R53 17% Pulley upgrade

[AJV8]

Hi all,

New R53 owner here. Got this as our runaround to go alongside the GLC63 👍 and absolutely loving being back in a manual, small car.

I’m wanting change the pulley on the supercharger, along with belt and plugs. The garage I’m speaking to don’t have a puller for the pulley so I was wondering if there’s anyone in West London that might have one I could borrow for the job?

Also, any suggestions on powder coating would be great. Currently looking a little too black for my liking:

[E-bmw]

AJV8 said:

Also, any suggestions on powder coating would be great.

Powder coating what?

If you do go down the pulley route you will need to get the car remapped correctly, not just a generic download to keep the engine safe in the long run.

The ECU in these does not auto-compensate & it WILL be running lean above about 3 or 4k RPM, which is never good for an engine.

[AJV8]

I thought that the ecu automatically adjusted to the amount of air it’s receiving?

[AJV8]

From Lohen’s website (below). I already have uprated plugs and intercooler so temps won’t be an issue. If you could confirm the ecu situation that’d be appreciated.

[E-bmw]

The ECU does not take account of an increased pulley.

Above about 3 or 4k IIRC the ECU is in open loop control & is running on standard maps, at this point on an increased pulley it WILL be running lean.

[The test driver]

E-bmw's advise is pretty solid when you consider the R53 JCW (210bhp) "only" ran an 11% reduced pulley and had bigger 380cc injectors plus a remap as part of the package.

Pretty sure the 200bhp JCW package was the same but without the injectors.

Theres a really good owners group on FB called surprisingly......R53 Owners Club! Which is worth joining as theres some extremely knowledgable people on there.

[CO2000]

Instead of just changing the pulley consider removing the Supercharger to service it (if it hasn't been done already) and change the pulley at the same time and it will be easier to do so (maybe with just a hydraulic press rather than the special puller)

[E-bmw]

CO2000 said:

Instead of just changing the pulley consider removing the Supercharger to service it (if it hasn't been done already) and change the pulley at the same time and it will be easier to do so (maybe with just a hydraulic press rather than the special puller)

Correct, the "Kavs" (others make them also) type that screw on have an increased possibility of failure causing shaft "nose" damage that will basically mean a new 'charger is required.

"Front-end maintenance mode" on the mini isn't as difficult as it looks for a decent home mechanic & will allow other jobs to be done at the same time with ease.

I built a trackable r53 with 17%/plugs/intercooler & other mods that made 235 at the crank and it was a real hoot to drive, but the same car only made 220 & had pretty major fuelling issues when I turned up to have it mapped as I did the mods myself before turning up to get it mapped after driving it at under 3k rpm on the way there.

Edited by E-bmw on Wednesday 1st June 11:15

[AJV8]

Thanks for the comments all. I don’t have Facebook so that group isn’t an option for me unfortunately. Kit from Lohen is due to arrive on Monday so it sounds like I’ll need to then find somewhere for a map doing.

I’ve always used Litchfield on the Porsches and Mercs but they don’t tune Mini’s so any suggestions around the London area would be greatly appreciated 👍.

Cheers,

[Ozzer2006]

Probably the best mini specialist is 1320mini but is in St Neots which is about 45 /50 miles up the A1 from London.

[AJV8]

Fab, thank you 🙏

[AJV8]

Well to put the debate to bed on remap with the smaller pulley, I had the below response from 1320:

“ Hi Adam

You dont need a tune as with the extra boost the smaller supercharger pulley produces and this raises the fuel pressure which compensates.

Probably best to put it on a dyno just to check the Air Fuel Ratios are OK”

So it would seem that I’m fine as long as I don’t put the bigger plugs in as well. I’ll try and get it in for a map with the bigger plugs before I go to cornwall, if not there’ll likely be a set of NKG injectors going begging.

[Ozzer2006]

1320mini are definitely the go to guys when it comes to the r53/r52. Glad that they gave you the info you needed. I have an r52 with an engine built by them and it runs better now than it did when the car was brand new.
Love the look of yours by the way definitely agree about the wheels too.

Edited by Ozzer2006 on Friday 3rd June 19:20

[AJV8]

Thanks Ozzer. Yea it’s Ceri’s not reassuring that I’m not going to be destroying my the car by doing the pulley alone. Thanks much, she’s getting there that’s for sure. A previous owner had a penchant for red so it’s taken a while to get rid of all that. Funnily enough, now that the wheels are spaced a bit and have silver bolts in, they are growing on me. Hoping the white bonnet stripes I’ve got coming break up the black sufficiently to not need to powder coat the wheels. It’ll definitely look a little less gangster with the wheels dark grey / silver though. Time will tell.

Cheers for the suggestion on 1320 👍

[AJV8]

Car has now had the pulley, also had new plugs as I called 1320 again to confirm whether I needed a map with the colder plugs. They said definitely not, that I COULD if I wanted one but they wouldn’t recommend it.

Car is transformed, really is even more fun to drive now 👍👍. Also stuck myself some go faster stripes on and have done the spacers on the wheels. That’s it for the modifications for me now, on to enjoying driving (until something breaks).

[E-bmw]

I would be very wary if I were you as I can 100% guarantee that over 4000 rpm the car will be running lean as the standard map for these cars is not a compensating map over 4000 rpm, it is a fixed map and you are putting more air in for the same amount of fuel.

You would also get around 15 to 20 bhp more for a correct map.

[E-bmw]

https://www.minitorque.com/threads/what-size-pulle...

Check out the first reply.

[AJV8]

Thanks guys, but who is it that’s actually saying this stuff, other than someone on a forum? I’m going to take the word of a renowned garage that fit these kits, and tunes r53’s, over someone on a forum, every day of the week.

It’s not really in 1320’s interest to turn down the business of mapping someone’s car so I struggle to see why on earth they would tell me not to bother if it actually needed it.

I asked if I should book in for a map anyway and they told me that they really wouldn’t bother. That the only reason I might do it would be to eek out a tiny bit more fuel efficiency.

Have you guys experience that suggests otherwise?

[and31]

1320 fitted the 15 percent pulley on mine,standard map,been fine for the last five years.

[E-bmw]

AJV8 said:

Have you guys experience that suggests otherwise?

Yes, as I said originally, when I turned up to get mine mapped at Big Fish, who have done lots of these before the AFRs were ridiculously lean at high RPM before mapping.

The standard ECU was developing 220 pre-map & 234.7 afterwards.

It is a well-known fact that these ECUs are on a fixed map from 4000 rpm, so by putting more air in you are running more & more lean above 4000 rpm.

Here is a thought for you, the web forum I linked to has a lot of very highly experienced guys on these cars, one in particular has a specialist workshop for these cars, why not go on there & ask?

But it is entirely up to you.