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Balance of an LS Swapped e30 VS Boosting the M20

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    Balance of an LS Swapped e30 VS Boosting the M20

    Hi Guys

    Not sure if this is posted in the right place but I've had my car for about 4 years and has seen some light track work.

    Running Bilstien B8 H&R combo
    M20b25 and 5 speed

    I want to add more power and honestly cant establish a clear direction on how to go forward as im worried about impacting the balance / agility of the car.

    Im deciding between essentially a built (boosted and stroked) m20 and LS swapping the car.

    Overall my decision is not being made based on cost but rather how the car will handle after the work is done. I don't want the car to be a straight line burnout machine i want to track it and want to maintain the balance of the car.

    Does anyone here have any experience with either.

    My concern with the boosted m20 is that the car will feel front heavy and not be fun on a track.

    Just want to hear from actual experience

    Thanks in advance

    #2
    A fully dressed LS1 weights around 208kg - ie. around the same as an M30 and slightly more than an M50. The extra weight of the turbo on the M20 + intercooler is going to make it weigh somewhere around the same.

    My M30 handles fine (hardly any different to when the M20 was in there) so either option you mentioned should work out - I think the bigger question is what kind of power delivery do you want for the track, and what sort of class do you want to run in?

    The car will be able to be set up to handle well which ever path you decide to go down.

    Don't believe the hype about LSx engines being a feather weight - they are vs. old cast iron V8s, but the single cam BMW 6s are hardly boat anchors. They're actually light and well designed for their era. The only advantage with the LSx would be that the weight is a little further back.
    My e30: OEM+ with M30B35

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      #3
      I have had both and while my car is a street car it all depends on how much power you want to make. Why I say that is you could get 300 usable HP out of a LS with plenty of tq in the low rpms. 300 hp out of a turbo m20 is going to be laggy. I got full boost around 3700 rpms with my hx35. Just things to consider. Both can be setup well for the track.
      1989 325i LS Swap (Money Pit):https://www.r3vlimited.com/board/sho...d.php?t=244933
      COTM Feb 2019: https://www.r3vlimited.com/board/sho...d.php?t=428404

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        #4
        If you're willing to do the work of building an M20... maybe you want to look into an M54 swap. They're much easier now than they used to be, are lighter than an M20, make as much power out of the box as any reasonable M20 stroker and can be boosted significantly.
        An M60 (or any V8) is a MUCH more involved swap, thanks to all the necessary pedal box and brake booster work.

        Comment


          #5
          As others mentioned above, the aluminum "ls" is only mildly heavier than a m20. I had the aluminum block 5.3 lm4 in my car and it handled just fine with a spec e30 suspension on it. (ie springs, bilstein shocks, cab front sway bar, no rear sway bar)
          While the swap may be a little more difficult, higher amounts of reliable power is easier to get with an LS without spending a bunch of money.
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            #6
            A dressed ls1 weighs 458lbs wet, stock clutch pack is another 50 and cast iron manifolds are another 25. That 533 ready to run. A matching dry m20 almost exactly 400lb (figure on another 8lb in oil). I recently shipped a turbo kit to Dubai and it came in at 70lb with all the packaging and large box. The turbo m20 will still be lighter - but - being an avid racer, I would not suggest turbo, nothing worse than upsetting the car mid corner because the boost rolls in. The turbo kit I shipped was actually from an e36, but would weigh similar to an m20 kit. The race car owner was making close to 400whp on his m50 and hated the lag. I built him a 255whp s50 and he couldn't believe the difference in drive-ability on the track. He is now winning races with the NA engine.

            I don't really buy into the lsx's moving the weight rearward in an e30, the v8 still has 2+ cylinders hanging over the front axle, and as Will mentioned, you are dealing with all the brake shenanigans with a vee engine in an e30.

            The e30 is a light car, you don't need gobs of torque for a fun track car. Our endurance car with a very mildly built m20 makes 180whp/180wtq and weighs 2670 with me in it post 30min sprint race (starting with a full tank), fully caged with 1.75" .120" wall DOM, central fire system, factory ballast still in trunk, aka not lightened at all. Last weekend we did a 14hr race and the car did a 2:43.2 best lap at Sebring on 205/50 Falken Azenis 200 tread wear summer tires - which would be a mid/upper field Spec e30 time (we run 205/50 Toyo RR in Spec). We were passing 328 e36's no sweat, and have a top speed of 147mph with a 4.10 @ 7000rpm.

            The m20 is pretty bulletproof, I have found as long as you don't miss a shift and keep it at or below 7k, or risk the chance of breaking a rocker arm (happened ONCE in the car since 2013).

            All that being said, a slightly more built m20 than I am using in our car, you could easily be at 200+ whp, maintain the handling with more power, maintain the weigh distribution, everything is plug and play, keep the braking system etc. A 200whp m20-powered e30 is no joke. One of my customers is making 208whp/184wtq and just won first place the SCCA Nationals...
            Last edited by ForcedFirebird; 09-26-2019, 03:51 PM.
            john@m20guru.com
            Links:
            Transaction feedback: Here, here and here. Thanks :D

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              #7
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              @turbovarg
              '91 318is, M20B25, T3/T04E 60 trim (15psi), megasquirt, coilovers, Z3 rack, cold AC
              [b u i l d]
              [Car of the month: April 2018]

              0c8b7c9527af628a346878feb14bf757

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                #8
                ^^^was wondering what the differences would be total package since I have picked up t56's and they are far from light. Been a while since I shipped a g260 and didn't record the weight anywhere. Didn't bother searching the internet when posting, knew the general weights from memory, good find Varg - forgot Vorshlag weighed everything back then.
                john@m20guru.com
                Links:
                Transaction feedback: Here, here and here. Thanks :D

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                  #9
                  A T56 is around 120 lbs, a G260 is in the 65-70 range.

                  Comment


                    #10




                    Vorschlag is doing God's work by weighing car parts and posting pictures of it. Good engine and transmission weight information is nearly impossible to find. The above is a Getrag 250 not a 260, so we can assume the 260 is a bit heavier than 70lbs since it is physically larger and stronger.
                    @turbovarg
                    '91 318is, M20B25, T3/T04E 60 trim (15psi), megasquirt, coilovers, Z3 rack, cold AC
                    [b u i l d]
                    [Car of the month: April 2018]

                    0c8b7c9527af628a346878feb14bf757

                    Comment

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