How To Get 500 Horsepower Out Of A 350

| How-To - Engine and Drivetrain

Building A 500hp Small-Cake Chevy - 500 HP For Cheap

Is It Possible To Build a 500hp Small-scale-Cake Chevy That Runs on Pump Gas for About $5,000? We Sure Gave Information technology the Old College Try.

Head-Flow DataRHS 220cc intake-runner Pro Action heads equipped with ii.02/ one.60 valves were flowed at 28 inches of h2o by Sherman on his SuperFlow bench. In theory, the period numbers indicate these heads should exist able to support virtually 620 hp at 0.700 inch lift.

LIFT (INCHES)	INTAKE (CFM)	Frazzle (CFM)
0. 100	68.4	55.two
0. 200	127.seven	99.4
0. 300	182.5	132.v
0.400	232.half-dozen	159.6
0.500	269.iii	184.3
0. 600	290.0	191.seven
0.700	301.ane	201.iv

Can you get together a small-cake Chevy, starting from scratch, that makes at least 500 hp and runs on pump gas, on a $5,000 target budget, without sacrificing immovability? That's what we wanted to find out, so we tried. The objective is to evidence that aftermarket parts technology availability combined with convenient parts pricing has advanced to the betoken that a streetable 500hp small-block engine is inside range of the boilerplate hot rodder's engine-building upkeep. Fourth dimension constraints due to the typical realities of running a monthly publication with stock-still deadlines influenced the approach and some of the parts choices: For this reason, we decided to get-go with a preassembled, big-displacement short-block, then become large on the heads and cam. We also went to ace engine builder Joe Sherman, who has built more budget modest-block engines that brand serious power than but about anyone else around. Sherman handled the cam selection, major component associates, and complete dyno test and tune-up.

If not constrained by sanctioning-torso rules, there is no replacement for displacement. Nowadays, 383 stroker assemblies congenital using a 4.030-inch, 350-based block with a 3.75-inch-stroke crank price the same to build as 350-based engines. On the other manus, the even larger 406ci packages, based equally they are on rare 400 blocks or aftermarket blocks, cost at least $900 more. The 383s take therefore become the sweet spot in upkeep, performance, small-cake Chevy engine building.

CHP offers an entry-level 383ci Street Fighter SS short-cake for around $2,000, just because it's forged, stock-replacement-type, iv-eyebrow pistons accept valve-clearance issues with the high-elevator cam we'd be using, then nosotros moved upwardly to CHP's $2,300 383ci Street Fighter. The extra $300 gets you lot better rods and full-floating, apartment-top, CNC-machined pistons that solve the valve-clearance issues.

Sherman estimated that to brand the power on pump gas, the cylinder heads needed at least a 210cc intake runner. Most aftermarket heads with this size runner are cast from aluminum, raising their cost across the scope of our budget. Locked into an iron head due to the budget, nosotros chose the RHS Pro Activity (formerly Pro Topline) 220cc runner design with angled spark plugs. Fully assembled with 0.100-inch-longer-than-stock 2.02/1.sixty valves, trick beehive springs, guideplates, and spiral-in rocker studs (with 716-inch threads top and lesser), they go for a very reasonable $ane,100. These heads flow great on the flow bench, accept production-style, 23-degree valve-angle valvetrains, and maintain the intake entrance and exhaust exit in the stock location. Withal, the intake-port opening is slightly larger than stock, and then it requires a Fel-Pro PN 1206 intake gasket and correspondingly large-port aftermarket intake, such as Edelbrock'southward Super Victor.

Feeding the Super Victor is a Demon 850-cfm vacuum- secondary carb. The toll is less than a Demon mechanical- secondary 850 and is no more expensive than its smaller 750 sibling. Later installing a low-cal-tension secondary leap and rejetting, it made the same power equally Sherman's reference 850 double-pumper. And information technology was cheap, since Jeg's High Operation sells remanufactured 850 Demon vacuum-secondary carbs for almost $370.

Normally, when yous want serious power, yous step upward to a roller cam, which also eliminates the demand to deal with the flat-tappet durability issues we've been encountering the past few years. But a roller and its associated valvetrain are mode across our budget, costing upwards of $1,000. That left a mechanical flat tappet as the merely viable choice. Oval trackers are virtually the just racers left regularly using solid flat tappets today, and so Sherman and Comp Cams specialist Billy Godbold put their heads together to spec out a radical oval-track grind that they felt could do the task. With 0.050 elapsing numbers in the 260s and more 0.600 inch theoretical lift with one.six:1 rockers, it's pretty aggressive.

