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| chappykg |
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{USERNAME} wrote: Remember at those sort of revs its not the rod/piston weight that you need to worry about if they are forged/aftermarket items. Its the rockers and valvetrain that has trouble keeping up to scratch above 7k. Au rocker gear is preferred when revving higher because the rocker ratios are better suited to higher rpms than the e-series units. Thats one of the reasons we are limiting it to 6800rpm plus we are still worried about the bottom end to much money to take un-needed risks on.
_________________ Turned L.G.AUTOMOTIVE Townsville |
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| wtbdlltd |
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dont you want longer ratio's with a turbo so its on boost longer. no point having low ratio and it running out of revs after 2secs of throttle
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| xf84 |
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Unless ya wanna run multiple shims to get the pinion correct, I'd stick with the 28 series ratios; ie. 3.27, 3.45 or 3.73.
You can run 25 series ratios, but it's slightly dodge having to run multiple shims (unless you get a proper size one machined). You have more choice here, inluding 3.9's and 4.11's. I would stick with 28 series, as it can be costly if you drive it hard. As I found out running 25 series gears in my 28 series diff.... EDIT: Can't spell for shhiit
_________________ Old - XF with XH XR8 Driveline... {DESCRIPTION} |
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| TROYMAN |
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{USERNAME} wrote: {USERNAME} wrote: keep in mind a turbo with auto trans will spool up better with more load/ higher diff gears, imo 3.45 would be ideal, 3.7 may still be fine but may fall short on top speed.. but also look at your rev range, if your engine is set up and can rev to 7000rpm then you can get away with shorter gears.. im running auto with 3.45 diff gears and im shifting from 3rd into 4th gear @5500rpm just before the line down the 1/4.@ 113mph... and keep in mind the 4 speed auto's 4th gear is just an overdrive and not ment to maintain high amounts of torque under load .. Ok thanks what sort of power yu running and what times1/4mile. im making 267rwkw and run a 12.9@ 113mph.. Even though the motor will be capable of 8000rpm we are limiting it to 6,800rpm for safety. |
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| maso1988 |
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{USERNAME} wrote: {USERNAME} wrote: {USERNAME} wrote: {USERNAME} wrote: why 4:11, why not something more streetable like 3.7 or3.9? Why do you suggest those ratio's? We looked at 4.11:1 because its auto and with the turbo and cam it would make the vehicle easier to get moving. It would have been good if you had provided us with ALL info when asking the questions. How are we to know it was turbo'd?? Even more reason not to use 4.11's. As stated above 3.45's would be a better option, even LSD what ever ratio is already in it. Is this car to be rego'd or purely track work?- more info needed! Ok point taken and sorry. Street registered and blue plated. So far the mods are - Garrett GT35/82R water-cooled, 6Boost manifold, 36lb Bosch injectors, Crow valve springs, MLS-R head gasket, Bosch external fuel pump and serge tank, Wolf V500 ECU, Wolf Boost controller, inter-cooler, turbo 4" inlet and 3" full exhaust. ( A Camtech Turbo custom cam to be fitted at the end of the month) The vehicle is only running 7lbs boost at the moment,t made 257rwkw. The way it is tuned now it starts coming on boost at 1800rpm and full boost at 2500rpm. Has heaps of torque. When the cam is installed it will be re-tuned and pushed up to 10lbs boost, we are hoping for somewhere around 320 to 350rwkw then. All the turning and dyno work is done by LG Automotive in Townsville and the mechanical work is done by J.B Automotive in Ayr. Coming mods are - Spool Pistons(8.5:1) and conrods, full engine balance, Head CNC ported, crank shaft stressed treated and oil mods made. All this work will be done by J.B. Automotive (John Barbagallo) Now back to the diff ok point taken again, but my son still wants to run a lower ratio diff probably 3.7:1 possibly. I wonder what ratio the standard EF Fairmont auto sedans had from factory. Cheeers 3.23.01 |
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| Krytox |
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{USERNAME} wrote: The way it is tuned now it starts coming on boost at 1800rpm and full boost at 2500rpm. Has heaps of torque. Then Use the torque? As the last person said 3.23:1 would be something I'd look at. Surely with all this work, the tuner would 'tell' you what you need'
_________________ Carefree, we may not be number one, but we're up there. |
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| madeaspack |
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id say stick with what it has, the more load on the engine the faster it will boost, changing the ratio will take load off the engine.
or if your interested i have a set of 3.45 gears
_________________ 97 el xr6,5 speed short shifter,sequential scoop,no arial,freshly resprayed,low on 17's,3 inch zorst,stainless hi flo cat,snort stage 3 stainless manifold,garrett t04e,front mount cooler,wolf 3d ecu,seimens 760cc injectors,walbro fuel pump |
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| clevo400 |
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Do you mean BW 75 and 78 series diff. And are we recommending 3.7 for na and 3.45/3.27 for boost.
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