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Not exactly C4 related but related to power at engine vs power at tires.
A few years ago I built a 468 BBC for my backup drag car (1983 Olds Cutlas) my primary car is a 1990 C4 vette so no freaking out! I built the engine out of left over parts that I had laying around and decided to dyno it (Engine dyno) to see what it made (I love information). By the way BBC are so easy to make good power with. (454 2 bolt block, stock forged crank, stock rods, 13:1 pistons, Dart 335 heads, solid roller cam, and 1150 dominator)
This engine made an easy 702 HP and 644 ft/lbs torque when it was fresh and not even fine tuned on the dyno (2 pulls and no changes made due to dyno failure). I have made approximately 50 runs with this combination, and have decided to chassis dyno it just so I had more information and could estimate future changes.
On the chassis dyno with a similar setup (dominator replaced with multi port efi and throttle body, powerglide and 9" with 4.11 gears) to what was run on the engine dyno it made 560 RWHP. This works out to approximately a 20% power loss through the drivetrain which I actually thought was pretty low considering the high stall convertor.
This information is consistent with other combinations that I have built and dyno'd in the past.
I have attached the dyno sheets for curious people. The strange looking chassis dyno runs are the results of the high stall convertor stalling to around 6000 RPM.
That is consistent with what my local dyno operator says is normal. Manual trans cars lose about 15% and automatics lose about 20%. The type of chassis dyno also seems to make a difference. I use the chassis dyno numbers primarily to compare before and after results of changes of parts and tuning parameters.
Very cool, also don't worry about it not being directly C4 related. The way I look at it is this is the C4 owner's (or perspective or asking legit questions) area to hang out and it is quite OK to share with all of us. That is my take.
My favorite video on youtube is a 700 HP 427 ci (in a C2) being flogged on a road course. There is something magical about a BBC and especially magical is the sound of a hot 427 being wound out up through the gears.
There are a couple guys local here with engines like yours in Vettes (BBBC ie: Built Big Block Chevy). 1 is in a 63 Grand Sport replica and 1 is in a real 67. They just have to be fun to drive.
Given it has a 9 inch, 4.11s and a high stall that seems right. Is it a power glide or turbo 400... assuming a power glide. Suprised it reads like that too. I've been told mustang dynos read particularly low.
I've seen people claim anywhere from 7% up to 25% loss depending on setup. Being new vehicles are all sae dynos tend to trend around 10% for the likes of challengers, camaros, mustangs.
I seen C4s run around 17% for autos and 10ish for manuals in stock form... harder you accelerate the dyno pull the more those losses will show as well. Great data.
Very cool, also don't worry about it not being directly C4 related. The way I look at it is this is the C4 owner's (or perspective or asking legit questions) area to hang out and it is quite OK to share with all of us. That is my take.
11-27-2020, 11:07 PM
Not exactly C4 related but related to power at engine vs power at tires.
