4 replies to this topic

[zomerzet]

Hi,

I've got the following engine and was wondering how much difference a set of 1:5 roller tipped rockers would make?

-1293
-Stage 2 Head (Bigger valves and smoothed inlet/exhaust)
-Newman, Phase 2 Fast Road Cam.
-Lightemed Verto Flywheel

I currently get 64BHP at the wheels and am currently using standard steel ones which apparently only give around 1:25 lift anyway.

I'm just curious!....

[MINI 1]

they should help a little bit , got them on my 1380 which is in bits now .. , if your going to get some, get the MED LD ones . their spot on . expensive but well worth it , when i fiited mine i dident need to adjust them at all using shims , like most over 1.5 roller rockers on the market.

http://www.med-engin...mp;vlang_id=354

ash

[Wil_h]

1.5s are a funny thing. Some people love them some people hate them. Someone once did a test which showed minimal gain by putting them on. However, the test was floored IMO.

Basically, will the extra lift be an advantage on your setup? If your current valve lift is maximising the flow of your valve and port then the extra lift will be of no advantage and just put strain on the cam etc. If not then adding 1.5s could help.

But they won't ever transform your engine, we're talking moderate improvements. I personally have always found my engines perform better with them, but I generally use Kent cams and these were all developed with 1.5 in the first place.

[zomerzet]

Hmm, interesting. Yeah I'm not expecting a sudden huge power jump but with such an easy mod it's certainly a good way of getting a little more power (Hopefully!).

I don't think I'd go as far as buying the MED ones due to the fact that I'm unsure of how much benefit they will have (If any). I am definately more interested in picking some up as even 1:3s should be an improvement, however small. I am also aware of the extra strain thay put on the cam so 1:7s are way out.

The lift on the PH2 cam is here

http://www.newman-ca...m/pdf/rover.pdf

So I currently have around a 1:275 ratio giving me a valve lift of 3.825.
If I move to 1:5 ratio, I will get a valve lift of 4.5.

That's a difference of 0.675 or a 17.6% increase...

[Ethel]

If you use lighter valve springs there needn't be any extra force on the cam. As you get proportionally more lift as soon as the valves come off their seats the effect is similar to fitting a longer duration cam. Even if other port restrictions negate any advantage over a certain amount of lift the valve will get there earlier and stay above that level for longer.