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320IS vs E30M3

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  • 320IS vs E30M3

    Hi Guys!

    I have a little dilemma for a half year now, and I still don't know what to think:lostme:

    I would like to build a track only car and I can not decide wich one to choose.
    Maybe your thoughts can help me to decide.
    Pros and cons:
    - the 20Is price is the half of the E30M3 (~3-4000EUR vs 8000-10000EUR)
    - The engine would be a 2.5 so it doesnt matter which one to choose.
    - The suspension prices near the same. (KW, H&R)
    - The M3 wheelbase is wider (!)
    - Big brake kit is near the same price for both, but he 20I has more cheap option from factory parts (used 540i brakes, etc).
    - Weight? The 20IS seems to be lighter base (my friend's drift E30 is 950Kg), but I'am sure an E30M3 can be as easy as that car, but for more money! (E30 fenders or bumpers from CF are much cheaper than the M3's because there is a lot of them out there)
    - Butcher a rare E30M3? Noooo...
    - 20IS is rare too. Ahhhh...
    And finally:
    - M motorsport GMBH built the E30M3 to win races. If the simple E30 could be as fast as this, they would not develop so many unique parts for only the E30M3.

    Any thoughts is highly apriciated,:thank you
    Nice is what makes you fast!

  • #2
    Im sure you know what you want...listen to your conscience...
    John A.
    "If your ship doesnt come in, swim to it..."

    M3 e30 2.5L | R8 v8 6mt | 996 GT3 mk1 | Integrale Evo Martini 6 | Dallara F303/4 Toms | Defender 90 NAS


    • #3
      maybe I can shed some light on this.

      I have a stock 4dr 320is (no sunroof, AC, 15" basket weaves, electric windows front, manual rear) on bilstein sport, eibach (~-35mm) springs on Toyo R888 205/50R15.
      End of August I took my stock M3 (power sunroof, no AC, 16" E28M5 wheels, power windows, leather, sound system) and lapped the nordschleife quicker and that was on standard street tyres (Toyo T1-S, 225/45R16).
      comparing onboard videos it's easy to see that the M3 is quicker where engine power is required but one can also see that although on street tyres (albeit wider and lower aspect ratio) cornering speeds are the same.
      Since you'd run a 2,5 anyway the power is no longer a difference, but the difference in track and aerodynamics will remain.

      This is what I'm doing: build a 2dr 320is (no interior just one seat and a cage) and run the M3 suspension. I'll still run the 2l engine but apart from that only the aerodynamics will be different from an M3. But even that can be solved easily by covering up the same aereas as the M3 has covered up underneath and get the c-pillar extension for the higher rake rear windscreen and M3 rear deck incl. wing.
      Those have currently come available from Austria (not Australia!) on german ebay (no affiliation:
      Since you probably wont be running 10x18 rear wheels you dont really need the blistered arches so frontal area of a 320is will be slightly less than that of an M3 thus increasing aerodynamic drag.


      • #4
        Great, great info!!!
        :thank you

        BTW if I spend that plus 4-5K EUR to make the IS faster, it probably will be faster than the M3 from the same budget.
        Nice is what makes you fast!


        • #5
          how many track days have you done so far?


          • #6
            The regular e30 chassis doesn't have the handling of the M3. Start right by getting the M3. If you only want to drift, then don't do that to the M3, get a regular 325is.

            [email protected]

            1969 2002 racecar
            1989 M3 racecar
            e39 Touring


            • #7

              Dont really know. Since 2000, I was out on every trackday in my country and a few autoX event too (only the faster ones, killing the car in first gear is not my favourite!).

              But now there will be trackday at every week so I guess I will be there more often then before.

              This is why I'm thinking of selling my mint condition M3 and transfer it to a track car and to a 318IS daily driver.

              The question is: which track car? 320Is vs E30M3

              Thanks for trying to help me!


              NO drifting! Trackdays are the target! I know that M3 is built for that, but the price is an important parameter too!
              Nice is what makes you fast!


              • #8
                So the 20is springs, dampers, ARBs and the control arms bushes could all be changed. What else was different on the M3 set-up? I was under the impression that was it?
                If everything seems under control, then you're just not going fast enough...


                • #9
                  Speak to Jake he has a 320iS.....

                  Schwarz 1990 Sport Evolution


                  • #10
                    PM-ed him, thanks.
                    Nice is what makes you fast!


