adding boost to a jrsc mp45

[mhj]

im interested to add some boost to my nb99 with the jr supercharged currently standard and only offering 5 psi
options ...

small pulley on sc....but i heard it can slip
large pulley down low...but does that mean expensive engine removal to get at it?( but then i could lighten the flywheel and add a tougher clutch)

if i add more boost do i need intercooler.....but ive heard that IC reduces throttle response...how bad is that ??

can i get to say 8-10 psi with perhaps just a radiator upgrade

im not a car thrasher...no track work...a daily driver.

whatdayareckon

enjoy

[Alex]

without an IC you could increase boost but you will need a different tune, probably running quite a bit ritcher.
Not sure about the pulleys but isn't there a tensioner of some sort which would allow you to use a different one without too much slack?

[93_Clubman]

If you don't already have one the upgraded belt tensioner is the wtg, especially if you want to increase boost. BRP (now Stage One Tuning) used to do one, as does Track Dog Racing, & now JR themselves. Some people find they get an extra 1/2psi just from the upgraded belt tensioner. 5-6psi is usual for the standard JRSC M45 with or without upgraded belt tensioner.

8psi is usually the maximum from the M45 with the Big Boost Kit, i.e. the larger (150mm) crank pulley etc. You should be able to replace the stock (130mm) crank pulley without removing the engine. As you mention there is also a smaller SC nose pulley (62.5mm) - you could run either the bigger crank pulley or smaller nose pulley for more boost, but if you run both be aware that over a certain engine rpm you will exceed the SC's maximum rpm (which is a little under 15k rpm from memory).

Water or methanol injection seem to be more popular with the M45 (certainly in Australia), however some people do use A/A or A/W IC (more popular in the US). A/W seems to be favoured over A/A, but it takes a bit of development to get it right.

You have to really work very hard for the gains in power & torque over 8psi - indeed even from 6 to 8psi the gains are incrementally less than from the initial fitting, hence the use of the MP62 for even more headroom & reliability. That said, the M45 is a good unit for someone that only wants a moderate increase.

P.S. Your setup from your other post sounds great!

[timk]

I had a custom pulley tensioner but ran the crank pulley overlay and it worked quite well. You should be able to get one custom made cheaper than buying from JR if you don't need the bigger fuel pump etc.

[wamx5sc]

I have a custom made S/C pulley (cheaper than getting in from JR, just got it made in a machine shop) running with an A/A Intercooler and producing 9 psi. I do have quite a bit of throttle lag, i.e. when I take my foot off the throttle the throttle stays on for about half a second, but it is something that you very quickly learn to drive around.

I get very little to no belt-slip but the workshop that I use have done a good job with the tensioning system, although it does need a crow-bar to apply the tension in the first place.