What is a good set up for mostly freeway driving?

[jrohrig]

Still in the planning stage. What is a good setup for a car designed for mostly freeway driving?

My goal with the build:
* Small road trips here and there.
* Drive to work occasionally (45 minutes of highway driving)
* No racing, no dragging
* A streetable, fun, comfortable car

My concerns are road noise and keeping rpms low at 75mph. Fuel economy isnt that* big of a deal as this car is built to be fun. I like the idea of a 351 Windsor with 400hp but realize that I probably don't need that much horsepower. I believe the standard IRS rear end set up from Ford comes with 3.55 gears.
1) Is that the ideal gear ratio for mostly freeway driving?
2) Is it easy to change the gears if needed?
3) Is a 6 speed transmission a better option than a 5?

[David Hodgkins]

IRS (3.55 gears is good), 302 with a .64 final drive transmission with quiet pipes is your best bet.

Very similar to my setup and I'm very happy.

:)

[GoDadGo]

A healthy 302 making only 300-HP will get you down the road with no problems because of the weight of the car or lack of it.
Lots of folks love Modern Power so the Coyote seems to be the ticket for many builds too.
Try to get a ride in a Cobra or two before you decide on what path you want to take.
Should you find yourself near New Orleans, I can arrange a ride for you in several Factory Five Cars that are powered differently.
I can tell you the more power you make with a pushrod V8, the louder your exhaust will be so I have to wear earplugs which sucks.

> 400 SBC / 4-Link / Automatic / 33 HR
> 396 FE / IRS / 5-Speed / MK4
> 393 W / 3-Link / 5-Speed / Daytona
> 383 SBC / 3-Link / 6-Speed / MK-4
> 351 W / 3-Link / 5-Speed / MK4

All of them are Fast As S__t!

[TMartinLVNV]

Still in the planning stage. What is a good setup for a car designed for mostly freeway driving?

My goal with the build:
* Small road trips here and there.
* Drive to work occasionally (45 minutes of highway driving)
* No racing, no dragging
* A streetable, fun, comfortable car

My concerns are road noise and keeping rpms low at 75mph. Fuel economy isnt that* big of a deal as this car is built to be fun. I like the idea of a 351 Windsor with 400hp but realize that I probably don't need that much horsepower. I believe the standard IRS rear end set up from Ford comes with 3.55 gears.
1) Is that the ideal gear ratio for mostly freeway driving?
2) Is it easy to change the gears if needed?
3) Is a 6 speed transmission a better option than a 5?

Whether a 6 speed or a 5 speed, the final ratio is nearly the same in top gear. I believe that one is .67 and one is .64. The 6 speed gives you another step between 4th and top gear. With my TKO 600 and 3.55 gears, I am at a smidge under 2500 rpm at 80 mph. The car just purrs along mile after mile.

For me, one of the best items that makes freeway driving more comfortable is cruise control. Rostera makes a nice unit. It is a bit of work to install, but not terrible.

[Jeff Kleiner]

IRS (3.55 gears is good), 302 with a .64 final drive transmission with quiet pipes is your best bet.

Very similar to my setup and I'm very happy.

:)

OR... Coyote+TKO600 (or the new TKX) with the .64/.68 fifth gear ratio+3.55 rear ratio=smooth, quiet, reliable and will deliver >20MPG while being as easy to live with as a new Mustang---but will sink your eyes into the back of your skull and pucker your rear end when you twist it's tail!

You're welcome ;)

Jeff

[nuhale]

I have coyote + TKO600 and a 3.27 rear. Rides very nice at highway speeds.

[KDubU]

For your reqs and with less cost I would keep it under 400hp. A nice 306 would do you well. I had a 351w that was just over 400hp and it drove very nicely. Did I need that much, no as I never raced it.

[jrohrig]

Whether a 6 speed or a 5 speed, the final ratio is nearly the same in top gear. I believe that one is .67 and one is .64. The 6 speed gives you another step between 4th and top gear. With my TKO 600 and 3.55 gears, I am at a smidge under 2500 rpm at 80 mph. The car just purrs along mile after mile.

For me, one of the best items that makes freeway driving more comfortable is cruise control. Rostera makes a nice unit. It is a bit of work to install, but not terrible.

