check out the before and after airflow numbers, taking note of the low and mid-lift flow gains. Given the max lift of 0.540 offered by our Summit Racing cam, we wanted to concentrate all our flow effort below 0.550 lift. That is exactly what the valve job and minor porting performed by Mulvey accomplished. The Pro Comp heads were torqued in place using a set of Pro Comp BBC head studs.

    The finishing touches on our BBC build included a set of 1.7 ratio aluminum roller rockers and single-plane Screamer intake manifold from Pro Comp, though we also tested a Weiand Team G (which added roughly $105 to the total bill). The intake was fed by what we thought was a Holley 750 double-pumper carb purchased off eBay. To our surprise, the part number revealed a larger 850 Holley (PN 4781S). With so many carburetors listed for sale on eBay, readers could easily duplicate the cost.

    For a distributor, we ran a stock HEI pirated from the wrecking yard with the motor. For a total cost of $19 (with wires), we made sure we got a distributor with both cap and rotor in good condition and ready to run. It took a little mixing and matching on our part, but there were plenty of HEIs in the wrecking yard available for us to piece together a usable combination. We also snagged a set of stamped steel valve covers for the paltry sum of $5.

    All that was left was to install a set of spark plugs, Lucas oil and break-in additive and Hooker 2.25-inch dyno headers (not included in the total). The motor was run on the dyno with a Meziere electric water pump.

    Before letting the hammer fly, we subjected the 454 to a pair of computer-controlled break-in procedures to seat the new rings and ensure the cam and lifters were properly acquainted. After this, the rat was run in anger to the tune of 565hp and 532 lb-ft of torque. Not only had we reached our goal of exceeding 500 hp, but managed to do so by a healthy margin. It appeared the new rings were money well spent. Despite its humble beginnings, the wrecking yard 454 offered a respectable torque curve, bettering 500 lb-ft from 3,500 rpm to 5,900 rpm.

    Now it was time for the juice. To help us reach our secondary goal of 700 hp, we installed a low-buck NOS Sniper nitrous system on the 454. The NOS Sniper kit included everything we needed to add as much as 150 hp to the 454.

    To ensure our cast pistons survived the test, we replaced the 91-octane pump gas with 114-octane race fuel and retarded the ignition timing six degrees before hitting the button. Some minor tuning with the bottle and fuel pressure allowed us to dial in the air/fuel mixture to a safe 11.8:1. After the minor tuning session, we were rewarded with peak power numbers of 736 hp and 691 lb-ft of torque.

    We had officially reached our goal of producing 700 hp and did so with a total expenditure of just $2,403. The total cost could be reduced further had we secured a running short-block that did not require new rings, but all in all, we'd say a 700hp BBC for less that $2,500 makes good financial cents.

    Cost list for BBC article Heads $875 (ebay On-Line Store)

    Intake $95 (EBay On-Line Store)

    Rockers $85 (EBay On-Line Store)

    Gaskets $37 (EBay On-Line Store)

    Head gaskets $43 (Auto Zone)

    Pushrods $53 (Elgin)

    Head bolts $37 (Pro Comp)

    Cam & Lifters $89 (Summit Racing)

    Carb $129 (EBay-Private Seller)

    454 Short-Block $85 (Pick a Part)

    Rings $75 (Hastings)

    Head Work $325 (Surface, Valve Job & Port-Dr. Js)

    HEI Distributor & Wires $19 (Pick a Part)

    Stock Valve Covers $5 (Pick a Part)

    Misc $24 (Carb bolts & gasket, paint, degreaser, Brake Clean) (Auto Zone)

    NOS Sniper $387 (Summit Racing)

    Bottle Fill $40

    Total $2,403

    The budget 454 not only managed to exceed 500 hp, but did so in spectacular fashion with peak numbers of 565 hp at 5,900 rpm and 532 lb-ft of torque at 5,400 rpm. Credit the flow rate of the excellent Pro Comp aluminum cylinder heads and extra work performed by Dr. Js for some of the power. The Pro Comp single-plane intake worked well to optimize peak power and our used Holley carb and HEI distributor both performed flawlessly. We took extra precautions to properly break in the hydraulic flat-tappet cam from Summit Racing, but this was even more power than we expected from something just snatched from the local wrecking yard. I guess the new rings and head milling were money well spent. Adding the 150hp shot of nitrous from the NOS Sniper kit actually improved the power output by as much as 170 hp (not uncommon when properly tuned). We made sure to optimize the bottle pressure by heating it prior to hitting the button in anger. After adding race fuel and dropping the ignition timing back 6 degrees, we were rewarded with a whopping 736 hp and 691 lb-ft of torque.

    The valve job performed to our as-cast Pro Comp BBC heads by Dr. Js yielded big dividends. More importantly, the flow gains came in the lift ranges (sub .600 lift) employed by our hydraulic flat-tappet cam from Summit Racing. No doubt these played an important role in the final power output of our low-buck 454.
    Last edited: Apr 26, 2018
  3. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Looks like that article kicked off the LS era Grumpy...
    No I wouldn't do the same with a Pontiac 455.
    Last edited by a moderator: Aug 29, 2018
  4. Indycars

    Indycars Administrator Staff Member

    The prices I checked out for ProComp heads were $800 for BARE heads, so $875 is not a realistic number. I just had my heads checked out and a competition valve job (No Porting, No Surfacing) and that cost over $300. The average guy cannot get a fantastic deal on EVERY PART needed, but the article sure did.
  5. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    The Factory Nylon coated coated cam sprocket is a dead give away.
    All Lies Grumpy.

