93FIM5

Hey everyone this is the same type of idea that I'm currently working on at bimmerforums for the M30 but since I actually own an M5 it will be moving a little quicker. Along with some help from some members from this board (roortube) I'm looking to work towards putting together a sort of DIY PDF file of hard numerical data that all E34 M5 owners can refer to for restrictions, and heat soak in the intake as well as modifications and fixes that improve flow and heat resistance. So I was hoping to use this as a sort of development area that members could contribute their ideas and concerns about intake development in, after all thats what forums are for. So as we gather data and develop modifications they will be posted up on here for everyone to see and comment on.

First off we are going to try and identify the restrictions and heat soak that exists in the S38 intake system from the air intake point (behind the headlights) to the plenum inlet. This will allow us to quantify which components among the air snorkel, filter housing, filter, velocity stack, MAF, and the rubber boot contribute the most to inlet restriction. With this information we will then go about designing a more efficient overall replacement system, if its even needed!

I have a few instruments and a pretty decent machine shop with composites ability at my disposal that should allow us to do this, so within a week or so I should be able to get all of the testing equipment and procedures put together and shipped off to roortube to begin some initial testing. Also just to get it out of the way yes this is a major undertaking and is going to take alot of work and contribution from this boards members but I say we might as well get this started, what are your guys concerns/wishes?

Dragonsi

The actual velocity stacks are small. I learned this from a member's thread who was comparing the stacks of an s54 to an s38. I 've always wandered how much of a hassle it would be to delete the air pump, would it throw any codes?

Lantz

Check out our Wout's 'Major Wrenching' thread, he deleted the airpump amongst other things. Very thorough and enjoyable thread!

I will be looking forward to this threads development, however even with my limited mechanical/engineering (none) experience, I feel little will be gained over stock.

Lantz

roortube

I think I'm gonna enjoy this. Even if there's little improvement, it'll be fun to play with this stuff and see what happens. I can't wait to see what kind of stuff 93FIM5 has in mind.

93FIM5

The velocity stack I'm referring too is the feed to the MAF sensor not the velocity stacks that serve the ITB's.

With regards to the velocity stacks that reside in the plenum the member your referring to (Will) and I have talked quite a bit about creating a hybrid S38/S54 stack that maintains the tuned length of the S38 stacks while at the same time adopting the inlet and throat shape of the S54 stacks as it looks to promote low rpm cylinder filling with its tear drop shape without hurting high rpm to a great extent (BMW's F1 group had a hand in designing them). Integrating a hybrid s38/s54 velocity stack would take a lot of work and research and would require a complete redesign of the plenum itself to accommodate this shape of the stack due to the length of the teardrop which requires the upper chamber of the plenum to be deeper but at the same time you have to maintain other critical geometries due to the way the plenum functions with the length and width of the chambers not being able to be modified without causing detriment to the tuning of the variable resonance system. Once we get the front portion (Plenum forward) of the intake system tweaked it may be possible to play around with the idea of a hybrid velocity stack setup. But that would definitely be a major undertaking to create a stack and plenum system that maintained OEM functionality of the variable resonance system (remember the CSL and thus the S54 don't need the variable resonance plenum because they have VANOS, and in my opinion a more low rpm friendly velocity stack!) but at the same time created better low rpm cylinder filling through the hybrid stacks, this may be beyond our reach but that's no reason not to do some research and try! That seemed like a jumbled reply if it is let me know and I can try and be more clear.

You have a good point the OEM system is well designed and I doubt they left much on the table in terms of power. But they did have internal and external NVH regulations and accountant's to answer too that I'm sure affected the design of the intake. Hopefully we will be able to quantify the areas that can be improved and then see if we can actually improved them.

Roortube and other members have mentioned a few things they would like to see in any potential intake system that potentially comes of this, mainly protection from a failed radiator and the ingestion of coolant as well as an improved intake sound. Along with those points I'd like to see the following.

- OEM BMW/Mahle/Mann filter element for ease of replacement, reliability, and quality.
- Proper sealed heat shield for the intake setup.
- Prepreg composite construction for heat rejection, low weight, and durability
- Improved internal geometries
- Improved/additional air intake point(s) with positive (It will be a small amount!) pressure at speed to try and lessen some of the existing restrictions (MAF, filter element, geometry). Think similar to the OEM E92 M3 air intake setup as seen below.

So again I'm sure we will find some areas to improve but we won't know till we start testing!

As far as test equipment goes we have two differential pressure gauges along with a modified OEM intake (Im providing off of my car, which makes me all the more willing to get this done!) to measure restriction points along the intake path as well as to find possible high pressure air intake areas to help overcome restrictions (MAF, filter, and geometries) that will exist even in the optimized system. Along with the gauges there is a dual input thermometer for analyzing heat gains across the system and for optimizing intake points as well as a laser thermometer for surface temperature readings (helps to optimize the heat shield). At the moment I'm working on modifying my OEM system for the research as well as writing down some notes for Roortube for testing, see below for a quick pic of the equipment.

Anyways keep the input coming guys!

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