I will definitely consider the cruise control. Great idea!
Just curious, what would the rpm at 80mph be if running 3.27 gears or less. Also, is that something that is easy to change?

[BradCraig]

OR... Coyote+TKO600 (or the new TKX) with the .64/.68 fifth gear ratio+3.55 rear ratio=smooth, quiet, reliable and will deliver >20MPG while being as easy to live with as a new Mustang---but will sink your eyes into the back of your skull and pucker your rear end when you twist it's tail!

You're welcome ;)

Jeff

100% agree. The TKX is going to make this combo kick ***. I almost want to buy one and sell my TKO.

[Al_C]

TKO with .64 fifth gear and 3.55 rear end results in 2000 rpm for me (assuming my speedo is reasonably close...) At those rpms, the engine is loafing.

Although you didn't ask, I'll contribute this: I'm not a fan of driving my roadster on the highway. I'm of the opinion that most highway drivers aren't paying all that much attention to what they are doing. Consequently, I'm cautious of others on the roads because just about all cars have way more mass than we do. Trucks pay attention for the most part, but they're loud and you get a blast of wind from each one of them. Earplugs help. If I were going to drive on the highway daily, I'd probably install some form of brake light high up on the roll bar. Just my 2 cents.

[GoDadGo]

Just curious, what would the rpm at 80mph be if running 3.27 gears or less. Also, is that something that is easy to change?

3.27 Gears + 25.7" tire (315/35-17)

2,250 RPM .67 O/D = 78.52 MPH

2,250 RPM .64 O/D = 82.20 MPH

Hope this helps!

I'd look hard at the New TKX Transmission because of the better ratios and upgraded design.

https://www.tremec.com/menu.php?m=183

[narly1]

What do you Americans mean exactly when you say "highway"?

Up here in Canada we have 2 lane (1 lane each way) blacktop roads with that designation.

Our 400 series highways are all 4+ lanes which correspond to what I think you would call "Freeways" or "Interstate Highways". Correct?

[MPTech]

If you plan primarily highway/roadtrips, I'd also suggest a soft-top and good ear-plugs (not for the exhaust noise, the wind buffering will keep your ears ringing after a long trip).

I also agree with the Coyote & TKO600 and IRS will sooth out the ride. To be honest, highway driving is kind of miserable in these cars, regardless of what you do to them. Much more fun on windy backroads!

[Rook]

Tremec has a handy tool for calculating speeds based on a given RPM, final drive gear, and tire diameter:

https://www.tremec.com/calculadora.php

[Al_C]

What do you Americans mean exactly when you say "highway"?

Up here in Canada we have 2 lane (1 lane each way) blacktop roads with that designation.

Our 400 series highways are all 4+ lanes which correspond to what I think you would call "Freeways" or "Interstate Highways". Correct?

Great question! I'll take a crack at it as I tend to use that term loosely. In my post above, I was actually referring to "Interstate Highway" or "Expressway". Some people (and I am definitely guilty of this) use highway, interstate, expressway interchangeably. Your point is well taken that people (e.g. me) should be more precise in our choice of words! ;)

[narly1]

Great question! I'll take a crack at it as I tend to use that term loosely. In my post above, I was actually referring to "Interstate Highway" or "Expressway". Some people (and I am definitely guilty of this) use highway, interstate, expressway interchangeably. Your point is well taken that people (e.g. me) should be more precise in our choice of words! ;)

Re being precise, No no not at all!

These cars beg to be run on those serpentine two-lane blacktop gems (even if you have to schlep the multi-lane monsters to get to them, LOL).

https://www.carthrottle.com/post/nk9xe73/

[CraigS]

