siggyfreud

^^^+1

If you're going to mod the car without tuning it properly, stick to appearance mods.

07BLACKGT

TUNE IT. Bama Tuning offers a fantastic Torque tune for the 4.6, so I'm sure they have it for the 5.0 as well.

Steps of buying a Mustang:

1. Sign papers.
2. Install tune.
3. Drive off lot.

...and I'm sure the 3.15 gears aren't helping things any either. 3.73's + tune and you will accelerate so effortlessly from the light you won't believe it.

Norm Peterson

Assuming decent pipe size and bends, the instantaneous restriction provided by the mufflers may end up governing, and that's going to be some function of the actual instantaneous flow(s). Marks' 7th Edition Handbook mentions 1 psi as costing 2.5%, though that would be for 1 psi all the time instead of briefly once per crank revolution. I think what it boils down to is that unless you're operating up toward where the backpressure spikes are significant (high rpms or relatively restrictive mufflers) the differences aren't going to be very big at all. I know I found some muffler flow ratings at either 25" or 28" of water somewhere back a dozen years or so ago when I was reworking the exhaust on the Malibu, so this information is probably still available one way or another. Perhaps this crude picture of exhaust line flows vs crank angle can be of some use.





Hope you like math and spreadsheets. Here's off the top of my head what's in the simulation I've been playing around with for precisely this sort of question since LBJ was in the White House. It seems to be good enough for comparison purposes that don't include the initial launch.

Acceleration = {[Gearing]x[Torque]x[Efficiency]÷[DriveTireRadius] - [TotalDrag]} / [TotalWeight]

Acceleration ≤ [SomeTractionLimit]÷[TotalWeight]

Torque = torque at rpm consistent with the mean speed of each speed increment and includes a deduction for the torque "lost" to rotational acceleration effects (consistent with the vehicle +X linear acceleration and gear reductions). A good enough basic engine torque curve for purposes of comparison can be fit to just the two normally advertised engine output data points plus a reasonable guess at the torque at 1000 rpm or thereabouts, or you could use a lookup/interpolation of an actual torque curve.

TotalDrag = drag consistent with the mean speed of each speed increment.

Incremental and total times and distances and the differences between different cases become simple bookkeeping exercises and are usually the most useful results.


Feel like you've unretired yet?


Norm

thelastsumurai

Interesting points raised in the last post. Mostly opinion mixed with technical truth. But valid points none the less. I had a 76 mustang 289 that used to come off the line at 5500 rpm and shift at 7500 rpm, not much torque there but I did very well in that class, (can't remember class or et's, yes I'm old 66) at National Dragway in Long Island. I have gotten some good advice and some dumb remarks about tuning. If you think your aftermarket tune won't void your warrantee you are sadly misten, as I was. I have read on several forums that peoples warrantees were voided by tunes.. After all, it is the opinion of the serviceing dealer that matters in these cases. I live in Ocala, FL and Ford of Ocala WILL cancel your warantee if they suspect you have tuned your car. I was having problems with my auto trans and mentioned using a tune to solve the problem and the Service Manager told me my warantee will be voided if I went ahead with it.. By the way a=f/m is the correct formula for acceleration. And yes I do feel a little unretired this has turned out to be a little more complicated than I thought it would be.. Thanks for your help.

Ford_Dude

the Service Manager was using scare tactics however if push comes to shove although legaly they can't void your warranty over a tune (Who has more laywer money?) is the real question.

the place I went to for warranty work was honest and would just say if its a non-oem part that that find caused the issue then that part won't be covered in the warranty

and on that note any thing you do if Ocala is going to use the void tactic then you are just going to have to stay stock unless you have some laywer money looking to be burned or you go to a differant dealer

any mod that lets a signifigant amount more air in at any given RPM will put you in limp-home-mode without a tune, any exhause mod will be of limited help without an intake mod, and gear change will need a reprogram (even if ford does it, it just means they do the re-tune), any change in outside tire size will require a re-tune (same as the gear mods)

under-drive pullies don't require a re-tune but could void your warranty as it might run your A/C slower and cause damage or the power steering slower and cause issues

Norm Peterson

Out of curiosity, and I'm assuming that the problem has been fixed, could there have been a TSB reflash involved?


For years it was just easier to work drive wheel weight % plus rear load transfer in decimal g to test the acceleration limit, so I left it all in 'a/g' format. Now I'm just too old, too lazy, and probably too stubborn to bother changing.


Norm

7gtthrilla

The main thing you need to focus on is weight reduction. Not only will it make your car quicker, it will also help the handling, especially if you lower it if you haven't done so already. Good luck

mapitts

You have wasted your money. You should have gotten a Ranger with the 2.3 w/5m and called it quits. This guy is unbelievable! Have you ever stopped to notice that you seem to be getting more or less the same advice? Yet they are completely wrong and you are correct every time. Believe it or not, many of these people actually know what they are talking about. Listen to what people are telling you about what they know. Holy smoke. You absolutely cannot get from were you are now to were you want to go without a good, quality tune involved somewhere. End of story.

bigblue95z

They can tell you that the sky will turn purple too. But it won't happen. Quit being intimidated. There are LAWS that they must follow that tells them when to honor your warranty. Look at the Moss vs. Magnuson Warranty Act.
http://en.wikipedia.org/wiki/Magnuso...s_Warranty_Act
Ill informed people like yourself are the ones that spread this misconception.
And your warranty is valid at more than one dealship, go to a different one that's not such a d-bag.

Diabolical!

Install some go fast parts without a tune. Report back to us.