rpms ?

[Yankee Transplant]

ok ,, is there a formula for figuring out what rpms you will be doing at 60 pmh or so with a 350 turbo transmission and 3.55 gears at the rear end ? or maybe a good guess ? I dont know about gears and stuff , Its says a 350 in third gear is a 1.00 I just thought there may be a way to figure rpms in this ..

 

[skull]

couple

here is a few l use.

tire size is also a factor on final RPMs. here is a site for tire size.

http://tire-size-conversion.com/tire-size-calculator/

1:1 is for standard tranny, if you have an 0D trans use the right gear ratio.

http://www.mustangtek.com/calculator/calculator.html

http://www.ringpinion.com/Calculators/Calc_RPM.aspx

http://www.crawlpedia.com/rpm_gear_calculator.htm

http://www.summitracing.com/expertadviceandnews/calcsandtools/gear-ratio-calculator

http://www.csgnetwork.com/multirpmcalc.html

Later

 

[Yankee Transplant]

thanks skull I think with this 3 speed gas mpg is going to sux at 4500 RPMs at 60 mph looks like i'll be hunting a 4 speed auto ,, something without a computer hook up

 

[05snopro440]

thanks skull I think with this 3 speed gas mpg is going to sux at 4500 RPMs at 60 mph

It uses tire diameter, not wheel diameter. Using a 26" tall tire you're around 2700RPM at 60MPH...

 

[Yankee Transplant]

It uses tire diameter, not wheel diameter. Using a 26" tall tire you're around 2700RPM at 60MPH...

hey hey ,, that sounds a heck of a lot better snopro Ive got a 235/70/16 on it I just measured it ,,,, and its 30" tall


ye haa Hey I said I didnt know much about this ,, just re-did the test thinggy and it said about 2400 at 60 mph .. I can deal with that .. thanks snopro you made me feel alot better ..

 

[skull]

trans

l am running a 2OOR4 and a 7OOR4 and am very happy with both of them.

make sure to get the correct converter. for peace of mind it's cheap insurance and a great idea to get a new converter. that way whom ever does the job can be sure the right pieces are all there so it will give years of reliable service.

find a good hot rod transmission person, l have 2 different kinds of lock ups on my rods, the 2OOR4 uses a vacuum switch and a couple of wires to a kick out switch and the tv cable

the 7OOR4 is special built to hold 5OO HP and a wicked 1-2 shift with a internal unit and has nothing to hook up except the TV cable.

both work very well.

YOU HAVE TO HAVE THE TV CABLE CORRECT OR YOU WILL BURN UP THE TRANNY. that can happen in a couple hundred miles or so.

Later

 

[Yankee Transplant]

skull snopro showed me how to figure the rpms I was doing it wrong I punched in I had a 16 tire instead of a 30' tall tire . That made it to about 2400 rpms at 60 thats not bad as the 4500

 

[Willowbilly3]

Yeah, I was wondering what kind of cog you were running to come up with 4500 rpm. That would have to be like a 6.50 or deeper.

 

[BlueNorther]

2 formulae that will help you.

MPH X GEAR RATIO X 336 ÷ TIRE DIA = RPM

(RPM X TD) ÷ (GR X 336) = MPH

 

[05snopro440]

Using the calculated tire size based on what size tire you're running, it says it is 29" tall, which gives an RPM of 2468 at 60MPH with your 3.55 gears and a TH350 (1.0:1 final gear). A 700R4 would drop you below 1800RPM at the same speed, so you would either want taller gears or shorter tires if you went with a 700. Stick with the TH350.

 

[Yankee Transplant]

well that's why I like this site .... thanks for the imfo snopro I'll stay with the 350 and build it ,, its going to be a back-up (spare) truck anyways ,, for when I have to down my main runner for a little while , so this will be ok .. and willowbilly what can I say but I get cornfused real quick and thanks for the imfo blue

 

[Hollow65]

What's max rpm of your engine? There's a whole lot more to mpg than rpms. Peak tq rpm?

 

[Yankee Transplant]

I got no clue its a 305 with a mild cam ( not much power ) I just didnt want to build a 350 transmission and the engine running wide open at 60 that was all. If it was, Id have to do something different But I believe im going to be ok for now

 

[Hollow65]

3.55's are pretty mellow. Even at 3k it's not too terrible. My 327 with 3.73/th400 and 26" tires was a decent cruiser. if you can run to 5k and your cruising at 3k it's only 60% of your max. Probably idles at 800 anyways what's another 2000?