                    • #11

                      Good questions, but what is ARB?
                      Nice is what makes you fast!


                      • #12
                        Hello Adam.

                        This is a good discussion. I went through this same dilemma earlier this year.

                        The short version is if you are on a budget the 320is is the better choice. Forget about the M3 handling better. If you're going to modify it for the track anyway then you can make the 320is handle just the same. Yeah yeah… I can hear all the M3 owners teeth clinching…

                        I decided on the 320is for budget reasons. I already had all the parts to build a track M3 so it didn't matter whether they were bolted to an M3 or a 320is. At half the price the 320is was just what I needed.

                        The suspension was converted to 5 stud using Leda coil overs and M3 brakes. There, now you can out handle stock M3's. If you bolted that stuff to an M3 why would it handle any different?

                        The M3 has a few advantages though. The biggest advantage I see at my level is wheel size. I had very fat tires (for a 215R16) that filled every mm of the wheel wells. Way more grip than I needed (Toyo R888 semi-slicks) so I later downsized. Even on 205’s I still had no problems with grip. But ultimately, the M3 should be able to fit bigger wheels/tires.

                        The M3 supposedly offers an aero advantage. I'm sure it does on paper, but I have yet to encounter a situation where I felt like I needed an aero aid for the 320is. I am not slow at the Ring and don't have much trouble keeping up with 2.3L and 2.5L M3's. My top speeds are nearly the same. I never once needed more down force. If I were doing under 8 minutes laps at the Ring then they would probably help. But at my level I don’t need them.

                        The next advantage the M3 has on paper is a stiffer chassis due to the bonded windows. My 320is is a non-sunroof shell and I can't detect any chassis flex that causes instability. I'm sure a non-sunroof M3 shell is better, but in my case it didn't seem to slow me down. I don’t think it’s so critical for a track day car.

                        Earlier this month I went to the Ring with a bunch of friends with their M3’s. On the 2nd and 3rd day they asked me to follow them so I could get them on video. There was 1 modified Cecotto, 1 Evo 2, and two heavily modified 2.5's, all making more power and torque than my 320is, especially the 2.5’s. Only one (Uwe) was really able to get away from me; at the end of that lap he was 5 seconds ahead; not bad for a little 320is I think. FWIW, both 2.5’s were stripped like mine.

                        There is nothing wrong with the 320is at all, and if you set it up right and drive it well you won't have a problem against M3's. The M3 will ultimately be faster but there just isn't a huge difference.

                        For reference here is the spec of my 320is.

                        Engine (approx 210hp):
                        - E3 intake cam
                        - E2 exhaust cam
                        - CF airbox
                        - Alpha N
                        - VAC pulleys
                        - Custom 50x50 exhaust with X pipe

                        - Leda coil overs (F 550/R 275)
                        - RD ARB's (22mm/19mm)
                        - GC adjustable top mounts
                        - Poly/Delrin bushings throughout (no stock rubber anywhere)
                        - F/R strut braces

                        - E30 M3 discs/calipers
                        - Brass bushings
                        - Performance Friction PF97 pads
                        - SS brake lines
                        - 25mm master cylinder
                        - SRF fluid

                        - Original 3.46 LSD
                        - Interior stripped
                        - Kevlar race seats w/6pt harnesses
                        - DTM style shifter from Markus
                        - 205/40R17 Toyo R888 tires
                        - Team Dynamics 17x8 ET15 wheels
                        - Evo light weight flywheel

                        FWIW, the track is now the same as the M3 due to the 5 stud conversion. With the added camber up front I have no clearance issues at all. The 215/50R16 R888 tires did rub the firewall a little at full lock but this would happen on the M3 as well. You could fit wider front tires if you wanted. I don't think you'd have a problem with 235/40R17. My road set-up uses that out back and it clears just fine.

                        Hope that helps Adam.

                        Take care,
                        Last edited by Jake; 09-21-2007, 07:34 AM.


                        • #13
                          Originally posted by Adam S14 View Post

                          Good questions, but what is ARB?
                          Anti-roll bars.



                          • #14
                            don't forget that essential part that makes all the difference on track.... the big nut behind the wheel...


                            • #15
                              320iS weighs how much less than a stock M3? 180lbs? US spec that is? 2.0L S14 makes the same hp as the ours here in the states stock also.
                              Who knows where I'll be, changes from day to Continent.