Ad Radar
Car Craft
Click here to find out more!

391ci LS with Magnuson Supercharger

391ci LS + Magnuson Supercharger = Easiest 1,000 HP On Planet Earth

By , Photography by

Power to the People

After that quick tour through the internals on this animal, we return to the dyno room to witness the result of all this assembly work. Even though this engine will be used in a '32 Ford, he retained the stock GM ECU, using a copy of HP Tuners to set up the positive manifold pressure fueling. One important aspect of this tuning includes ensuring that the fuel pressure is boost-matched to the manifold pressure. This usually means at least 1 psi of fuel pressure for every 1 psi of positive manifold pressure. This is required to maintain the original fuel pressure in the manifold. Generally, the LS engines run at 58 psi. So at 18 psi of boost, the fuel pressure ascends from 58 psi to 76 psi.

With the fuel and spark maps tuned, Duttweiler landed on 26 degrees of total ignition timing as the peak power number. This may seem like a small number compared to the old days of small-block Chevys requiring 40 degrees of lead. What this really indicates is excellent combustion chamber efficiency. Basically, less ignition timing means the engine can initiate the combustion process later and still maximize cylinder pressure at around 15 degrees after top dead center (ATDC) where the piston can exert maximum leverage on the crankshaft. Lower total timing numbers also reduce negative work because the engine doesn't have to expend energy to overcome increasing cylinder pressure in the combustion space approaching TDC. To reinforce the idea this is a great street engine, Duttweiler also checked the leak-down after two whole days of abuse and dozens of dyno pulls and saw less than 1 percent leakage from the Total Seal Gapless rings.

As you can see from the dyno curve on page 22, this engine makes some astounding power. Let's start with 900 lb-ft at 3,600 rpm. This massive torque means you don't need nearly as much torque converter stall speed to get the car moving or nearly as much rear gear as leverage to accelerate the vehicle. We plugged this power curve into the Quarter, Pro dragstrip simulation, and with a 3,500-pound car with a 3.31:1 rear gear and a TH400 trans with a 3,000-rpm stall speed converter (assuming you can hook it up—our simulation showed tire spin all the way through the 60-foot mark), we saw 9-teens at 151 mph. That is some serious acceleration and fully capable of sub-9-second times. Plus, best of all this combination would fit under all but the lowest hood line and does not demand all the custom plumbing of a pair of turbochargers. Sure, the Magnuson kit is expensive—but look at the power you're making. Folks, the days of a 900hp street engine are here and bangin' on the front door. Better let 'em in!

WCRCH-Ported All-Pro Head Flow

Valve Lift Intake CFM Exhaust CFM Exhaust/Intake
0.200 153 111 72%
0.300 225 170 75%
0.400 288 210 73%
0.500 344 234 68%
0.600 375 253 67%
0.700 398 262 66%
0.800 417 271 65%
0.850 422 273 65%

Power Curves

RPM TQ HP Fuel (lb/hr)* BSFC Boost
3,600 907 622 379 0.621 20.6
3,800 912 660 406 0.612 20.8*
4,000 938* 715 429 0.600 20.6
4,200 937 749 448 0.598 20.3
4,400 937 785 461 0.588 20.5
4,600 937 820 486 0.593 19.8
4,800 932 851 505 0.594 20.3
5,000 932 887 523 0.590 20.2
5,200 933 923 542 0.587* 20.0
5,400 925 951 560 0.589 19.8
5,600 912 973 577 0.593 19.8
5,800 901 995 588 0.591 19.9
6,000 885 1,010 594 0.588 19.7
6,200 867 1,023* 607 0.594 19.4
6,400 833 1,015 645 0.636 18.9

*BSFC is an evaluation of how efficiently the engine uses fuel, expressed as pounds of fuel per horsepower per hour, or lbs/hp-hr. Generally, a normally aspirated engine is very efficient at 0.450 lbs/hp-hr. Roots style supercharged engines always exhibit higher BSFC numbers because they require additional fuel to make power to drive the blower. In this case, at 20 psi with a 2.3L supercharger, it requires roughly 150 hp to drive the blower. This means that the engine was actually making around 1,165 gross horsepower. The engine also makes 2.61 hp per cubic inch.

West Coast Racing Cylinder Heads
Total Seal Piston Rings
AZ  85027
Granatelli Motor Sports
1000 Yarnell Place
CA  93033
Leading Edge Performance
Diamond Racing
23003 Diamond Drrive
Clinton Township
MI  48035
All Pro Aluminum Cylinder Heads
1985 Cedar Bridge Ave
NJ  08701
Left Coast 32
Chevrolet Performance
Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
Car Craft