What Motor / Tranny / Rearend Gear are you running?

[Mslone]

Hello,

Still in the Planning Phase and I know Drivetrain is a decision you need to make early!

I'm torn between Old School Carburated vs. New Coyote Technology. I like the fact I can actually work on the Older engines, but also realize if you go with a Coyote... you probubly will not need to work on it... Plus I'm kinda intimedated byt the new Coyote technology and install, Computer... Wiriing...etc

Anyway just wanted to hear what Engine and HP / Tranny / Rearend Gear you choose and why. I would like as light as these cars are anything more than 400HP would be useless for the street.

I have always like the torque of a lower gear like 3.73 but imagine 3.55 is a great gear for this set up.

Budget is a consideration, So as of right now I guess I'm leaning towards a 351 with 415 HP Tremectranny with 3.55

Maybe something like this: http://www.fordcobraengines.com/engine/351w-cobra-kit-5-speed-tranny/ I'm sure better deals are out there for a similar combo...

Lets hear what you have found is a great combo?

Thanks, Michael

[edwardb]

Lots of variables. One of the big ones is how you intend to run the car. Street cruising only could be very different than for auto-x or track. You won't find "400HP" and "useless" used in the same sentence around here very often. 400HP is a nice number, and will go like crazy. But many are very happy to run more and doubt would call it useless. But with 400HP, likely you don't want or need 3.73 final drive. You will run out of 1st gear almost immediately. 3.55 is the most common from what I've seen (what I have in my 350-375HP Mk3) and when getting into higher HP's, many go to a 3.27. That's what I have in my 450+ HP MK4 build. But haven't driven it yet. Also, for the Tremec, you have choices for the 5th gear that also factor in. Some choose the .64 full overdrive. You can also look at the .82 model. It does give a somewhat higher RPM at highway cruise, but does make 5th more available for other than just highway cruising. Suggest you may want to use a calculator to look at the various combinations. I like this one: http://www.tremec.com/calculadora.php

[Gumball]

Old-school carb'd 347 in the range of 400hp/400tq with a refreshed SVT T5 out of a '94 SVT Mustang and 3.27 gears.

[lilnuke]

I currently have a 351/400 with a Tremec 3550 and 3.73. gears. First gear is nearly useless but there is a lot of torque available. Will most likely change to 3.55 or 3.27 in the future after I have a little more drive time.

Previous FFR had a 306 with a T5 and 3.55. That combo worked very well but was lacking in HP.

[Avalanche325]

347 carbed. approx 500HP (at flywheel). TKO-600. 3.31 gears.

[Mslone]

Sorry I was'nt saying 400HP plus is usless, in Street use the power to weight Ratio just seems like 500 HP would not be worth the $$ and would be hard to utilize with Street tires... I have a new Z06 Corvette with 505HP and its hard to keep that power on the ground with a ton of Technology behind it ( Traction contral...etc ) and these Cobra cars have none... Thats all I was saying. Trust me I love Big HP! I just sold a 69 Yenko Camaro Clone that had a BBC with 520 HP / 4 Speed and it was too much to really use... but sure was fun! plus it weiged 1000lbs more than these Cobras... The real question I'm asking I guess is what have people found to be the sweet spot for street use!

just planning to build this Cobra as Street cruiser to take to the shows and jump on it on the weekends occasionally... proubably never take to the track unless as a complete random event... I'm thinking I'll go with classic look - 15 wheels. Just think they look killer!

Here is the build I was thinking of replicating:

26228


Thanks for the feedback and info!


Lots of variables. One of the big ones is how you intend to run the car. Street cruising only could be very different than for auto-x or track. You won't find "400HP" and "useless" used in the same sentence around here very often. 400HP is a nice number, and will go like crazy. But many are very happy to run more and doubt would call it useless. But with 400HP, likely you don't want or need 3.73 final drive. You will run out of 1st gear almost immediately. 3.55 is the most common from what I've seen (what I have in my 350-375HP Mk3) and when getting into higher HP's, many go to a 3.27. That's what I have in my 450+ HP MK4 build. But haven't driven it yet. Also, for the Tremec, you have choices for the 5th gear that also factor in. Some choose the .64 full overdrive. You can also look at the .82 model. It does give a somewhat higher RPM at highway cruise, but does make 5th more available for other than just highway cruising. Suggest you may want to use a calculator to look at the various combinations. I like this one: http://www.tremec.com/calculadora.php

[ClemsonS197]

5.0L Coyote / Tremec 3650 / 3.55

Should make ~400rwhp after a dyno tune.

