I decided to add a new exhaust and installed a diffuser to enhance the effects of the belly pans. All done with few modification.

 

Did you have that done at the Dragon?

 

have you noticed a difference in handling at highway speeds?

 

Yes...and....Yes.

The weight savings with the different exhaust and different battery mixed with the addition of the diffuser the car turns, or pivots, easier and much more stable at 'highway' speeds. Will be taking it on the track at the end of the month will get a better feel then, but now very happy with the set up.

 

I'm impressed. Would you mind posting a picture of under the diffuser?

 

I plan to, but for now I am working out of town for the next couple of days. But, I will try to post some under car photo's before heading back out of town.

 

 

Any pictures of the battery and battery box? I've seen the box removed before, but never split like that. Very innovative. Do tell

 

Well its like this........I did take photos of the battery box while we adapted it for the exhaust, but when I left for the Dragon my wife took the memory card with the photos for her camera and.....accidentally erased all the photos on the card.
So, I have to go out of town till mid week and when I return I will take some photos of the diffusers from under the car and new photos of the battery box (inside and out), and post them soon after.

Sorry and stay tuned!

 

In the meantime,

First, we cut a tunnel in the batter box to a depth that would allow the exhaust to run through, but not make the box totally unusable. The tunnel is only about 4" deep and is slightly off set to the left. Group 4 will be handling Oddysey batteries and we installed a smaller race battery on the right side of the box. Battery is in a metal jacket and weights about half of the original battery. And later, the fellows who installed the exhaust just bent the exhaust pipe enough to work with the tunnel and exit the facia.
But, this was just a first attempt and found that with a few small bends in the exhaust we could have dropped the pipe a little lower and could have altered the battery box less.
Though, everything worked really well and looks great from the battery box to the new exhaust.

 

Sorry for the delay, summer got busy early. Here are some photo'es of the Group 4 diffusers that we installed on my GP. They continue the smooth belly of the pans clear through and leaves area for the suspension travel. I took the car out to the track a couple of weeks ago and did notice that the car was more planted in the faster corners or softer apex'es, carried more speed with more positive turn in. So up next would be a Group 4 splitter because of the lighter front now at higher track speeds and better set of tires to take advantage of the better grip produced by the downforce. The car does feel to have more balanced weight with the change in the exhaust and smaller battery in the slower corner.

 

Does the diffuser make a difference?

My thought had always been that in order to make one work correctly you would have to extend the flat floor most of the way along the bottom of the vehicle although I guess if you just had the rear part of it working it would work properly on the rear...

How does that affect the balance though? MINIs already have a tendency to understeer and if you're putting more downforce on the rear wheels then that would make it even more prone to understeer right?

Third question - how does it affect stability at highway speeds? Getting the nice smooth airflow out from the back has to make the rear of the car more stable. Do you think that would allow you to run a more aggressive alignment settings back there to get more rotation out of the rear without compromising road/straightline performance?

Aside from all of that though it looks f-ing cool!!

 

On the track, carrying ample speeds the rear end feels more planted and turn in is more balanced, negating some of the understeer but a splitter would balance the downforce being created on the car. The understeer balance is more in affect in the slower and tighter corners and this is where the straight exhaust and the smaller battery lighten up the rear end making it easier to turn in. With a proper suspension set up or adjustments, you could take more advantage of this. The diffuser works mostly at speeds around 70 to 80mph and above at which time the balance is shifted a little to the rear and the front then will need a splitter to plant the front and balancing the car even more at higher speeds on straights. I believe with the belly pans on the GP, the diffusers affect is apparent at slightly lesser speeds (maybe between 60 and 70mph) compared to MINI's without the belly pans.
On the road, the car is quite more sorted and planted and lane changes are quickly an after thought once committed.

 

Wow, looks very nice. The GP should have came with a similar design stock

 

That has to be REALLY loud on the streets since you eliminated the 2 rear mufflers- What's it sound like to you Steve?

 

Thanks gnarleyOmarley! I know, at least for a GP only part.

bahawton.....It is louder inside, definitely, but mainly on throttle so highway speeds are 'tolerable' . Suprisingly though, living around and travelling though parts of Pittsburgh, no one really blinks an eye cause of all the work vehicles, buses, and cars in various levels of dis-repair that are as loud as the GP. Even over-runs dont raise attention.
I always thought the GP version should of had a more distinct sound beyond the JCW exhaust. This muffler and exhaust set-up was devised by Group 4 Autosports and they do have levels of 'loudness', which my set-up is the second loudest. I have a noticeable addition of power and torque due to the exhaust and muffler change. They are figuring a way not to alter the battery box on the 2006 and older MINIs and keep the straight exhaust benifits and integrate the diffuser at the same time .

 

My big question since it seems you have hit all the other bases........

Is there less dirt/dust accumulation now on the boot/rear glass ?


Nice Mod and great pics. Glad to see someone modding a GP. I hope someday to see a IC diverter cover ( Alta or DDM ) designed for the GP Intercooler. Mostly so I can take that factory plastic shield off the bonnet.

Only way that will happen is if more GP owners get the modding bug.

 

Well Grey, it really increases the amount of spray (also dirt) to occur closer to the rear of the car and eventually collect. Since this has only been on the car since late spring, the amount of dirt hasnt been too noticeable or beyond the norm for now, but come winter that may change. Group 4 also has smaller diffusers that can be attached to the underside of the GP wing which is to help reduce some of the turbulance from the wing and in turn reduce the build up of dirt on the rear of the car.

And in response to the IC diverter, I will let you know cause that is another item that is currently under developement and will be fashioned to work with the GP. Possible soon.... I'll keep you posted.

 

dammm!! great job on the diffuser, it gave the GP a more of a GP look on the rear than stock....

where can we get that exact diffuser, is it custom and how much $$$ are we talkin....thanks

 

Your dome light is on!

 

GP0297......I had the diffuser put on by Group 4 Autosport and it was a prototype that was shown at the Dragon this year in May. The diffuser is custom made for GPs, Wayne and the guys there have had other interested GP'ers. If you look at the photoes closer, I did also switch out the exhaust to a straight exhaust eliminating the JCW exhaust cans. Although I did modify the battery box and installed a race battery, the gang at Group 4 have devised away to keep the 'straight' exhaust and NOT modify the battery box. With the deletion of the heavier JCW exhaust and lighter battery, I have save some weight and added power with the new exhaust. The diffuser works well with the belly pans and has made a difference on the track with handling.
Here is Group 4's link.. http://group4autosport.com/ They are a great bunch of guys enjoying what they're doing and it shows.

 

Heading over to look at the pics.

Any new info on the GP4 Intercooler cover / diverter Steve ?

Thanks !

 

I threw the question past the Group 4 fellows and does not sound as though they have a cover/diverter in the works. I thought there were rumblings about a diverter, but I guess that has gone....for now. I know that they are finallizing a wing for the GP, which I hope to get my hands on in the near future. Its going to sit higher to catch more of the air flow over the roof and be adjustable for track use. I am also looking forward to one of their splitters. The wing will look similar to the GP wing, but will be more useable for when the car will be used on a track, or for an indulgent rump through the countryside.

 

That's a shame. Many MCS owners with this IC would love to dump the bonnets plastic diverter which traps tons of heat and lacks the ability to effetively track the air flow through the intercooler......

It is what it is.........back to square 1.

Thanks

 

The wing looks AWESOME!!!! I was doodling the other day trying to come up with a signature and drew a cartoon GP with an oversized spoiler, looks almost exactly like it. Hope they put it into production, I am going to start saving my pennies now just in case!

kenny

GP0360