First, don't forget that 351 idea. They are a great engine. All the internals are one size up compared to a 302 so a bone stock short block is easily good for way over 400hp. The extra cubes also mean that for any given amount of torque or hp, you can get there w/ a slightly milder tune than w/ a 302. Slightly more torque will let you run a taller diff for lower rpm cruising. I don't remember exactly which cars trucks had the last couple years of 351s but find that out, buy one of them, and stick the completely stock engine in your FFR. That would probably be 250-300 hp and run for ever. Then, when you decide more HP would actually be more fun, do a top end kit for 400-425hp. There are several manufacturers who sell them. This is one. The 400hp kit is a great deal.
https://www.edelbrock.com/shop/power-packages-main.html?cat=603&efm=3605&efn=3631&efs=3697
When you look for IRS parts look at ebay for complete rear suspensions and get one that has the oem brakes included. That will save you a bunch and they are actually great brakes. 355, 327 and even 315 diffs will work. The 315s are the least expensive but you can't change the gears themselves if you later want to change ratios. OTOH, these diffs are cheap and readily available so just get another assembly if you want to change ratios. You can do a 6 speed but it is mostly a waste and there are a couple of things that need to be dealt w/ vs a TKO 5 speed, which bolts right in, so I wouldn't bother.

[Mike N]

For what you are looking for, if you have the budget a Coyote with 3.55 gears and a 5 or 6 speed would be perfect. If you decide on a 302(306) or 351 pick a cam with good low speed driveability. In other words don't get hung up too much on peak horsepower numbers look for something that has a nice broad torque curve. Driving on of these cars at low speed through town, in traffic or through parking lots / car shows and having to keep feathering the clutch to stop the engine 'bucking' is a pain. Not to say that you can't run a healthy sounding cam just be careful not to overdo it.

[John Ibele]

Since you listed road noise as your top concern, I'll just be vote #4 for earplugs. You're driving an open top car, so regardless of highway / freeway / engine / sidepipes, you'll be inviting hearing loss without 'em. Having spent too much time playing bass without hearing protection earlier in life and now on the other side of age 55, I can say ... its not fun. I go to enjoy the silence of nature and get accompanied by the screech of tinnitus from both ears :rolleyes:. I'm still building, so I'm trying to get in practice by grabbing hearing protection every time I turn on a power tool ... its habit now. Not trying to be a nanny, just hoping to point in a direction that will make the whole enterprise as enjoyable as possible.

Have a blast sorting through the powerplant choices!

Edit: could be worse. At least it's tinnitus and not a bass solo.

[Jim Wehr]

My mild 306 with GT-40 heads and some upgrades to the factory MAF would suite your needs very well. No issues. Starts every time. More power than you will expect given the overall weight of the car. Will not abuse a T5 transmission. Couldn't be happier.

[Norm B]

As already stated, if you don't go with modern Coyote power, then be careful with your camshaft selection. Pick one that is built to operate in the lower rpm range.
That said, I do my best to avoid multilane major highways. Noise from other traffic is one problem. The other issues are, there are a lot more morons on phones and large transport trucks that are no fun to be around in one of these cars. The real fun starts when those two subsets overlap.

Norm

[davekp]

Since you listed road noise as your top concern, I'll just be vote #4 for earplugs. You're driving an open top car, so regardless of highway / freeway / engine / sidepipes, you'll be inviting hearing loss without 'em. Having spent too much time playing bass without hearing protection earlier in life and now on the other side of age 55, I can say ... its not fun. I go to enjoy the silence of nature and get accompanied by the screech of tinnitus from both ears :rolleyes:. I'm still building, so I'm trying to get in practice by grabbing hearing protection every time I turn on a power tool ... its habit now. Not trying to be a nanny, just hoping to point in a direction that will make the whole enterprise as enjoyable as possible.

Have a blast sorting through the powerplant choices!

Edit: could be worse. At least it's tinnitus and not a bass solo.

Or a drum solo.

[jrohrig]

Thanks for all the advice.

To address something that keeps coming up; I will mostly be driving on the highway cause that's my commute to work. I have a little Mazda for that job now and will still use it most of the time but weather permitting, I will drive the cobra every now and then. My schedule is different that the typical 9-5. I leave for work at 4:30am and miss most of the traffic. I know it will be cold and dark but that's ok. I drive home after work at 8am 3 days later and the traffic goes the other way. My 45 minute drive home has always been a chance for me to catch my breath, decompress after work, and prepare myself to fill the duties of husband and dad, and I can wait to do it in a cobra.