[montyals]

302 carbureted engine
T5 Tranny
3.55 geared rear end

[edwardb]

Sorry I was'nt saying 400HP plus is usless, in Street use the power to weight Ratio just seems like 500 HP would not be worth the $$ and would be hard to utilize with Street tires...

Just pulling your chain because so many HP discussions turn into mine is bigger than yours debates. :D Sorry if it didn't come out that way. It's all good.

[Blue MK3]

347 stroker, QFT 650 carb, 455 fwhp, 435 tq, T5 w/.82 5th gear, 3.73 rear. This setup came with the completed car I bought. If I had my druthers, I'd drop back to a 3.54 or 3.27 rear. I use the car for street driving only and think the higher rear ratio would result in more relaxed highway cruising. That said, these ratios do keep the engine in the power band for instant acceleration, even at the expense of (probably) poorer gas mileage.

[skullandbones]

302 with T5 and 3.27. Don't have the HP necessary to justify the 3.27 but I think a 3.55 will change that. The 3.55 will make all the gear ratios more useful.

WEK.

[Mustang Man]

427ci Windsor stroker with a TKO-600 five speed (street overdrive, not the road race overdrive) and 3.27 gears. The gears make OD hard to use at city street driving (frankly I don't like the sound of the side pipes lugging it in 5th, so I stay in 4th around town). Get on the highway and you can cruise nice with those gears.

It makes 500hp and is very streetable with the gears I run and EFI and a gentle right foot!

HTH...
Mark

[JL1958]

302, T5, 3.55.
She's a cruiser, car show, Sunny day driver. I occasionally take her to work or to run errands just for fun.

[carlewms]

347 Stroker with EZ EFI 2.0 Throttle body Fuel injection matted to Super Alloy T5 with a 3.27 rear end. Not run yet!

Carl

[Plebeian]

Way back when I had 418 rwhp (near 500 fwhp), I had 3.08 gears with a Gforce 5 spd and it was a real nice driver with no wheel spin in 1st if I rolled into full throttle (not stomping on it). It's all in the set-up.

[PaulW]

385hp 302, T-5 and 3:08 gears. Nice around town and a great highway car.

[mike w]

Sorry I was'nt saying 400HP plus is usless, in Street use the power to weight Ratio just seems like 500 HP would not be worth the $$ and would be hard to utilize with Street tires... I have a new Z06 Corvette with 505HP and its hard to keep that power on the ground with a ton of Technology behind it ( Traction contral...etc ) and these Cobra cars have none... Thats all I was saying. Trust me I love Big HP! I just sold a 69 Yenko Camaro Clone that had a BBC with 520 HP / 4 Speed and it was too much to really use... but sure was fun! plus it weiged 1000lbs more than these Cobras... The real question I'm asking I guess is what have people found to be the sweet spot for street use!

just planning to build this Cobra as Street cruiser to take to the shows and jump on it on the weekends occasionally... proubably never take to the track unless as a complete random event... I'm thinking I'll go with classic look - 15 wheels. Just think they look killer!

Here is the build I was thinking of replicating:

26228


Thanks for the feedback and info!

I'm running a 351W with 420HP, T-5 Trans and 3:08 gears. I have enough torque to use the 3:08's and you can have fun winding out 1st gear. I think 3:27 might be a little better makeing 5th gear a little more usable.

26233

[Bob Cowan]

Hello,
Budget is a consideration, So as of right now I guess I'm leaning towards a 351 with 415 HP Tremectranny with 3.55



I think this is just about the perfect combination.

The 351W is "Old School" (I hate that term). Been around forever, parts are easy to find, simple to build and repair in the average shade tree mechanics garage. Makes excellent torque down low if you build it right. Plenty of room for upgrades if you want more power later (and you probably will). Relatively inexpensive for a quality product.

Plan on using EFI. It's more expensive and complicated than a carb, but so much easier to live with in the long run. I'll never go back to a carb. You'll get the same amount of power with EFI, but better efficiency.

The Tremec TKO is an excellent transmission. It's a little bit bigger and heavier than a T5. But the price is reasonable and you won't be able to kill it if you try. I would choose the 500. You won't be making enough power in such a light weight car to risk damage. The 500 has a lower 1st gear and a slightly wider spread; I like that in a street car. You have 2 choices in OD gears. The .62 is the common "street" gear. And that works really well if you commonly cruise at 75'ish mph. If you generally cruise around 55-60mph, consider getting the road racing gear, which I think is .82.

There is no such thing as the perfect rear end gear. Unless the car is dedicated to one single limited task - like drag racing - everything is a compromise. For a street car, I think the 3.55 is perfect with the above mentioned engine and trans.

