Chassis Dyno=Engine HP - Chevelle Tech
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post #1 of 10 (permalink) Old Jul 2nd, 20, 9:37 PM Thread Starter
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Bob
 
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Chassis Dyno=Engine HP

Chassis dyno came in at 740 to rear tire. What would engine HP be. I know this just a estimate as there are many variables but just an estimate. To name a few things about car is TH400, 410 gears, 28" tall MT Pro Radial tires, 10" wide wheel, TCI Super Str Fighter Trans. Engine is BBC/548 with 14 comp. As I said this is just a ball park estimate. Thanks!
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post #2 of 10 (permalink) Old Jul 2nd, 20, 9:53 PM
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Re: Chassis Dyno=Engine HP

740 x 1.2 = 888. Pretty stout in anybody's book.

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post #3 of 10 (permalink) Old Jul 2nd, 20, 11:40 PM
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Re: Chassis Dyno=Engine HP

I would guess 850
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post #4 of 10 (permalink) Old Jul 3rd, 20, 8:37 AM
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Re: Chassis Dyno=Engine HP

Some say add 10%. Some say add 20%. 15% is in the middle.

Pick a number. I'd use 15% but consider it a little high.

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post #5 of 10 (permalink) Old Jul 3rd, 20, 9:28 AM
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Re: Chassis Dyno=Engine HP

Depends on what chassis dyno you use. But would say your closer to 25% loss then even 20%. My guy has a custom designed 3500hp all wheel drive dyno. He said they regularly see 22% with auto and torque converter. And he knows it accurate as you can do 1/4 mile runs and track to dyno has been within 1/100 of a second. So would say your horsepower really is about 925.

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post #6 of 10 (permalink) Old Jul 3rd, 20, 10:00 AM
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Re: Chassis Dyno=Engine HP

Several iterations ago I tested my SBC on an engine dyno at 672 HP. I then installed the engine in the car. The difference being the engine had an alternator installed in the car. TH350. 8" 5000 RPM converter, 12-bolt rear with 4.56 gears. MT 28x10.5 stiff sidewall bias ply slick.

I then tested on the chassis dyno - 548 RWHP or about 18.4% difference.

Similar test years later with a different engine configuration and the engine had more changes between the engine dyno and the chassis dyno. Same drivetrain, but MUCH looser converter (flashed to 6800 RPM on dyno). 915 HP engine dyno. 689 RWHP. 24.7% difference.

The converter fall back RPM is usually 6400-6600 RPM at the track depending on the weather/DA. Flash stall at 1800 RPM off the footbrake is 5400-5600 RPM.

Converter efficiency is a big factor in drivetrain efficiency.
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post #7 of 10 (permalink) Old Jul 3rd, 20, 10:10 AM
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Re: Chassis Dyno=Engine HP

I'd say whatever that engine is in, the car will be fast.


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post #8 of 10 (permalink) Old Jul 3rd, 20, 11:03 AM
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Re: Chassis Dyno=Engine HP

Lots!! But just for braggin rights, depending on the day, 850-900.Haha
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post #9 of 10 (permalink) Old Jul 3rd, 20, 12:24 PM
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Re: Chassis Dyno=Engine HP

740/0.8 = 925 hp

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post #10 of 10 (permalink) Old Jul 4th, 20, 1:09 AM Thread Starter
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Bob
 
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Re: Chassis Dyno=Engine HP

Thanks for the replies. I'm figuring 925. Why I asked is had engine dyno'd at 902 then installed in car. Put on chassis dyno and got 720. Then decided to a carb changed and jumped to the 740 I posted so was figuring 925 but just wanted to see what people thought. Wish I could say what dyno was used but not known at this time. Figuring TQ probably went up slightly also.
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