It's actually wild how much the low weight gives you in races. I've pulled cars with a stage 1 that I probably shouldn't have been trying to pull.

 

F5666,

This may be slightly OT, since you are obviously building primarily for the track, but I'd appreciate your opinion on suspension setup for "spirited" street use:

1: Why did you go with spacers? Was this instead of wider wheels? (I would think 400 HP needs more rubber contact.)
Or did you do both, to get better cornering without too much rolling resistance?

For the street, and maybe 270 - 300 hp, would you suggest 7" wheels + spacer, or 8" wheels and no spacers?

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2: With scrub radius about 1" further out, do you think any of those adjustable parts would be beneficial for street use? (AFAIK, you can't re-set original scrub radius, only caster and camber, correct? )

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3: Again, for street only: Would you suggest coilovers (KW street, I guess) or stay with the McPhersons + dynamic damping?


Any thoughts would be much appreciated, thx.

 

So first and for clarity, I am not building for the track per se. I am building a Time Attack/Fast Road car that will see occasional track time.

1. Spacers are an interim measure until I am ready to do custom wide body modifications and didn't want to spend money on rims/tires just to replace them in less than a year. Yes, 400hp needs more traction but honestly with the Wavetrac I am not spinning often unless in crappy/wet weather. The 215 series PS4s do an astounding job at hooking up, plus 1 & 2 are torque limited. Soon that will go away and I m sure wheels will spin easier at that point. I would always suggest fatter contact patch with any power upgrades. **I should note that I go through tires like no one's business up front - a brand new set of PS4s all around yielded me baldies up front in ~6mo lol!

2. In order to alter scrub radius, you would need to be able to adjust the suspension angle independent of the wheel camber. This is much easier on a double wishbone setup vs a MacPherson strut configuration. Technically you could adjust scrub radius with a custom billet steering knuckle. I am not ready to begin addressing this as I have not finalized the dimensions and specs of the widebody setup. Never say never So yes, only camber and caster but recently swapped out 3-way KMACs for 2-way Vorshlags with a 32mm monoball. I will be selling the KMACs soon for anyone interested.

3. A good quality and highly adjustable coilover + suspension polyurethane + Vorshlags + adjustable swaybars/endlinks + Michelin Pilot Sports. Hands down. You need the other parts to round out the solution. Often I see forum members talk about component upgrades in a vacuum - meaning they only consider the one thing - but the key to truly great setups and performance (actual performance & user experience performance) you need to make upgrades with supporting mods and details, not just the main component or it will always and forever feel incomplete or unsatisfactory.

 

@F5666 Do you mind sharing any info about the engine internals? Did you do any work there? I saw this youtube video where the guy is pushing about 500 hp on a B48 engine inside his BMW 330i - are there any differences between the JCW B48 and BMW 330i B48 engines? I always thought that you might bend a rod or break something else when pushing over 350 whp or so on the stock JCW B48 engines for example. Great video and great setup by the way:

 

So to make sure we are clear on differences, the JCW B48 engine (and S models, difference in output is a difference in how they utilize the identical turbo) is a B48A20O1 with 228hp output and the video is a 2019 330i, making it a G20, not an F30 car. The G20 uses a 255hp B48B20O1. I am not sure what the internal differences are but from my understanding, only the GP3 B48 motor has different internals which include a reinforced crankshaft, larger journal bearings and pistons that lower compression down from 11:1 to 9.5:1 plus reworked intake plumbing (read: opened up and optimized).

There is far more that goes into determining how much you can ultimately run, it's not just compression and internals strength... that is just the main starting point. I am keeping my setup under wraps as this project is extensive and I will be documenting and showcasing all my work but only after the completed and finished target has been hit.

 

Important to also understand that the JCW B48 has lower compression ratio as well, vs the "S" B48. (shorter pistons.) IIRC, it's 10:1.


I've read this as well.

 

I thought I saw that somewhere, thanks for the clarification.

 

Things like this help

 

so are you running the stk internals with a bigger turbo and larger injectors to get to the 400hp range,

 

No my friend. But if the STK I am thinking about is the one you are talking about, STK makes auto tranny's only from what I understand. That was a wavetrac install. Custom turbo/manifold, custom software tune (I am a tuner and tune my own vehicles), fuel pump, monster IC and a thousand other little details. I am already working on the next stage with Xona Rotor who is a sponsor of my car