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'92 sr miata

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  • '92 sr miata

    just found these forums not sure what took me soo long. ok, its not totally nissan, but it is rockin an sr . i'm currently in planning stages for power upgrades and would be grateful for any advice you guys have.

    car is intended for autox and track days. since its got full spec miata cage, its more track than autox, but its fun for both

    the car:
    '92 miata rockin a sr20det blacktop (currently stock turbo/boost/ecu) giving 196whp
    spec miata cage
    fatcat valved bilstein suspension
    aim mxl strada dash
    3.9 torsen diff
    besides that pretty standard fare
    2286lbs wet

    i've got a os giken 1-3 gearset tranny i'll be installing pretty soon
    also got a gt28rs i would like to put along with a manifold upgrade

    here's a pic.

    crapy pic. i'll get a real pic this afternooon

    i do have one of the v-band exhaust tip
    Last edited by tonto; 08-11-2010, 10:49 AM. Reason: aded weight, hp, and engine pic

  • #2
    Still, very cool. Some pics of the engine bay, please.


    • #3
      My friend Chuck built an SR miata as well. He had issues with the rear diff. I can't remember if he made a Nissan diff fit, or the OEM diff kept blowing.

      He said it was a helluva a lot of fun though!


      • #4
        muchas graz. added a quickie engine bay pic there. i'm 196 wheels so no trouble with rear end. judging by the turbo miata guys, i think i should be good at 300, but theres only one way to find out

        since the ppf or whatever that thing is called was taken out, the rear subframe diff mount has been reinforced. so far seems ok, i get some looading/unloading in 1st gear but so far the rest seem ok. as i get the car sorted and bring my speeds up i'll have to monitor it to see if there is any loading/unloading at speed which might upset the car. for moment fingers crossed.


        • #5
          The big issue I hear about the rear diffs is if you go offcourse and are back on the gas too early. one wheel is on the track and grips while the outside one is spinning in the dirt. soon as the other wheel hits the concrete, it stops slipping and BOOM goes the diff.

          spec Miata guys blow up their torsens all the time around here like that, and that's at 110-120whp levels.

          just be wary of that if you ever go off course.
          Originally posted by SoSideways
          I don't care what color they are as long as they are LONG AND HARD.
          '04 G35 Sedan 6MT- The DD
          '96 240SX- The Track Toy


          • #6
            Did you build the car and do the swap? SR20 miata sounds like a fun time. Is it lighter than an equivalent BP car since it's an aluminum block? Mazda builds nice cars but the powerplants tend to be a little off in some way... the FD3S got a pretty fragile mill that makes relatively low power for the amount of fuel and air people push 'em, and the "lightweight basic roadster" got a relatively weak iron block 4 banger. If you compare it to even the SR20DE of similar vintage, there's not much to recommend it, to say nothing of the engines that Honda was putting in cars at the time.

            So, I applaud you for putting a nicer engine in there. I'd run a S14 T28 with the stock manifold (assuming it fits) and be done with it....easy 260-280 whp there.
            ~1992 240SX, SR20/Koni track day car
            ~2016 M3, daily driver


            • #7
              100% agree with everything you said wrt mazda/honda. i'm driving the miata now but my background is in bmw (not yer typical miata fanboy). the genesis for the project was my '95 m3 doesn't like the track (best guess is head gasket was pressurizing the coolant) and a friend of mine suggested taking over a miata project he knew about instead of dumping money into the e36.

              turns out the project was a sr miata so we decided to do the project together and bought it from a local shop. it ran but needed to be sorted a bit. the quality of the work i think is quite good except i'm not wild about the log mani. at first it seemed the car was such an odd freak of nature but the more i learn about miatas and the ultra-rare elusive reliable turbo miata the more i like it.

              the sr block is a bit lighter which offsets the weight of the turbo hardware. the thing weighs in at 2286 wet, which i don't think gives up much to a 1.6 spec miata. i would guess in the 50lb range at the most as i havent done much to lighten it yet. i can get rid of bumper support/headlights/wipers/sound deadening all kinds of stuff. with a turbo upgrade same basic parts (at same basic weight) should be good for ~300whp. hey, this might just be worth the trouble. shoot, at its present 196whp stock level its a hoot on track. got the engine temps under control and everything seems to be pretty reliable at the moment. driving wise, its great. so easy to drive so easy to work on and the consumables are so cheap.

              100% agreed about your manufacturer comment. as incestuous as the auto industry is, why didn't mazda source a motor from honda or somebody to make a mx5-r? or at least use the turbo 1.6 they already had from the 323 gtx. they just rode that miata pony as long as she would go.

              or, rather, why didn't honda make a miata? the early-mid '90's was the sweet spot for technology to make these cars and not all of the electronics crap to make them weigh 3000lbs. the s2k came, but a decade late and 600lbs too heavy imho.