A mean cam similar this requires special care and feeding to survive in today's world. Comp highly recommended we get with its optional Johnson-style lifters and take the cam nitrided, a special process that increases the cam's forcefulness while making the lobe surface more glace. Although nitriding adds about $125, the durability increase and peace of listen is worth the added toll. "Anytime you become a flat tappet by 0.500 elevator or 330 pounds [of leap force per unit area] over-the-olfactory organ, nitriding's the all-time matter you can exercise to improve the cam'southward vesture characteristics," said Comp Cams' Godbold. To further neglect-safe the flat tappet, Sherman slathered plenty of moly-lube on the cam lobes, filled the half-dozen-quart CHP oil pan with Shell Rotella T diesel fuel oil (unlike mod street-car oils, it still has a total complement of extreme pressure additives), and then dumped in some GM EOS (Engine Oil Supplement).

Most experts maintain that an engine of this caliber requires at to the lowest degree 134-inch primary-tube headers, just fifty-fifty the almost affordable 134 tube configurations are nigh $seventy more 158-inch headers. Then, nosotros stuck with Summit 158 headers for the baseline exam.

Thank God for Superlative's depression prices, both on its own branded items and on proper noun-brand parts. Non merely was Summit the price-source for the headers and many of the major proper name-make parts used on this engine, it also had great prices on all those nickel-and-dime accessories--front cover, valve covers, fuel-pump cake-off, water neck, distributor clamp, long pushrods, and other assorted pocket-sized parts.

We as well saved bucks by using generic foreign imports for the rocker arms, harmonic damper, and flexplate. Sherman's preferred supplier for these parts on low-buck builds is Performance Racing Warehouse, which sells nationwide through selected distributors, including Sherman himself. Generic parts, such as a remanufactured water pump and starter, were priced from standard auto parts stores like NAPA. We also saw some really friendly prices for GM items like a head-commodities set from a place called GM Parts Directly, which basically sells 18-carat GM stuff for 10 percent over dealer price. Where a unique fastener wasn't really needed, we were also able to use generic SAE Class 5 or 8 bolts and AN or SAE washers. Outfits like the Bolt Depot and Aircraft Spruce sell bolts and washers by the piece at very friendly prices.

Sealing the engine also can nickel-and-dime you to death--but good sealing is a prerequisite for reliability and longevity. Fel-Pro'south heavy-duty line was our choice for all critical gaskets. Even though many of the new parts already came with the necessary gaskets, nosotros found it was however cheaper overall to purchase a consummate gasket kit plus the oversize intake gaskets than to toll individual gaskets separately. This may not necessarily agree truthful if you purchase small-scale gaskets separately through a friendly auto parts store. And then of course there are additional sealant compounds and cements. Ka-ching, ka-ching: in that location goes $five,380.

Fully assembled, the engine'south static compression ratio came in at xi.02:i. Yikes! Compression is good for making ability if the engine doesn't get into detonation, merely at showtime glance, this high a ratio seems excessive for an iron-headed engine on 91-octane. However, with the large-overlap cam, cranking pinch was only 182-185 psi, well within Sherman'south comfort zone. In his feel, annihilation less than 200 psi is permissible for running a small-block Chevy successfully on pump gas. And in fact, running 91-octane, the engine would make its best numbers with 36 degrees of full advance with no evidence of detonation using NGK UR6 plugs gapped at 0.039 inch.

For now it was time to pull the handle on the dyno. Did we make the right parts choices? Dialing in the engine showed the cam liked a tighter valve-lash setting than the recommended 0.016/0.018 effigy. In fact, ability kept improving every bit Sherman tightened the lash all the way downwards to 0.010/0.010, indicating the engine wants an even larger cam--Sherman estimates at to the lowest degree 5 degrees more at 0.050 inch tappet lift. Nevertheless, once the lash, best timing, and carburetor jetting were established, the assembly did exactly what information technology was supposed to, coming in at 502 hp at vi,400 rpm and 471 lb-ft of torque at 4,600.

Of course, in that location are extra-cost, power-adding options. In Sherman's experience, a i-inch phenolic spacer is commonly worth power on single-plane intakes like Edelbrock's Victor series. Height sells a spacer with mounting hardware and gaskets that adds well-nigh $17 to the price of this build. On this engine, it was worth 8 hp and vi lb-ft.

All this was still with the 158-inch headers. Moving upwardly to 134 headers and the spacer adds well-nigh 19 hp at the price of xvi lb-ft of torque at the peaks for a new total of 529 hp and 461 lb-ft. Withal, with more surface area nether the bend, on the street in its present class, the 158-inch combo would likely yield amend overall operation and driveability, even though it gives away some on top. Assuming even the most inexpensive 134 headers, you're now looking at about a $5,480 outlay. Merely recollect, that assumes you accept nothing and includes everything needed to run this engine.

