There has been so much talk about the new BMW E82 135i being the second coming of the 2002. Will it have the flavor, the appeal, the feel and following. But, we think there is a much higher calling than the 2002 similarity. We think that the 135i can be made to exceed the capabilities of the new E90/E92 M3, even with its incredible motor. We think it can be made into a near super car category car, and at a price that would put all other cars in that category to shame.
And, just like any good project, we started with a plain, blank white version.
The car itself is a great car…nimble size, easy on gas, subtle handling, and all the traditional BMW traits. The N54 motor is a great motor as well….plus, holds lots of promise. The biggest hurdle that we faced was getting the understeer dialed out…and this is not the easy fix as it has been in the past w other BMWs…you can’t just put on bigger front tires or go square all the way around.
Here’s where we’re at so far
- AST 5300 triple adjustable front struts, w remote reservoirs (see our blog write up on these amazing shocks and the great value they represent)
- AST 5300 triple adjustable rear shocks, w remote reservoirs
- UUC upgraded front(27mm) and rear sway bars (19mm)
- Vorshlag front adjustable camber plates
- HyperCoil springs, front and rear
- BMW E90/92 M3 lower front suspension tension arm
- BMW E90/92 M3 lower front control arm
- VMR CSL replica, 19 x 8.5 (f), 19 x 9.5 (r)
- Toyo T1R 225/35/19 front
- Toyo T1R 255/30/19 rear
- BRR custom center section (2nd CAT set delete)
- Meisterchaft GT Race rear
- Hawk HT-10 pads
Still stock….big changes planned here, but we want to get the suspension working right first, before we just throw more power at it.
We didn’t just pick any kit for the suspension, we picked the best, and the best value. Since we know a lot about suspension tuning, and how we can tweak it to meet our specific needs with the valving, we wanted as much adjustment variation as possible. This would also help deal with some of the nuances of the handling of the 135i that we are still dealing with as well. BUT, remember, this is a STREET car (daily driver) that can be taken to the track and driven very hard and very fast, but NOT a track car that can be driven on the street. There is a BIG difference in that statement. We are not making tradeoffs for the benefit of the track, we are adding features and functionality that allow us to alter the performance and handling as needed. When we drive it on the street, we want it to be BETTER than it was stock in terms of ride, smoothness, noise, and handling. When we move to the track, we want the best solution there as well.
One of the key attributes of the AST system that truly sets them apart from ALL others, is the inverted front strut shock piston shaft design. Once you think about this, it makes perfect sense, and you wonder why anyone wouldn’t do it this way, but the usual answer is cost. That’s why the AST is such a great deal….you get so much more value for the $$. Now, the reason for the inverted design on the 5xxx series of struts. On a BMW, the front strut is the upper suspension geometry element, and takes all the load. The bottom control arms take the horizontal and lateral loads on the bottom of the hub as transfered from the wheel, but the strut on the top does it all. So, now think about turning left and doing hard cornering. The wheel is turned to the left, the tire is screaming for mercy and grip, and hence, the tire is pulling the bottom of the wheel, and in the old engineering / physics principle, the opposite is happening on the top of the hub. It is trying to be moved to the outside….and what’s holding it back? The strut. The result is that a normal strut either bows under this stress, and therefore causes stiction at the radial bearing interface where the strut shaft exit the strut body. Now, take the new AST inverted design. The strut piston is nearly 4 times or more in diameter than a regular strut, and therefore, the radial bearing at the top of the strut housing. They do NOT produce stiction at that point, and the strut shaft, due to the thickness, does not flex or bend….meaning all energy is handle the way it should be, and the strut/shock does its job. The other way to think of it, if stiction is induced, the stiction becomes the determining factor of the shock valving, not the shock itself….so, how can you tune the suspension…..you can’t. AST isn’t the only one to do this design….look at the very best shock in the racing world, which is widely regarded as the Penske shock, and their design is the same. Having this capability in a shock for street and track is unheard of….till now. Take a close look at the piston size on the front struts in the pic below….HUGE. AST also thought about packaging and ease of installation…as most remote resv systems have the hose coming out of the bottom of the strut….that’s easier for mfg….but a pain when you go to install and locate the remote resv….you either have to greatly increase the length of the hose (which is not good), or have to locate them where they are not accessible for the quick changes and adjustments you will want to make. You can also now get the AST w “quick disconnect” hoses, furthering the ease of implementation and use.
