Lord Ashram

Hey all,

I am in a debate with a friend, and am afraid I am being stupid...

Lets say you have a mustang that has been severely modified; new motor, new chip, new exhaust, supercharged; new everything. Do you need to get a tune done by a mechanic with a dyno? If you go to a mechanic who has a computer but not a dyno, what would the difference be in the work they can do?

I know this sounds like a strange question, but some help would be great.

Birdieman4

What needs to happen, (in that case) is you need a baseline tune to start. Once you have a general baseline for your parameter settings, then you NEED to take it to a dyno. The dyno needs to have O2 sensors to be able to monitor your air fuel ratio. Once at the dyno, you need to have a way to adjust the car's tune accordingly. This is usually accomplished with one of those hand held tuners like a Diablo Predator or a Superchips SCT calibrator. The 2 big factors in tuning your car are timing and A/F ratio. Once you have a handle on those 2 variables, you are set. A dyno that can't measure your A/F ratio is useless for tuning. Make sure your dyno has this ability. Also, I highly recommend a baseline pull before the car gets it's updates.

Lord Ashram

Thanks man... I have already had my car to the dyno and gotten the tune done... where my buddy and I got in an argument is that he insisted the dyno does nothing that a simply computer cant do except tell you the HP to the rear wheels... he has an old mustang, and was saying a "tune" just consists of tightening a spring... I think he is just thinking about what it means to "tune up" an old car, but doesnt quite get what it takes for a modern car. He was insisting a dyno is only need to get those last few horsepower out of a car... I argued that you need a dyno to make ANY sort of tune that will work in heavily modded, not-stock-computer-chip-or-program car. He insisted the only reason all the mags use dynos is to "sell" the idea of them being necessary, but they really only bring out the last few horsepower in a car.

Can a person with just a computer give you a good tune on a modded car? Or do you really need the dyno? And if you did just get a tune on a computer and not on a dyno, how different would the results be? You mention in your first line a "baseline" tune; can this be done effectively without a dyno?

Again, I appreciate any and all help... my buddy is rather insistent he is right, but what he is saying just isnt matching anything I have ever heard about late model mustangs and their tunes, especially since I have been keeping fairly up to date with this since i got my mustang.

gt96stang

Older mustangs run off a carb where all this tuning isn't as important to them...

Birdieman4

Let me add this. All a dyno does is measure your tune, and record results of hp. It tells you how good (or bad) your tune is. Adjustments need to be made accordingly(with a tuner), and then the car goes back on the dyno to 'measure' the changes made. That's all. A dyno that can measure rwhp only, is only good for letting you know your car's hp. It can't be used for tuning.

93BlackNotch

Your A/F ratio is what makes the car run good, if you lean the car out you will have detonation which will destroy your motor... A Dyno just reads horsepower to the rear wheels and gives you your current A/F ratio.... A tuner has the ability to adjust settings to make your tune "safe"... A regualr scan tool, or computer can't read all of your paramaters, so they are almost useless when it comes to tuning...

sandcracker21

i think your budy is confused

it sounds like he has a mustang that is old enough to not have a computer, therefor,

he is right in saying that a tune is mostly usless in his situation....but only to his type(carb) of mustang!


a dyno tune is nessisary like every1 else is sayin, to measure hp ratings and a/f ratings
so you know your tune is 100% perfect for your exact setup

93BlackNotch

Carbed cars can still be tuned... The whole thing about a dyno is getting your A/F ratio, they put a probe in your tailpipe that reads the A/F... Dyno's have been around for years, they didn't come out in 96 when Ford started making MOD motors... All of my friends still get their cars Dyno'd to check A/F on motor tunes and nitrous tunes....

Lord Ashram

So you CAN get a tune without a dyno, but it wont be exact, but rather it will be sort of generic, since you dont know the actual horsepower? Do I have that right? And how "off" would a non-dyno tune be? Would it be totally worthless? Or only a few hp off?

Sorry for so many dumb questions; I feel like I know this already, but the argument is fierce

93BlackNotch

You can get tuned without a dyno, but it's a trial and error thing... This guy was running 11.0's, he had a guy come down and start tuning at the track between runs, he ran a 9.80 by the end of the day... The guy had a wideband and data logger so he could tell what the A/F was during the runs through every RPM... This was on a stock block, S-trim, Edelbrock heads, C4 with a trans brake, and suspension work... It's all in the tune...