I occasionally think of changing my rear gear ratio, knowing that I can get more speed on the front stretch with something like a 3.27 or 3.08. But the gearing is so good for the street I'm afraid to change it.

But, that's just my opinion. I could be wrong. ;)

[Mslone]

Good stuff guys!

Bob Cowan, some Very good points!

Thanks much!

[cgundermann]

450 horse/347 stroker which is EFI; 3:55 gears in a G-Force T-5...

[Ray]

Carb'ed 302 (warmed but not a race motor) world class T-5 with 3:55's in the live axle.

Here is a good site with lots of gearing/tire/etc. information....http://www.wallaceracing.com/Calculators.htm

Ray

[OVCobra]

347 stroker with AFR 185 heads & 650 Quickfuel DP, World Class T5 and 3.73 in 8.8 live axle.

Dave

[Hans944]

My car has a 5.0 /302 Ford Racing crate motor (340 HP), T5 Transmission, Currie 8.8 Rear end with 3.73 gears... I'm like Mustang Man, I like driving around town in 4th gear and use 5th gear on the highway due to being a taller OD type of gear...

This car is a street cruiser and is reliable... so far anyway... May go to the track sometime in the future...

[pyronuc]

You provided a link to Engine Factory's website, I just got done buying an engine from them and I would have to recommend them. It may cost you a little more, but they seem to know what they're doing building engines, know what parts work well together, and they take the time to talk with you about your plans to make sure they get you set up with just what you need. They are pretty easy to get hold of, either by phone or email, and take the time to answer your questions, so top-notch customer service in my book. Not to say that you won't get the same service from anyone else, just saying that in my experience, Engine Factory guys are good to deal with. They took tons of pictures of my engine build from short-block on up to complete and running on the test stand. You can see the pictures in a thread I posted the other day: http://thefactoryfiveforum.com/showthread.php?13344-My-Cobra-now-has-an-engine!!-%28tons-of-pictures%29 They do a great job of labeling everything for you to make installation a snap, and even send you a DVD video of your engine running on the stand, and they do a complete walk-through of everything on the video. Not to try to steer you away from anyone else, or say anyone else won't provide you the same service, just wanted to let you know that my experience with Engine Factory was good (so far). I have not installed or run mine yet (I just got it last week) so who knows what surprises I might discover, but I feel pretty good about the quality of the engine build.

As far as my setup goes: I bought the Moser Engineering axle they make for the Factory Five 3-link suspension, which has the 3-link bracket welded to the axle. The differential case seems to be refurbished, but the tubes and flanges and mounting points, etc. appear to be brand new, with quality welds. When I ordered the axle from Moser, it was only available with 3.31 gears in the rear, which seemed like a nice compromise for me. I am getting a TKO-600 transmission with the 0.62 overdrive 5th gear. By my calculations given rear tire size, rear axle ratio, and transmission gearing, that will put me right at about 1900 rpm or so at 70 mph, and 5th gear should be useable down to about 50 mph (although that's getting it down to the low 1,000 rpm range and out of the bottom of the power band). The engine that Engine Factory built for me is a 347 stroker, Edelbrock heads and air-gap intake manifold, Holley 650cfm Ultra Double Pumper carburetor, MSD billet distributor, March polished billet underdrive pulley set, etc. Engine Factory recommended a transmission dealer to me to get my transmission from. They said they could sell me the complete engine/transmission package, but they said I'd be paying more for markup on the transmission if they sold it to me. So, just a thought, you can do what I did and buy an engine/clutch package. They set me up with a fully aligned clutch, bellhousing, starter, etc. so my engine is ready to slide a TKO-600 transmission right into the back and bolt it on up ready to go.

If you give Engine Factory a call and talk to them for a bit, they can get you setup with whatever will work best for you. You're not really locked into the engines they list on the website, think of those as just examples to start from. They'll do a whole custom setup that meets your needs.

Your ideal setup will probably be different than mine. But the 347 stroker I bought is supposed to be good for 425hp/425tq, or something close to that. With the gearing in the TKO-600, and with the 3.31 gears I have out back, I think it will be a good balance for me. The hp/tq of the motor will allow me to run taller 3.31 gears and still pull strongly, first gear shouldn't be too-too quick, and cruising at highway speeds I should be at a comfortable 1800-2000 rpm. My car will be used for cruising around town, some "spirited" driving (can't condone street racing, of course), and some highway cruising. My car will be set up to be a balance between a good-looking "show" car, a quick and strong sporty car, and a bit of a highway cruiser. That's the balance I'm going for. You may need something entirely different. And I chose to go carbureted just because I like the "old-school" carbureted motors, and wanted to keep it kind of classic. You may be better suited to fuel injection, or you may figure out a carburetor would work well for you, too.

