This project will help some of understand the differences between engine dyno numbers and chassis dyno numbers. Also nice to have a 400 TBI in the mix. I don’t have much on the website with chassis dyno numbers for a 4×4 as I don’t currently have one and don’t get many customers putting their vehicles on a chassis dyno. This is why the customers project page is so small, not because no one is doing chassis dynos of their projects when they are done. Since Bryan had the opportunity to have his engine put on a engine dyno as well as chassis dyno I am going to try and explain why the numbers come up different so if your looking at buying an engine that has strictly engine dyno numbers, its important to know all the conditions of the engine dyno test to see what kind of realistic power numbers its going to make in the vehicle.
Bryan has agreed to me posting his email address. firstname.lastname@example.org so that you could ask him questions about his project.
First lets knock off the details of the engine. This whole setup was designed to pass a strict emissions test and make massive torque to move this big 4×4 beast.
1. 412ci SBC which is a .060 overbore on a 400 cubic inch SBC which survived 9 chassis dyno pulls and who knows how many engine dyno pulls..
2. A nice set of Edelbrock 200cc E-Tec vortec heads. Which is a nice intake runner size for a 400ci motor.
3. A mild comp cams 12-402-4 cam 212/218 duration @ .050, .444/.444″ lift with 1.5 rockers on a 114 degrees of lobe separation angle for a nice emissions friendly setup.
4. GMPP TBI vortec intake bored to match a 47mm throttle body from www.rvmorsemachine.com with flowmatched 80lb/hr 454 injectors from www.tbiparts.com running at 18psi to get that flow in the mid 90lb/hr range. also running the EGR tube to driverside header with EGR valve running ton the vortec TBI itnake for complete emissions compatibility.
5. Nice mid length headers feeding 2 3″ pipes through 2 high flow cats to a dynomax ultra X pipe muffler and dual 3″ out in front of the passenger side rear tire.
6. Nice 4.5″ K&N open element air cleaner assembly with filter lid as well. .
The next 3 pictures are dyno graphs. This first one is the rear wheel chassis dyno numbers and you may say those numbers don’t look 2 impressive for a 412ci motor and you have to look at the bigger picture. 1. this is a 4×4 where torque is more important and those big 35″ tires and transfer case as well as just being an automatic all guzzle more power than my little 2wd projects and he isn’t running electric fans or anything of that nature. Also you can see down there it was 95 degrees while we were making those dyno pulls so it actually did quite well. Down below I will show how I came up with these numbers but I am figuring a 27% drivetrain loss for this project and that figures out to 340hp at a mighty low 4600 rpm and 480lb of torque at 3000 rpm.
Below is the engiine dyno numbers which shows the motor is capable of 414hp and 486lb or torque that I highlighted in the chart below. I used that 486lb number to help me calculate the % of drivetrain loss as I know the restrictive GMPP intake and small (for a 400ci motor) wouldn’t affect the torque number as much as the horsepower number. You can see though that both the horsepower and torque peaks are at higher rpms on the engine dyno than they were on the chassis dyno and that is due to using a far milder intake and lower cfm throttle body than they used on the engine dyno. the engine dyno numbers were in a nice climate controlled 60 degree environment with a big intake and 750cfm carburetor and 1.75″ headers which are all bigger components than was actually used on the finished project. If we didn’t have such strict emissions testing to pass we could easily have used a more aggressive intake and larger throttle body to get much closer to those numbers. The nice thing about engine dyno numbers is they list the BSFC or brake specific fuel consumption and from the research I have done on BSFC, anything less than .450 is good and below .420 is awesome. This motor spends most of its time right in between these numbers and from 3300-4700 rpms is really efficient. I would not be surprised at all if Bryan emails me what great gas mileage numbers he is getting from this setup. We also have fuel lb/hr numbers so we know how much fuel this thing is going to require at maximum power output which from that graph at 6000 rpms we need 182lb/hr worth of fuel or right at 2 (90lb/hr) injectors. We ran 2 80lb/hr injectors at 18psi of fuel pressure to give is in the neighborhood of 96lb/hr worth of fuel to support the full 414hp potential.