E30 S85 V10 Motor Swap
Here we go. Another crazy one off build. What’s it going to be this time? Another wide body? Another motor swap? Another boosted car? YES, YES, YES!!!
So lets start from scratch. Here we have a 1989 325i that recently came in for one of the most insane builds we’ve had to date. Cody is one of our returning customers, having already done our 2M GT3 widebody just last year. He wanted to turn it up another notch with this E30, and embark on a very adventurous build. The plan all started around making the S85B50 V10 from the E6X M fit on the chassis while retaining much, if not all, of the usability of the original car. As one can imagine, this is not a plug and play motor swap. Inspired by our V10 E46 GTR build, we began working with the body in white that Cody provided us. Almost everything on this build would need to be bespoke, as there are very little parts available for these kinds of swaps.
Step 1: The Plan
We have the car and the ideas but where does a build like this start? Just like building a home, you really need to start from the ground up. First and foremost, we started by determining the wheels and suspension setup that we would be using. Although they won’t be the first parts installed on this car we needed to determine the direction we were headed with this build. Street car? Track car? Show car? Garage queen? SEMA car? It’s really hard to choose just one aspect to build off of, so we try to accommodate each client’s request. In this case, we focused on building the perfect dual-purpose setup, a street car that is track ready.
Step 2 – Laying the Groundwork
It was decided that this build is going with a S85 V10 Motor from the BMW M5/M6. Knowing that we are going to retrofit this motor into this chassis is a job that will need HEAVY modification in order to not only make work but make it work properly. After we sourced and purchased all the necessary parts such as the engine, transmission, steering rack and suspension. The first mock up began. We started by removing the core support and the front end, and then sliding the motor between the frame rails to determinine how we would need to modify the chassis to make the motor and transmission fit properly. After we were satisfied with the fitment of the motor, we fabricated a custom set of engine mounts that rested the motor low in the car, with room to spare for any vibration or movement. Luckily, the bank angles of the V10 and it’s short block length allowed us to have a very low and far-back center of gravity, even more so than the iron-block inline 6 that came in the car initially. Next, we began to modify the front subframe so that we could fit a faster factory steering rack that we sourced from a newer Z3. To accommodate the low mounted engine, we also modified the factory oil pan so that it would not interfere with the newly reinforced subframe. We carefully designed a custom steering steering shaft using gorgeous 4041 Chromoly steel pieces from Flaming River that would travel the least distance with the fewest amount of joints, all while still utilizing the factory splines and clearing the header with room to spare.
Once the headers were clear of obstruction and the motor was mounted properly, we began working on a one-off exhaust setup. We utilized a custom muffler setup while still maintaining true dual flow all the way out the back of the car. The customer wanted an OEM style exhaust appearance, keeping in tune with the aesthetic direction of this build. We opted to use the factory pinch-collector headers while the remainder of the full system would be 304 Stainless Steel in 2.5″ diameter, which is the same size as factory. A small exhaust diameter and short length provide the optimum balance of performance, while maintaining that distinct BMW V10 sound. At this point, progress has been made consistently, with relatively little hiccup. The massive motor and CATUNED suspension are fully mounted in the car, and we are beginning to make the plans for the next steps: installing an ESS supercharger, a one-off driveshaft, and a custom-built differential designed to manage all that power.