MX5 supercharger kit information

mx5gem · Postby **mx5gem** » Thu Aug 20, 2020 6:17 pm

Necro bump......

To re-ask rowdytoots question from 2 years ago, has anyone here since used/installed a bullet rotrex kit on their mx5.

I'm wanting to go rotrex on my NB, and TrackDogRacing seem to have an awesome kit with plenty of satisfied owners over in USofA, but shipping & Customs makes its ~$2000 dearer for the similar thing to Bullet is offering.

Some first hand experience of Bullet kit would be awesome, hence the question...

bruce · Postby **bruce** » Mon Aug 24, 2020 7:49 pm

16bit installed a rotrex on his gold NB quite a few yrs ago.

greenMachine · Postby **greenMachine** » Mon Aug 24, 2020 11:29 pm

I know of a 10AE down the South Coast with a Rotrex, had it for a decade or more probably. He doesn't post on here anymore, unfortunately, or he could provide more details - he was very happy with it.

:mrgreen:

Red_Bullet · Postby **Red_Bullet** » Tue Aug 25, 2020 9:42 am

I've got a Bullet installed Rotrex kit, located Brisbane. Originally with a chiptorque piggy back and stock ECU, I flicked that and installed a megasquirt MS3 Pro. I bought the car with it fitted by a previous owner. Pretty happy with it, although there are a couple of issues. What do you want to use the car for?

mx5gem · Postby **mx5gem** » Tue Aug 25, 2020 12:15 pm

Pretty much just track work - circuit racing. up to 30 min sessions.

I'm sold on the rotrex itself, just unsure of the Bullet kits, and particular the mounting bracket/system which seems to have given some owners some alignment and/or belt issues.
TrackDog seem to have a better sorted kit but $2000 more (by the time exchange rate, shipping and customs weighs in) which is a hefty chunk of cash if the Bullet one does the job without causing belt issues.

What were the issues you had?

Red_Bullet · Postby **Red_Bullet** » Tue Aug 25, 2020 1:59 pm

1. Over flowing of fluid return canister with track use, new revised lower fluid level, combined with an extra filter on fluid return line fixed this. Could be temperature related, my canister is hot side, thinking of moving it to somewhere cooler. Piggy back ecu was a bad idea, although it was done probably 10 years ago now. No issues with belts or alignment. SC is a c30-74, producing around 175 kpa at 7000 rpm. Could fit a smaller pulley for more boost if needed. at 7000 rpm my SC impellar is doing 95,000 rpm, redline for sc is 120,000 rpm. so some room for saftey. Not a lot of torque down low, you still have to rev the crap out of it to make it go, doesn't do much below 4000 rpm.

mx5gem · Postby **mx5gem** » Tue Aug 25, 2020 2:41 pm

That's sounds promising, as my main concern was belts/alignment issues.

I've heard of the fluid level so can manage that.
I'll be using a standalone ecu so that also should be ok.

Lack of torque down low also not a problem, as a) thats how they work b) it spends its life at high revs so <5000rpm is not important at all..

Thanks for the real world advice, much appreciated...

Looks like I may not have to get mauled by exchange rates or customs...

rascal · Postby **rascal** » Tue Aug 25, 2020 3:01 pm

Red_Bullet wrote:1. SC is a c30-74, producing around 175 kpa at 7000 rpm. Could fit a smaller pulley for more boost if needed. at 7000 rpm my SC impellar is doing 95,000 rpm, redline for sc is 120,000 rpm. so some room for saftey.

Out of interest what size pulley is on it?

Red_Bullet · Postby **Red_Bullet** » Tue Aug 25, 2020 5:31 pm

As supplied c30-74

Crank pulley 135
Rotrex pulley 90
Crank RPM 7200
Rotrex ratio 9.49
Rotrex RPM @ 7200 102492
Rotrex max RPM 120000
Percentage of max 85.41%

Thought about fitting an 80 mm pulley, but couldn't be bothered, more time to be gained in improving the nut behind the wheel to be honest.