[rich grsc]

You were very clear on your intended use of the car. Not sure why so many are trying to steer you to a higher hp engine (351, coyote) as you said he wouldn't be tracking the car. A 302 or 306 sbf would be perfect for you. Stay with the T-5 transmission, you can't find a smoother shifting transmission. For your needs, I'd look at a 3:31 set of gears for the rear end, that would help get the rpm's slightly lower on the drive to work. The IRS rear suspension is highly recommended.

[Jim1855]

I was pretty comfortable with 3.27 rear, .064 OD TKO-600, 315/35-17. 2,200 RPM at 80 MPH. Did 2 trips MI, CO, MT, MI and 1 MI, CO, MI of mostly expressways with a bunch of 2-lane state highways. 65,000 miles with this combination. Don't need a high HP engine to do this but you might shift more than I had to.
Jim

[Bob Cowan]

A coyote is an excellent choice. Not simply because it makes a butt-load of power. But because it's a modern engine, with excellent engineering. It's easy and comfortable to drive in pretty much all situations. It has a very smooth power band. And it gets excellent gas mileage. Once a year change the oil. Once a decade change the plugs. And that's pretty much it. Turn the key and go.

I would consider a stock 6 speed. That middle 5th gear is great. They are very durable, and shift a lot smoother than a TKO. Might be lighter than a TKO, too.

If you're looking for a used engine, they are all over the place. And relatively inexpensive.

Pay attention to comfort and ergonomics. If your driving position is relatively comfortable, a long drive is a real joy. Comfy high back seat, cushioned steering wheel, heavily padded floor, dead pedal, heat and sound insulation, etc. Small annoyances become big after about an hour or so.

I love my cruise control. Try driving your Mazda to work one morning without using it.

[skullandbones]

Hi jrorhig,

Funny that I find myself in a similar situation and mindset as you but not at the beginning (registered 2013) like you. I still have a 302 soon to have it's third different induction system and I still at the same crossroad deciding what CID, HP, final gear ratio, etc to change to. I have an aftermarket 351 block that will eventually go into the Cobra but not for a while. So my set up is a T5 and 5 link live axle with 3.27 gears. I think my trans final ratio is ~0.69. On the expressway, it is so good. On a surface road, I can idle along at 1K rpms without jerking. The engine/trans/rear is important but I think the fit in the car is as important. I moved my vertical crash bar on the drivers side about 2 inches forward and to the left. That enabled my left foot to relax to normal position. Then I did a 2 inch push out on the left wall of the drivers foot box which I called a "mini mod". That allows my foot to rotate out for a comfortable natural position. Also allows for a perfect position for a dead pedal. Along with moving the drivers seat up and adjustable, removable steering wheel, I fit in it "like a glove. This makes the driving much more comfortable. This took lots of hours but helps personalize the project. I spent some time spacing the pedals optimally for me. As I remember getting the shoulder straps perfectly angled at ~10 degrees made the feel and efficiency better. All these things will improve your comfort. also, I think ear plugs are a necessary safety device to reduce hearing loss. Good luck!

[Big Blocker]

Just my 2¢ here;

My 18 year old MK-II Roadster is set up with a factory stock 302 EFI (315 hp at the crank) and its matching T5 transmission. It's reliable, inexpensive to maintain, easy on tires and brakes, gets 22 MPG out on the interstate at a sustained 80 mph with 3.73 rear gears. Engine mods include a complete GT-40 upper dress (manifolds and heads), a FORD E-303 cam for that little bit of HP boost over bone stock, factory EFI with some mods to eliminate smog equipment. Engine tacks 2600 rpm at 80. My own custom exhaust keeps the pipes [sorta] quiet - there's more road / wind noise than pipe noise at 80 mph. Oil gets changed yearly as I only put approximately 3000 / 4000 miles per year.
Car is garaged during the week unless it was my "daily driver to work" (baring weather conditions here in Vegas).

Car is a dream to drive long distances due to numerous "mods for comfort" as opposed to HP gains, MK-IV seats are the most noticeable upgrade for comfort, along with extended foot boxes and sound deadening and foot box fresh air vents.

