383 TBI

 BEFORE & AFTER

  

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Stock 350cid Chevy TBI

 

GM 167cc Iron Heads - CR.9.4:1 - Cast Flat Top Pistons .018 Deck Height
STDRockers 1.5:1 - Stock Flat Tappet Camshaft:-
STDManifold - Throttle Body to 1-11/16" - 61lb per hour injectors 
Iron Exhaust - GM Distributor 

 

StokerEngine 383 TBI

 

AFR 180cc Aluminum Heads - CR.10.0:1 - Forged Flat Top Pistons - Zero Deck Height
Full Roller Rockers 1.6:1 - Custom TSEC Hydraulic Roller Camshaft:-
In 218 @ .050  .518 lift - Ex 224 @ .050  .534” lift - Center Line 110 - Lobe Separation 113 (Passed California Smog)
Edelbrock Performer Manifold - TC Bored out Throttle Body to 1-13/16" - 68lb per hour injectors
JBA Headers - MSD Distributor - Jacobs Multispark - Reduction Pulley

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TORQUE

In this chart you can see the maximum rear wheel torque was 258lbs-ft stock and we cranked it up to 336 lbs-ft a gained 78lbs-ft. Figure 30lbs-ft came from the extra stroke, the heads and cam did the rest.

 
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 HORSEPOWER

Here you can see what the extra torque did for Horsepower. You will see the rear wheel horsepower climbed from 162 to 249 a 80rwhp increase.

  

RPM

This chart also shows RPM so as to compare to MPH.  Notice how TBI keeps the curve from climbing like a carburetored motor. This is the "fly in the ointment" with TBI, this motor with a carb would have made closer to 315rwhp with enough fuel supply.

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BHP

Finally this chart we show the estimated Brake Horsepower at the flywheel. While the computer calculated this number, a good rule of thumb is an 20% power loss through the drive train.
In this case we used 18% to get the final BHP number of 319. This is as much as I could have hoped for in this case. The 68lbs per hour injector were mathematically calculated to only support 320bhp. The engine was still making more BHP when we shut it off, but the gain would not have been more than 322bhp.

Using the same conversion factor we made 393lbs-ft Torque.

 

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Conclusion

While this was a successful project I personally would have like to have seen all those expensive parts make even more power, but the laws of physics can only be bent. This motor was in a California truck and had to pass smog. When I tested it, it was compliant, but awful close to the line. Next time I'll use a smaller cam in California, but if your motor is not under such strict restrictions, this camshaft works very well, has a slight lope to the idle, and if you don't mind running rich at idle, two 74lbs per hour injectors can make a little more power.

 

Even if you stick with a 350cid, the bigger TBI system will raise you power output level.

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This next chart was generated by my simulation dyno. As you can see I meet my BHP goal, but I was down on torque by 30lbs-ft.

 

Just for fun I show what this engine could do with a better intake manifold and a 750cfm carb.

 

80BHP gain, but look at the torque almost 500lbs-ft. That's what you get when you use AFR heads, they flow big numbers with small ports, fantastic for making a flat torque curve.

TBI Kit