Gkn Overdrive//economy Related To Max Torque?

Hi there,

Ok, you can see my modifications to my TD5 below. This post is a bit about the overdrive and the link between peak torque and economy.

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I normally get 280-300 with my chipped intercooled td5. With some recent long runs with the overdrive activated I achieved around 380 on a full tank which was great!

Now then:

Q1) Do you have the best economy at peak torque?

A thorough GKN overdrive review was undertaken by someone, they stated:

"The O/D puts less stress on engine, drops revs I reckon by 800rpm at 70mph which was calculated and is proved by the fitted rev counter. Which now means 70mph is closer to peak torque for the engine at 2100rpm."

Q2) If peak torque is near 70mph will I do more mpg at 70mph with overdrive on than say 55-60 with overdrive on?

Q3) This is one for overdrive owners I guess. When I do 70mph, the noise I hear, to say the engine is doing around 2100 rpm is the noise from the transmission? The engine cant be humming and buzzing away that much right? Its relaxing with the overdrive surely!

Lots to talk about. But I appreciate your time.

Thanks everyone, look forward to replies.

James

ps: I normally do 60-70. However, late for the England game yesterday did 90 easy! Was a great experience haha

Dunno realy but I do know that water is at its dencest at four degrees centegrade.

...and I guess your at your densest at 12:31 am?? haha

James

No but I am at my ****edised.

grunt!! are you drinking the brasso again??

BBBUUUUUUUUUUUUUUUUUUURRRRRRRRRRRRRRRRRRRRRRRRRRPPPPPPPPPPPPPPP AAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHH thats better!!!!

nice to see you have a good mpg on the motor


btw you ask some weird and wonderfull questions lol

The following is based on something worked out andsort of calculated, so it should be rightish.

I belive sitting in 5th doing about 60ish will have the engine sitting at its most economical speed, so if you sit at 60ish in 5th with no OD, then engage the OD, and then bring the revs back up to the same speed, that should give the best economy.

Surely if the engine is at its most economical it wont be running?

Just a thought.