We also mated the AST front struts to a set of Vorshlag adjustable camber plates….and you all know the GREAT reputation Vorshlag has….and we have NEVER had a set wear out, nor ever induce the awful “clicking” sound that comes from improperly designed camber plates that use inferior radial bearing and monoballs.
We installed the rear canisters in the lower storage compartment in the rear trunk to make ease of adjustment a snap. Just pop open the trunk, lift the storage lid, make the adjustment to the high and low speed settings, then reach forward to the flaps we opened up in the inner carpet, and you can reach the top of the rear shocks as well, so you can get to all 3 adjustments on the rear of the car just from inside the trunk, and we have kept all the stock linings and look…..no racer shortcuts…and the fit and finish and installation work great….no rattles, no disturbing of the amount of trunk space available.
The same is true in terms of ease of adjustment on both the AST struts/shocks and the Vorshlag camber plates. We run -3.5 degrees of camber up front for track days, and then, by just loosening the three strut tower nuts, we can slide the camber plate back to -1.8 degrees of negative camber on the front, which is what we run for street usage. We have run over 15 full track days in 2010 alone…..and we haven’t had one issue….NOT a single thing.
On the sway bars…..you can use stock M3 versions on the 135i, but we wanted adjustment, so we selected the UUC versions, and they have worked great for us.
And, finally, as almost all know to do on the BMW E82, is to upgrade the control arms and bushings to the BMW E9x control arms and bushings. The M3 units are a direct bolt-in, and the front lower control arms add some additional negative camber….but mostly, you get an upgraded (strength) and stiffer bushing…so, less deflection under suspension load. These alone make a huge difference in helping to dial out some of the understeer of the 135i
Next Steps –
We still have more to do on the suspension, as the addition and recent change to the AST and Vorshlag setup dialed out about 50% of the understeer that we still had versus the previous coil-overs set up (this is the third full coilover setup we have tried..and we like this solution a lot), but we did not eliminate it….but the adjustability and flexibility of this setup is amazing, we can go from multiple track settings, to a nice street setup just by opening the hood and trunk of the car…and click (three adjustment knobs to play with), we have just what we need. We are going to be changing wheels and tires for track use, and moving to 18″ wheels from the current dual use VMR 19″ wheels (new wheels and tires likely Breyton GTS-R w Toyo R888′s or Hoosiers).
The brakes also need more help…the stock calipers just can’t produce the bite, even w upgraded pads. The cooling of the front brakes is also a problem.
We’re also not thrilled w any of the intakes yet…..we want a complete system, not just bits and pieces. We need to get some weight out of the car (other than the wheels, tires, and brakes)…but also haven’t seen the right body parts to solve this properly and w the look we want.
Intakes…there are so many different views on what the “right” solution is for this motor (N54). The early products on the market took the easy approach….just yank off the OEM intake system, replace with new filters only. But, if you take a look at intake development on any other turbo motors on other makes of cars, or even NA motors, and the eventual market determination and feedback of what works and what doesn’t, you don’t have to be a rocket scientist to understand what has worked. Add in the other elements that are unique to this car (too much heat in the engine bay, even more heat when you increase the power output), and you have all the ingredients to understand what the product requirements are for a good intake. Plus, while BMW made this car for a street car, if you look at the development on their original F1 turbo motor, look what Audi did on all their race turbo motors, you have additional validation of what is needed. More volume of air, closed system, keeping the heat out of the incoming air, better flow.
