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Thread: 300hp NA 2JZ

  1. #1
    casual poster rb3torana's Avatar
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    Default 300hp NA 2JZ

    Looking at a new challenge of trying to make approx 300fwhp out of an na 2jz. Specs will be a stock 2jzge short (10:1 comp) 230/240@50 cams, ported head(should flow roughly 260cfm), good plenum and a good set of pipes. All going in a lx torana to try and run consistent 12.50's @107-110mph. Its got a a340e with a 4-4500rpm stall and will get 5.14 diff gears (8500rpm limit) Any thoughts on whether this should reach my goal? And yes its staying NA ( already run a 9.6@141 with a twincharged 1jz in this car and dont want to cage it etc and just up for a new challenge )Cheers

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    Hi, you will come up short by about 50hp.

    The cam is only slightly bigger than a standard which gives around 212–227 hp at 5800 to 6000 rpm and 209–220 lb-ft of torque at 3800 to 4800 rpm (Wikipedia and other general sites).

    Using the generally observed formula, a good breathing 10.0 compression engine will produce approx 1.2 lb-ft torque/ci (a 10.5 engine approx 1.25), it will lose about 10% by peak hp, peak torque is usually about 1500rpm below peak hp. Then put that into the standard formula HP = TQ x rpm / 5252

    So using the formulas:
    3.0 litre engine = 186ci
    Standard engine: 186 x 1.2 = 223lb-ft torque @ approx 4500rpm
    223 x 0.9 x 6000 / 5252 = 229hp @ 6000rpm
    Formulas very close to real world standard engine figures.

    To get to 300hp, bump up compression to 10.5 and put in a cam that gives you peak hp @ 7500rpm.
    So onto a bigger cam.
    186 x 1.25 = 233 lb-ft torque @ approx 6000rpm
    233 x 0.9 x 7500 / 5252 = 300 hp @ 7500rpm

    The 4-4500rpm stall will then only just be high enough, as you usually use a stall speed from approx 1500rpm below to peak torque (new cam peak is 6000rpm).

    Hope this helps.

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    Correction.

    I made a mistake, I was looking at the wrong cam info.

    The Cams you have will give the required rpm and therefore HP.

    I would only be concerned will the stall of the torque converter, needs to be higher (5500 approx).

    With the low first gear (2.8) and deep rear gears (5.14) you will have to be quick on the gear change as it will be about the 60ft mark.

    This should get your 12.5 @ 107

  4. #4
    casual poster rb3torana's Avatar
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    Quote Originally Posted by SRH11 View Post
    Correction.

    I made a mistake, I was looking at the wrong cam info.

    The Cams you have will give the required rpm and therefore HP.

    I would only be concerned will the stall of the torque converter, needs to be higher (5500 approx).

    With the low first gear (2.8) and deep rear gears (5.14) you will have to be quick on the gear change as it will be about the 60ft mark.

    This should get your 12.5 @ 107

    Yeah the low 1st gear I was hoping may cover up the low stall speed, hopefully theres not too much rpm shift drop on change. After looking again I can also get a 253@50 with a little more lift but might still go with a 238 on the intake with more lift aswell. I figure if holden 202's can make 300hp I should get close lol. Cheers

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