Reply to Thread

Post a reply to the thread: Split Second MAF (laptop version) Write-up

Your Message

Click here to log in

Please correctly re-type the phrase f o o t d o c t o r in the form box. Re-type it without the extra spaces and put the one space where it should be. We apologize for having to do this but this silliness helps slow the spammers.


Additional Options

Topic Review (Newest First)

  • 06-23-2006, 10:29 AM


    This is an old post. Not sure why it got bumped. However I would like to know if anyone has an update on the new SS hardware if there is any. I would like to do a comparison on the kit that I've managed to put together to see how it compares with SS current offerings. I was thinking of putting an ad in the Roundel to see if I could sell the thing I put together and I was wondering if I have something here - insofar as a sellable product.
    I have gotten a few responses from the M5 community here but haven't sold any kits for M5 yet. (Sold a bunch for 745i and M30.) Not sure why since I had thought us M5 guys were used to dumping tons of money into 'em. :)
    Scottie Sharpe
    Provider of Mass Air Flow Conversion Kits for BMWs

    88 Dinan-badged M5, M88 motor with BTP mass air flow conversion, Dinan Stage 4 suspention, Dinan 17x9.5 3pc wheels, 255/40 Conti Sport X 4, Racing Dynamics software, e34 rear brakes, B&B Stainless steel Exhaust, F&R LaDue stainless steel strut bars.
    91 318iC
    73 Bavaria
    67 1602 Ireland coil overs, brembo brakes, Dual Solex 40 PHH
    Do you ??

  • 06-23-2006, 12:36 AM
    mike mckee

    Re: Split Second MAF (laptop version) Write-up

  • 08-17-2004, 03:39 PM

    Re: Good stuff Dan

    I'll measure the flapper position relative to voltage the next time I reinstall the AFM. I will have to figure out how to equate open area and/or angular position with voltage, though I'm leary of opening up my AFM. It might be a while, however, as I'm enjoying the fruits of my labor.
  • 08-17-2004, 03:32 PM

    Summary of HP vs Cost

    I have read many posts over the years of individuals performing a wide range of engine modifications like increasing throttle bore, shortening horns, increasing exhaust valve size, euro headers, cams, etc. It would be interesting to get a summary of all these mods along with the recorded gains and relative costs so that we can individually decide what suits our goals and budgets. Anyone interested in doing it or know of such a document?
  • 08-17-2004, 03:27 PM

    Re: Split Second MAF (laptop version) Up-date

    I think the improvements in drivability over stock are all due to the adjustability of the programmable PSC1. The maximum voltage that I have seen from the MAF is 4.2 volts. All of the tuning adjusts the signal that the DME sees based upon MAF signal at a given rpm. Unless I change some physical aspect of either the intake (porting/polishing) or the exhaust (high flow cat), I won't see any increase in air mass that the MAF is measuring.

    Good luck.

  • 08-16-2004, 09:25 PM

    Re: Split Second MAF (laptop version) Up-date

    Sounds good Dan I wonder how much of the improvement in general is down to the tighter programming/control of the A/F ratio with the MAF over the AFM.
    What is the output voltage of the MAF at full power now?
    Iím interested because your work has resurrected my interest in my own project to replace my AFM or improve it more.

  • 08-16-2004, 01:11 PM

    Split Second MAF (laptop version) Up-date

    I talked with Mark (at Split Second) further on how to fine tune their system. Since I don't have the auxiliary input for data logging, I had a friend help me drive my car while I watched the A/F meter and the fuel map on my laptop. From this I was able to closely figure out where I was running too rich, causing the minor hesitation. I thought I was still not giving it enough gas under acceleration. I was basically running too rich in nearly all lower rpm settings. I think the biggest help was that I had the mixture at idle too rich. Leaning it out at idle and at certain load/rpm combinations has made a huge difference. Though idle quality is the same, my car is smooth in all acceleration situations. It is much better than the AFM now! It also seems like there isn't a step at 3.8K rpm anymore. It just pulls strong all the way to redline and it does it very quickly.