If you give Engine Factory a call (or any of the other reputable builders, for that matter), they can talk with you to figure out what would work best for you.

[chopthebass]

I have just ordered my kit based on a 351W based 427CI and TKO-600. MSD Atomic EFI

I see there are calculators around for working out gearing, but I'm not sure what MPH you should aim for in, say, 4th gear. My engine builder has found me a suitable rear end that he is rebuilding for me and he said the existing gears are 3.55. He said these are perfect for the tranny ratios. I am going to take his word for it as I don't know what effect going to 3.27 or 3.73 will make!

[edwardb]

I have just ordered my kit based on a 351W based 427CI and TKO-600. MSD Atomic EFI

I see there are calculators around for working out gearing, but I'm not sure what MPH you should aim for in, say, 4th gear. My engine builder has found me a suitable rear end that he is rebuilding for me and he said the existing gears are 3.55. He said these are perfect for the tranny ratios. I am going to take his word for it as I don't know what effect going to 3.27 or 3.73 will make!

Probably the more experienced members of the forum will disagree with this -- but I wouldn't get too worried about 4th gear. At least not as a high priority. The two really important data points to look at are 1st and 5th in my opinion. 1st because with a lot of power and a lower diff ratio (3.73 and to a lessor extent 3.55) you will run out of first gear very quickly. My 350-375HP Mk3 with 3.55 rear gears and a T5z jumps off the line great. But you need to watch the wheel spin and usually need to change to 2nd very quickly. It's not enough engine to perform how I would want at 3.27/3.31, so it's about right. 3.73 would be much worse. I'm surprised, to be honest, how people have responded citing 3.73 gearing. For 5th gear, look at the RPM's at 70mph, and decide how suitable it is for your engine. Some high performance engines don't like too low of RPM's. On the other hand, too high RPM just increases noise and reduces mileage. Also realize that if you go for the low RPM's at 70, 5th gear will basically only be a highway gear, with a pretty big change between 4th and 5th.

These are the reasons I suggested (post #2) using a calculator. It doesn't replace seat of the pants actual driving experience. But it sure helps to see factually what the different combinations produce.

[pyronuc]

I'm no "expert" myself, but it would seem like 3.55 would probably be alright, especially with a 0.64 5th gear ratio, although a little too high revving for my taste. Assuming the same size tires, that should still be a decent engine RPM for 70mph (based off of my 3.31 w/ 0.64 5th gear calculated to be around 1900 rpm at 70mph). First gear might be a little quick, though, but probably not terrible. If it was me, and I was going with a 427ci motor, I'd personally go with a little bit taller axle ratio to keep the rpms a little lower, but I'm not racing mine -- different strokes and all that. It just seems like the extra hp and tq of a 427 (over the 347 I'm using) would afford going down to the 3.27 gears in the axle. Just my take. Everyone drives differently and wants their car to perform differently, though.

[306rangerfordguy]

I am running a 347 with the factory mustang fuel injection. I have a tremec 3550 with 3.55 gears. The car runs well, does good on fuel and I like how easy that it starts.

[Bob Cowan]

EdwardB, as usual, I agree with your conclusions. But this time for different reasons.

You often hear people say that 3.73 or 3.55 (or whatever) will make first gear useless. You'll be shifting so quickly that you might as well start out in 2nd. That just isn't true. If you compare the two gears and pick a reasonable/casual shift point like 2,500 rpm's, you find the the difference in speed is right about 2mph. Not enough to even notice. I think people get that impression because the lower gear does make the car so much quicker. Small gear changes in these light weight cars can make a big difference in feel.

My car originally had 4.11 gears; and I loved them, and used 1st all the time. I changed them for track use.

I also agree with you about 4th and 5th gear. I think your rear gear choice should be based on where 5th gear puts you. I frequently cruise at 80mph - higher speeds are common. And that puts the engine near the bottom of the power curve. Not at the bottom, just near it. So when traffic slows to 65-70mph, I don't have to down shift. Because - again- that is a big jump from .62 to 1.0; it's about 1,000 rpm's in my car. If I geared it so 80mph was right at the bottom of the power curve, I'd be constantly shifting gears between 4th and 5th.

If you live where you routinly cruise at 50-55, a 3.55 will be way to tall, and you'de want something like 3.73 to get your power band into your driving range.

