Supercharger advice
Turbo Mini Forums

It’s been a while since I last posted on here and I should really get round to updating my project thread since I have quite a lot to updated. Anyway I am looking for some advice regarding a supercharger kit I brought. I went a spent what I think was a good price on the jonspeed kit Tomf saw on ebay and posted on here last week.

Now my plan is to put it on to my present 998 with the below spec, now I have been reading up on here and TMF and see that the Eaton M45 is a little over the top for a 998 without changing the pulley ratio. Now I am wondering if I am better sticking with the below spec or switching to a standard 1275 bore block (will obviously upgrade everything else to account for the charger) any thoughts or advice are really appreciated.

I am not looking for mental power figures, I will be really, really happy with about 100 bananas if possible, the car will be used for weekends blasting around b-roads etc so does not need to be setup as a daily driver but i dont want to be re-duilding it every couple of months either.

Block: 998 A+ bored +30, pocketed for use with 12G940 cylinder head
Crank: crossdrilled, wedged crank, on std bearing sizes
Rods: 998 A+ lightened and balanced fitted with powermax +30 offset pin pistons
12G940 head will be worked to achieve the correct CR (not to sure what this will be yet so please help if you can)
Not to sure on cam choice at present (again advice is appreciated)
No matter which block I go for I will obviously also fit
Up-rated clutch and X-pin diff etc

Cheers
Dan

Paul S was selling the smaller supercharger earlier, have a look in the for sale section,
the CR will mainly depend on what boost your going to get
if you get the details sorted the rest falls into place quite easily

Yes i moved to the darkside

Instagram @jdm_brett

if you have the jonspeed kit don't they do a bottom pulley for a 998?

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

If you are insistant on 100bhp and running an M45, then go for the 1275.

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

Thanks guys,
Will, im not insistant on 100bhp but as a ball park figure it would be great. I am just thinking that the work i have done on the existing engine should give me a fairly nice bottom end but it is not worth anything if the supercharger to too much and causes excessive wear in the bores.

Also I already have the full kit (charger pully manifords carb etc) so dont want to go changing too much, I could always see if jonspeed do sell a different bottom pully for the 998 and sell on the existing one.

I though i had read somewhere that the m45 on standard pulley's produced 7psi boost but cant find thatc anywhere now to confirm. Can anyone confirm that?

It's not really about wear and tear, mor about the efficiency of the SC matching the engine cc and boost requirements.

It will work.

1:1 ratio on the pulleys will give around 7psi by my calculations, this will equate to 80bhp ish, maybe a bit more maybe a bit less.

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

to keep it simple cant you just get a pully from Jon speed... dont they sell this kit for a 998 so a assume they can provide the correct pulley? The tried to sell me one before my I decided to go with my sc12 setup

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

Thanks Will, i dont even know where you begin to work out things like that. 80bhp is still a figure i would be happy with. Not quite like some of the power you guys are getting but will be ok.

I think its worth a call to jonspeed like Graham mentions to see if they do have different pulleys for the 998. I am sure i remember hearing somewhere that they dont and that the only difference between the 998 and the 1275 kits is where the breather is located.

Thanks again for the help this site is a wealth of knowledge.