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Volvo K24 7400 Rebuild question

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  • Volvo K24 7400 Rebuild question

    Alright gents,

    After some turbo advice here if anyone can help.

    Basically, as some of you may know i went to fit the Volvo 7400 turbo i have to my S2 a couple of weeks back. On removing the compressor housing damage was found to the compressor wheel. I sent the turbo away to Turbo Technics who said yes it can be repaired no problem, however the standard compressor wheel is no longer available and the only option is to fit a billet wheel. I also have the option off uprated seals and 360 deg thrust bearing if i so choose.

    My predicament is this, the chips i have for the K24 7400 are from S2central and were designed for a standard turbo, well as far i know it was standard, and not for one with a billet wheel.

    If i go ahead and get the turbo overhauled with a billet wheel how is it going to affect my fueling? Is the best option to source another standard turbo or will it perform perfectly well with the chips i have?

    Any experience or advice on this matter would be greatly appreciated.

    Cheers guys

    Gordon


  • #2
    I've asked Turbo Technics to weigh both cast and billet compressor wheels to see the difference so currently waiting on that info.

    Comment


    • #3
      You need to find out if the billet wheel they're offering is a copy of the old design, so just lighter, or is it a new design that will flow more air at the same speed. If it's just lighter I wouldn't have though you'd have any problems, but if it's going to flow more, you may need a map tweek.
      sigpic
      1991 Audi S2 3B - 2.5 Stroker engine
      1997 A6 2.5TDi quattro avant - C4
      1976 RD250E / 350LC cafe racer

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      • #4
        I had same on k26/7 just lighter wheel unless the cover has been machined And has different blade setup I don’t think it will affect your chip setup but it’s always good to have afr egt and boost gauge keep an eye on things all best michael

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        • #5
          Cheers for the comments guys, i was kind of rushed when speaking to the guy today so didn't really ask any specific questions. Told him i'd have a think about and get back to him. Good call with asking if it's a direct replacement / copy of the original wheel, i guess if it is it should be fairly close in performance to the original. He never mentioned that any machining of the housing would be required either so will quiz him on that. I've got an AFR and boost gauge in the car but no EGT.

          Comment


          • #6
            I've been mulling over this from Turbo Technics-

            "We have inspected the turbo you sent in.

            We can repair the unit with a Billet wheel, competition bearings and seals, 360 thrust bearing.

            £450 + Vat, plus £30 + Vat carriage"

            Or they can supply the turbo with a 270 thrust bearing and normal seals for £50 less.

            What do you reckon guys, is this a fair price?

            Do i go for the 360 thrust or cheaper 270? They said defo 360 thrust if running 1.7 bar which the chips are rated for but could just be sales talk.

            Also i asked them about a warranty, this is what they said-

            "All our Hybrid, performance and modified turbos do not have a warranty.

            We are unable to warrant any modifications made to an engine which could have an impact on a turbo including remaps, chips etc

            Although if you do have any issues, we will help where we can"

            I'm a bit concerned that no warranty is on offer, am i being unreasonable?

            Any thoughts on this lads?

            Cheers
            Gordon



            Comment


            • #7
              For what it's worth, in my opinion, I would have thought that the phrase " although if you do have any issues, we will help where we can" would cover you unless you're trying to over load and wring every last ounce from the unit way beyond what was reasonably expected. "Normal" use producing an issue I would have thought Turbo Technics would be willing to stand over their work without offering a specific warranty.
              1996 S2 ABY Coupe silver
              2003 S3 8L dolphin grey
              2014 RS4 B8 prism silver

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              • #8
                Go for the 360 bearing

                S2 Coupe 3B Project


                Ur quattro restoration

                S2 Avant

                Boost is the new rock and roll!
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                • #9
                  Whats the rest of the recipe for this conversion? Is the ecu modified (map sensor), different injectors?
                  Obviously any low cost durability mods would be desirable and more economic to do at the rebuild.
                  It's getting quite expensive, nearly a decent RS2 turbo price which arguable would give you less hassle and more headroom. I personally find it hard to believe that these turbo are able to pump out the figures that are quoted with such a small turbine. There doesen't seem to be much reliable data out there to support such claims.

                  Comment


                  • #10
                    I've been running full RS2 spec for the last year or so with TS Tuning chips to suit the K24 7200. I've enjoyed this but missing the low down punch that original K24 7000 provided. I bought this Volvo turbo a few years back but been sitting on a shelf ever since. Decided now is the time to do the conversion.

                    I've got the the software which was mapped by S2central, 440 injectors, FPR etc to run this turbo, just need to do some plumbing mods to make it fit.

                    But yes, i feel it's a bit pricey considering when i first phoned them they said they could provide a recon unit for £350.

                    I could take the risk of buying another second hand turbo for £300 but no guarantee of it's condition.

                    Hmmm decisions??

                    Comment


                    • #11
                      I see!
                      One way to look at this is that you are effectively getting a billet comp wheel/competition bearings &seals for £100. (£450 vs £350).
                      There does appear to be a few variants of the comp wheel, different blade config or larger dimensions which would mean compressor housing machining. Assuming you were after as close to stock as possible I guess you are looking at the 6/6 which is the closest to stock.
                      I'm afraid I have more questions than answers. Where are the comp whels from? (Looks like they are from the far east!) What exactly is the difference between stock bearings and competion ones? I have seen the staggered seals so I guess thats the upgrade.
                      Lastly I am not sure that the small K26 turbine housing is the optimal. Sure it fits but as the K26 turbine wheel has a major of 64.2mm rather than the Volvo's 59mm it would seem to me that a properly sized K24 housing would be better, possibily the 7000 one opened up for the Volvo minor, assuming that the major is identical. I seemed to recall that someone in the US was doing this. Thats one of the major differences between the K26 and K24 family. The RS2 also has the 59mm major if I remember correctly.
                      Its a shame that the Volvo's guts cannot be fitted to Audi hardware so there were no fitting issues. I seem to recall that John B used a K24 from AET I think that had good results. It looked like they had used possibily Porsche based stuff as the comp housing was different but similiar. Thats all I could tell from the outside!
                      Going back through some threads I see that some people really rated them. Presumably you have scoured the internet for a decent used comp wheel before commiting yourself to a shiney billet one?

                      Comment


                      • #12
                        Decision made, going for the upgraded 360 thrust, seals and billet wheel. Now then, due to the limted space available to plumb this in to the ABY airbox, i'm weighing up my options. I've been thinking of trying a cone filter, however, has anyway one used this type of filter with success with regards to heat soak etc?

                        If so i'f be interested to see what kind of setup was used. I can easily buy some double skinned aluminium sheeting, the type used on the underside of cars around areas subject to heat. I'm sure something fit for purpose could be fabricated using this of material.

                        Any advice much appreciated.

                        Cheers lads

                        Comment


                        • #13
                          I’ve used the aluminium for heat shield before its easy to shape and form used air box nuts to fasten it down my filter was a con filter pipercross haven’t got any pictures to show you but it worked.

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                          • #14
                            Been reading about people having issues running Apexi cone filters and the need to possibly fit a cross in the pipework to smooth out airflow. Is this actually true? Certainly something i hadn't thought about! Hmmm?

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                            • #15
                              I’ve got a GT 3071 running from an RS2 airbox, it can be done

                              S2 Coupe 3B Project


                              Ur quattro restoration

                              S2 Avant

                              Boost is the new rock and roll!
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