Now, there is even a secondary reason why keeping the incoming air cool is important. Most just jump to the conclusion that cooler air means denser air, denser air means you can provide more fuel to keep the same air/fuel ratio, and hence, the more air and fuel, the more power. So, you want an intake that keeps the air cool. But, there is a secondary benefit that is important on this motor as well when keeping the air cool. The turbos, and their packaging, and the cooling of the turbos (oil), is important as well, as they are the main generators of the heat. So, if the turbos are hotter, then the incoming air is hotter since it is just sucking from the engine bay area (as the dual cone air filters solutions do), then you both lose power, AND you heat the turbos more, as the cold incoming air charge actually provides a cooling benefit (why does everyone know that doing methanol injection also cools the motor??….and why wouldn’t this same impact occur from a colder incoming intake charge?)….it does. So….we searched, and found ASR Engr’s intake system. Larger volume, leverages the forced air intake solution, better and higher flowing intake filters, closed system, and sucks air from the outside where it is cool.
In addition, taking notes and lessons from the racing world, we wrapped the complete intake system in gold foil, which is what the leading Porsche and Grand-Am prototype and F1 teams all use to reflect heat and battle heat.
And….the proof is in the pudding….it has worked GREAT.
And, as part of the package from ASR, you get a new charge pipe and Blow Off Valve (BOV) (TIAL brand). This now completes all elements of the intake, as we have already installed an Evolution RaceWorks race intercooler in the front of the car, with larger intake pipe, larger exit pipe (that now connects directly to the new ASR hard pipe charge pipe that leads to the intake manifold).
Here is a pic of the complete Evolution RaceWorks Intercooler kit….including the Carbon Fiber shroud to improve ducting and flow from the front lower grill openning to the intercooler.
You can see the new BOV below, that is part of the new ASR charge pipe that connects to the hard pipe from the Evolution RaceWorks hard exit pipe -
One of the items most surprising to BMW E82 135i owners, when they subject the car to track use, is the brakes. When you first see the 135i, one of the items that jumps out at you as part of this great car is the very large, BMW front brakes. These things look massive….big, big rotors, multi-piston calipers. Surely these can dish out all the performance one could ever need for not only daily driving, but track use. Surely. This has been a weak spot for BMWs in the past, but just look at the size and type of brakes they put on the stock car -
And, if you look at the above picture, you can already see that the calipers have discolored when we took these pics…….too much heat. And the heat scoring on the front rotors (we don’t drive these cars lightly, we drive them hard). So, changes had to be made on the brakes. We have run Brembo race brakes on many of our other project cars, and know how they perform, but we have also been very impressed with the design, quality, technology, weight, and price of the StopTech brake systems. We have had these brakes on many of the American Le Mans and Speed World Challenge race cars we have worked on the last two years, and know they can dish out the performance. Plus, we like the flexibility that they use the same pad design as the Brembos, so we have a very large selection of pad choices…..this has really limited other brake designs in the past. Consistent with intent of this project, and since we also have our Porsche GT3 project car, we put the normal StopTech ST60 6 piston front kit on the 135i, and the STR (full race version) on the GT3. Here is a pic of the great ST60 kit before installation on the 135i -
Key features – 6 piston calipers, incredible strength, ease of pad change, 2 piece floating rotors with special cooling ducts (even the inner hats have special cooling ducts to direct air across the face of the outer rotor face to ensure even cooling across the face of both sides of the rotor). We have also put these on several other BMW 135is, and have several of them being driven in heavy duty track duty across the US, and the brakes have absolutlely delivered. We have NOTHING bad to say, no bad experiences, no bad pad choices, no uneven wear, no issues with quality. Add the price point, and the StopTech solution is a great deal. Plus, we switch from the StopTech performance pads for street us to the PFC-01 race pads and back again, so we again have the perfect combination of race or track setup, and daily driving performance pad with no noise or squealing.
