JMM DEV5

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Firstly hello all :)

Quick question i know you are all into the older 6's but i have an AUI with a DEV 5 cam kit and valve train modifcations, i have lost a lot of power under 2500rpm what would help? Highstall or UNI Chip?
Cheers Chris

BTW heres a pic with all the new gear http://www.geocities.com/BhoowA/Aug03-021.jpg you will have to copy and paste the link to view.
 
Firstly hello all :)
Click to expand...

:nono: We'll have none of that here, if you don't mind.

:D Just kidding! Anyone and everyone's welcome, pretty much. :D

Do you feel that the performance delivered is in line with what was suggested to you? Or did you buy car thus fitted? just thinking through any "warranty" type issues. Poor ol' JMM seem to split the fans down the middle.

I'm not at all familiar with the four-speed OD autos on these cars, but have to question whether a high-stall would actually work. It would likely be the cheaper option to try, but could be (a) another can of worms in itelf, or (b) ineffectual, and therefore dead investment. Do you have any shift control or enhancement on the box? As (I believe) it uses tailshaft speed and engine data to help determine the shifts, things could go really pear-shaped... And those shift points will need to raise, to meet the new lock-up speed.

Aint much of an answer there, really. :? It'll probably be a hit-and-miss affair for the first couple of tries, either way. What "guarantee" can UniChip offer? Not being cynical, just curious.

Cheers, Adam.
 
I'm assuming the drivetrain is Ford OE here.. I think that with lots of JMM installations, many people have overlooked diff ratio changes.. When someone changes a cam to get more power, they sacrifice low range torque. Generally speaking, Ford 4.0 vehicles, with the BTR trans, have a tall-ish diff (3.27:1?). This ratio is excellent if you never see the sunny side of 2000 rpm, but its awful if you've gotta wait for the engine to spin up enough to get into the powerband..

I reckon you should take it to a diff shop, and talk to the blokes in there about a ratio change.. 3.7:1 or 4.11:1 would be a good match with the 4-speed auto's .68 OD..
 
At the moment i have a LSD from an AUI XR but thanks for the info guys i'll see what i can find out :)
 
hey fancy seeing you here eh ytry?

i am guessing, that the diff you have installed is a 3.45 xr diff.

3.9 gears is the ideal for the 4 speed auto
3.7 for manuals.

mocks dev 5 kit has a usable power range of 3000-5800rpm, anything below that and it will feel worse then normal,

generally for the gain you get up top you loose out in the bottom end,

horsepower is just rpm times torque. so in order to get better power, you move the engines torque band further up the rpm range.

advanceing the timing may help a bit (but very hard to do on an au falcon- jeez thats a lot of two lettered words!! :twisted: )

what i can suggest is, a 2800rpm stall converter with a lock up feature, and maybe a gear change in the diff. up to 3.9, fuel economy on the highway wont change too much but around traffic you may spend 5-10 bucks a week more in fuel.

but you leave any manual for dead on the quater with the same mods you have!!

hey any other mods you wanna do, i'll do them for ya i'll look after ya!

cheers.joe.
 
Thanks heaps dstroya, i have a good mate that works at a Lynford Over here and i'll print out what you told me about the diff gears and i'll let you know before i do anymore to the car.
 
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