Does your desktop dyno lie?

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10-01-2007, 12:27 PM
chevydrivin

Does your desktop dyno lie?

Ok I have not spent the money to upgrade my desktop dyno. I have the 2000 version. Has anyone ever played with the same combos with only changing the cubic inchs?
Here is what i came up with heads/cam and all stayed the same only change was the cubic inchs............
283-410HP@7500
302-413HP@7000
307-408HP@6500
327-414HP@6000
350-406HP@6500
383-410HP@5500
400-410HP@5500

Yeah, Yeah I know different cams for different cubes and different heads might make some of the larger cube have more power but, I just wanted to make a comparison of say:
I already have X heads and X cam what block do I want to put it in:
10-01-2007, 03:55 PM
gassersrule_196

:toocool: :D :toocool:
10-01-2007, 04:03 PM
pat mccarthy

you will not pick any up on hp but it is lower rpm as the cid went up but the TQ should be better with the bigger cid
10-01-2007, 05:09 PM
Dave Severson

Pat's right. Got to look at the torque numbers along with the horsepower.

I think all the media rags have made everyone so horsepower conscious they tend to over look the fact that torque is what creates motion in heavy cars, horsepower is nice on the big end with a light car but for street or bracket racing in a car over 2500 pounds, I'll build my engines for big torque numbers, and let the horsepower fall wherever it will!!!!
10-01-2007, 06:41 PM
chevydrivin

283-370-tq@5500
302-390-tq@5000
327-418-tq@5000
350-432-tq@4500
383-459-tq@4500
400-475-tq@4000
10-01-2007, 06:44 PM
Dave Severson

There ya go!!!! The torque numbers are the one's that matter!!!! Horsepower numbers are little more then bragging rights!!!!!
10-01-2007, 07:22 PM
500caddy

dave is spot on. i always asked my customers would you want a 500hp and 600ftq or 600hp and 500ftq!! i can tell you that the torque will make all the differents in the world in a heavy street car and be more user friendly.
10-01-2007, 07:30 PM
pat mccarthy

well i was thinking i was right to:LOL: i build for TQ alot of the time thats what the guy wants he just has no clue:3dSMILE:
10-01-2007, 07:33 PM
chevydrivin

So here is a converter for tq to wheels. Just going to compare two.

TQ * 1st gear (2.5) * rear gear * .085
small cube high rpm
405tq x 2.5 x 4.56 x .085 = 393tq at wheel will go 135 mph in 1/4 @7400rpm.

large cube lower rpm
500tq x 2.5 x 3.70 x .085 = 393tq at wheel will go 135 mph in 1/4 @6000rpm

So 405 tq at motor looks the same as 500tq at motor.
10-01-2007, 07:39 PM
pat mccarthy

sure and your small engine will burn out long before the big cid engine will look at your rpm things like oil hitting the crank will kill power and parts like springs crank. rods.cam. lifters. will see the beating block will move a round the more RPM the better the parts
10-01-2007, 07:45 PM
Dave Severson

Quote:

Originally Posted by chevydrivin

So here is a converter for tq to wheels. Just going to compare two.

TQ * 1st gear (2.5) * rear gear * .085
small cube high rpm
405tq x 2.5 x 4.56 x .085 = 393tq at wheel will go 135 mph in 1/4 @7400rpm.

large cube lower rpm
500tq x 2.5 x 3.70 x .085 = 393tq at wheel will go 135 mph in 1/4 @6000rpm

So 405 tq at motor looks the same as 500tq at motor.

That's all kewl, but what's the ET???? MPH only wins races at Bonneville!
My simplified drag math:

Big Torque Numbers at low rpm + lightweight car with good hook = lower 60' times...

Lower 60' times + big torque to pull the top end = winning car!!!!

Easy and simple, works, too@@@@
10-01-2007, 07:56 PM
chevydrivin

If tourqe at the wheel is the same then the et will be the same whatever it is.
Just say 12 seconds for both setups. Because they both put 393 ft/tq to the wheel.
10-01-2007, 07:56 PM
500caddy

i like the most of both !!!!!!!!!!!!! 1000hp and 1000ftq will do just fine..
10-01-2007, 07:58 PM
pat mccarthy

Quote:

Originally Posted by 500caddy

i like the most of both !!!!!!!!!!!!! 1000hp and 1000ftq will do just fine..

i am working on just that right now with no power adders :3dSMILE: **) :whacked:
10-01-2007, 08:01 PM
500caddy

ya ya geter done!!!!!!!!!!!! we will race for a steak dinner. i get 3cars thuo
10-01-2007, 08:02 PM
pat mccarthy

Quote:

Originally Posted by 500caddy

ya ya geter done!!!!!!!!!!!! we will race for a steak dinner. i get 3cars thuo

well i have no car to put it in ?:(
10-01-2007, 08:04 PM
500caddy

ok i will let you put in my car.
10-01-2007, 08:05 PM
pat mccarthy

Quote:

Originally Posted by 500caddy

ok i will let you put in my car.

you are to kind:rolleyes:
10-08-2007, 07:52 PM
rhamm1320

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Computer simulations will never completely replace real world testing, but they can save you iterations and money spent on parts if you even catch one little thing that can improve your engine.

Also, people get too caught up in a exact number. So and So magazine article says this combo of parts is xxx horsepower, but I calculated xxx +/-15. I have witnessed dyno runs on the same exact engine with slightly different results (either different day, weather or shop). The dyno's have correction factors, but its not a exact science.

The most important use for simulation is finding trends and relative changes (camshaft, intake) and ultimately finding the best combination for the intended application of the engine (racing, street, torque, horsepower).