We drove the car this way for many track days, tuning, tweaking, making small spring changes…all to find the right setup. We even changed tire types, to get a feel between regular sticky street tires to full DOT R track tires (Hoosiers). What showed at this point as the next improvement was that we still had a way to go on the grip, and that we needed to maximize the foot print on the front. We had lots of tire space room at the rear, but we needed more rubber at the front.
Enter APEX Wheels….who saw this need long before any of the other wheel manufacturers, and developed a set of wheels optimized for track use, footprint, strength…..and brought a GREAT price along the way as well. Not often, or really, hardly ever, that you get that combination.
The APEX wheels have used every single mm of space to get the biggest rim possible on the front of the car, and still work without rubbing or unnatural acts or body massaging. As mentioned, these wheels are STRONG….just like forged wheels (these wheels use the new “flow form” techonology), light weight (only 18lbs in an 18″ wheel….woo hoo), and great looks. These wheels come in multiple colors options (like Hyper Silver, Anthracite, Hyper Black, and Satin Black). Plus, the look is awesome as well. We now have multiple sets, one for street, and one for track (or, for like the GTGP, we used all the sets to run multiple tires as we tried to get the optimun setup and stick on the track). Here are the various wheels on the 135i.
Not that this was part of the project, but just in case someone wants some feedback on tires…we have now run so many sets of tires into the pavement, that we have a realatively good feel for what works, and how. Our favorite tires in general go something like this -
Street Performance – but you want long life
- Continental DWS
Street Performance – but you want the best price, grip, no noise, lots of stick, then you choose
- Continental DW
- Hankook Ventus V12
- Yokohoma S.drive
Street Performance – but price doesn’t matter, you just want the best tire
- Michelin PS2
TRACK tires -
You want the best grip, last a long time, and have a VERY progressive break-away (this is key for most drivers), then go with -
You want track tires, but you have to stay above a tread wear rating of 180 for rules reasons (like the GTGP rules), then go with -
Yokohoma AD08 or
Dunlop Direzza Sport Z1
You want the plain best track tire, without moving to full slicks – and realize they won’t last as long as Toyo’s – then go with -
Once we had the wheels, tires, and suspension working well for us, the next soft spot was the rear differential….in the stock BMW 135i coupe its an OPEN Diff…..no limited slip at all. And, as those who have 135i’s know, even the traction control is not implemented with the differential, but by the brakes. The DSC on the car is very effective for safe street driving, but HORRIBLE for track use. This is absolutely one of the cars where we turn the DSC OFF when we go on the track. But, what shows its ugly head as soon as you go to the track, is the diff. Once you have the suspension set up for stiff use on track days, you will indeed pick up the inside wheel when trying to put power down. Nothing is more frustrating than having setup the corner just right, you are spot on the apex and hard on the throttle already…..but you get no response, other than spinning the inside wheel……oh good grief. We have to find something to solve this issue. There are quite a few rear diff options on the market for the 135. Even the 335i model uses a slightly different version of the diff. There are two parts here….the type of LSD to choose, and the gear ratio. Popular options for the diff are: Quaiffe, Wave-Track, OS-Giken (clutch type), and true clutch pack LSD. Each one of these has some benefits and tradeoffs, and in our selection, we probably leaned more on the track side use (I know, I know…that’s not consistent with our “objective” for this project car)….but we had used the other choices, so selected what we knew to be the BEST LSD on the market…period. For BMW racers on the West Coast, they know the BEST LSDs come from either Dan at DiffsOnline, or Jim at Performance Gearing. In our case, we went with Jim at Performance Gearing….he built us a custom LSD to our specs. We also went with the larger rear diff housing (there are two sizes that came on the 135/335 model range), as the extra strength and fluid capacity is a good thing. Next, gear choices. There is a higher gear choice that came on the “automatic” transmission cars, so we went w the higher diff ratio (3:46 instead of the 3:08). This gear ratio has worked very well on the track, and has not induced any driveability issues on the street. The “true” LSD nature of the diff does show itself when turning in parking lots (if you listen real close when we make a tight turn, you will hear the inside wheel “chirp” due to the “lock” issue with the rear diff.
