T56 Gear Ratio question (Coyote engine)

[bishes]

Hello, I'm a week out from delivery of my first FFR kit and struggling to find any discussion of the two different gear ratios available for the T56. I'm getting the IRS with 3.55 rear end (planning on 18in wheels) and I've run through the gear ratio calculators but I guess I don't know how to properly interpret the data. Close ratio vs wide ratio for a 95% street driven car? At the end of the day I don't really care about fuel economy but I do care about driveability.

Unrelated, but has anyone figured out how the Gen 4 engine cover is supposed to fit on the Gen 4X? The mounting points seem to be off, maybe even the same as the gen 3?

[dbo_texas]

I'm also interested in understanding the gear ratios a bit more. I have a Gen2 Coyote + T56 (TUET11010) from Forte and 18" FFR wheels and 3.55 IRS rear end - pretty much same setup as you. I wasn't the original builder so didn't select this setup specifically but Forte knows these cars very well so I'm guessing this is the right setup. Mine has gearing ratios: 2.66, 1.78, 1.30, 1.00, 0.80, 0.63. The other option for the T56 is 2.97, 2.10, 1.46, 1.00, .74, .50.

For the calculators, Tremec has a nice one on their website HERE (https://tremec.com/aftermarket/resources/gear-ratio-calculator/). For my tires, I have the Mickey Thompson 295/35R18 in back which equates to 26.13" diameter (use this in Tremec's calculator). If you punch in the numbers you can see what your speed will be at a specific engine RPM and transmission gear. If you compare the 2.66 vs. 2.97, you will see that with the 2.66 transmission at lower speeds you'll be going a little faster for the same RPM, but when you get to the higher gears, it flips (i.e. for same gear and rpm you would be going slightly faster in the 2.97 model). So in those higher gears, the 2.97 would let the engine run a little slower at the same relative mph as the 2.66 version. So if you will do a lot of highway driving, that may be appealing. It just depends on how you want to drive it and where you would spend most of your time. For me, the 2.66 version I think is better.....let's you stay in 1st gear a little longer, and at freeway speeds (let's say 50mph) I could hit 6th gear around this speed without going much beyond the 1500rpm. I think either version would be a good choice but some of the folks who autocross might have stronger opinions (and are far more knowledgeable than me). I'm sure others will chime in with good opinions.

[bishes]

Thanks for your input, I really appreciate it! Are you happy with the current setup? Do you think you'd prefer the other gear ratios?

[edwardb]

Highly recommend the 1st: 2.66, 2nd: 1.78, 3rd: 1.30, 4th: 1.00, 5th: .80, 6th: .63 version T-56 for your setup. That's what my Coupe with a Gen 3 Coyote has and I'm very happy with it. I have a 3.73 Torsen IRS diff in mine, so the numbers are slightly different. But most with the 3.55 also choose this version T-56.

Only help I can give on the Gen 4X engine cover is I don't think you want a Gen 3 Cover. At least not without modification. The stock Gen4 cover isn't bad looking. I know they're using those on Gen 3's with adapters from Sanders Street Rods. Are you sure it won't fit the Gen 4X? The dual intake on the regular Gen 4 is in front of the cover. There are a number of Gen 4 Coyote builds underway. I suspect others will show what they're using.

[Skuzzy]

I'm also interested in understanding the gear ratios a bit more. I have a Gen2 Coyote + T56 (TUET11010) from Forte and 18" FFR wheels and 3.55 IRS rear end - pretty much same setup as you. I wasn't the original builder so didn't select this setup specifically but Forte knows these cars very well so I'm guessing this is the right setup. Mine has gearing ratios: 2.66, 1.78, 1.30, 1.00, 0.80, 0.63. The other option for the T56 is 2.97, 2.10, 1.46, 1.00, .74, .50.

For the calculators, Tremec has a nice one on their website HERE (https://tremec.com/aftermarket/resources/gear-ratio-calculator/). For my tires, I have the Mickey Thompson 295/35R18 in back which equates to 26.13" diameter (use this in Tremec's calculator). If you punch in the numbers you can see what your speed will be at a specific engine RPM and transmission gear. If you compare the 2.66 vs. 2.97, you will see that with the 2.66 transmission at lower speeds you'll be going a little faster for the same RPM, but when you get to the higher gears, it flips (i.e. for same gear and rpm you would be going slightly faster in the 2.97 model). So in those higher gears, the 2.97 would let the engine run a little slower at the same relative mph as the 2.66 version. So if you will do a lot of highway driving, that may be appealing. It just depends on how you want to drive it and where you would spend most of your time. For me, the 2.66 version I think is better.....let's you stay in 1st gear a little longer, and at freeway speeds (let's say 50mph) I could hit 6th gear around this speed without going much beyond the 1500rpm. I think either version would be a good choice but some of the folks who autocross might have stronger opinions (and are far more knowledgeable than me). I'm sure others will chime in with good opinions.

