2003 325i ESS Twin Screw

I have had my car for six months now, first car purchase so price was essential in getting the loan. I know it would be better to start with a better base platform and that this can end up costing me more money in the long run than getting an M, but it is the route I am choosing to go. Plus I love my four doors.

I ordered the Twin Screw kit last Friday and purchased everything I need for the manual swap today. Catless headers and custom 2.5" pipes will be in the next few weeks. M3 subframe swap or sticking with the 3.46 and getting a LSD is the only thing I am on the fence about. Depends if I can handle the cruising RPM with 5 speed.

This post is just the beginning of the transformation from a nice car (I think) into a decently quick car that will hold it's own. I will include many photos along the way and hopefully it works out well.

Thoughts, input and criticism welcome. Excuse the long post.

You will love the twinscrew. That's all!

I have mine for 6 years, no issues

Originally Posted by paraklas

You will love the twinscrew. That's all!

I have mine for 6 years, no issues

Werd! I've had mine for 7 years and still love it. Think I'd love it more if I could go TS3... LOL

sub'd! 3.46 w/ lsd will be a GREAT combo with the added power when you do the 5spd swap. 3.46 gearing shouldn't be a problem to you for highway cruising on a 5spd at all. Many people around here have it and I don't think I've ever heard anyone complain about cruising RPMs even though they'll be a BIT higher. 3.46 is ideal on a 5spd IMO. You'll love the TS2 I've heard MANY great things about the kit. Make sure you get it on a dyno asap, would love to see numbers in compassion to AA's kit. Also why didn't you go with the AA kit out of curiosity if you don't mind me asking?

I had it narrowed down to aa and ess. The twin screw low end is what convinced me. My eventual end goal is to swap m54b30 internals in and go ts2+. Even With the 3.62 my cruising ratio would only be around 3400 at 70. So I'm not sure if I'll go the M3 subframe route or not. My transmission swap should ship Monday so I will have pictures and updates this weekend of the progress. Hopefully my supercharger ships soon!

The Tourings came with a 3.46 74mph 3600rpm... I have a six speed for mine..

Have you thought about a TT turbo kit? he makes them for 325's now...

I didn't know he was making them for the 325. My kit will be here sometime next week.

I suggest you start with the engine and worry about the rear end later. 3.46 with 5speed is a little too short for my taste.
What gearbox did you buy?
The link in my sig could have some valuable info for you.

IMO, 3.46 is too short for 5 speed as well. I have a 3.38 on a 6 speed and it is just about perfect.

Once I get the transmission in there I will see how it feels and if the RPMs are too high for my liking. Nothing will be higher than the 3.91 3 speed torqueflite I used to drive around though. The transmission is out of a 2003 325i.

My only advice is make sure your engine is working well. I never ran full diagnostics on mine, Was running euro 98 octane tune and only supplying roughly 97 octane.Drove the Sh!t out of it and its now fried with no overheating or anything..

My engine is fried but its goint to be re-done and put in my e30 so the BMW graveyard will have one less Munich Legend to mourn over!

When I got the car I did the cooling system, vanished rebuild, vcg,oil filter housing gasket, new plugs, all the basic stuff.

The reason I asked about the gearbox is that the 325 transmisson is rated for 250lbs/ft of torque. My 330 with TS2 pulled 365 (at the crank).
That's why I got the 6speed from a 330 (that's rated at 370lbs).

I read about that rating on the automatics but I didn't see anything for the manual transmission.

The 325 5speed is 250, the 330 5speed is 320, and the 330 6speed is 370, M3 is 420. But that's just factory rating. M3 guys are putting 600-800 through them without too much drama.
I'm pretty sure it can take the abuse for some time (and you'll have M54B25 with stage 1 at first, right?). I spent 2K on low mileage 6speed and the 3rd gear syncro is screwed

I can't find any ratings on the manual transmissions anywhere, but what I have read is that it will hold up just fine. I know my automatic is rated at 250 so I would think the manual is significantly stronger considering it is constant mesh gears, the clutch would be the weak link.

the 325 clutch had no problem with stage 1 (240lbs torque at the crank), the 330 6spd clutch is not very happy with the stage 2 and LSD (more traction = more load on the drivetrain). I think I'll go for Sachs HD clutch when this one dies.

Sometime in the next year I'll be doing 330 internals swap then I'll go ts2+ and be done with the engine. I was hoping to get my transmission swap done this weekend but it doesn't look like it's showing up until Tuesday. So one more week with auto.

I'll be following your 330 crank swap closely. I don't think it has been documented very well. There are still some questionmarks about which parts are the same between M54b30 and b25.
I'm planning on rebuilding my spare b25 to b30 (possibly low compression)

Originally Posted by lab rat

I'll be following your 330 crank swap closely. I don't think it has been documented very well. There are still some questionmarks about which parts are the same between M54b30 and b25.
I'm planning on rebuilding my spare b25 to b30 (possibly low compression)

Want the B30 internals? lol.