My E28 535is Turbo Buildup Thread by Brad D.

8 minute(s) of a 53 minute read

Recently I had become curious what my car would sound like without a cat so I set out to remove it and replace it with a test pipe. Removal was no where as easy as I had anticipated it would be. I made the mistake of not flanging the connection and using u-bolt style clamps which cut into the metal and almost "swage" the two pieces of pipe together. This makes it hard to pull the pipes apart. I ended up having to cut a notch into the cat with a die grinder to get it off. 

When I eneded up getting it out of the car I was greeted with a cat that sounded like a maraca. The brick is pretty much wasted being blown apart and melted. This is with about 8 months of driving and tuning. It definitely did not hold up well and had to have been costing be power. Looking through the matrix with a light shows a good portion of what was left is clogged. I cut a section of tubing to replace the cat and clamped it in place with Dynaflex Truseal clamps which are awesome. I haven't driven the car far yet with it out but the exhaust note is almost unchanged at idle but sounds so much raspier and has much more character than it did with the cat under load. 

It's much worse even that it looks in the pics as it is has crumbled inside the matrix and it is hard to get it to show up in a pic.

Well, I can say that after having driven the car today without a cat it sounds a little throatier under load but definitely not loud. It doesn't even come close to loud like a Tri-Flow on an NA car. Boost builds a few hundred rpm earlier and I would be willing to bet that post turbine EGTs are also down (I don't monitor them). It also feels like it revs much freer now.

12/7/2008

Dyno results here.

5/20/2009

Tonight I finished my heat shield for my intake. I wanted to prevent the intake from ingesting hot, underhood air so I fabbed up a nice little heat shield from some sheet metal and sprayed it with plastidip and trimmed it with some vacuum tubing. It looks pretty decent. I have some insulation I may add to the outside of the box, but I'll see how this does. I have some new stainless hardware to replace the crusty bolts on the compressor cover, I just didn't get around to it. 

09/21/2009 

Update: 

It's been a while since I have updated this thread even though I have done a fair amount of work to the car. I just thought I would compile some of my mods here for future reference in this thread. I just completed my wasted spark install which was highly successful and a very worthwhile mod. A few months ago I added Homelink to the car so I can get rid of all of the openers that were scattered around my car. I also updated the two gauge dash pod I had to a three gauge pod, but I don't have any good pics of this mod yet. 

Some upcoming mods include poly UCABs and poly subframe bushings for Ireland Engineering. I will also be modifying the rear subframe so that camber and toe are adjustable.

11/28/2009

Today I installed my S3.25 that I found at the local PnP. The fluid that was in it was super clean and the magnet had almost no accumulation on it. I also replaced all of the half shaft bolts. It was filled with M1 75W-90 LS synth gear oil. It went in very smoothly and took about an hour. 

Impressions: 

For reference I am changing out my S3.73 that I was running. 

I am going to get a speeding ticket. I am used to cruising at almost 3000rpm at 70mph, and now I am under 2500rpm. It just doesn't "sound" or feel like I'm going as fast as a I am. 

First gear is usable again. Second gear pulls almost as hard as before but is much more usable. It still has massive wheelspin, but since you get more time in gear, I think it is actually faster. Third is awesome and it feels like it just wants to pull forever. Cruising is must nicer too as it's like I actually have an overdrive gear again. 

I can't wait to get my new Clutchmasters clutch from Todd so I can turn the boost up and see what I can get out of this turbo and injectors. This diff will suit more power very nicely and is a huge improvement over the short 3.73.

12/1/2009

I have another observation that is worth noting. The diff loads the engine differently and spools the turbo much sooner. In 4th gear, almost 500 rpm sooner. In 5th it's almost 800rpm sooner. This has led to me having to retune a portion of my fuel map as there was never any boost in that area before. It's definitely a problem I can deal with.

12/2/2009

Well, I got a little bit of tuning done tonight on the way home. The lower boost onset region is finished and I am almost tuned to 11psi (was at 8.5). It definitely feels a lot better now and the turbo is really coming alive and it feels like it complements the diff nicely. It should be dry out tomorrow ( I found the rev limiter a couple of times) and I'll try to get it fully tuned at 11-12 psi. The amazing part is that the clutch hasn't flared yet, but if it does, I don't really care.

12/3/2009

The car is now fully tuned to 12psi, and it feels great. It feels really fast and pulls awesome on the freeway. The turbo is really starting to come into its efficiency island and hit very hard. The diff is definitely a welcome addition at this boost level. It still spins in second, but not as violently which means better acceleration. And the amazing thing.....the clutch is holding....

It held a full pull to redline through 4th. I lifted at 6100 as I was running out of real estate and that was right about 130 indicated. It scoots. I can't imagine this thing at 17psi.

12/6/2009

I would like to point out that I am able to run 0.030" gap with no spark blowout at 12psi running a MSD wasted spark setup. I know there have been people who have reported blowout at boost lower than this at this gap running the stock ignition system. Now I just need to track down a spare flywheel so I can have it machined so I can just install it when I do my clutch install.

4/13/2010

 My lazy butt (more like way too busy) still hasn't done the clutch yet but have been daily driving the car at 12 psi. I am almost at 80%DC on the 42lbers at 6400rpm. I am totally comfortable running them to over 90% which means I have a bit of headroom left in them. I could also raise the fuel pressure to gain a bit more flow. For now though they are supplying enough fuel to keep the party fun.

1/3/2013

Wow, I haven't seen this thread in a while. A quick update which isn't very exciting - the car is running well at 12psi and has been since this thread was updated. It's crazy to think that the last post in this thread was 2010. Time flies when you are having fun.

I did finally put the clutch in last summer. It has been great. Pedal feel is basically like stock and engagement isn't touchy at all. All in all I would highly recommend that clutch for anyone wanting great driveability with good holding power.