    Pontiac SD 389 & 421 engines used the Heavy Duty Tempest T4 3 -piece timing chain set.
    All steel and iron.
  6. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    yeah, those nylon timing sets were a damn joke, as the shredded nylon shrapnel ,coming off the timing gear,
    regularly resulted in burnt bearings from clogged oil pump pick-ups



    it takes hundreds of pounds of force to bust rocker studs and or bend push rods, if you have those issues STOP AND LOCATE the geometry or CLEARANCE ISSUES CAUSING THE PROBLEM
    theres several manufacturers and models available , heres a basic 1.5:1 ratio SBC version.
    the grooved rocker pivot ball design was an effort by G.M. engineering to economically solve the issue of marginal oil flow causing rocker ball galling, and resulting noisy, or broken valve trains


    SOME ROLLER ROCKERS CAN AND DO BIND ON ROCKER STUDS, or rocker adjustment nuts, youll need to check carefully
    some roller rocker too retainer combo clearance issues cause problems easily solved with beehive springs and smaller retainer diameters


    check all valve train geometry and clearance on any engine you assemble or modify the valve train on.


    Last edited: Sep 2, 2018
  7. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

  8. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    Overheating – it’s a major concern for many after rebuilding or repairing an engine, especially if an overheat was the reason it had to be repaired in the first place. A recent trending topic on the Fel-Pro® Forum and social media pages is the relationship between overheating and the size and/or position of coolant holes in our head gaskets:

    “I’m concerned that the coolant holes in the gasket are way smaller and not the right shape compared to the block.”

    “…I noticed that the water jacket holes in the head gasket did not match those in the block and head.”

    “Why are the water jackets restricted on the gaskets & can they be drilled out?”

    “…the holes seem pretty small in the gaskets and some holes in the gasket are only half open on the head side. Should I open up the gasket holes to max the flow or are they this small for a reason?”

    Controlling the temperature of an engine is critical for longevity and drivability. Overheating can lead to gasket failure, casting warpage and severe engine damage. At the same time, an engine that runs too cool will experience lower fuel economy, increased emissions and wear more quickly. The temperature an engine runs at needs to be properly regulated. The thermostat, radiator, and coolant play a big role in this – but they aren’t alone! Head gaskets are engineered with precisely shaped and sized holes to meter the flow of coolant through the engine.

    Let’s take a look at a Big Block Chevy as an example – on the left we have a bare casting, on the right, a Fel-Pro head gasket is installed:

    The coolant holes in the block casting are much larger than those in the Fel-Pro head gasket – this is by design!

    To better visualize how much the coolant holes really control the flow of coolant, we’ve superimposed the gasket on the block:

    Aside from the reduction in size of the top coolant holes, the large coolant hole on the bottom right is partially blocked off. There are also holes in the gasket which are not open in the block. Some Big Block Chevy engines have these holes while others do not. This will depend on the generation, application and the intended use of the block. These are not design flaws or oversights – the size and placement of every hole in the gasket is intentional, and this is true for every gasket we manufacture.

    What is the purpose of using smaller holes in the head gasket or blocking off holes in the block?

    The holes in the head gaskets are there to meter the flow of coolant properly through the heads. In most engines, coolant flows from the water pump at the front of the engine block toward the rear, goes up into the head(s), to the thermostat and finally to the radiator once the thermostat opens before returning back to the water pump.

    An improperly sized or placed hole can create a “shortcut” which prevents coolant from following the correct “path” through the engine. If the coolant takes a “short-cut” because a coolant hole is too large at the front of the engine, the rear cylinders can overheat. If the holes are properly placed, but too large, the coolant can pass through the engine too quickly and fail to absorb enough heat, also resulting in overheating.

    So why are the castings made with holes that are larger than they should be or unneeded for proper coolant flow? Engine blocks and heads are sand-cast, meaning sand forms the mold for the casting. The holes must be large enough, and sometimes extra holes must be added, to allow the sand to be completely cleaned from the casting once it has solidified. Also on older engines the holes may not always line up due to “core shift” – that is, the blocks are not always perfectly cast, so the gasket needs to accommodate the fact that different castings may have slightly different hole positioning.

    Fel-Pro® Gaskets Design Philosophy

    During the Fel-Pro head gasket validation process, we sometimes find that holes should be added, deleted, changed in size or moved to better control the flow of coolant through the engine. On certain applications, holes in the head or block will be fully or partially sealed off with the head gasket. While the visual differences may seem extreme, you can install Fel-Pro gaskets with confidence because every hole is precisely placed and sized to ensure that coolant flow is properly controlled by the head gasket.

    With this in mind, a Fel-Pro head gasket should never be modified in any way – doing so not only prevents proper coolant flow, but also can affect the gaskets ability to seal, as the specialized coatings can be damaged.

    Last edited: Jan 14, 2019

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