After a much longer timeline than I originally expected, my 1974 3.0 CS is finally back together, sorted well enough to drive hard, and I wanted to post a proper update for the forum crowd that has followed this project and helped me along the way.
The short version is that I am extremely happy with the end result.
This car is now running a freshly built/refreshed high-compression Euro 3.5-liter six sourced from a European-spec 1989 735i, paired with a newly refreshed 5-speed. The goal was not to build some over-modernized restomod, but to keep the car feeling mechanical, raw, and true to the character of an E9 while giving it the torque, sound, and urgency I always felt the chassis deserved.
The engine build centers around the 3.5 bottom end, higher compression, a more aggressive camshaft, and dual carburetors, along with a freer-flowing exhaust. The result is a car that feels dramatically stronger everywhere in the rev range than it did with the original engine. Based on the build, it should be producing north of 230 hp, versus the original rated 174 hp of the stock US-spec setup, and more importantly it feels alive in a way the car simply did not before.
What I love most is that the car still feels completely analog. There are no computers, no ABS, no traction control, no filters between you and the machine. Just steering, throttle, sound, chassis movement, and whatever talent or lack thereof the driver brings to the equation. That is exactly what I wanted.
For those interested in the broader project, I’ll continue to reference the project thread/build sheet because I know many of you care about the specifics: engine source, compression approach, cam choice, carburetor setup, jetting, exhaust, transmission work, and the inevitable sorting that comes with getting a car like this really right. As with most projects, getting to the finish line took longer and involved more details than expected, but standing here now, I can say it was worth it.
One unexpected confession: before this engine transformation, I was starting to get a little bored with the car. I liked it, I appreciated it, but I was not fully in love with it. That has completely changed. With this new engine, the way it pulls, and especially the way it sounds, this has very quickly become my favorite car to drive. That is saying a lot, because the garage also includes a Ferrari GTC4Lusso and an Alfa Romeo Spider, both of which I love for very different reasons. But this E9 now has a kind of charisma that is hard to overstate.
The real test comes next: on Saturday I head to Arizona for the Copperstate 1000. Some of you may remember that I took this same car on the event two years ago with its original engine, and it broke down on the last day. So there is something especially satisfying about coming back with the car in this form and, hopefully, doing the event the way it was meant to be done.
Thanks to everyone here who has followed the journey, answered questions, given advice, and generally helped keep me pointed in the right direction. I genuinely appreciate it. I’ll keep posting updates, and if there is interest I’m happy to put up more of the build-sheet details and driving impressions.
Here’s a short driving video on Highway 74 out of Palm Desert. The road is spectacular, the car sounds terrific, and for the first time in a while I feel like this project has really delivered on the vision I had for it.
Also attached is the invoice from Carl Nelson for the engine and 5 speed, if you are interested.
The short version is that I am extremely happy with the end result.
This car is now running a freshly built/refreshed high-compression Euro 3.5-liter six sourced from a European-spec 1989 735i, paired with a newly refreshed 5-speed. The goal was not to build some over-modernized restomod, but to keep the car feeling mechanical, raw, and true to the character of an E9 while giving it the torque, sound, and urgency I always felt the chassis deserved.
The engine build centers around the 3.5 bottom end, higher compression, a more aggressive camshaft, and dual carburetors, along with a freer-flowing exhaust. The result is a car that feels dramatically stronger everywhere in the rev range than it did with the original engine. Based on the build, it should be producing north of 230 hp, versus the original rated 174 hp of the stock US-spec setup, and more importantly it feels alive in a way the car simply did not before.
What I love most is that the car still feels completely analog. There are no computers, no ABS, no traction control, no filters between you and the machine. Just steering, throttle, sound, chassis movement, and whatever talent or lack thereof the driver brings to the equation. That is exactly what I wanted.
For those interested in the broader project, I’ll continue to reference the project thread/build sheet because I know many of you care about the specifics: engine source, compression approach, cam choice, carburetor setup, jetting, exhaust, transmission work, and the inevitable sorting that comes with getting a car like this really right. As with most projects, getting to the finish line took longer and involved more details than expected, but standing here now, I can say it was worth it.
One unexpected confession: before this engine transformation, I was starting to get a little bored with the car. I liked it, I appreciated it, but I was not fully in love with it. That has completely changed. With this new engine, the way it pulls, and especially the way it sounds, this has very quickly become my favorite car to drive. That is saying a lot, because the garage also includes a Ferrari GTC4Lusso and an Alfa Romeo Spider, both of which I love for very different reasons. But this E9 now has a kind of charisma that is hard to overstate.
The real test comes next: on Saturday I head to Arizona for the Copperstate 1000. Some of you may remember that I took this same car on the event two years ago with its original engine, and it broke down on the last day. So there is something especially satisfying about coming back with the car in this form and, hopefully, doing the event the way it was meant to be done.
Thanks to everyone here who has followed the journey, answered questions, given advice, and generally helped keep me pointed in the right direction. I genuinely appreciate it. I’ll keep posting updates, and if there is interest I’m happy to put up more of the build-sheet details and driving impressions.
Here’s a short driving video on Highway 74 out of Palm Desert. The road is spectacular, the car sounds terrific, and for the first time in a while I feel like this project has really delivered on the vision I had for it.
Also attached is the invoice from Carl Nelson for the engine and 5 speed, if you are interested.
