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  • Low comp pistons

    What avilable today for yb? I consider to build one bottom end with 7.x-1. whant it relible and high boost on pump fuel, so dont realy whant "high comp"

    Prefer 136mm rods
    www.sapphirerscosworth.com

  • #2
    Mine are custom made to any spec. High comp is fine you just need to manage everything properly but low comp gives you a wider window. Horses of corses as they say.

    Mark

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    • #3
      Thanx. Yes custom is possible, but was searching quikley around, and i didnt find many "off shelf" pistons anymore, atleast not for 136 rods. So just wondered if it is not any that makes any today, other then custom?
      www.sapphirerscosworth.com

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      • #4
        I think low comp is quickly becoming old Skool. Most tuners can now use electronics to monitor ignition boost, temps o2 and knock so that higher compression ratios can be used compared to the old days. I think either Mark ( MAD) or SCS are the ones to have a chat with?
        sigpic


        Sunnyside B&B and camper restorations
        www.sunnysidebb.co.uk

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        • #5
          I know many look at low comp as old school now. but honestly always liked the lowcomp engines, and seems to live much longer(and bad quality pump fuel dosent do it better...)

          And is it realy that much advantages with higher comp? When low comp, can be much more aggressive on ignition right? More boost, and normaly less heat? I just ask, since thats alwsys been my inpression? Remember back In the days, i felt often that thodr buildt and setup with lowcomp was aggressive and very little problems with, vs high comp engines? Sure allot of technology has moved on...
          www.sapphirerscosworth.com

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          • #6
            Originally posted by twin turbo View Post
            I know many look at low comp as old school now. but honestly always liked the lowcomp engines, and seems to live much longer(and bad quality pump fuel dosent do it better...)

            And is it realy that much advantages with higher comp? When low comp, can be much more aggressive on ignition right? More boost, and normaly less heat? I just ask, since thats alwsys been my inpression? Remember back In the days, i felt often that thodr buildt and setup with lowcomp was aggressive and very little problems with, vs high comp engines? Sure allot of technology has moved on...
            That is still a valid argument Having had both I feel the higher comp ( normal comp) engines are more responsive when not on boost.....which lets be honest if its a road car that 90% of the time. Fuel consumption is better as is starting the engine when the plugs and cap have a lot of miles on them. My 7.1:1 engine was back in the late 80's early 90's when RED were building massively powered GPA cars with no restrictor and even then with a 40mm restric could give good power. I continued to use my low comp engine on the road doing 3k per month for at least 4 years and found plugs and cap and arm had to be change much more frequently and fuel consumption was poor. However it wasn't closed loop, Ran greys and had MT Cams so if I am honest it wasnt really suited to long term road use. I just spent sdo much money on it i wasn't going to sell it for buttons so drove it.....hard and a lot.
            I suppose a good low comp engine with a really good tune on closed loop etc should be fine but you can go high comp these days, which you just couldn't do 25 years ago.
            sigpic


            Sunnyside B&B and camper restorations
            www.sunnysidebb.co.uk

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            • #7
              I has a BW S200SX on my old engine that was 7.5-1 with ported head, BD16 inlet and 14 exhaust. It was good on the Gt30 it used to have but brilliant on the S200, I think turbo choice for low comp is very important.

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              • #8
                Fuel consuption, and plugs/service stuff i dont care about, since barley use them anyway. But Nice to get more info from difrent pepole had both i have a set of pistons (909) and out from partnumber they where 6.8:1 that engine was abused from late 80's to upon early 2000, before some "supermechanic" whanted to overhaul it...

                I fully trust mark shead and you others on that its no problem to run higher comp today, thats not why i ask, just Nice to collect more info, and positive and negative both ways
                www.sapphirerscosworth.com

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