I'm trying to find out what valve springs to change my M40 ones for to aid me adding a turbo, any ideas would be great!!
Thanks
Which valve springs?
Moderator: martauto
-
maggspower
- Turbo Farmer Tractor Driver
- Posts: 2376
- Joined: Wed Oct 12, 2005 11:00 pm
- Location: Nowhere near South Wales, ok butt
hi there, stiffer valve springs are used to counteract the effect of valve float, this is where the the valve fails to came to rest properly and instead bounces off the valve seat.
when this happens it feels simular to to a rev limiter, not good for high reving engines, it will only happen at above stock revs and will be made worse by a high lift cam and tired springs. (have a look at jazzman's 2.8 thread there is a pic of some springs that are a couple of mm shorter than new ones!!)
if you are going turbo, the good news is you will probably be keeping the stock cam profile
if you dont increase the rev limit by too much, i would think a set of new stock ones would do you
another thing to bare in mind is that increasing the spring load also increases the stress in the valve train, more stress, more wear more pains in the a?se, another reason to go for stock, that is unless you beef everthing up to cope with it
hope this helps, just my thoughts cheers maggs
when this happens it feels simular to to a rev limiter, not good for high reving engines, it will only happen at above stock revs and will be made worse by a high lift cam and tired springs. (have a look at jazzman's 2.8 thread there is a pic of some springs that are a couple of mm shorter than new ones!!)
if you are going turbo, the good news is you will probably be keeping the stock cam profile
if you dont increase the rev limit by too much, i would think a set of new stock ones would do you
another thing to bare in mind is that increasing the spring load also increases the stress in the valve train, more stress, more wear more pains in the a?se, another reason to go for stock, that is unless you beef everthing up to cope with it
hope this helps, just my thoughts cheers maggs