              • #8
                Very cool! Must be a ball to drive.


                • #9
                  Originally posted by turtl631 View Post
                  So, I applaud you for putting a nicer engine in there. I'd run a S14 T28 with the stock manifold (assuming it fits) and be done with it....easy 260-280 whp there.
                  actually, this is a topic i'm currently mulling over. i could sure use some advice as this is my first turbo car. i was thinking about starting a thread in the FI section, but i don't want to annoy everybody with another gt28rs thread.

                  in a nutshell, it looks to me like stock mani won't fit in the car (see pic). i'm thinking a topmount will end up to work the best, even though i hate to move weight higher. i picked up a gt28rs used so i was hoping to use that. of all the manifolds i've looked at, the synapse v-band looks it would be the easiest to make fit (using the new smaller tial WG)


                  the synapse

                  my goals are:

                  14psi boost from 3000rpm up. anything more than 14 is gravy. (rational: with the giken gears, 3000 to 7500 puts me 20mph to 50mph in 1st. in 2nd, that becomes 30-75)

                  ive read of folks using external wastegate and ve heads getting 34X whp out of the gt28rs, so i would like to see what i can get on the det. what i can't find is good data on the combo of tubular mani/tial exhaust housing/external wastegate/gt28rs.

                  shoot, i'd take a dyno of boost vs rpm for the t2 .64 vs .82 with an EWG.

                  thanks for reading. i know most of this is well-trodden ground.
                  Last edited by tonto; 08-11-2010, 04:39 PM. Reason: bads grammars


                  • #10
                    Nice, one of the few Miatas I actually like.

                    My advice, with a car that weighs just a hair more than yours - ditch the GT2860RS - overhyped turbos that don't make much power, and 99% of them have the big 0.86 A/R housing which means lag city(4k+ RPM full boost threshold). A GT2560R(stock "T28" on the S14/S15 SR20DET's) is good for within 10 rwhp of the GT2860RS, and costs about half as much or less. Plus the 0.64 A/R housing matches that size turbo much better.

                    That said, had a GT2560R, fun turbo compared to the stock T25, but still had power roll off up top. I felt like the car was a 3.5-6.5k RPM car really. Sure, it'd pull to 7.5k RPM just fine, but peak power was about 6400-6500 RPM and rolled off pretty fast with the stock intake manifold beyond that.

                    My recommendation, a GT2871R 0.64 A/R on a stock manifold(mildly port it with some sanding drums and stuff, makes a pretty big difference). Forget the tubular cheap eBay manifolds. Throw in some mild cams and the usual bigger injector, Z32 MAF and you're at an easy 300-320 rwhp on track at ~13-14 psi, and will do 350+ rwhp on the street around 18 psi.

                    The smaller turbos are fun, and as much as you say you don't want that much power, when you know how easy it is to get, it's something you just can't resist if you stick wit the car.

                    Don't worry about the E36 M3 and the leaking HG - they *ALL* do that given enough track time. I've had two of them, and have a ton of friends that still have/had them. I'd say 90% of them that get any sort of track time blew HG's(which warps the head in all cases by the time you catch it). Dirty little secret about them IMO, as a lot of the track guys in the BMW crowd are in complete denial about how prevalent it is, and it's not really brandied about much in casual talk. Especially since a resurface of the head and a new OEM HG will fix the problem for a while. The main problem is just lack of clamping force on the head and a design that's not really good at applying even pressure to the HG.
                    '18 Chevrolet Volt - Electric fun hatch for DD duty!

                    DefSport Koni Sleeve and Spring Perch Buy!!!


                    • #11
                      I see, can't use stock manifold and have a T3 flange.

                      Solution - get a small A/R GT3071R and call it done. You'll nut yourself at the powerband and power potential. It'll spool just a tick behind the GT2860RS, and probably put out near 400 rwhp without much trouble.

                      A 340 rwhp GT2860RS is either a VERY optimistic dyno, or a turbo that won't last long at all. You definitely couldn't track it at anywhere near that power level - it'd be so far off the compressor map it'd be blowing 400 deg F air.
                      '18 Chevrolet Volt - Electric fun hatch for DD duty!

                      DefSport Koni Sleeve and Spring Perch Buy!!!


                      • #12
                        Def, thanks for ideas. all kinds of stuff to chew on.

                        first, this mod is a little bass akwards. i'm trying to find a mani that will fit in there, and then see about what my turbo options are with it. so far all i see that looks like it will definitely fit is the one i listed above. interested in ideas here.

