Another Eurosport Twinscrew revival

[robb1887]

If you've seen the ESTS parts/discussion thread it was apparent I found one of the unobtanium kits mostly complete.

I will be installing it into my 1 of 1 Mcoupe and while I had always planned to turbo the car, plans change as does life, so here we are. I'm not really sure how to document in the F/I section as I don't feel it good to double post everything and I'm at post 409 of my build thread in the Z3 subforum as this car has "been in process" for a while for boost.

Initially plan to install on the "stock" ESTS pulley and tune.

I had already started to collect parts for a dedicated boost motor build, and will be lowering the pulley and uping the injectors when the S52 comes out and the Franken motor goes in.

The ESTS install starts at post 409 as stated in my build thread https://www.bimmerforums.com/forum/s...5#post30861735

I'd love some input hopefully from some of the ESTS guys on "golden" compression ratio for these as I plan to do custom pistons and rods to target the ESTS power delievery system. I saw jmc put in a specific 0.094 HG that made better power than his 0.140, but I'm not savvy enough yet to say what the differences are there.

[pbonsalb]

How much boost do you want to run? Will you ever want to run more? What octane fuel will you be using? Is the ECU stock with a tune or standalone?

[robb1887]

How much boost do you want to run?
As-built is 6-7lbs iirc

Will you ever want to run more?
I'll eventually go to a smaller pulley to maybe 11-12

What octane fuel will you be using?
93 Octane is readily available, I do not plan to run an E-85 (et all) due to not readily available around me

Is the ECU stock with a tune or standalone?
Stock ECU with tune from ESTS originally, I have all the ROMraider and cables to "self tune" later but may just go straight to TRM as they were the "people" when these kits were new.

Replies in red

[pbonsalb]

A twin screw makes full boost at low rpm, in the knock window, 11-12 psi is a fair amount for 93 pump, and a tuned stock ECU has no safeguard beyond the knock sensors. I’d err on the less risky side for compression. I don’t think I would use a 0.098 MLS. That probably gives 9.5 to 10.0:1 compression.