calculate the cars speed and rpm in gear

[grumpyvette]

http://users.erols.com/srweiss/transc.htm

http://www.drivetrain.com/autotranscrossref.html

http://www.tciauto.com/Products/TechInfo/trans_dims.asp

http://www.tciauto.com/Products/TechInfo/gear_ratios.asp

youll find what you want here

http://www.geocities.com/z_design_studi ... zx_tt.html

http://www.datsuns.com/Tech/whentoshift.htm

http://www.circletrack.com/drivetrainte ... index.html

FIRST, THANK YOU IFATGMC!!!
THATS VERY USEFUL, IF YOU DON,T MIND ILL MAKE THIS A STICKY :grin:

http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html

HERES OTHER INFO LINKS

http://www.xracingsports.com/tirecalc.html

http://www.secondstrike.com/Technical/GearCalc.asp

http://www.5speedtransmissions.com/calculators.html

http://www.geocities.com/z_design_studi ... zx_tt.html

http://www.datsuns.com/Tech/whentoshift.htm

http://www.wallaceracing.com/reargear.htm

http://users.erols.com/srweiss/calcmph.htm

http://www.tciauto.com/Products/TechInf ... tors.asp#8

http://users.erols.com/srweiss/calcrpm.htm

http://users.erols.com/srweiss/calcrgr.htm

http://users.erols.com/srweiss/transc.htm#tabtop

http://users.erols.com/srweiss/transc.htm#Auto

http://www.gmtuners.com/gmtransinfo.htm

 

[grumpyvette]

many guys want the acceleration a lower rear gear ratio like a 3.54:1 or 3.73:1 gear will give a car over the more common 2.87:1-3.07:1 rear gears many performance cars came with recently, as a compromise on mileage and emissions with performance and acceleration, now with the factory cams in most cases engines are designed to cruise at 1700-1900rpm in overdrive on the freeways, but hot rodders, being the type of guys we are, screw up the combo with significantly larger cam duration, better intakes and bigger port heads and a low restriction exhaust and headers, we have effectively moved the whole power band from the factory designed 1500rpm-5000rpm up to a 2200rpm-3000rpm lower threshold, and we want to spin the engine up over 6000rpm, all in a quest for significantly more usable horsepower. and we get that extra hp IN THOSE upper rpm bands but the cars gearing tends to keep the engine in the original rpm band so we get a combo that's a dog until the rpms build....
its no secret that a higher stall speed converter and a lower rear gear ratio, like a 3.54:1-3.73:1 or even a 4.11:1 rear gear ratio will place the engine back in its NEW intended rpm range, but guys are reluctant to make major changes because they still want the cruising mileage, well, everything's a compromise, and you'll need to make choices,
heres links to all the math you'll need if you want to get the reason why you'll select a specific rear gear ratio.

http://forum.grumpysperformance.com/viewtopic.php?f=71&t=741

viewtopic.php?f=71&t=604&p=802#p802

but assuming your running about 1900-1950rpm at 70mph with a 3.07 rear gear, now swapping to a 3.73:1 rear gear will boost your rpms at the same speeds to only about 2450-2525rpm in OD, if you've got a 700r4.
A 3.54:1 ratio will only boost you to about 2225-2300rpm

the 3.73:1 ratio is a MUCH BETTER MATCH TO THE CAMs designed rpm band
personally ID sellect a 3.90:1 if it was available, even with a 3.90:1 rear gear a 700r4 trans behind that engine should easily allow 160-170mph PLUS, which your very unlikely too use enough to even worry about.

the 3.54:1 ratio will work ok,and you certainly won,t regret going that route, but you can improve things a bit more with the 3.73:1 ratio, that slight lag you have now if you punch it in od on the expressway,with the current 3.07:1 ratio will be much improved but still just noticeable for an instant with a 3.54:1, but it will be much more responsive with the 3.73:1
BOTH WILL WORK, but I think youll find the 3.73 the slightly better choice.
what most guys understand is that the change in rear gear ratio allows the car to cruise at a higher engine rpm, at any given road speed so its more responsive, when you floor the car as the cars engine is closer to the power bands sweet spot, what many guys don,t seem to grasp is the change from 3.54:1 to 3.73:1 not only increases the rpms about 10% it increases the usable tq at the rear wheels about 10% all thru acceleration in each gear,and allows the engine to build rpms as it accellerates up thru each gear in the transmission about 10% faster, yes it makes a noticeable difference


practice launching and get the tire pressure adjusted so you get an equally dark, full tire width patch of black rubber on the pavement,too little air pressure usually makes the outer edges darker, to much air pressure usually tends to make the center of the tire marks darker

AS a general rule, a performance street cars rear gear ratio multiplied by the transmissions first gear ratio should fall in the 10:1-10.5:1 range with tire diameters in the 25"-28" diam. range

http://www.cprparts.com/HPcalculator.html

http://www.wallaceracing.com/et-hp-mph.php

http://www.ajdesigner.com/fl_horsepower_trap_speed/horsepower_trap_speed.php

http://www.gregraven.org/hotwater/calculators/qm-from-wt-hp.php

http://users.erols.com/srweiss/calcehp.htm


related info threads
http://garage.grumpysperformance.co...electing-a-torque-converter-stall-speed.1715/

http://garage.grumpysperformance.co...late-gear-ratios-and-when-to-shift-calcs.555/

http://garage.grumpysperformance.co...earing-and-trans-choice-made-correctly.11697/

http://garage.grumpysperformance.co...hing-the-drive-train-to-the-engine-combo.741/

http://garage.grumpysperformance.com/index.php?threads/select-a-gear-ratio-or-trans-or-both.10493/