Ok so heres the latest...had the car rechecked with the tuner I took it to one of the guys who drags 2 of his own vehicals (95 cobra and a dakota truck) he has a dyno machine that the car goes on and this neet lookin devicce that sits in the car while testing(anybody know what the hell that thing was) he changed my air/fuel mix and the shift points through the rpm range he also up'd my rpm limiter and suggest that I started using at least 91 octane so I drained tank and filled with 91 and took the wife for a cruise finished 1/2 tank and filled it with Sunoco 94 for ***** not even sure if that matters but holy what a ride scared the outta myself a couple times lol I'm still lookin at changing the gears but not sur if i wanna go as high as 4:10 is there some thing between 3:55 and 4:10's for the mustang????? later!

 

Glad you got it straightened out.

You can get 3.73's for your car if you feel 4.10's will be too much.

 

That's great he was able to adjust the tune for you. With the results you got it obviously was the problem. It's also good he adjusted the air/fuel. That way you know it will be running safe. (depending what he adjusted it to. I'd suggest not any leaner than 13.0 with 12.5 usually being the best for n/a)

If he tuned it for 91 octane you don't need to spend the extra cash on 94. Just make sure you DO NOT go lower than 91.

If you have 3:55's going to 3:73's would not be worth the money for the slight difference. 3:93's would be good BUT people tend to have problems with gear whine. Trust us you'll love 4:10's. I still get 25mpg highway. The fun factor is more than worth any downside.

 

ok for the 91 octane what happens if you run lower one of the guys at work said i just lose the hp gains from the tuner ..not true???...something more damaging??? as for the 3:93's could you explain the "gear whine" comment im not sure what this means. with the 4:10's Ive been told at cruzin speed I'll be hovering around 3500rpm@100kmph(60mph) is this what you are at getting the 25mpg?

 

You won't necessarily damage anything but there is definently a higher risk of it. As far as I know it all has to do with the a/f, timing, and combustion of the fuel. A lower octane fuel doesn't combust the same which can cause problems.

As far as the gears the "whine" is an audible sound the gears make, that you can hear in the car. It can sometimes be fairly loud. Here's a clip where you can here it. s197 gear whine on Yahoo! Video

No not even close to that high rpm. I think it's somewhere around 2700 at 60mph in 5th. At 120kmph is where I'm getting 25mpg around 3000 rpm.

 

Glad to see it's all been figured out!That's awesome!
Since we both share the same trans ,the 3650.....you will be around 2500/2600 rpm in 5th with 4.10's.I wouldn't even waste my money on 3.73's,not really a big jump from your 3.55's,you wouldn't even notice the diffrence really.4.10's are fine.It's the only way to go with the modular powered cars.It would be equal to a 5.0L with 3.73's.
A lot of modular guys fear the gear,people with modular powered stangs need to unlearn what they had learned with the old pushrod cars.Erase the info from there minds.Push rod engines make loads of torque down low,so going to big of a gear in a pushrod vehicle will rev out way quick,the modular engine is the opposite,they are a pig down low,but lots of room up top.So to gain the torque down low,the modular needs gear to keep up with the pushrod boys!

 

Ok so can anybody give me some feedback on what 4:10's there using I dont care if there just your fav's or if your using them now I'll research them all just need some start point ..hey guys thanks for all the info all was a really big help!

 

Go with ford racing. They are reliable and if installed properly won't have any whine.

 

Go with Ford Racing's 4.10's!

 

actually the stock 235/55/17 are 27.17" in diam. the 255/50/17 are 27.07" so there wider but smaller over all...I think what I'm saying makes since I knew if i went larger ya it would have effect but i stayed with in .52% in size change and smaller to boot.