Early Ford V-8 Club Forum

EFV-8 Club Forum / General Ford Discussion / High speed gears and horsepower

Reply to Discussion | New Discussion << previous || next >>

Posted By Discussion Topic: High speed gears and horsepower     supereal 07-31-2010 @ 1:02 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Bill: "High ratio" indicates the relation of the drive gear to the driven gear. Thus 4:11 to 1 is a "high" ratio, requiring more turns of the driving gear (pinion) for one turn of the driven (ring) gear, and 3:54 to 1 is a "low" ratio, requiring fewer turns. This tends to be confused with the "high speed", and "low speed" terms commonly used to describe the rpm of the engine to mph due to the difference in ratio. Sorry for the confusion. wmsteed 07-31-2010 @ 10:30 AM reply profile send p.m. Senior Posts: 613 Joined: Oct 2009 Super... I think you got your definition of gearing backwards. The bigger the number, the lower the ratio, e.g. a 4.11 ratio is low gearing, more power, loss of economy, at high engine RPM's. The 4.11 ratio was pretty well standard on the early V8 Fords up through the mid '40's. The 3.78 is higher geared, a mid range between the "high speed" 3.54. The 3.54 gearing was generally found in cars from the flat land because they required constant down shifting in the hills/mountains. At highway speeds, 55+ the high speed 3.54 would provide longer engine life and better economy because of the lower RPM's. From a practical point of view, the 3.54 gearing requires more horse power to move the vehicle from a standing start when compared to a 4.11. Racer's always like the 4.11/4.56 or lower for quarter mile drags. The larger the truck, the lower the gear ratio. Standard gearing for a 3/4--1 ton use to be 4.56 or 5.13. Larger trucks would alter the gearing with two speed rear ends, either going up or down in gear ratios depending on the intended use of the truck. Modern trends have been to higher ratios in cars, 2.90's/3.05, or there about's, with Lt. trucks using 3.05. 3.42, 3.73.. Many of the heavy duty trucks now use ratios around 3.90, w/7 spd, or more transmissions, however, they also use 350 + HP engines. Bill 36 5 win delx cpe supereal 07-31-2010 @ 8:44 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 The idea is to place the engine revs when in high gear close to the best part of the power band for the most used driving speed in the terrain you live in. Most flatheads produce the most "power" where the curves for horsepower and torque meet. For stock engines, that is just above 2,000 rpm. The higher rear end ratio, such as 3-78 or 4-11 tend to top out in the 50-55 mph range. If you go to a lower ratio, such as 3-54, you will push the rev-mph equation higher, but at a noticeable cost of low speed power. That is why trucks have high ratio gears, and low road speeds. 37RAGTOPMAN 07-30-2010 @ 5:26 PM reply profile send p.m. Senior Posts: 1961 Joined: Oct 2009 Moxie maybe it could be said,the bigger gear set will take more horepower, not to turn the gears but how much power you can add,then the smaller gear set, KEEP ON TRUCKIN 37RAGTOPMAN Bill4d1merc 07-30-2010 @ 3:46 PM reply profile send p.m. Member Posts: 48 Joined: Oct 2009 let me rephrase my answer. No it will not take more horsepower because the ratio is the same so it will act the same. Bill 35gal 07-30-2010 @ 3:16 PM reply profile send p.m. Member Posts: 66 Joined: Jan 2010 He is asking will it take more horsepower to turn one set of gears as oppose to the other set. Not will it deliver more HP. Bill4d1merc 07-30-2010 @ 3:01 PM reply profile send p.m. Member Posts: 48 Joined: Oct 2009 As long as the ratio is the same it will deliver the same performance regardless of horsepower. I've read on this forum that one may be noisier than the other but I don't know if that's true or how much noisier. I wonder if one would be stronger than the other, bigger fatter gears as opposed to more gears meshing together at the same time? Bill MOXIE 07-30-2010 @ 2:08 PM reply profile send p.m. New Member Posts: 102 Joined: Oct 2009 There’s no such thing as a stupid question (I hope) so here goes. I purchased the 3:54 replacement gears and the number of teeth are different than the original high speed gears. The pinion has 9 teeth and the ring has 32 teeth. The original 3:54 gears have a different number of teeth. Eleven on the pinion and 39 on the ring. Regardless of the number of teeth, if the ratio is the same, will any one set require more horsepower to run.

<< previous || next >>

NOTE: YOU MUST BE A REGISTERED USER AND BE LOGGED IN TO POST (and reply to) messages in this forum. If you are a first time user, please click the CREATE A NEW ACCOUNT in the masthead above to register and Log In. After that, all you do is LOG IN to enjoy using this site.

DISCLAIMER: The V-8 Club does no independent testing of any of the opinions, thoughts or suggestions presented in the website on the Forum, in the Tech Tips section, or any section. A reader should consider the website to be a forum wherein differing solutions to a particular set of circumstances may be discussed. Ultimately, the selection of an item for an individual's vehicle must be based upon the independent study of the vehicle owner in consultation with people in the hobby and restoration experts.

EFV-8 Club Forum Home | Back to Home Page | Contact the Webmaster

Copyright © 2009 - EFV-8.org
Powered by < CF FORUM > v.2.1