torque converters compared, and general tq converter info




Re: two, torque converters compared

Postby grumpyvette » January 15th, 2009, 10:12 am

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: torque converters compared, and general tq converter info

Postby grumpyvette » January 15th, 2009, 10:36 am

(1)quality and depenability and having the part match the application is far more important than price, find a decent product with a good track record and satisfied customers

(2)install the tq converter per manufacturers specs

(3)your rear gear ratio MUST match the engines power band

(4)a tq converter that fails can easily destroy your transmission, DON,T SHOP PRICE ALONE, GET A WRITTEN GARAUNTEE, IT may not be worth much but it helps at times, RESEARCH the companys reputation and track record

(5)USE A GOOD TRANS COOLER

(6) compare features, anti balloning plates and custom built converters tend to be better than stock or slightly modded stock converters rebuilds sold as high performance converters

this takes some detailed info
the quality of manufacture and the basic design of the converter has a huge influeance on the results, youll see.
now your stock converter has about a 1800-2100 rpm stall, depending on the option, and year and engine in a c4.
naturally the CAM you sellect should match the compression and rear gear and stall speed to take full advantage of the usable tq band.
and as Im sure your aware the car moves fine without reaching that rpm range under light accelleration, swapping to a higher stall converter will allow the engine rpms to build up too the stall speed far faster and will tend to allow the average rpms to be higher before the car moves BUT thats NOT the same thing as needing to rev the engine far higher before the car moves, its more like you have a clutch your controlling with how hard and fast the engines rpms build, and YOUR in control of that RATE.
your transmission SHIFTS at a PROGRAMED OR SET RPM under full accelleration, which limits your effective use of the reachable rpm band, and your valve train tends to be rpm limited. BOTH tend to limit a stock engine to under about 6200rpm max.
the rear gear ratio and CONVERTER STALL dictates the basic TIME that your engine spends between gear shifts and the rate at which the rpms build and the speed the tires rpm reaches in relation to the engine rpms, and the mechanical multiplication of that torque. ITS A BALLANCING ACT OR COMPROMIZE!

theres lots of info here, but the basic facts are the HIGHER the AVERAGE RPM BAND and THE HIGHER the average TORQUE CURVE the faster you can apply the hp thru gearing

gear spread sheet that comes in handy THANKS TO 1FATGMC

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

HERES OTHER INFO LINKS

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

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

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.thirdgen.org/calculations

http://www.revsearch.com/dynamometer/torque_vs_horsepower.html

http://vettenet.org/torquehp.html


LOOK heres a DYNO CHART
Image

if you built this engine (power curve above)and stuck it in a stock vette with stock gears it would be a DOG! compared to the same vette with a 3.73:1 rear gear and a 3200rpm stall and a trans set too shift at 6000-6200rpm simply because youll be limited to an rpm range, thats far below peak or even the most efficient rpm range and youll spend far to much time in the lower non-productive rpm band.
swapping to the higher stall and 3.73:1 rear gear (the highest most vette differentials easily acommadate) moves the EFFECTIVE AVERAGE rpm band hundreds of rpms HIGHER makeing the effective power reaching the wheels far higher
then theres the torque multiplication
use that dyno curve in a stock drivetrain and youll probably average 350-370 ft lbs times a 2.57:1 ratio or about 925 ft lbs of tq at the rear wheels
use the higher stall and gearing and your more likely to see an average of 420 ft lbs time 3.73:1 gearing and have closer to 1550 ft lbs at the rear wheels on avearage
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: torque converters compared, and general tq converter info

Postby grumpyvette » April 8th, 2009, 2:23 pm

IF your building a street/strip engine combo with over 500 ft lbs and a cam suitable for the 2700rpm-6500rpm power band that most street strip combos fall into,ID SUGGEST a

Precision Industries , Vigilante with a 3000rpm-3200rpm stall speed

http://www.converter.com/vigilante.htm

talk to these guys , get thier advice and follow it, I know from experiance they know how to build a decent converter, Ive seen several in use with no failures, keep in mind youll (NEED)to install a very effective trans cooler and a 3.54-4.11 rear gear in most cases to work correctly


http://www.yearone.com/serverfiles/fbshopmain2.asp?hid=026DK73488&trk=12

if your refering to the 502 big block engine that I think you are ID be looking for a 2800rpm-3000rpm stall converter, now for the guys reading this not familiar with converter stall speeds that in no way means the car won,t move untill the cars engine reaches 2800rpm any more than your stock stall converer rated at 1900-2200rpm in most cars prevents the car from smoothly pulling into traffic at 1500-1600rpm, it simply means that if you run street tires,and put your left foot on the brake and stomp your right foot to the floor the engines likely to reach about 2700rpm rather quickly before the tires turn into smoke, while a stock converter would start smoking the tires at about 2200rpm, but the differance is in the power you can instantly apply if youve got decent traction, lets just use my current vettes dyno curve as a quick example(IT WAS HANDY)
Image

a stock converter would allow you to launch at about 100 hp lower on the power curve than a 3000rpm stall converter, and make idling in tracffic miserable if you use a more radical cam while the 3000rpm stall makes things work far smoother
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida



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