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Maximum RPM for SVT Rotating Assembly

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  • Maximum RPM for SVT Rotating Assembly

    I understand that the 2.5L SVT Bottom End is limited to 6,750 rpm from the factory based on ECU limitation. Does anyone have a feeling for what is actually possible and niot explode the thing into shrapnel? I hung a valve in my race motor a few weeks ago and the damage is very severe, so to do a race in 2 1/2 weeks, I am looking at swapping all of the race bits, including cams, from the race motor and I was hoping that I could turn the stock bottom end to about 7,200 rpm. If I can get that rpm, I should be close on power (or at least within 4%).

    Eric

  • #2
    Would it really be worth it?? because honestly how much power are you going to pick up in that other 400rpm?? probably not THAT much to be noticeable, I'd rather have a engine spin a little slower but make good decent power and be RELIABLE then have to run the thing to the moon to get it to move. Your flavor may vary.

    I would think a 3.0 overall would be better instantly..why even waste the time spinning the 2.5 I may be wrong but pretty much anything your going to do with the 2.5 u could do to the 3.0 with better gains??

    Being that these 2.5's are notorious for spinning bearings I wouldn't even attempt it. Just my 2 cents..

    U drop good internals in it and Im sure it will spin 9K...

    It just sounds like a fail from the gate your going to be putting "race bits" on a stock bottom end that is known for coming apart under NORMAL power...
    Black/Tan #0719 SVT..Gone to heaven
    Black/Tan #2013 SVT..being built/driven
    Green/Cloth 98 Zetec, Atx, Mystique..Gone
    Tan/Tan leather 99 Mystique LS V6 ATX...Daily Driver

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    • #3
      I understand your concerns, but there are reasons why I want to stay with the SVT 2.5. I have 2 full on 2.5L race motors built up with the best of rotating assemblies and that are good for 9,000 + rpm. I actually even own the 2.5L motor out of the Mirko Contour that ran in WC. The reason I want to run the SVT 2.5l is that it comes with 10:1 compression and that this particular motor has been raced before and didn't grenade. The spinning bearing issue is mostly caused by running the pick up dry in sustained cornering. I will be swapping on the baffled and gated 7 quart pan, plus running a 3 Quart Accusump as well as oil coolers and remote filters. Everything bolts on from the Kinetics built motor that ate the piston. My understanding is that the 3.0l only has 9.0:1 compression and the cams wont run with that low of compression. Too much overlap at lower rpm. If there is a year of a DOHC 3.0L with 10.0:1 compression or higher, I would love to know.

      The 2.5 race motor was generating 265 hp at 7250 rpm with stock heads and 11.8:1 compression. If I can turn the stock 2.5L bottom end that high, I will be in the mid 250ish HP range. The other reason I want to use the 2.5L SVT motor, is that I have one and everything bolts together with no issues. At 6,750 rpm, the old motor dropped 14 hp in those 500 rpms and I really need every single one of those ponies. I actually race both the Mumm Bros. Cougar and the Capaldi Cougar and have a race in 3 weekends with the Mumm Bros car and I just don't have time to reassemble the Mirko motor in time. That's why I am asking if the stock bottom end will hold 7,250 rpm and if anyone has already done this? Its the easy button for the weekend and if it wont hold together at 7,250 rpm, I will run it to 6,750 rpm and live with the 245 hp.

      I thought you might like to see what I am talking about with the cars.

      Eric

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      • #4
        3L has identical comp ratio to svt 10:1

        It won't last long, but it sounds like you don't have much of a choice anyway so send it.
        '98 SVT E0 BLK/MNB#1663 3L Always broke. - Now with a supercharer for even less reliability! Not sure if fun.
        '99 SVT E1 BLK/TAN#0741 Sold. Lots of fun.
        '07 MAZDASPEED3 GT Reliably quick groceries. Sorta Fun

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        • #5
          Get the 3.0 motor, same parts, more torque.

          Spun rod bearings are from the rods not able to hold shape, not really an oil issue. Too bad you can't put forged parts in them in time and make it bulletproof.

          You will have to take the front cover off a 2.5 as well to put cams in, so there is no assembly time difference between the 2.5 and the 3.0. For road racing you will want the added torque coming out of the corners...
          Don Higgins
          Crew Chief Pro Drag Racing Software
          http://www.crewchiefpro.com
          1999 3.0 Turbo CSVT ** 2013 American Dragster with 1100 Horsepower 7.28 @ 185 mph

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          • #6
            Reading what you've done externally to the oiling system is probably the best insurance you can have, short of dry sumping the motor. The weak spot in these motors is the big end of the powdered metal connecting rods, and as crewchiefpro said, they will eventually go out of round, no matter how good the oiling, and then you're done. You might get a race of a stock 2.5L bottom end, but you're building a hand grenade.
            I collect Ford's Red-headed step children.
            1985 SVO Mustang (turbocharged track rat)
            1989 Taurus SHO (supercharged track rat)
            1999 SVT Contour (Sedanus-Grocerygetter-Rapidus)
            2008 Mercury Milan Premier (Comfy boat)

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