                        once i got a mani then i gots to find a turbo. i checked and the 28rs i have is a .64. but it doesnt' really matter anyway with the synapse because i'll have to change to a tial housing anyway.

                        heres my thoughts on turbo selection

                        1st and foremost, reliability. and this is a track only car, so this means long-track-day-in-the-heat reliability. obviously there is a learning curve aspect to this, so i want to start with 14psi because that seems pretty safe if you don't do anything stupid. (and i did get fuel starvation once, so i'm already borderline-stupid).

                        gt28rs: i have it, so points there. if i'm gonna spend money on mani+ewg then cheap "starter" turbo is fine with me. looking at compressor map, it seems 14psi-18psi is the top end but still in the most efficient island. this works well with keep-it-simple-till-you-learn-at-14psi idea.

                        the 34Xwhp 28rs i mentioned i saw from cortrim1@sr20forum. obviously a apples-oranges deal because he is running NA compression on that, but he does claim a external wastegate is good for 20whp. so i'm thinking the 28rs has potential that most folks just skip over for the 2871...

                        2871: i konw this is a popular turbo (started by you and codyace?) but looking at the compressor map it looks to me that at 14psi, i'm paying an angular momentum price for the bigger wheel but not using the higher pressure ratio it offers. obviously if i bump the boost up, that will change... which leads me to the 3071.

                        3071: i like this idea. if i pay for the mani+wg now i can put a 3071 when i have everything well and truly sorted and just skip the 2871 entirely. if i have done a good job with the mani+wg selection, the car should work really nice with a 3071. i'm not sure what a 400whp miata would look like tho, ive never seen one
                        Last edited by tonto; 08-11-2010, 07:17 PM.


                        • #13
                          Ok - 0.64 is a T2 flange housing - not compatible with ANY of the T3 topmount manis. Yes, you could get a new T3 housing for it, but at that point, you're probably 80% the way towards a new turbo(that's better suited for your usage IMO).

                          What about going with something like a FWD SR mani? I think they put things closer to the "middle" of the ports, so that'll help you with front/back spacing.

                          I think that red thing is the Bluebird stock manifold. Supposedly they don't flow as well as the RWD manifolds, but IMO it's probably not a huge difference. Cheap and reliable solution IF things don't run into the motor mount bracket(moving the turbo forward can do that... possibly, but I think most turbos would be fine).

                          As far as power, again, you are *NOT* going to make anywhere close to 300 rwhp on a GT2860RS on track for very long and keep things together outside of race gas($$$). It will take 18-19 psi.

                          The bigger wheels of the GT2871R/GT3071R will give you way more power at low boost(14 psi) on the track, and way way more power on the street at higher boost. The response difference is negligible IMO, especially for a track car. I have a GT2876R because it was cheap. Not an ideal turbo, but the response really isn't bad, and I have no huge complaints about it on track. It gives a great 4-7.5k RPM powerband, which is easy to drive around on 90% of the tracks out there. A 2871/3071R will be just a hair more responsive(but honestly feel close to the same seat of the pants, there's just not a HUGE difference between the 2860/2871/3071 except the power really).

                          If you're going to just jump in and buy a T3 topmount, I definitely recommend the 3071R with a 0.63 A/R housing, or 0.78(right number?) divided housing if you've got the scratch for one of those manifolds. The 0.82 A/R housing is too laggy for track usage, ignore the drag guys that tell you to go with that one.

                          14 psi is perfectly doable on a stock internal SR with cams/bolt-ons. That's exactly what I do, and it works out just fine. It's about as fast as a 400-440 rwhp modded C6/C5 Z06 Vette on the straights, and then when you want to get stupid when it's cooler out, just toss in a bit of race gas and see how it feels on ~16-18 psi.
                          '18 Chevrolet Volt - Electric fun hatch for DD duty!

                          DefSport Koni Sleeve and Spring Perch Buy!!!


                          • #14
                            For what it's worth I'm running 18psi through my 0.64 GT2860RS with no issues on local pump 98 octane stuff. (Equivalent to your 93 octane off the top of my head?) I have knock logging on the track and am able to keep it from rearing its ugly head and still manage 12-16 degrees timing at full load. Been going for a few years now.

                            But yes the shaft is spinning quite fast. Around 20% faster than a GT2871R at full load.


                            • #15
                              Sounds difficult. You probably have low ambient temps? It's all I can do to keep things together when it gets over 100 deg F here. If you go by those crazy metric units, it hit 41 deg C last track weekend here. I felt cool running 14 psi on my car, but 18 psi would be pushing things IMO.
                              '18 Chevrolet Volt - Electric fun hatch for DD duty!

                              DefSport Koni Sleeve and Spring Perch Buy!!!