using 1.5 ratio rockers
Turbo Mini Forums

my engine spec is as follows
1293cc , t2/t25 hybrid turbo running 10psi , 8.5-1 comp ratio , benross head , forged pistons , kent md266 cam , running on 3.1 gearing.
the car is not a race car although it will keep up with them ! it is relatively quiet , very drivable , its very smooth at idle and has a nice power curve / delivery. the question is I am looking at changing the rocker shaft assembly from the standard to roller 1.5 ratio . I am looking for opinions on how this will effect the smooth idle and the off boost low end torque considering I'm using the md266.
I know some will comment why change it if your happy with it ! well I use the following principle

can it be modified.....................yes
does it need modifying..............no
is it getting modified.................Yes
why........................................its a bloke thing

Edited by braziers on 30th Mar, 2018.

The 266 will respond to the 1.5s very well. NA or turbo.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

Bang a set on. If they are an improvement then it's happy days. If they make it shite sell them, which you won't have any trouble with.
I do agree, you always need to look for improvements/, upgrades.
Will does know his stuff so go for it fella.

As you're using a small turbine you may find the higher ratio rockers don't help as much as they would on a tuned NA motor. As the rockers increase lift at any given point they will increase lift at overlap to, in a small restrictive turbine pressure can often be higher than the incoming boost leading to exhaust reversion, not something you want.
The higher ratio also lifts the valve off the seat quicker so at low RPM & slow port velocities performance is often reduced. If higher revs and a bigger less restrictive turbine are used & the head is ported to take advantage of the extra lift that's when they become a real advantage.

Phil.

WWW.TURBO-MINI.COM

For what it is worth I tried 1.5 rockers on my engine with a similar spec to the above apart from a GT 1752 and found it knocked out the low and midrange in return for more top end and noisier valve gear.My engine had been tuned by Robert specifically for midrange and had conservative ignition timing so may not be wholly representative.

well I took the plunge and purchased a set of med ldx 1.5 rockers they looked well made item. idle was still relatively smooth although I used 19" thou clearance to achieve this. I found 15" thou a little on the tight side and this made for a rougher idle. off boost was no different in terms of delivery. no apparent loss of torque. on boost has made a noticeable difference to the extent it was worth doing. I could probably loose a couple of psi and keep the same power output while lowering intake temps with lower boost. win win