Rocker ratio choice for 1098 turbo with MD274
Turbo Mini Forums

been a long time since ive looked at the mini finally getting back into it im looking at the head and related parts leads me to roller rockers and what ratio to chose 1.3 or 1.5 ive herd of people running both on the 1098s but as to what will best fit my build im stuck

low end torque is important as im running the 2.95 FD and clubman close ratio gear set with the old metro T3


also witch brand is preferred med?

I'm happy with my med 1.3 roller tip rockers. The car produced the numbers with on of phils heads on the rollers

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

From my personal experience Kent cams always work better with higher ratio rockers.

However, as you want low end torque the 1.3s might be the better choice.

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

www.twin-turbo.co.uk

the 1.5's pushed the peak torque up the revs when I used them on 1400 with the same cam. No surprise there really as they tend to increase the valve lift on overlap. Not sure on a turbo motor whether the gain would be better than the loss

I guess it will depend where you expect to be in the rev range when driving it.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I used 1.5:1 on a NA 1275 with a similar cam and surprisingly, it was not as fun to drive on the road. I don't know if it made less torque at lower revs, but because of the nice gains higher up the revs, it certainly felt lazy lower down the revs.

I'm building a 998 turbo with standard rockers now. My reasoning is that with low CC and lower CR, I don't want to risk compromising torque at low /med revs. I'd imagine the turbo can make up any power difference at high revs with a touch more boost, if needed.

Edited by PhilR on 21st May, 2015.

I'm using 1.3s on the 998 Ti ST2. 12G295 head, MD274 GT17 etc.

The MD274 already has decent amount of lift. 1.5s will only give more power if the cam is the limiting component, which it is unlikely to be.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

1.3s i think it will be for the turbo if NA id favor 1.5s from those comments

to chance the 1.5s moveing torque to far up making the FD feel taller than it already is probably a silly move

gains i might be missing as said should be regained by a few pounds more after all im going for the higher end of the scale anyway

so far with the stock 202 thats way passed its prime it seems to start boosting around 2.9 3.1 mark thats about 35 40 km/h only set for 6 pound atm

factory pressed steel rockers are 1.3 aunt they? so the only thing im changing is (hopefully) a better flowing head well how much worse can the 202 be made no really if i do a half way decant job on the head all else stays the same i think the low end can only be made better

im planing on 30 degree intakes for that tinny low lift flow gain with a smaller bowl (for the valve size) to get the nice seat roll over radius going to run a high ish compression ratio to help the low end a bit too