BUT, man, does this make another HUGE difference on the track. Not only does it allow us to put the power down…you can just hammer the car when rolling on the throttle, but it actually changes the whole attitude of the car in the middle of the turn. We love it….
Now that we can put the power down, the new matra was …..Capt’n, we need more power….give us more power, please.
Here are the improvements that we had already made to the engine and performance -
- ASR intake, charge pipe, and Blow-Off valve
- Evolution RaceWorks Intercooler and piping
- Powerchip software tune
- BRracing custom mid-pipe, Meisterschaft race rear exhaust
But, the one piece missing from that list was the downpipes. No question on a turbo motor that well designed down pipes can improve performance. So, we implemented several as we evaluated what was out there, how they fit, and how they worked. We also implemented them in two fashions, one with CATS, and one set without CATs. For the “catless” versions, we used the EAS / Macht-Snell version. Great fitment, beautiful welds, great quality, and impresssive performance. For the “CATTED” versions, we used the AR Design. Again, beautiful flanges, amazing shift from the 3″ initial bellmouth to the main downpipe where it mates to the standard center section. And, again, great performance. We loved both these versions.
In this first set of pics, you can see the gains in flow from the AR Design “catted” downpipes vs the stock versions. Plus, you lose some weight as well.
We are still fighting the heat issue from the motor and the oil temps….and we have added data acquisition tools to the car to help us isolate this animal. We had added a second oil cooler, in the left front fender well, with custom ducting and shrouding, and this helped reduce the oil temps, but not to the level we want. We added a Setrab oil cooler in the left front, and ran it in “series” with the right front oil cooler, using an oil distribution block from AR Design….but we just need more air flow to both coolers. This will come with the next major change to the car, as we will now move to make the car like a 135i M version, that is coming next year from BMW…..so, bigger front wheels and tires, more fender space, better cooling for the motor and oil, and cooling to the brakes.
We again must stay true to the objective of this car, and run with enhancements that are consistent with daily driving. No wild wings or custom attachments….that would not be right. So, as many know, we were the test car for Vorsteiner for their prototype CF front lip, and we have the Vorsteiener CF front hood, and then added the BMW Performance CF rear trunk lip. All of these have not only had “look” impacts, but functional improvements as well. We can feel the downforce from the front lip, and the rear has settled a little more as well.
We have not made a lot of changes to the interior, as we have loved the stock pieces, and again, we did not want to deviate from the street car that you can use at the track theme. But we did add to the safety with the BRracing interior roll bar/harness bar/down bar/rear shock tower brace.
We also added a BMW Performance Steering wheel….nice alcantara, cut off bottom….all the better to hang on to when flinging thru the corners….woo hoo.
If you look closely at the picture, you can also see some gauges that we added to the car to help us monitor the heat issues that we have been having. The car comes with an oil temp gauge in the main gauge panel, but you can’t monitor any other functions while driving (at least not safely). So, we found what we think is a killer “win-win” solution for gauges. Garmin, the company known for their GPS solutions, offers a feature on some of their systems for Eco-friendly driving, so that you can monitor the gas mileage. BUT, what a lot of people don’t know, is that they added a whole “gauge” set option. They have an interface to the OBDII port that collects all the real-time engine data. You can then select the gauge options you want to display, and for us, we made one of them the water or coolant temperature. In this way, I can compare the oil temp and water temp at the same time. This has been very helpful. The price is great too….about $200 for the gauge, and it includes a full GPS system.
Here are some pics of the Garmin installed, with the OBDII cable connected (you can see it in the above pic of the steering wheel, look down at the lower left hand corner of the picture, where the OBDII port is, and you can see the cable w the red tag on it. We then ran the cable up inside the dash to hide it and make the install cleaner…….and for power we just plugged it into the center console outlet.
That’s it for now….but there is always more….always.