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355ci Budget 350 HP Chevy Small Block
355ci Performance Budget Small Block Chevy
This engine was a package deal with the currrent 1968 Camaro where most of the work had already been performed. At the time of original purchase by Brett, it couldn't power brake the back wheels free at all. As a testimate to Brett's engine building capabilities, it has progressed into an impressive mouse with a suprising bite. His first modification was to the exhaust where he equipped full length 1 5/8 Hooker Competition Headers with true dual 2.5" exhaust into Flowmast 50 series muflers and no exit pipes. Adding on a free flowing open air filter element and the Camaro began to sound more like it should... but still didnt break the tires free at will. Next, Brett equipped a set of reworked 462 casting 64cc camel hump heads with a fresh 3 angle valve job and added a holley spread-bore dual plane intake to repalce the cast iron boat anchor and maintain compatibility with the Q-jet. This was a huge improvement over stock and the car was finally moving making power. I can still hear the bellow of the Q-jet at wide open throttle. Not satisfied, Brett researched a cam replacement which would emulate the classic cams found in that era and found the Crane Muscle Car Grind. This really brought the engine alive and now it could brea the back end at wil off the line.
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Just as everything was looking good, the outer tang of the block where the starter bolts in strangely broke off. Suspecting previous unseen damage, the choice was made to scrap the block and machine a new one. Brett called up the folks at H.D.S Machine in Escondido, CA and had them Blueprint a .030 over 350ci short block with Federal Mogul flat top hyperuetectic pistons. This kept the cost down while ensuring reliability and street performance. Once completed, the heads, cam, intake, roller timing chain, cam button and accessories were fitted back on. A compression of 9.5 to 1 was realized and again the Camaro felt even more powerfull. This is when the suspension began showing its age and bushing started to fail all over, necessesitating replacement with good poly right up to the engine mounts. Once again the car went under the knike for more power, this time with a Torquer open plenum manifold and a Holley 650 Double Pumper Carb. The Holley was a different animal than the Q-jet and almost felt like it lost power from the moan of the spread-bore secondaries we were used to. A lot of tuning and the Holley began to show its strengths where it built up a more predictable power curve. But something was still missing, this is where the 2800 stall converter comes in finished off a great setup. Now the car was scary fast! Jumping on the gas lit the back end up like a firework, always jumped to the power band and really let off a scream. Small modifications from here forward like a Proform HEI to smooth out the top end and subframe connectors to keep the frame twist to a minimum. The mono-leafs needed to be swapped out for multi-leafs to control the axle wrap and a turn-buckle from the block to the front subframe on the drivers side to keep from busting engine mounts. This is where I come in and the condition of the engine at my purchase. It sits about the same today with a few minor modifications. Feeling the car was missing a little bottom end to midrange with the short runner of the Edelbrock Torquer intake manifold, I dropped an Edelbrock RPM Air-Gap on. This made busting loose the rear in first gear much easier and leveled off the power band to leap through the midrange much quicker - but lost top end. give this intake had a dropped plenum, i decided to run a 1" open spacer and see if this brought the top end back... yep! It also managed to smooth out the off-idle burst off the line and gave me a little more control to reduce wheel spin and hook up. Adding the Lakewood Lift Bars that came with the car allowed a lot more pedal off the line an ultimately pushed the car to its best time of 0-60 in 5 seconds, 1/4 mile in 13.22 at a speed of 120 mph. All this on the stock 2.73 open diff rear and a 3 speed auto trans.
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This engine has seen a lot of transformation over the years from a stock 350 to the 355ci beast it is today. It was always well known that something about this combination was special, even with the open plenum torquer manifold it used to run, but we were convinced that the horsepower figures couldn't be as high as it performed. It wasn't until we plugged the numbers into the desktop dyno that the torque figure came to light. That explains a lot.
