AuthorTopic: whats diffent with a camshaft for an auto???  (Read 339 times)

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Offline disco-v8

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whats diffent with a camshaft for an auto???
« on: November 18, 2007, 23:31:25 »
each time i look at camshafts every company seem to do one for 4x4 auto's

whats so diffent with the cam that its made for an auto box????

is the cam designed to give less torque to stop damaging the box, or is it the other way around?????

basicaly whats so specail about these sort of cams????
I LOVE MUD!!!!!! but my engine doesnt


Offline Range Rover Blues

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whats diffent with a camshaft for an auto???
« Reply #1 on: November 19, 2007, 20:25:28 »
They do :?  oh.  Well I've put an auto 3.9 in my manual car and noticed no difference.  Mind you it is gutless but I thought it was due to low conpression in one cylinder.

Whereabouts have you been looking?
Blue,  1988  Range Rover 3.5 EFi with plenty of toys bolted on
Chuggaboom, 1995 Range Rover Classic
1995 Range Rover Classic Vogue LSE with 5 big sticks of Blackpool rock under the bonnet.

Offline disco-v8

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whats diffent with a camshaft for an auto???
« Reply #2 on: November 20, 2007, 01:26:02 »
Quote from: "Range Rover Blues"
They do :?  oh.  Well I've put an auto 3.9 in my manual car and noticed no difference.  Mind you it is gutless but I thought it was due to low conpression in one cylinder.

Whereabouts have you been looking?


well ive already got a piper RP4 cam shaft in mine from RPI and its designed for 4x4 autos

also if you go to piper cam, kent cams, crane cams and alot more they all do one for an auto

i understand that as its for a 4x4 its going to have low down grunt and hardly any power in the topend of the rev range

but ive also seen normal torquer cams!!!!!! so whats so specail about the auto one, what has the cam profiler done so its recomended for an auto????



spoke to some one who knows this type of stuff, and one thing thats diffent for an auto cam was that if the overlap was to large at tick over, when the car is put into drive there is some friction between the engine and the drive train, so it can make it stall, but you wont have this problem in a manual, as you have control over the clutch..... so the cam has to have hardly any over lap to stop it stalling....

which fair enough shudnt make any difference in torque but it upsets the air flow between the inlet  and exhaust so top end power realy suffers
I LOVE MUD!!!!!! but my engine doesnt


Offline Range Rover Blues

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whats diffent with a camshaft for an auto???
« Reply #3 on: November 20, 2007, 13:00:00 »
Ah, so basically what he's saying is that you can't go as far with an auto box cam because of the creep at idle.  Makes sense as most performance cmas get the power by letting the engine rev harder, which comes at the expense of low speed performance, unless you have VVT there has to be a compramise.
Blue,  1988  Range Rover 3.5 EFi with plenty of toys bolted on
Chuggaboom, 1995 Range Rover Classic
1995 Range Rover Classic Vogue LSE with 5 big sticks of Blackpool rock under the bonnet.

 






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