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Thread: Maximum power

  1. #1
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    Maximum power

    My IVA form is asking for the engine maximum power and the engine speed at which it is obtained. Well i know my engine is basically 350 BHP more or less a standard small block.
    But at what engine speed maximum power is achieved i dont know. Does anyone have a rough guide as to what it might be.

  2. #2
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    It depends on your engine spec.
    The main thing to note here is:
    The IVA noise test is based on this figure.
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  3. #3
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    Is the IVA noise test at 3/4 the RPM of maximum power? If so, perhaps maximum power RPM should be 4/3 the quietest RPM (excluding zero RPM, of course).
    Kittihawk: Pilgrim Sumo MK3 built '93/'94 with 2.1L Stage 2 Pinto and Ford Type 9 5-Speed Gearbox

  4. #4
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    Standard SBC's redline at about 5000rpm. Max power will be a bit less than that. I think I read somewhere that 4850rpm was a reasonable figure to use for max power rpm.

  5. #5
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    Thanks Incey
    If I assume nobody really wants to take it to the red line of 5000 rpm then a figure around 4800 seems realistic, I don’t want to go to low otherwise it gives the impression that the car produces high decibels at low revs, anyway the Iva inspectors must have a good idea of what is normal for this type of engine.

  6. #6
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    Quote Originally Posted by methoni View Post
    Thanks Incey
    If I assume nobody really wants to take it to the red line of 5000 rpm then a figure around 4800 seems realistic, I don’t want to go to low otherwise it gives the impression that the car produces high decibels at low revs, anyway the Iva inspectors must have a good idea of what is normal for this type of engine.

    you need to ensure you get this correct as it affects the rpm at which the noise test is performed, so the lower rpm max power is produced increases you chances of passing the noise test.

    google is your friend, I found a power graph on line for a crate 350 190hp engine that had max power at 4400 rpm -Street Muscle magazine article.

    there’s another showing max hp at 4000

    passing the noise test at 75% of 4000 (3000) will be easier than passing at 75% of 5000 (3750) .

    there are also other factors that can increase the noise like engine timing so check that as well.
    Last edited by RogerKnill; 25-06-21 at 01:16 AM.
    Roger

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  7. #7
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    Have you got AK Side pipes?? If so give at AK a bell. They should be able to advise accordingly.

  8. #8
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    Rogar is spot on as you dont want to have to over rev the engine if your max power is lower.
    If you have as much information of the camshaft and pull a power profile will be a good indicator. A build receipt of the engine, date of engine, with cam power profile will really make thinks easier as evidence on the day. The more paperwork backs your case and will alleviate any doubts by the inspector.

  9. #9
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    Good idea, I’ll talk to Jon at AK to see what he recommendeds

  10. #10
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    Quote Originally Posted by methoni View Post
    Good idea, I’ll talk to Jon at AK to see what he recommendeds
    I put my max revs as 4600 on my tuned SBC that had hot cams and bored out from 5.0 to around 5.4.

    I put power as per standard 5.0 SBC which for the year of engine was 200bhp... this was not tested or questioned by IVA testers.

    They admitted they thought it probably wasn't going to pass Db test, which was done at 3200 revs, but it just passed with reading 98.5.

    If I had been tested on about 5400 revs as max power it would have failed!

    Good luck with IVA

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