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| Short Block Specs: |
| Block: | 78 Chevy 350ci | | Type: | Cast Iron |
| Cylinders: | 8 | | Displacement: | 355.12 |
| Bore: | 3.03" | | Deck Height: | 9.025 |
| Stroke: | 3.48" | | Bore/Stroke Ratio: | 1.158 |
| Rod Length: | 5.7" | | Rod/Stroke Ratio: | 1.638 |
| Pistons: | Keith Black | | Piston Type: | Hyperuetectic |
| Piston Rings: | 3 standard tension | | Piston Top: | Flat Top |
| Timing Setup: | True Double Roller | | Timing Options: | Crane Roller Cam Button |
| Dampner: | Stock | | Balancing: | Internal |
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| Head Specs: |
| Head: | 462 Camel Hump | | Type: | Cast Iron |
| Valve Dia. In.: | 1.94" | | Valve Dia. Ex.: | 1.5" |
| Avg. Port Dia. In.: | 1.59" | | Avg. Port Dia. Ex.: | 1.3" |
| Port Length In.: | 5" | | Port Length Ex.: | 3.5" |
| Port Flow Coef. In.: | .45 | | Port Flow Coef. Ex.: | .45 |
| Comp. Ratio: | 9.5:1 | | Burn Rating: | typical |
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| Cam Specs: |
| Cam: | Crane Cams 222/222 | | Type: | Hydraulic |
| Centerline In. ATDC: | 114 deg. | | Centerline Ex. ATDC: | 114 deg. |
| Dur. @ .050 In: | 222 | | Dur. @ .050 Ex: | 222 |
| Open @ .050 In. BTDC: | -3 | | Open @ .050 Ex. BTDC: | 45 |
| Close @ .050 In. ABDC: | 45 | | Close @ .050 Ex. ABDC: | -3 |
| Max. Lobe Lift In.: | .298 | | Max. Lobe Lift Ex.: | .298 |
| Rockers: | Crane | | Rocker Type: | Aluminum Roller |
| Rocker Ratio In.: | 1.6 | | Rocker Ratio Ex. | 1.5 |
| Gross Valve Lift In.: | .447 | | Gross Valve Lift Ex.: | .447 |
| Total Cam Advance: | 0 deg | | Lobe Sepparation: | 114 |
| Lifters: | Stock Hydraulic | | Pushrods: | stock" |
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| Intake Specs: |
| Intake: | Edelbrock Performer RPM Air-Gap #7501 | | Type: | Aluminum |
| Intake Heat: | Low | | Plenum: | Dual Plane - dropped plenum |
| Runner Dia.: | 1.68" | | Runner Style: | Straight- No Taper |
| Runner Length: | 7" | | Runner Flow Coef.: | 3 |
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| Carb Specs: |
| Carb: | Holley 4150 #4777 | | Type: | Double Pumper |
| CFM: | 650 | | Air Cleaner CFM: | 800 |
| Power Valve: | 10.5 | | Idle: | 1000 rpm |
| Pri. Jets: | 68 | | Sec. Jets: | 76 |
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| Exhaust Specs: |
| Exhaust: | Hooker Competition Headers | | Type: | Full Length |
| Muffler: | Flowmaster | | Design: | 50 Series |
| Inside Dia.: | 1.5" | | Length: | 40" |
| Runner Flow Coef.: | 1 | | CFM | 800 |
| Collector Length: | 8 | | Collector Style: | Simple |
| Collector Size: | 3" | | Exhaust Size | 2.5" |
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| Drivetrain Specs: |
| Transmission: | TH-350 | | Type: | Auto |
| Torque Converter: | Corvette | | Stall: | 2800rpm |
| Trans Ratio: | 1st=2.52, 2nd=1.52, 3rd=1 | | Mods: | Shift Kit |
| Driveline: | Stock | | Rear End: | 10 bolt |
| Gear Ratio: | 2.73 | | Diff.: | Open |
| Front Brakes: | Disk | | Rear Brakes: | Drum |
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| Tire Specs: |
| Front Rim Size: | 15"x8" | | Rear Rim Size | 15"x8" |
| Front Rim Offset: | 3.75" | | Rear Rim Offset: | 3.75" |
| Front Tire Size: | | | Rear Tire Size: | |
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| Additional Specs: |
| Cooling Fan: | Electric | | Water Pump & Drive: | Production Style |
| Ignition: | Proform Hi-Amp | | Ign. Type: | HEI |
| Peak RPM: | 6000 - high piston speed | | Maximim Flow | 458.48 CFM @ 87.5% VE |
| Vehicle Weight: | 3800 lbs | | Aero Dynamic Drag | |
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First Pass Of the Spec's loaded into Performance Trends Engine Analyzer exposed the following.