If I were going to build another car right now, I'd use a T-56 behind a torque monstor motor, with a .75 and .50 5th and 6th gears. And I'd probably back that up with 3.73 gears.

[sneasle]

Bob, your comments line up with what I'm 'spreadsheet building' for whenever the stars align and I can start my cobra, torque heavy motor with the T56 and the 3.73, with a suitable tire, should make for a very nice car.

[EBarnes]

In case you haven't done it already, get some rides. I think these cars are different enough than others in weight and feel, that using past experience in Mustangs/Cameros/you-name-it.

I have an old spec challenge car that is quite entertaining with the stock 302. Soon to be upgraded. I have riden in 350 and 400hp cars, as well as a turbo 550rwhp in an autocross. I think you (anyone) needs to find the point where the entertainment is maximized for the intended purpose. Then work on the engine speed vs. wheel speed for your driving and pick gears.

347s are supposed to be great, with flat torque, etc. as noted above. Just not convinced, for your purposes, it would be better than a 351 putting the same numbers down with less work.

One one end I have an old-spec challenge car (stock 5.0) and I can tell you... You will be happy with what ever decision you make!

[Mslone]

Great Thread! I Love all the Opinions and Info! Thanks Guys!

[Stengun]

Howdy,

I have a Spyder, not a roadster, but here's my combo:

414W +500hp w/ EEC-V 4.6 V-8 EFI system controlled by a Moate's Quarterhorse, Vic Jr intake w/ a 4-barrel style TB, AFR 205 heads.

Tremec TKO 5-speed and an 8.8" IRS w/ a Torsen differential and 3.55:1 gears.

It's not on the road get but I keep getting closer and closer everyday.

Paul

[Mslone]

I guess one question I have is when you order the kit, you have to specify what engine you are going with, but what is the flexibility? So if I choose 302 does that mean I can go with 302 or 347? and if I choose 351 does that mean I can go with 408? 427? I'm a Chevy guy so not real familiar with all the Ford Blocks and sizes per platform...etc

I guess the bigger question I'm asking is If I order a car and say I'm using a 347 but then decide to go to 351, or 408...etc are the mounts completely different? or can that change still be made?

Sorry I'm sure these are silly questions to you ford guys! just trying to Measure twice and cut once!

[edwardb]

I guess one question I have is when you order the kit, you have to specify what engine you are going with, but what is the flexibility? So if I choose 302 does that mean I can go with 302 or 347? and if I choose 351 does that mean I can go with 408? 427? I'm a Chevy guy so not real familiar with all the Ford Blocks and sizes per platform...etc

I guess the bigger question I'm asking is If I order a car and say I'm using a 347 but then decide to go to 351, or 408...etc are the mounts completely different? or can that change still be made?

Sorry I'm sure these are silly questions to you ford guys! just trying to Measure twice and cut once!

You're good. The standard kit will take all the engine choices you listed without any modifications to the mounts on the frame.

[OVCobra]

Just remember that IF you use/order headers with your kit, there is a difference between 302 and 351 (to account for the differences in deck height). Otherwise mounts are the same, as edwardb has already pointed out.

[edwardb]

Just remember that IF you use/order headers with your kit, there is a difference between 302 and 351 (to account for the differences in deck height). Otherwise mounts are the same, as edwardb has already pointed out.

Good catch. Should have pointed that out. The headers are definitely different between the 302 and 351 based engines.

[2FAST4U]

Motor: 331 with Trick Flow CNC'd heads, Lunati roller cam, Weber 48 IDA's, 11:5.1 compression

Transmission: T5Z

Rear End: IRS with 4:10 gears

[Bob Cowan]

I guess one question I have is when you order the kit, you have to specify what engine you are going with, but what is the flexibility? So if I choose 302 does that mean I can go with 302 or 347? and if I choose 351 does that mean I can go with 408? 427? I'm a Chevy guy so not real familiar with all the Ford Blocks and sizes per platform...etc



There are two basic Windsor engines commonly used: 302W and 351W. The only real difference is the deck height. Of course, the internal parts have to match the deck height.

Stock 302 blocks can safely be bored and stroked to 331, and some people even go to 347.
Stock 351W blocks can safely be built to 408. You can do 427 with an early 70's block, but you can't beat on it very hard.
Aftermarket companies like Dart make blocks that can go much bigger, like 454.

Don't worry aout asking "simple" questions. Everyone's new at some point. I have decades of experiance building and racing small block Fords; the last SBC I worked on was in about 1985. I'm currently working on an LS1. I have zero experience with LS engines. So I go to the appropriate message board and ask simple questions. The LS is a very different animal.