Gear/Dyno Expectations
 

Hi all. This is the situation. I've got a manual, convertible 2003 Centennial (same as a GT). I've put Steeda UDPs, Accufab 70 mm Throttle Body and Plenum Combo, Steeda CAI, BBK Shorty Headers, Magnaflow Tru-X X-pipe, Magnaflow Catbacks, 17x10.5 Bullitts with 315s, and an XCal 2 Tune. I have Motive 3.90 Gears sitting in my closet and I'll soon be getting them installed. Here are my questions;

1. Should I spend the extra money to have the car dyno tuned considering all the mods I've made?

2. If I do have it dyno tuned, what kind of numbers can I expect (hp, tq, et)?

3. Does anyone know of a good installer in the Atlanta area, and what is a reasonable price for the install and dyno together (I'm also supplying the install kit and a new bearing kit)?

4. Considering the mods I have, what would be the next practical mod I should make? My top choices are either subframe connectors, or an aluminum drive shaft, but I'm open to anything within a reasonable price.

Thanks for any help!

You shouldn't see any increase in hp/tq after the gear install.

Yeah I know that, I mean from the dyno tune and the mods I already have.

go to modular powerhouse in cartersville. they will not steer you wrong

ok...here are my thoughts. For the mods you have, you are kind of "borderline" when it comes to a decision on a dyno tune or not. I think it is a 50/50 proposition as to if it is worth it or not.

One advantage you will have is that with all your bolt-on intake and exhaust mods, a dyno tune will also correct any idle issues you may be having too.

I would estimate that you are in the 240 to 250 hp range...with an absolute max of 255. The dyno tune will net you anywhere from 0 to about 10 hp depending on how good/bad your current tune is now. For example, if you are getting 240 now, then get a duyno tune, I would expect to see 245 to 250. But, if you are seeing 250 now, you may even loose a little with a dyno tune, but at least the tune will be correct.

Some of your mods may actually be making your car run lean....a bit too lean and thus be making more power then it should.

A dyno tune will prbably cost around $150 for your car with $200 as a max and $100 as an absolute low. You want the tuner to spend time on the car, but your car should be pretty easy to tune for someone who knows stangs.

Now, for the gears, expect 3.90's or 4.10's to cost you some hp on the dyno. In other words, a gear swap will cause you to loose hp on the dyno....about 8 - 9 hp. You don't actually loose hp, it is more a factor as to how the dyno is calibrated etc.... It is not real hp loss.

Gear install should run around $250 if you have all the parts. So, if a shop charges $400 to $500 for both, that is probably a good range. IMO, I think you will be very happy if you did both and the money will feel well spent if you did both together.

Lastly, a lot is made of hp numbers. They are great for bragging rights, but really don't mean squat. Sort of like a kid who lifts weights who claims he can bench 350 lbs, but can't win a fight. HP should be used to monitor improvement, but the best mod is practice. You vert is heavy....so is mine....the gears will really wake it up and get it moving down the road a lot quicker.

+1

WaterDR, thanks for your thoughts, I appreciate it. I'm surprised my hp is probably that low. I mean I've put an easy $7000 into the car, but I guess if I think about it none of them really were great power adders such as cams or heads. Well, when I get the work done, I'll post all the numbers here ( cost, hp, tq ).

Just keep in mind that money does not equal power unless you are doing a power adder or using nitrous. All the mods you have done are small, incremental changes. Don't pay attention to the advertisements.

I am assuming that much of your investment has been spent on "look fast" mods too.

There are probably hundreds of members on this board who would agree with my hp assessment because thare are hundreds of cars just like yours that have been dynoed.

If I understand you correctly, here are your mods. You car came out of the box around 225 rwhp before any mods:

Steeda UDPs - Good for about 5 - 8 hp.
Accufab 70 mm Throttle Body and Plenum Combo - Good for about 8 - 10 hp
Steeda CAI - Probably netted you 0 to 5 hp.
BBK Shorty Headers - 0 - 5 hp.
Magnaflow Tru-X X-pipe - 8 - 10 hp
Magnaflow Catbacks - 0 - 3 hp

So, 20 to 25 is about all you will see.

But, don't panic....those little changes will help the car more when you decide to add a blower, ported heads, or cams. What you have done is started to build a solid platform. The best two mods on the car are the X-pipe followed by the throttle body and plenum.

Just adding a set of cams could get you over 280 hp......closer to 295 if you added long tube headers. The shorties are really not good for much at all.

Ditto all that waterdr'y goodness.

Just always remember, we don't race on dyno's. We race on race tracks. Only track performance is a valid indicator of true performance. Dyno's are just tuning tools. You can strap the car down and punch out 250rwhp one day and come back the very next day and spit out 242 with no changes and the same weather. Come back then next day and it's at 251. This is why we don't get hung up on dyno numbers. If there's a dyno number to get hung up on it's average tq.

That is some of the most useful, real world info that has ever been put a post without someone chiming in with a big turd and splashing all the water out of the toilet. :D

Good one!

Thanks for the help everybody, that sounds like some great advice. So I guess if I do a baseline first and the a/f is fine then there really is no need to further tune it, right? Another thing that I'm confused about is the XCal 2. They say you can update the gear ratio on the hand held device and reflash your computer with the new tune, but I don't see that option anywhere when I scroll through the options on the device. Anyone know about that?