I ran these graphs for you. Hope that helps. (Sorry about the resolution, but I had to shrink them from 2K resolution in order for them to post, and the text took a beating)
209250209249

[bishes]

Highly recommend the 1st: 2.66, 2nd: 1.78, 3rd: 1.30, 4th: 1.00, 5th: .80, 6th: .63 version T-56 for your setup. That's what my Coupe with a Gen 3 Coyote has and I'm very happy with it. I have a 3.73 Torsen IRS diff in mine, so the numbers are slightly different. But most with the 3.55 also choose this version T-56.

Only help I can give on the Gen 4X engine cover is I don't think you want a Gen 3 Cover. At least not without modification. The stock Gen4 cover isn't bad looking. I know they're using those on Gen 3's with adapters from Sanders Street Rods. Are you sure it won't fit the Gen 4X? The dual intake on the regular Gen 4 is in front of the cover. There are a number of Gen 4 Coyote builds underway. I suspect others will show what they're using.

The cover definitely won't fit. Not only are the mounting points spaced out differently, the intake manifold has 4 standoffs sticking up that also prevent the cover from sitting low enough to even reach the mounting points. That part I can deal with when the time comes but not the spacing difference. I do look forward to seeing how others tackle this.

Once it warms up I'd love to swing by your place sometime and see your coupe, if you're okay with that. From another pilot, I'd also really like to see the plane you're building! I'm down in Belleville, and Todd from Stewart told me that the truck my car is shipping on will have 6 cars all coming to Michigan!

[dbo_texas]

I ran these graphs for you. Hope that helps. (Sorry about the resolution, but I had to shrink them from 2K resolution in order for them to post, and the text took a beating)
209250209249

Skuzzy these graphs are super helpful! Thanks for posting these

[edwardb]

Once it warms up I'd love to swing by your place sometime and see your coupe, if you're okay with that. From another pilot, I'd also really like to see the plane you're building! I'm down in Belleville, and Todd from Stewart told me that the truck my car is shipping on will have 6 cars all coming to Michigan!

You're welcome to come to Lake Orion for show and tell. I enjoy visitors and sharing. I'm retired, so my schedule is relatively flexible. PM when you're ready to propose dates/times. My airplane build may not be in the garage shop by the time the weather changes. Depends very much on how soon the build center in Sandusky, MI takes it for paint and final assembly. Once the wiring and avionics are installed -- should be in the next month or so -- I will be ready when they are. Obviously, also depends on when the weather changes.

[bishes]

You're welcome to come to Lake Orion for show and tell. I enjoy visitors and sharing. I'm retired, so my schedule is relatively flexible. PM when you're ready to propose dates/times. My airplane build may not be in the garage shop by the time the weather changes. Depends very much on how soon the build center in Sandusky, MI takes it for paint and final assembly. Once the wiring and avionics are installed -- should be in the next month or so -- I will be ready when they are. Obviously, also depends on when the weather changes.

I’ll check my schedule and see if I can find some time in the next few weeks.

Regarding the 4X engine cover, I watched a youtube interview of someone at Ford Performance and he says “below the intake” is all Gen 4 so while I’m still a long way away from that point, the 3 to 4 adapters will probably be necessary.

[Randy312]

I went with the first option.. 2.66 first gear. I agonized about this decision because I wanted the car to be a little quieter when cruising on the highway. So I went in a different direction with the IRS gearbox. Forte made me one with a 3.31 gear ratio. Just slightly taller than the standard 3.55. I saw that some mustangs use a 3.27… I figured the car is so light that I will have no problem getting off the mark even with the 3.31. Maybe the car would be a little less twitchy. As someone with no experience with this kind of power I figured that would be a good thing. Anyhow… that will give me lower RPM’s on the highway vs the 3.55. Oh…. This is just theoretical at this point. My car isn’t finished yet. But I’m getting closer!

[Skuzzy]

I went with the first option.. 2.66 first gear. I agonized about this decision because I wanted the car to be a little quieter when cruising on the highway. So I went in a different direction with the IRS gearbox. Forte made me one with a 3.31 gear ratio. Just slightly taller than the standard 3.55. I saw that some mustangs use a 3.27… I figured the car is so light that I will have no problem getting off the mark even with the 3.31. Maybe the car would be a little less twitchy. As someone with no experience with this kind of power I figured that would be a good thing. Anyhow… that will give me lower RPM’s on the highway vs the 3.55. Oh…. This is just theoretical at this point. My car isn’t finished yet. But I’m getting closer!

I went with the 3.31 gear as well and a Torsen anti-lock. While the Mustang does come with a taller gear, it also comes with a automatic first gear of 4.7:1, if I recall. Still, I think you have a valid point about the weight being a factor. I am not going to be racing, as I am too old to get out there now. So I am building a cruiser.