    In regards to fuel maps, I'm willing to share my maps with any non-Split Second individual who is interested. I probably won't post them for general download.
  • 08-16-2004, 10:47 AM
    Todd Kenyon

    Similar experience w/ old version

    My impressions of my car's performance after running the SS MAF kit w/ the 4-knob controller for 4 months are very similar to Dan's - definitely more torque and quicker response as noted by butt dyno (have a JimC chip but otherwise stock). I have not switched the AFM and MAF back and forth, but that is a great data point, as of course is the dyno. It is not our imagination. I need a brake upgrade next, the car really hustles.

    Dan's hp/torque gains on dyno are similar to SS's data on website. Tough to get those kind of gains with any other "simple" mod. I continue to have no problems whatsoever. I am sure others will appreciate Dan's pioneering work here w/ the laptop version maps. If you are less inclined to spend time tweaking, the old version works fine and no dyno is needed (altho if you log the O2 signal the same may be true for the laptop version).

    I agree with Dan that there is still a bit of a flat spot at 4000-ish rpm when accellerating from a stop. Mine was more pronounced w/ the AFM, and there were more flat spots. Now I just have the one and it is minor, and not always there.
  • 08-13-2004, 09:44 PM

    Great write up! There's a reason that all new BMWs

    ...use MAF's in favor of the obsolete technology of the AFM! Glad to see that someone has put this to the test and has so articulately and comprehensively written it up. BTW, your horsepower gains are extremely significant, so don't feel disappointed about that!

  • 08-13-2004, 05:17 AM
    ian M635UK

    See post above on air flow. (eom)

  • 08-13-2004, 04:28 AM
    ian M635UK


    Read all the recent posts with great interest as I am thinking of going down a similar route. Great info all round.

    I have been investigating air flow restrictions on the M635 head to see how I can make mine breath better. The following link has given me a head start -

    It has a great deal of info on the air flow characteristics of the E30 M3 head which has 26mm inlet tracts and 46mm throttle bodies with 37mm inlet valves. These dimensions are EXACTLY the same as my M635 head (I know the cam durations are different). Metric Mechanic claim (with some good back up info) that it is the inlet tract on the head that limits air flow, not the throttle bodies or the air box. They even port the inlet tract to 31mm diameter without making a change to 48mm throttle bodies.

    I would suggest that the air flow meter capability on an M6/M635 should never reach fully open (apart from transients) as I can't see BMW designing a flow meter that reached fully open before full air flow was acheived. They would always build in some margin (but not in there inlet tracts it would appear)

    Hence maybe why you are seeing 4.2v at full air flow. i.e. there is capacity left in the breathing capability. With you getting 4.2 v with the MAF this demonstrates to me that it IS the inlet tracts that are the restriction. MM look at exhaust flow but this is 120% against a normal design of 85% and so there should not be a restriction here.

    My route to more power is perhaps opening the inlet tracks to 29mm and creating the same crossectional area of the 46mm throttle bodies hence maximising the throttle body capability. A schrick 272 inlet cam would then encourage more air flow. Exhaust side to remain standard. Then off with Alpha N or SS to give the tunability.

    With the increased breathing of the schrick cam I would hope that the air flow meter capability is not exceeded as it isn't a radical cam profile. Again your info stating 4.2v at WOT is invaluable as it gives me the confidence that there is still some capability left in the air flow meter and hence I can do the head porting (spare head), cam install and then engine management progressively and not in one go (ouch on the £'s). I know mine is a M635 but I would welcome confirmation that the inlet tracts on an M6 are 26mm and inlet valves are 37mm. The only concern I have now is that the M635 may use the same air flow meter. M635 delivers 286bhp against 256bhp for the M6 and hence my flow meter MAY be aproaching max open now.

    Phew - anyway my thoughts only as I have been trying to do a lot of research before going down the engine modifying route. Open to be corrected on any of the above or for further info on air flow characteristics.

    Thanks for making the board alive again.

  • 08-12-2004, 09:02 PM
    Evil EM5

    Excellent post Dan and great threads by all! (m)


    Would you mind posting your maps? If you'd like, I could host the files as downloads for anyone that may need them. Or have you already hosted them with SS or other?

    Your write up was first rate. I definitely learned quite a bit through this thread. Good work.