Test's suggest a peak of 337 hp at 4700 rpm and 440 ft-lbs torque at 3900 rpm. As per the target of this build, the engine should make close to 380 ft-lbs of torque at its stall speed of 2800 rpm and grows to near 5000 rpm. It's peak of 337 hp is below the desired rpm of 6000, probably due to the small valve heads.
Engine_RPM 1500 1900 2300 2700 3100 3500 3900 4300 4700 5100
Brk_Tq 328 355 378 397 418 437 440 409 377 336
Brake_HP 93.6 128 165 204 247 291 327 335 337 326
Exh_Pres 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.1 0.1
Int_Vac 0.1 0.1 0.2 0.4 0.5 0.8 1.0 1.2 1.3 1.3
Vol_Eff 74.5 78.6 82.7 86.7 91.4 97.1 99.9 97.6 93.2 87.5
Actual_CFM 115 154 195 240 291 349 400 431 450 458
Fuel_Flow 42.07 56.2 71.6 88.0 107 128 147 158 165 168
Nitrous 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Ntrs_Fuel 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
BMEP 139 151 160 169 178 186 187 174 160 143
A/F_Mxtr_Qlty 91.4 97.4 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0
BSFC 0.450 0.437 0.433 0.431 0.432 0.439 0.448 0.471 0.489 0.514
Thermal_Eff 32.83 33.82 34.29 34.59 34.64 34.22 33.76 32.67 32.19 31.48
IMEP 153 166 177 187 198 208 211 199 188 172
Frctn_Tq 32.79 36.48 40.25 44.12 48.09 52.2 56.3 60.6 65.0 69.4
Frctn_HP 9.36 13.20 17.63 22.68 28.38 34.76 41.82 49.61 58.1 67.4
FMEP 13.92 15.49 17.09 18.74 20.42 22.15 23.92 25.73 27.59 29.49
Mech_Eff 90.9 90.7 90.4 90.0 89.7 89.3 88.7 87.1 85.3 82.9
Motoring_HP 11.79 17.25 22.74 27.75 33.85 43.98 58.8 80.4 95.4 112
Pumpng_Work -2.43 -4.05 -5.12 -5.07 -5.47 -9.23 -16.95 -30.82 -37.29 -44.61
Residual_Exh 8.3 5.9 4.7 5.3 5.2 3.9 3.1 3.5 4.0 4.8
Shrt_Circuit 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Exh_Temp 1231 1292 1352 1346 1357 1368 1389 1427 1424 1404
Mx_Cyl_Pres 812 860 904 948 996 1053 1082 1056 1007 946
Mx_Cyl_Tmp 4375 4529 4588 4560 4552 4592 4619 4602 4571 4538
In_Port_Tmp 105 96 90 86 80 75 72 70 70 71
Piston_Spd 870 1102 1334 1566 1798 2030 2262 2494 2726 2958
Piston_Gs_@_TD 150 230 340 470 620 790 980 1190 1420 1680
Coolant_HP 41.02 50.9 60.0 68.4 77.2 87.4 98.2 111 121 132
Blow_By 4.1 4.3 4.5 4.7 5.0 5.2 5.4 5.3 5.1 4.8
In_Tun_Pres 0.0 0.0 0.1 0.5 1.1 1.9 2.8 3.3 3.6 4.0
Avg_In_Vel 87 110 134 157 180 204 227 250 273 297
Avg_Ex_Vel 136 172 208 244 280 316 352 388 425 461
Mach_# 0.153 0.193 0.234 0.275 0.316 0.356 0.397 0.438 0.478 0.519
Act_In_FlowAre 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
Act_Ex_FlowAre 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
Valve_Toss
Knock_Index 1.6 1.4 1.4 1.4 1.3 1.3 1.3 1.2 1.0 0.9
Spark_Advnc 25.6 26.5 27.4 28.6 29.4 29.6 30.1 31.1 32.4 33.7
Primary_Jet .1254 .1173 .1179 .1167 .1174 .1169 .1151 .1151 .1152 .1151
Secondary_Jet .0912 .0856 .0861 .0852 .0857 .0854 .0842 .0842 .0843 .0842
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Copyright © by M.Dowdell All Right Reserved. Published on: 2005-12-16 (213 reads) [ Go Back ] |
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