M54 Madness, the remix

[TheAxiom]

Bump.

[hoveringuy]

I'm still sorting some little stuff before I commit to another dyno. I've put together a 3.5" MAF using a generic housing and an HFM5 series Bosch MAF sensor.

The older euro 803 that I was using worked Ok but I think it was too susceptible to reverse flow error. The HFM5 series is more modern and should make it run a little better, although I'm not expecting more power with it. The actual sensor is Bosch 0280217007 which is used in Boxsters and Carerras.

Also, I've sent my throttle body off to Maxbore to be machined from 64mm to 68mm. The stock size for the M54 is 68mm so that only makes sense. The stock MAF on the M54 is also 3.5".

[Jaker]

I'm still sorting some little stuff before I commit to another dyno. I've put together a 3.5" MAF using a generic housing and an HFM5 series Bosch MAF sensor.

That's really cool! I'm very curious to hear how that works out. I'm planning something very similar, but the tube it'll be incorporated into will be CFD designed and optimized for that awful 90 degree turn into the TB, built with CF layup and include the run to the filter down by the headlight.

[hoveringuy]

That's really cool! I'm very curious to hear how that works out. I'm planning something very similar, but the tube it'll be incorporated into will be CFD designed and optimized for that awful 90 degree turn into the TB, built with CF layup and include the run to the filter down by the headlight.

I want...

[mike25]

That's really cool! I'm very curious to hear how that works out. I'm planning something very similar, but the tube it'll be incorporated into will be CFD designed and optimized for that awful 90 degree turn into the TB, built with CF layup and include the run to the filter down by the headlight.

Are you planning a rubber concertina section to absorb engine movement?
Photos of the finished article would be good too.

[hoveringuy]

My throttle body is back from Maxbore, $150 to bore it from 64mm-->68mm.

The stock M54 has a 68mm TB so it makes sense to me that I should go to that size.

Between the bigger TB, a silicone intake boot, and the the 3.5" MAF with the HFM5 sensor, it'f running great. I need to spend some time tweaking the tune for the changed configuration, and then to the dyno!

[2mAn]

That's not a bad price to do that!

[hoveringuy]

That's not a bad price to do that!

They did nice work. 3 day turnaround.

I figure 68mm is what BMW thought was the best size on the stock M54. By my maths, the extra 4mm is at least a 14% increase in area.

All 3.0 liter motors should probably have this size.

[Jaker]

I currently have a 68mm from Riot Racing on my build. I'm sincerely hoping it's holding back my top end power because I'm about to bolt on a 75mm VAC with opened up IM and hope its worth the effort!

[Sh3rpak!ng]

Curious to know what both of you find with the larger TBs.

I've been hesitant to go larger myself because as I understand, an effect of the larger TB is increased throttle response and my throttle response is already very sensitive with the very lightweight flywheel.

[Jaker]

my throttle response is already very sensitive with the very lightweight flywheel.

Can you elaborate? I have the UUC 8lb flywheel, my crank is 12lbs lighter than stock and I have lightweight pistons and rods. I am ecstatic with the throttle response.

[Sh3rpak!ng]

Can you elaborate? I have the UUC 8lb flywheel, my crank is 12lbs lighter than stock and I have lightweight pistons and rods. I am ecstatic with the throttle response.

Well, I read a bunch of reviews a while ago regarding larger TBs increasing "throttle response" and throttle sensitivity (some of those people didn't like it). But now that I think about it, that probably doesn't pertain to someone like you or I who actively search for ways to make our throttle an on/off switch :)

Sounds like you probably have a much lighter rotating mass than I do anyway. I am running a twin disc setup from clutchmasters which is a very light rotating mass, and also smaller diameter, though I don't have the extreme weight cutting like you have from the crank etc. The throttle response is fantastic with the super lightweight clutch setup but its also very grabby and tricky to modulate at low speeds. I drive the car a lot on the street still so I don't want it to be impossible to drive in traffic.

I am very interested to see how/if this effects the top end though

[ForcedFirebird]

There's a local company that makes large TB's that have a progressive linkage on them, mechanically making the throttle open less at tip-in, then opening more rapid as it nears WOT. Think it might be a Wilson Manifolds product.

[Jaker]

Dyno, dyno, dyno. We demand Dyno!!!

[hoveringuy]

Dyno, dyno, dyno. We demand Dyno!!!

Getting closer, I promise! I have a fresh WB O2 sensor coming today to make sure my A/F is accurate.

I think my MAF curve is dialed-in for 14.7 everywhere, now I need to update the enrichment for higher fuel loads.

Car is running friggin' awesome!