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    s38 supercharged?

    Hi All,
    I'm new to your forum here but have been reading r3v posts for years.
    Finally decided to become a member and post some questions of my own now that I've found there is a s38 specific forum.

    Just so you know I'm not a total newbie :
    I have built s14 and s38 engines to stock / Evo specs and my current projects are an s14b25 race motor and collecting parts for FI s38 build, both engines to go into e30m3 chassis.

    My questions for experienced engine builders are these :

    We've all seen the YouTube videos of 1000+ hp s38 m3s, what goes into these engines?

    How far can one go with stock crank and rods? ( I think I've heard 6-700 hp?)

    Has anyone built a FI s38 using supercharger instead of turbos? ( I have Paxton blower and wiseco turbo pistons )

    Has anyone tried the cheap H beam rods found on ebay in an s14 or s38 FI or na? ( I know, nuts! Huh? )

    Thanks for reading...
    Looking forward to your thoughts.

    Old school ///Ms rule!

    #2
    Well I don't know if you already knew or not but generally the B36 block + 94mm bore is more desirable to boost than the B38 because of thicker cylinder walls, but the B38 have been proven successful too.




    Haven't built one but from gathered information from various sources on the S38;


    You don't need to replace the crank for 1000Hp, I don't think I've ever read of someone having anything other than the stock crank with some treatment.. the entire head can be left stock for ~800hp. There's 1000hp+ engines with stock cams and valves, with the cam lobes being modified for more duration.

    I don't remember if it was the stock pistons or rods that are weakest in the S38, I believe it was the rods, but neither of those need to be replaced if you're looking for 500hp, but the rods are not that expensive really so there's no use in not replacing them for something proven, and the pistons aren't too great either so going over 600hp on the stock ones, with ethanol, isn't too wise either IMO, Altho' I think the 700hp region is what I've read of stock rod/pistons being dynoed at.. don't know how long it lasted.


    I was going to supercharge my B38 with a Vortech centrifugal... 2 years ago.... but have never gotten round to it, I was going to leave it completely stock with a 0.3mm thicker I believe it was gasket to just slightly lower the compression as well as using ARP bolts. I was planning on only using about 0.4-5 bar of boost which I think I came to the conclusion to yield just under 500bhp..



    That's pretty much what I have to add..



    Here's some engine specs on a few S38's, in swedish, but you'll probably get the idea with a translator.. http://www.garaget.org/search.php?q=...=1&y1=&y2=&p=1
    Last edited by Xat1cZ; 09-16-2014, 08:27 AM.
    ლ(ಠ益ಠლ)Be Afraid Of The Future

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      #3
      Thanks for the reply, mine is b36. I have wiseco ceramic coated turbo pistons at 8.5:1 cr and a Paxton centrifugal blower. Other than lightening and balancing of rotating assembly and some minor port work and mls head gasket with arp studs in top and bottom ends I plan to leave the rest of the engine stock.
      Hoping for around 600 hp without compromising reliability. This will be a track toy/hill climb/silver state classic racer .

      Does anyone else have any tips or experience for building this type of engine?

      Comment


        #4
        Have a look.............

        http://www.driftworks.com/forum/drif...and-print.html

        https://www.youtube.com/watch?v=UL1B0FLOiRI

        https://www.youtube.com/watch?v=jR7tFuVlwvM
        Sveinbjörn Hrafnsson

        E30 CABRIO V12 M70B50 ///
        ALPINA B10 BITURBO 346 @ 507
        E34 550 V12 JML


        Finnish wisdom : If you want to Win,, hire a Finn

        http://alpina.123.is/pictures/

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          #5
          Thanks Alpina, great links to some s38 drift machines.
          I'm still looking for answers to my question of how much power I can safely build to using stock rods and forced induction.....
          Surely someone out there has found the limit of what stock rods can handle?
          And just out of curiosity: has anyone tried the Chinese 4140 H - beam rods found on ebay?
          Intuition tells me they are probably junk but what if they are actually well made and as good or better than stock? It would be a shame to pass up a good deal for good parts, right?

          Comment


            #6
            Originally posted by porsdude View Post
            Thanks Alpina, great links to some s38 drift machines.
            I'm still looking for answers to my question of how much power I can safely build to using stock rods and forced induction.....
            Surely someone out there has found the limit of what stock rods can handle?
            And just out of curiosity: has anyone tried the Chinese 4140 H - beam rods found on ebay?
            Intuition tells me they are probably junk but what if they are actually well made and as good or better than stock? It would be a shame to pass up a good deal for good parts, right?

            stock internal is extremely strong,,,,,,,, on M30 they are blowing out some insane numbers with everything stock,, but often on 8-9.5 cr......... S38 have 10.5

            IMO i think you should be safe under 12 psi... but cylinderpressure is often what counts
            Sveinbjörn Hrafnsson

            E30 CABRIO V12 M70B50 ///
            ALPINA B10 BITURBO 346 @ 507
            E34 550 V12 JML


            Finnish wisdom : If you want to Win,, hire a Finn

            http://alpina.123.is/pictures/

            Comment


              #7
              Thanks again Alpina, (do you go by Sven?)
              I am gaining confidence in the stock bottom end. I have not done the math but I'm guessing I'll need 12-15 psi to achieve my goal of 600 hp with 8.5:1cr hopefully the rods can handle that.
              New question: what injectors will I need for this number and what ecu? I have an m30 unit I could modify. Or will I need a stand alone system(megasquirt, etc.)?
              Thanks for reading,
              Jeff

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                #8
                Great project you have here as the s38 is a powerful platform when boosted.:o


                are u making brackets accs for the location of the blower?:D

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                  #9
                  Yes I will be making the brackets to mount Paxton blower on left side of engine. It will locate approximately where stock air box is usually fitted. Ironically blower outlet is almost perfect to route into plenum but I will be ducting it forward to intercooler. Awkward piping to be sure, I am looking for blower outlet casting that points in a better direction or may have to cut and re weld for optimal placement. This blower was made for a '68 Shelby mustang. I drove that car and was blown away (pun intended) by the instant torque available.
                  Hope the s38 is as responsive.

                  Comment


                    #10
                    I'd love to see a V7 or YSI Vortech on a stock compression S38 with E85 in an E30! The high CR + E85 and say 12 psi would make a REALLY nice power band!

                    Good luck with your build. Would you be going with a stand alone?
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                      #11
                      Any more updates on the project?

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