We priced basic machining costs at a local Southern California store. The price to clean and mag the block, bore and hone without a torque plate, deck to foursquare off the original deck, install cam bearings, and balance the assembly generally costs effectually $450. Fancy procedures like deck-plate honing, squaring using a BHJ fixture, or even marshal-honing aren't needed at this level to make the numbers, according to Sherman. Bearing this in listen, the bones build with small headers and no spacers would come in effectually $five,010. With the large headers and spacers, the total comes to just over $5,100. But any manner you slice it, that's a heck of a lot of ability for a very reasonable outlay.

Blueprint DataThese dimensions were verified by Joe Sherman on CHP's preassembled curt-cake and the RHS heads. All dimensions in linear inches, except every bit noted.

COMPRESSION RATIOBore x stroke: four.030 ten 3.75Block deck elevation: Milled to 9.019Piston deck elevation: 0.006 (below deck)Piston volume: -4cc valve reliefsHead gasket compressed volume: 9.1 ccCombustion-chamber book: 64 ccStatic compression ratio: 11.02:1Cranking compression: 182-185 ps

CAMSHAFTManufacturer: Comp CamsType: Mechanical flat tappetGrind: CS 6255/6266 S106.0 (+4)Duration, 0.020 tappet lift: 286/297 degrees

Duration, 0.050 tappet lift: 260/268 degreesLobe displacement angle: 106 degreesIntake centerline: 102 degreesLobe lift: 0.376/0.387Rocker-arm ratio: i.60:1Valve lift at cipher lash: 0.602/0.619Valve lash (design): 0.016/0.018Valve lash (best performance): 0.010/0.010Valve elevator at best running lash: 0.592/0.609

VALVESPRINGSManufacturer: Comp CamsValvespring PN: 26120Type: Single beehive with ovate wireRetainer PN (steel): 741Valvespring od: i.095/1.445Valvespring id: 0.650/1.000Seat pressure: 155 lbs @ 1.880Open pressure: 377 lbs @ ane.28Spring charge per unit: 354 lbs/inCoil-bind height: 1.230

DYNO RESULTS
	158 HEADERS		158 HEADERS		134 HEADERS
	NO SPACER		ane-INCH SPACER		1-INCH SPACER
ENGINE SPEED	TORQUE	POWER	TORQUE	POWER	TORQUE	POWER
(RPM)	(LB-FT)	(HP)	(LB-FT)	(HP)	(LB-FT)	(HP)
iv,600	470.6	412.2
4,700	459.three	411.2	477.3	427.1
four,800	463.0	423.two	474.2	433.four
4,900	458.one	427.4	470.9	439.three	459.9	429.1
v,000	449.three	427.7	467.4	445.0	461.ane	439.0
v,100	454.3	441.three	472.iv	458.7	453.0	439.ix
5,200	456.viii	452.3	470.4	465.7	454.vii	450.two
5,300	460.6	464.viii	470.viii	475.1	459.iii	463.5
5,400	450.5	463.2	462.two	475.2	450.5	463.2
5,500	457.1	478.seven	457.1	478.vii	444.6	465.6
v,600	445.0	474.v	447.6	477.iii	436.six	465.v
five,700	450.6	489.0	450.9	489.four	454.2	492.nine
5,800	443.0	489.two	448.iv	495.ii	447.1	493.8
5,900	429.seven	482.vii	439.4	493.6	454.0	510.0
6,000	439.8	502.4	434.1	495.9	452.nine	517.4
6,100	430.6	500.1	428.0	497.1	449.half dozen	522.two
half-dozen,200	420.iii	496.2	430.ii	507.9	446.1	526.6
six,300	413.three	495.8	423.3	507.eight	440.half-dozen	528.v
six,400	411.7	501.7	416.nine	508.0	428.6	522.3
6,500	399.7	494.vii	412.two	510.ane	425.2	526.ii
six,600	388.1	487.7	405.five	509.half dozen	416.v	523.4
6,700	381.5	486.7	396.vii	506.1	407.i	519.3
6,800	376.8	487.9	389.ii	503.9	401.ii	519.5
6,9O0	367.2	482.4	382.ix	503.0
Avg. overall	432.iv	469.seven	440.3	482.7	442.ane	490.9
Avg. four,900-5,800	452.5	460.8	461.viii	470.0	452.ane	460.3
Avg. 4,900-6,800	430.viii	477.two	439.7	487.0	442.one	490.9
Avg. 5,900-six,800	409.2	493.6	417.6	504.0	432.2	521.5