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Is over to the dark side
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515 Posts
Discussion Starter #1
HI All,

I've been speaking with Lohen about how to increase the performance of my JCW to a significant level yet keep the car relatively standard. The guys suggested a 230BHP conversion including the following:

Alta Enlarged & lightened crank pulley
Alta Alternator pulley
GRS Enlarged Intercooler
Replacement belt to suit
Iridium Spark Plugs

Sounds very good and excluding the intercooler, all would look relatively standard.

First question was whether anyone had such a conversion on their JCW and whether you feel 230BHP offers good performance gains over standard JCW?

The second question was for all people wih tuned cars, does anyone have any problems with Mini honouring TLC packages with tuned cars? That would probably be the biggest put off for me.

Thanks for your help.
 

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2,209 Posts
my dealer knows mines a GTT 260 conversion and simply puts the bits i don't want changed like air filter and belt in the boot of my car. I have never had a problem.
 

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Turbo Schmurbo...
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822 Posts
Alta Enlarged & lightened crank pulley
Alta Alternator pulley
GRS Enlarged Intercooler
Replacement belt to suit
Iridium Spark Plugs
.
Alta Enlarged & lightened crank pulley:
Risky. Some swear theres nothing wrong with it but a few shops in the US caused a ruckus about it being the common link with a lot of damaged engines. The stock unit on the GP is light enough not to lag the engine but still has the vibration damper to stop any vibrations to the crank being transferred to the oil pump housing. People who sell the crank pulley will defend it and say oil pump failures have nothing to do with it... however, I'd rather not take my chances (and I'm not alone either).

Alta Alternator pulley:
Only needed with the crank pulley, again personally the risks (and costs) don't outweigh the gains.

GRS Enlarged Intercooler:
Very good product Graham (who makes these) is very talented and this products been proven on many high powered cars. However I run the GP intercooler on my tuned MCS running 16PSI of boost and a previous dyno result of 199whp/235bhp... and its fine.

Replacement belt to suit:
Again, only needed with the above.

Iridium Spark Plugs:
The GP's plugs are upgraded anyway so not really necessary unless you need to replace them.

On a GP I don't think thats the way forward (unless all you want is a long mod list), Lohen may have experience in tuning but your best speaking to GP owners in a similar boat. I don't think the difference will be noticeable enough for the money spent. I'm sure "Snowie" on here will be very happy to help if you drop him a PM. He has been through the ins and outs of tuning a GP and spent more than he probably had to finding the right combination. The main problem being the GP is "pre-tuned".

The easiest upgrade for a MCS is a smaller (15/17%) supercharger pulley (got me roughly 20-30hp for less than £300!), however, on a JCW or GP the 11% pulley is notoriously hard to remove hence why a different approach is needed.

I'm sure plenty will use some marketing to explain how that the above is right for your car but on such an limited, expensive (and stunning) car I suggest you hold on to your cash until some proper research on real world examples has been done mate. 15bhp over what you have (or may not have) is not enough for the money imo.

Note: The GP is unlikely to ever need a remap so stay away from things like superchips or bluefin.. they don't suit it.

Edit:

Just to show most of the stuff on the GP is ok here my spec:

ALTA V1 15% Pulley Reduction & Belt -11% on a GP
NGK Iridium (BKR7EIX) Spark Plugs - Same (Near enough)
05' MCS ECU Map - GP has a better map
JCW GP Uprated Intercooler - Same
JCW/M Air Intake System & ITG - Same, bar the ITG filter
JCW 380cc Injectors - Same
JCW Catback Exhaust System (Without flat section) - Same
Janspeed 4-1 Manifold & Sports Cat - Not on GP

As you can see, just the pulley and manifold that separates them really, warning though... the manifold is loud. Also I believe the JCM4-2-1 manifold is better to suited to the GP.
 

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Is over to the dark side
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515 Posts
Discussion Starter #4
Oh...sorry...my site name is misleading. I sold my GP a couple of months ago so am now driving a JCW.

Wouldn't have touched the GP due to it's special edition nature but the JCW is different.

Was the Alta pulley replacement failures based on cars that were perhaps pushing out 260BHP+, i.e. more extensive mods, or was this also on 220/230 conversions? I think if you take the pulley options out then power increase is limited. Correct?
 

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Turbo Schmurbo...
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822 Posts
Same goes for JCW really, that has the same 11%.

I'm not sure on the full details of failures and power of them but I know they deemed it the common link. Still its a no no for some and a yes for others so its personal choice. I'm keeping my beloved S as long as I can so I'm steering clear. Roland GTT recommends a oil pump rebuild at 50k he has said this is nothing to do with the crank pulley of course, that may be the case but I still see it as a risk.

I don't think the crank pulley makes too difference to bhp, its more engine response if you have an early (heavy) stock pulley. Also note the Alta is all aluminum, anyone into engineering will tell you an aluminum fit to a steel crank is not a good idea.

If you want my honest opinion all of the above are a waste of money better spent on a better performance head and/or cam (like snowies car) or more recently black20vt who has the most powerful JCW on stock pulley and head:

http://www.mini2.com/forum/engine-drivetrain-tuning/157448-most-powerful-m45-11-john-cooper-works-world-terms-conditions-apply.html

As you can see... no crank pulley... its your money mate I'm just offering good advice.

Good luck with it :D
 

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M3 CSL
Joined
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724 Posts
HI All,

I've been speaking with Lohen about how to increase the performance of my JCW to a significant level yet keep the car relatively standard. The guys suggested a 230BHP conversion including the following:

Alta Enlarged & lightened crank pulley
Alta Alternator pulley
GRS Enlarged Intercooler
Replacement belt to suit
Iridium Spark Plugs

Sounds very good and excluding the intercooler, all would look relatively standard.

First question was whether anyone had such a conversion on their JCW and whether you feel 230BHP offers good performance gains over standard JCW?

The second question was for all people wih tuned cars, does anyone have any problems with Mini honouring TLC packages with tuned cars? That would probably be the biggest put off for me.

Thanks for your help.
If you are interested in your bhp figures I would recommend to dyno the car first so you have a benchmark. Then go from there really. I would avoid any parts you don't really need.

Just to give you some idea of basic mods that will give you power I used to be at 225bhp with the following mods (on stock Cooper S not a JCW car):

15% pulley
GP I/C
JCW airbox
380cc injectors

My engine was low on compression on cylinder 2 as well and BMW replaced the engine under warranty so I wouldn't worry too much about warranty claims with some mods as most dealers don't know or are not bothered

I would swap the supercharger pulley rather than fit a light weight crank pulley. Stick with the stock crank pulley with the dampener on:)
 
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