General Q&A/Troubleshooting

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Euroboidrew
Posts: 8
Joined: Mar 20, 2024 12:38 AM
Location: Virginia Beach

General Q&A/Troubleshooting

Post by Euroboidrew »

I had a few questions to run by all of the E28 experts.
1. Looking to do a 2.5 head swap within the next 6 months. Any tips, suggestions?
2. Curious about an issue I've been having with my transmission when the car was running. It got stuck in gear when I had it running and after I had it parked for a month. Also, it refuses to go into reverse. I can get it into reverse, but it immediately pops out of gear and doesn't want to go into gear. Thoughts? Possible Fixes?
3. Horsepower Limits on stock 2.7 Block, 2.5 head, and the transmission?
4. Is there a 6-speed conversion out there for the M20B27? I think a 6-speed transmission would be much more desirable than the current 5 speed transmission. I have not been able to find a definitive answer or guide to this question so I ask all of you, my fellow brethren if you may guide my in the right direction.
5. Upgraded Differential? End Goal with the car is 500whp (turbo-charged obviously), I don't know the exact specs of my E28 and all of the parts that follow.

If you have grueling made it this far, thank you. Any Tips, Advice, or guides are greatly appreciated as I am majorly starting to love this car more and more each and every day. (Even though it doesn't currently run), I am looking forward to having a fun, comfortable car and get this OG back on the road in due time. Thank you all.

Photo of my E28: https://mail.google.com/mail/u/0?ui=2&i ... w1872-h966
Shawn D.
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Re: General Q&A/Troubleshooting

Post by Shawn D. »

4. There's no "conversion," but there are 6-speeds that fit the bellhousing pattern. Look for later 3-series with engines with the same bellhousing pattern. IMPORTANT: These transmissions will not have the reference sensor locations, so you'll need a different engine management arrangement from stock (yes, you'd likely use one anyhow, but it's mandatory for this mod). Obviously, mounting, shifter, and driveshaft mods are also required.

5. The stock medium-case diffs hold up to TCD S2 systems, so they're incredibly stout, especially given that E28s are tire-limited. You can also swap to a large-case diff from an E23 or E24 (plenty about this in the archives, no need to go into detail here).
Euroboidrew
Posts: 8
Joined: Mar 20, 2024 12:38 AM
Location: Virginia Beach

Re: General Q&A/Troubleshooting

Post by Euroboidrew »

Shawn D. wrote: Apr 10, 2024 5:55 AM 4. There's no "conversion," but there are 6-speeds that fit the bellhousing pattern. Look for later 3-series with engines with the same bellhousing pattern. IMPORTANT: These transmissions will not have the reference sensor locations, so you'll need a different engine management arrangement from stock (yes, you'd likely use one anyhow, but it's mandatory for this mod). Obviously, mounting, shifter, and driveshaft mods are also required.

5. The stock medium-case diffs hold up to TCD S2 systems, so they're incredibly stout, especially given that E28s are tire-limited. You can also swap to a large-case diff from an E23 or E24 (plenty about this in the archives, no need to go into detail here).


Thank you for the info Shawn. I think versus modifying the entire driveline, as I want to keep the underneath clean and looking nice. I'll stick with the 5 speed. My only reasoning was since I love taking road trips, I feel like the 6 speed would be more desirable but I can suffer with it for awhile. I will be reading into it to see if its feasable. As I'm doing most of this on a tight budget, with the biggest expenses being a little body work, and the 2.5 head and getting the OG block decked and polished. Other than that, its just OEM gaskets etc; up until that point. Thank you for your feedback :D
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