HTH

Doc

[Vspeeds]

Jrohrig
My goals were the same as yours. And I drive my car alot. I put over 11000 miles on it in 2020. All those miles were driven with a big smile on my face. I have a 351W producing over 500HP. It does have a mild cam so its very driveable. I have a TKO600 with the .64 ratio. Also the solid rear axle with 3.55 and 15” wheels. Cant remember the tire size. Freeway cruising is at about 72mph and the engine runs happily in 5th gear. (Tremek has a calculator on their website for gear ratios). If you really want an easy drivable car, i recommend using a hydraulic throwout bearing and a dual disc clutch. My 500hp car has a clutch pedal that feels like my old honda civics clutch. No problems driving in the San Francisco hills and bay area traffic.

[Vspeeds]

With your work schedule you sound like a Jakee?

[jrohrig]

With your work schedule you sound like a Jakee?

Haven't heard that term since I visited the east coast a few years back. ;)

[GoDadGo]

I had a chance to ride in this car when it was sold to a fellow that lives in my home town.
I'm posting this link because Mike Everson (A Professional Builder) built this car so it was a real treat for me to see since I'm a 1st time builder.

https://thefactoryfiveforum.com/showthread.php?27437-Mark-4-Roadster-for-sale&highlight=slidell

The 331 produced a spirited drive and the car drove well and was quite quick yet well mannered, unlike my car which is far more radical.
The exhaust note wasn't bad either because it was a more streetable engine combination with 50 fewer cubes than my Mighty Mouse 383 SBC.

https://www.factoryfive.com/whats-new/customer-steve-l-graduates-his-mk4-roadster/

I liked the 331 because it gives you a few more cubes over the 302, and has better rod angles than a 347 which is actually an excellent option too.
Just know that you don't need 450-500 horsepower for cruising around unless you like buying rear tires.

[jrohrig]

Haven't quite decided on an engine, but I'm pretty sure its going to be a pushrod. I like everything about the Coyote except what it looks like when you pop the hood, and I can't get over that. haha :D Will probably have an EFI sniper or something to keep the look. My kitchen shares a wall with my garage so to be nice to the wife, I'm going to stay away from a carb. Haven't decided on horsepower either but I don't want to regret not having enough of it. We shall see.

Reading these comments has really helped me out. As lame as I sound saying this, I never considered the wind noise to be greater than the engine/exhaust noise while on the highway. I guess the RPMs being low while cruising isn't "that" big of a deal

[GoDadGo]

Reading these comments has really helped me out. As lame as I sound saying this, I never considered the wind noise to be greater than the engine/exhaust noise while on the highway. I guess the RPMs being low while cruising isn't "that" big of a deal

My engine is so darn loud that I don't find the wind noise to be an issue.
I do have a big container of Home Depot Orange Ear Plugs on hand which really helps.
Just remember the Horsepower to Weight Ratio really comes in to play with these cars quicker than you think.

Good Luck!

[Norm B]

I have a 331 with a mildly aggressive cam (1500 to 6500 rpm operating range) and the FFR stainless steel side pipes the I have modified for noise reduction. You can hardly hear the exhaust in cruise. The wind and tire noise from large vehicles is far higher. That said, most of the time we can carry on a conversation without shouting. Wind noise is greatly reduced with proper use of wind wings and sun visors. Plan on completing my headrests this winter. I believe they will reduce the buffeting a bit. Ear plugs are used to further reduce the fatigue of driving long distance.

HTH

Norm

[Hoooper]

Something with fuel injection would make a cruiser a bit nicer, but in southern CA not as nice of a benefit as it could be in areas with a bit more variable weather. If you were planning to do a lot of drives into the mountains that are right near you, fuel injection starts to be pretty nice since it automatically adapts to the significant air difference between your 100F sea level air and the 65F 6,000 FT air that is basically right in your backyard.

For cruise control, something that uses a drive by wire throttle body sure makes setting up cruise control nice and clean. No vacuum actuators or any of that nonsense.

A 6 speed can be nicer on the freeway, but also nicer all around if you are comparing a T56 magnum/TR6060 to a TKO600. The T56 is just a better all around transmission. It shifts better as standard which would be the benefit for your use, and the lower 6th gear will drop your highway RPM by a few hundred at 80 if you opt for the wide ratio 6 speed (0.50 6th gear). It also weighs more, but for some reason costs the same new. There is also the new TKX transmission which is supposed to be just as good shifting as a T56 mag, so the only difference for you at that point would be weight and the final drive.

