AH64DFlyboy Posted August 17, 2012 Report Share Posted August 17, 2012 So I have been wondering why people are not doing the speed limit. I was on base the other day and driving and noticed every one was doing ten under the speed-limit no problem I go around them and even a cop. They followed me until I got to where I was going. After I got out they said very nice car oh by the way do you know the speed-limit? I said sure its 35. Well he was clocking me doing 45. He didnt give me a ticket and was nice but this has me puzzled. I am trying to figure out if the tune I have doesn't take in the 331 rear end or tire ratio. I called Lethal and they told me the tire rev/ mile is 750. So I did that and still not sure if its right? I found a website and it says 724. What should I do? Can anyone tell me @ 45 MPH in 4th gear what they RPM should read. Link to comment Share on other sites More sharing options...
Snoopy49 Posted August 17, 2012 Report Share Posted August 17, 2012 1800 RPM = 45.1 MPH with a 27.85" dia tire 285-35-20 1400 RPM = 35 MPH with a 27.85" dia tire 285-35-20 724.2 rev/mile 27.85" dia 750 rev/mile = 26.89" dia Link to comment Share on other sites More sharing options...
AH64DFlyboy Posted August 17, 2012 Author Report Share Posted August 17, 2012 Well I am turning just over 2000 rpm @ 40 mph. I am not sure what I need to do to fix this? Link to comment Share on other sites More sharing options...
Snoopy49 Posted August 17, 2012 Report Share Posted August 17, 2012 Maybe this will help. Link to comment Share on other sites More sharing options...
svt13 Posted August 17, 2012 Report Share Posted August 17, 2012 I can go do it tomorrow and see on the actual car what it is and let you know. But I think 45 in 4th is a little under 2k. Because I shift at 2k and I shift to 5th around 45 mph so it should be a little under 2k if not 2k. Link to comment Share on other sites More sharing options...
AH64DFlyboy Posted August 17, 2012 Author Report Share Posted August 17, 2012 Maybe this will help. Thanks that does. Now to get it fixed in my tune Link to comment Share on other sites More sharing options...
R U TRIPIN Posted August 17, 2012 Report Share Posted August 17, 2012 Well I am turning just over 2000 rpm @ 40 mph. I am not sure what I need to do to fix this? do you have an iphone?? if you do go download a gps app and check your speed with it... ive done this before on my super duty cause they dont have a programmer for the 2011 that does 37' and above tires... Link to comment Share on other sites More sharing options...
svt13 Posted August 17, 2012 Report Share Posted August 17, 2012 Alright so I went 45 in 4th today and looked at the RPM. Its literally right inbetween 1750 and 2000 RPM. So thats probably 1850 at 45? Link to comment Share on other sites More sharing options...
AH64DFlyboy Posted August 17, 2012 Author Report Share Posted August 17, 2012 I will try the stock tune again and see. If I go with the defualt values it should be good? shouldnt it? Link to comment Share on other sites More sharing options...
svt13 Posted August 17, 2012 Report Share Posted August 17, 2012 Should be. If its a properly done tune. I'm assuming its Lund. Mail in tunes always make me nervous. I don't think I will everr tune my shelby. A gt or v6 I wouldn't care but definintley not with this car at least till warranty expires. Link to comment Share on other sites More sharing options...
2010KonaBlueGT Posted August 17, 2012 Report Share Posted August 17, 2012 What should I do? Your sig has 6 different cars listed so I'm not sure what year you're talking about. Here's something for you, or not; http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=22362 My FRPP Whipple 2.9L Supercharger kit included a Pro-Cal tuner and which allows me to change parameters for both tire size and gear ratio changes. There is also a aftermarket unit that allows you the same, plus change the RPM rev limit and the Vehicle Speed limiter. I think it sells for 2 or 3 hundred dollars. Phill Link to comment Share on other sites More sharing options...
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