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Author: Subject: Building another Locost based on BMW325

posted on 21/6/22 at 07:28 PM Reply With Quote
Building another Locost based on BMW325

So i've built up an MX5 based track car. It's 1.8 non-vvt with stand alone ME442 ecu and LSD etc, sticky tyres etc and it's good fun. My wife and I appear at track days a few times a year. It's in Gulf colours if anyone sees us.

I want to build something quicker. The obvious route is to use the 1.6 MX5 engine I have, turbo it and drop it in the Locost chassis that is suspended from the garage ceiling that I bagged off ebay for 52. Well trodden route can easy make 200hp without engine mods. on the other hand...

I own a BMW 325, and the engine is a peach, for good reason it stayed in the top 10 best engine list for so long. It's only 192 HP, but it spins and sounds great. At 175kg it's only 40kg heavier than the MX5 engine also as it's all alloy.

I did a forum search and the best nearest build i could find was craigdriver, but looks like he recently sold the completed car and has responded to a PM as of yet.

Any other known 325 based Locosts, i'd love to see.

My plan at the moment is to use the MX5 LSB and hubs etc as per my current car, and mate this to the BMW gearbox via a custom prop. yet to work out the gearings but this feels lighter than than using the BMW rear which is by all accounts heavy. I could even use an mx5 gearbox and make an adapter plate, but the mx5 transmission is actually heavier than the BMW one. The front end, i'll likely keep MX5 though the rack needs to be wider, either with just longer arms, or i use the bmw rack with the PAS looped out.

I'd plan to go stand alone ecu as I feel the loss of cats and redesign air feed etc would upset the standard ecu enough to need to tune it, and this i can do already myself so long as i get most of the engine loom.

I think I need a 442 chassis, though i saw mention of a 442E but wasn't sure what this means. Modifying the chassis hanging from the ceiling doesn't look like a likely option. I could could keep the cab section backwards and rebuild the front end wider, i.e. make the chassis more square but it would be ugly.

Any tips, links, comments much appreciated.

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posted on 22/6/22 at 08:44 PM Reply With Quote
I was in the process of building a (BMW based) GKD legend. I had to pause the build for some years to build myself a house with garage and in the meantime it is very unattractive to get the car approved here in the Netherlands (due to tax).

So most probably I will get myself a Fury which is already registered and work from there. I am holding on to the GKD for the time as I might be able to use parts I already bought for it. However, if it is of interest to someone it might as well be sold as is.

Not too sure which 325 you currently have. I owned a E36 325i which has the M50TU engine doing said 192hp, but this is iron block. The engine I have chosen for the GKD was the E36 323i one. This does 170hp as standard from the 2.5 all alloy engine. Reason for this choice was partly tax as I could do CO2 calculation with this 170hp and then unleash the true potential with the intake to take it to 200hp. Also it can easily run stock ECU.

Without tax restriction the 328i engine would be the more obvious choice. Could be that you currently have the M54 engine? That might be more difficult with stock ECU but it seems you are already planning to go aftermarket.

Whichever engine you would fancy, try to keep the gearbox at 5sp. The 6sp boxes are a fair bit heavier. (The 420G I have laying around is about 60kg!).

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posted on 23/6/22 at 07:17 AM Reply With Quote
thanks for the post.

I have seen the GKD, and it's a good looking thing.

the 325 engine i'll use will be from a E46, so all alloy names M54. It came after the 323/328 and is lighter i believe. 5 speed box is ample for a car with poor aero, even in the mazda based locost, don't really use 5th gear anyway on the track. Interestingly the bmw 5 speed, is a little lighter than the mazda 5 speed so will keep that to keep the clutch aspect simple.

As this is for track use only i don't have to worry about tax or emissions etc. I've never thought a Locost would be great on the road anyway, some sort bursts of fun but getting it road registered is a hassle and i don't think worthwhile for me.

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posted on 23/6/22 at 09:13 PM Reply With Quote
I don't think there is a significant weight advantage of the M54 over the M52, but the M54 is a bit more modern with dual vanos. It would probably be a good idea to do away with the dual-mass flywheel. I have a single mass, much lighter one lying around. I believe it comes from an M20.

If you'd be interested to start from my part build GKD, let me know. If I can provide some further info for your own build, likewise.

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posted on 24/6/22 at 01:17 PM Reply With Quote
> If you'd be interested to start from my part build GKD, let me know.

sure, send me some details and pictures. i'll send my personal email to you

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