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Gryphon Programmer Edge Product has discontinued the Edge Evolution 2, but we still provide support and tuning for it. If you have a question or comment relating the Gryphon (or Evolution) programmer, post it here. |
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#1
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Tire Size
Should the tire size be set at actual size according to the chart or allow for a "squish" factor. I currently have the stock 255/70/17 tires inflated to 37#.
I have the tuner set with a 3% squish factor that I have read about in some threads on FTE. Was wanting to make sure the setting is correct to get accurate benefit from the tunes. Thanks.
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2005 F150 XLT SuperCab 5.4L V8 4x4, 3.73 LS Rear end, Auto Spring 2" Leveling Kit, Gryphon tuner custom 87 Performance tune, AEM Panel Air filter with modified stock intake, 14" Magnaflow muffler |
#2
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Whatever value you try, it's a "starting point". The way I first calibrated mine was on a trip to California on the interstate. Over a distance of 100 miles (using highway markers - which are quite accurate) I found I had less than 0.1 miles error on the odometer. Later, using a hiking GPS with WAAS, I found the Gryphon's and GPS' speed matched (while the dashboard speedo read 2MPH faster - it always will read fast). My guess is, you MAY have to increase your "squish" factor more for the tires and pressure you use. Let's say you tried the "distance" test like I did and found your odometer read 101 miles after 100 actual miles. That would be a 1% error, so, you could subtract an additional 1% from your tire's circumference. Hope this makes at least a little bit of sense! - Jack
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2014 F150 Platinum SCrew 3.5L EcoBoost 4x4 with SCT programmer |
#3
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Maybe this is something you and Bluejay Thought about!!!! Also how much does tire size play in shift points. I run my stock tires all the time I can, but I have a second set of tires for off roading and hunting.... Such other things. I used to switch them out for a weekend here and there.... But with money being tight lately I have been running them as they are the only set that has a any good tread for winter driving in Montana. Anyways my stock tires are 265/70-17's and I’m running 285/75-16's. There about 2 inches bigger on diameter. Would it make a big difference. I told bill to write my tunes for 265/70-17's. Can I still mess with the tires size on my custom tunes when I get them for the times I will be running my Mudder's??? Thanks Jack!
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SUPERcrew AF1, EDGE, and EFANS with Magnaflow Exhast SISO. Expy Console and Rear Seat Swap! Eagle 16's with 285-75/16 ST's Gryphon Tuner soon to have custom tunes by PHP! |
#4
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Adjusting your tire size in the Custom Options menu on the Gryphon has two (three?) benefits. First, if you enter the right value, (and your gear setting is also right) your speedometer and odometer will be correct (that's two). And, since normal shifting is partly dependent on speed, your normal shift points will be correct (that's three!). With odometer values right, you'll know what your real gas mileage is, if you calculate it the old-fashioned way at fill up.
Since tires are compressed by the weight of the vehicle, the distance they roll in one revolution is somewhat less than their unloaded circumference. Bill has thoughtfully provided a tire size calculator in Pegasus. It's under Calculators->Gear Ratio Calculator. Simply enter your tire size in the first box like this: 285/75-16 and right away you'll see the rolling circumference (the value you enter in "Tire Size" in the Custom Options in the "Old Circumference" window assuming a 5% squish (which is a good starting point). For your tires, I get a value of 2551 mm. 5% seems a good starting point, but you can go down to the "Squish" window and change that value too to see it's effect with different numbers. I've found my tires have closer to a 7% squish, using the calculator. What's the effect of not including squish? Oh, maybe 3-4% error in speed, distance and shift points. Not really much in the great scheme of things, but still.... If it were me, I'd adjust the tire size anytime I changed tires. - Jack |
#5
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SUPERcrew AF1, EDGE, and EFANS with Magnaflow Exhast SISO. Expy Console and Rear Seat Swap! Eagle 16's with 285-75/16 ST's Gryphon Tuner soon to have custom tunes by PHP! |
#6
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- Jack |
#7
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So you're saying that the squish factor isn't really related to the amount of road kill you encounter while driving .......yuk yuk yuk !
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#8
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- Jack |
#9
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Well....I don't know about this technolgy stuff...I am suppose to have my new programmer delivered on Monday, but now I am getting a little scared about installing the dadgum thing....all these postings about trouble with starting...camshaft settings ...running too lean on canned tunes with CAI (my customs most likely are gonna take another 2-3 months), battery needing a external charge if the thing stays plugged in....tire size....tire pressure (don't know, the darn things are filled with nitrogen is all I know) ...squishin $hit.....tweekin this.....torquein that!.....geez.....hell I have to type all this stuff with two fingers as it is !.....only mechanics I do is hand me a BFH and stand back, anymore! Looks like ole Bill may just get a call before I start connecting anything....I havn't talk to anyone on the phone at PHP as of yet.....reminds me of when I was just teenager.....DAZED and Confused ....oh well! Story of my life I guess
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#10
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If you need to chat, let me know when it would be a good time to call! We're here for ya!
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~ Corey Resting in Peace - 1969 - 2019 |
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