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Thread: Upgrade BP285 to BP300

  1. #1
    Bodger

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    Upgrade BP285 to BP300

    I am thinking of upgradiing my x-flow engine :

    Curernt configuration is Stage three head ported and gas flowed .

    A very nice manifold . The engine is fully blanance.

    Pistons are decked .

    Üiston pockets had to be reworked to allow to P2V clearance which is on the limit ( risky)

    Running of 40 Delloertos and electronic ignition with a hot coil.
    The current cam in the engie is 285 piper .

    As i have pulled out the engine for service I am thinging of doing some upgrades .

    The car is used for Stage rallying as does performs quite well and has been trouble free.

    I would like to take the engine the next level and keep the reliabilty .


    So the choice is do i increase the compression ( 1300 pistons) or better go to a BP 300 cam and the compression

    Until now i got away with a standary gaskest but i guess will need to upgrade the gasket too...


    Any advice is apprecaited

  2. #2
    Tyre Kicker

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    Re: Upgrade BP285 to BP300

    Sadly, it isn't quite as straightforward as simply changing the camshaft and pistons. Whether it's a good idea or not depends also on your gearbox and diff ratio. You may find you need closer gear ratios and a lower diff ratio if changing to a peakier cam where the power is made higher in the rev range, unless of course you already have a close ratio box.
    If your budget allows, I would fit either a BP300 or Kent 254, and also a set of forged high compression pistons. The standard rods will be fine to 8000+ rpm, but you'll need some competition rod bolts. Yes you will need a higher spec. head gasket. Check valve springs for coil binding. Your 40 Dellortos will be struggling to supply enough airflow for the upgraded cam (assuming it's a well ported head). Really you need 45s with 36mm chokes.
    Last edited by Memphis; 03-01-2020 at 11:05.

  3. #3
    Bodger

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    Re: Upgrade BP285 to BP300

    yes i was expecting this response which is resonable

    the car is using a quafe close ratio g-box but because we do tarmace rallies the diff ratio is standard and the combination of the tow works fine . Can rev up to 7000 without . This is due to a good ported head i have on the car .

    As budget is an issue and need to spend the money on upgrading on a new roll cage ....

  4. #4
    Racer Decade Plus User

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    Re: Upgrade BP285 to BP300

    Unless you can generate a LOT of power, you 40 Dellorto's will be fine. They are bigger as 40 DCOE (unless late 40 DCOE) and can work with 34mm chokes, up to at least 160 bhp and even more.

  5. #5
    Bodger

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    Re: Upgrade BP285 to BP300

    Thank you for that.

  6. #6
    Racer Decade Plus User Forest_rallying's Avatar

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    Re: Upgrade BP285 to BP300

    If your budget is tight I would stick to your origanal engine specification especially with you using a std diff ratio. There's no point over camming your engine without changing a lot of other components.

    Put safety first and get your Roll Cage sorted.

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