  • 08-12-2004, 07:25 PM

    Re: Good stuff Dan

    Dan the AFM just uses a simple voltage divider setup it gets a regulated 5V reverence from the ECU then outputs a voltage via the divider between about 1V to 4.9V depending on the position of the flapper.
    4.2V is about only a ĺ open flapper from memory (itís a while since I measured mine) but you can easily check for yourself by turning on the ignition with the AFM connected (that will provide it with the 5V ref) put your DVM on the output signal and physically move the flapper with a stick and note the position /volts etc.
    There was a difference between the early ones and late being log/linear etc but the fully open voltages about the same.
    Exhaust backpressure build up at full power maybe stopping you getting a full inlet charge on the overlap.
    Measure your flapper position as above Iíd be interested to know the results-maybe you can get more power yet.

  • 08-12-2004, 04:12 PM

    Re: I've been thinking of that wbo2 also....

    Prior to my decision to get the SS MAF system, I almost bought a Maxx Alpha-N. I talked with John, a US rep who has an E30 M3, and they have a "money back" type of gurantee but in the end the additional $300+ for the Alpha-N tipped the scale for me. I recently met another E30 M3 guy who has a highly modified 2.5L S14 with the Alpha-N and he is making 245 rwHP! One thing the Alpha-N has over SS is that you can define the rpm columns compared to set rpm's with SS. This allows fine tuning around specific rpm problem points. And of course, you don't have any obstructions in the intake.
  • 08-12-2004, 01:34 PM

    I've been thinking of that wbo2 also....

    from innovative. It seems like the best deal out there. If you do it, don't forget to do another write up :) I've been thinking of going with a Maxx alpha-N set-up, the only concern I've had is the lack of basemaps but it seems like that wasn't too much of a problem for you which is promising.<img src="">
  • 08-12-2004, 01:30 PM

    Your RWHP numbers are awesome!

    <img src="">
  • 08-12-2004, 12:24 PM

    Re: Dan, great write=up. I'm guessing, but one >>>

    Split Second's PSC1 can log data. It can record rpm, MAF voltage and the map value that is used to modify the MAF signal. For $50 at the time you order, you can have the capability to log four auxiliary inputs like O2 signal. It would be a great set-up to record a wide band O2 along with the base PSC1 data. As a minimum, with the auxiliary input feature and even a stock O2 sensor, you would have a very good set-up for tuning. You then could get by without spending the big dollars on dyno time to ensure you don't run lean. It is very difficult to look at the A/F meter and the laptop while your driving to see where you are operating on the fuel map. You are right about recording the AFM signal, as this is what I did with the PSC1 to help figure out a base line map.

    I'm glad to hear that I'm not off base about the airflow signal not being ignored.
  • 08-12-2004, 12:07 PM

    Re: Good stuff Dan

    It is interesting that the airflow signal was 1V at idle and 4.2V at WOT at peak power for both the AFM and MAF. This kind of indicates that the AFM is probably measuring accurately. Do you have any voltage readings for the AFM relative to flapper position?

    It would seem logical that full open of the flapper should be at or very close to 5.0V. If this is the case, you would be right about the AFM still having capacity and therefore other parts of the intake or exhaust systems are restricting flow. The dyno technician noted that he thought that the engine wanted to make power but hit sort of a "wall", most likely an exhaust restriction.

    One thing I forgot to note is that Split Second's R4 software map is set up with fixed rows of RPM's at 500rpm intervals and columns of load voltages from 1 to 5V at .1V intervals. The interval of load voltages seems fine but it would be great if the RPM rows were either adjustable or had smaller intervals, like 100rpm. This would allow more fine tuning off idle.
  • 08-12-2004, 11:43 AM

    Re: Great write up....

    The local dyno shop is RPM in Kirkland, WA. I believe they have a Dynojet 224x. I am using the stock O2 sensor though I have read and heard that Innovate Motorsports has a wide band kit with handheld readout that can synthesize a narrow band signal for the DME via an adaptor. It's also supposed to have data logging capabilities! I'm going to check this out.
  • 08-12-2004, 09:32 AM

    Great write up....

    and impressive rwhp numbers for stock. What kind of Dyno are you using? Are you running a wbo2 and if so, which one?

    Andy<img src="">
This thread has more than 20 replies. Click here to review the whole thread.

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
1e2 Forum