[CFranks]

Hey, if you want me to take a xxx in a box and mark it guaranteed, I will. I got spare time. But for now, for your customer's sake, for your daughter's sake, ya might wanna think about 3.27/3.31 gears in the rear to keep the RPM down at HW speeds.

(I assume the OP will understand this based on his Avatar!)

[jrohrig]

Hey, if you want me to take a xxx in a box and mark it guaranteed, I will. I got spare time. But for now, for your customer's sake, for your daughter's sake, ya might wanna think about 3.27/3.31 gears in the rear to keep the RPM down at HW speeds.

(I assume the OP will understand this based on his Avatar!)

This post wins. :D Well done Sir

[jrohrig]

Anyone have any experience with the T56 running a .50 6th gear?

[CraigS]

I can't imagine that. Can you run at 80mph on your commute? Getting the rpms lower on the highway has a limit below which they may be too low. For the relatively mild 351 and 408s I have had, I'd say the minimum would be 1800. Both engines would run at 1300 w/o any bucking which was nice around town in 3rd and 4th, but 1300 in 5th would need a shift to 4th on any slight rise. Of course you can drive it 90% of the time in 5th and simply not shift into 6th.

[NiceGuyEddie]

Good tires such as Nitto NT-05 make a tremendous difference in road noise at highway speed. (I used to have crummy tires.)

Windwings and visors are a must to keep down wind noise. You'll sit a bit lower in racing seats or big & tall roadster seats and that helps with the noise in your ears. Racing seats not as comfortable, of course.

I work in Montclair and I should swing by Rancho after work some time and take you on the 210. I have 3.55 gears, good tires, .68 overdrive on a T5 transmission. I also have really, really, REALLY loud sidepipes so it will be worst case drive.

The car is "exceptionally quiet" at 70mph @ 1,200 rpm. You can actually have a conversation. The wind noise practically doubles at 80mph.

What CraigS said: 80mph is the "middle lane" in SoCal under covid... even moms in minvans do 80 on a clear day.

[cobrajj]

Eddie, are you sure that 70mph @ 1,200 rpm is correct? I have the same drive train setup w/ 17" wheels--70mph @ 2,200 rpm. Jim

[jrohrig]

Good tires such as Nitto NT-05 make a tremendous difference in road noise at highway speed. (I used to have crummy tires.)

Windwings and visors are a must to keep down wind noise. You'll sit a bit lower in racing seats or big & tall roadster seats and that helps with the noise in your ears. Racing seats not as comfortable, of course.

I work in Montclair and I should swing by Rancho after work some time and take you on the 210. I have 3.55 gears, good tires, .68 overdrive on a T5 transmission. I also have really, really, REALLY loud sidepipes so it will be worst case drive.

The car is "exceptionally quiet" at 70mph @ 1,200 rpm. You can actually have a conversation. The wind noise practically doubles at 80mph.

What CraigS said: 80mph is the "middle lane" in SoCal under covid... even moms in minvans do 80 on a clear day.

That would be great! and I can always make the drive down to the LBCeeeee area if that's easier. I appreciate the offer.

[NiceGuyEddie]

140719
140720

cobrajj: I was a little off.

1600 rpm = 62 mph
2200 rpm = 90 mph

I am positive the speedo is correct, could the tach be off? I dearly hope not!


jrohig: The Cobra is kept in Chino, I work in Montclair. We can work something out, we'd be outside wearing masks so let me know if you are OK with a quick drive. If it matters, it'll be a while before it's light out after work, so send me a P/M and we can schedule something. I need an excuse to take the car out.

[jrohrig]

140719
140720

cobrajj: I was a little off.

1600 rpm = 62 mph
2200 rpm = 90 mph

I am positive the speedo is correct, could the tach be off? I dearly hope not!


jrohig: The Cobra is kept in Chino, I work in Montclair. We can work something out, we'd be outside wearing masks so let me know if you are OK with a quick drive. If it matters, it'll be a while before it's light out after work, so send me a P/M and we can schedule something. I need an excuse to take the car out.

NiceGuyEddie, I send you a PM. I would appreciate a ride! I think getting out in one would help me with the decisions I have to make.