can someone give me their dyno numbers, and engine specs...

OK, if I go to the dyno, will the numbers I get be better if I run smaller tires on the rear? Currently, the car is slow due to the large tires I use on the highway.

That is what always worried me about doing a chassis dyno...I don't know if it takes into account tire size, gears, and all the other stuff.

 

hmmm i wouldnt think so, interesting point

 

I saw a article in one of the Mag's, I will try an find it later an post. you can change both ways on the chassis dyno just by strapping down car, air pressure etc. Tire size you will change numbers in rpm range, not sure if high numbers will change.

Take it to the strip and see your wheel horsepower on the floor.

 

I don't think so. The output values (Torque & HP) are based on how much work is being performed as it relates to the engine's RPM's.

A smaller tire will allow the engine to rap quicker, but the resistance of the dyno drum remains a constant.

The same applies to gear ratios. A car that has 4.56 gears has no more power if the gears were swapped to a 2.73's. It just takes the 2.73 setup more time to reach the same output.





I think.....

 

Rick, that makes sense...

 

A dyno guy once told me the gear ratio and converter will greatly effect numbers. And that basicly a chassis dyno is a tuning tool and not a good indication of actual power. I dont know. Thats why i asked him. But think of like this Gears multiply torque and torque converters do the same thus the name torque converter.So its hard to figure how efficient any of that stuff is without some experience with that perticular setup. My car made 306rwh on a chassis dyno in atlanta and went 7.21 the next day with full interior.

 

More like 18-20%.

 

Interesting how this thread morphed into an informative and factual chunk of information.

seriously.

And it just makes me more anxious to get in on the dyno.

 

..my chassis dyno guy took down my air press. so when i bring it back it would be comparing apples and apples. this would make you believe there is a diff. if tire press. is changed.

...frank...

 

Popular Hot Rodding, dec 06. Has the article on dyno cheating. With the difference in ratings they got 7.5% better hp. Not a big difference! Best thing to remember is, it's a guide and should be run the same way every time. Numbers are only numbers and street talk on power is always big numbers.

Always best to take what you got and tweak it the best you can, Some sob is always gonna outpower you, I always like it when they do it on paper!

 

No way in hell.

Aaaaaahhhhhh.....The Truth. Finally.

 

im just wondering how your HP is so much more than mine and yet i am faster.. i mean, it could be all tires... but i have 2.79 gears and 256" tires.. you should be alot faster with the 3.80, mini spool and 27 " tires

 

I agree. The circumference of the tire is the same no matter what the tire pressure is. (edit: "within reason").


chit. I had a long novel written about how torque converters should (do) NOT affect the numbers as they only increase the torque at launch, once they're locked up, they provide the same 1:1 ratio as a 3-speed would in 3rd gear.


Ultimately, there is only one fact: A dynamometer is a good tuning tool - and only if the same dyno is used and the environment, engine's temp, etc., are close (enough) each time a run is made.

---

Note from Dr. Obvious: We're involved in a "Bench Racing Session" (or is it a "Dyno Racing Session") and each racer is going to have their own beliefs and convictions. We can all agree that a dyno should really only be used to tune - regardless of the output numbers - and then only under controlled conditions (ie., relatively same environment, engine temps, etc., during each run).


And finally.....it all boils down to this one fact;

I'm right - you're wrong - and there's nothing you can do about it.

 

i called the dyno near cordova raceway, 65 for baseline... 110 an hour for tuning..

i am going to get a baseline then do the engine upgrade stuff and gears.. and then take it down and do the tuning and get it dialed in... then drive the 10 miles down the road to the drag strip and run it the same day.. then i will know for a fact what it does

 

take scott with ya