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Thread: Getting HP out of L28

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    Default Getting HP out of L28

    I have a 77 280z with dual SU carbs. I want to get some more power out if the motor and still drive it daily. I wanted to go to an oversized flat top piston, a shaved .080 P90 head, a stage 3 Schneider cam, a forged crank, and a new header. I was wondering what compression I should expect from the motor and could I still run 91 pump gas? Also will the motor run hot I'm running a 3 row 1 inch core aluminum radiator. Lastly could anyone tell me the HP I expect out if this setup.
    -Thank you

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    Nova Scotia,Canada,Earth Blue's Avatar
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    forged crank is very expensive along with the machine work for the above build

    if you want a low cost way to power up a daily driver, just get an L28ET turbo from a 280zx and turn up the boost. Add an intercooler and you are good to ~ 10psi of boost.
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    NA builds are more spendy than most Cjolly. Since you are in California, I would stick to a compression ratio of 9:1, and not a drop more. 91 octane will have you fighting detonation all the time if you choose to push it. It is far more important to get the timing right, than to push for crazy compression. Ask me how I know. I have to run octane booster with every single tank I run in my Z to run the appropriate timing curve my L28 likes. I am probably running too much compression, about 10.5:1, and 93 octane does not like it. A bigger cam may help, also a larger combustion chamber, etc. It is better to build it right and safe from the onset.

    You do not need a forged crank. A OEM Datsun Crank is very strong and just getting it trued is enough. Also, get the whole thing balanced, but most OEM rotating assemblies came balanced from the factory, so you just need to verify it. Concentrate on getting your induction spot on and having an nice free flowing exhaust. Timing, induction, and exhaust will make you a wonderful little torque'y L28. You are not going to be making big impressive HP numbers, but you will have a very responsive and drivable engine.
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    Ummm- L28 HAS forged internals already ( crank & rods). You would be pissing money away for anything else. It's all in the head. P-90 shaved would be great, but you need the flat tops to compliment that. Might consider finding a zx flattop motor and work the head( p-79), or just use the block with your P-90.
    As far as detonation, using a modern design chamber like the P-90 or 79 should help deter that.
    brownclee likes this.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
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    Supporting Member Diseazd's Avatar
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    C/R ......9.7 to 1 to 10 to 1........h.p. .......180 to 190 at the crank....160 to 170 h.p. at the rear wheels....all numbers based on shaved P90 head and .040 over flat top pistons and a Stage III cam. As Steve says....detonation should not be a problem with the modern P90 head. Just make damned sure you've got someone building the motor that knows what they're doing. The total cost of a professional build should be about $4,000.00 give or take. It's a perfect street motor.....you'll really enjoy it.
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    Thanks everyone for your responses. I have one more question and I don't want to ask stupid questions. But I'm expecting this build to go pretty easy. I'm just worried about the head so Just to double check the head should bolt rite on. ?

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    Registered User madkaw's Avatar
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    It's hard to figure out what you are asking because of your poor grammar. Pretty much everything is interchangeable on the L motors. The P-90 will bolt on any L28.
    Diseazd and brownclee like this.
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    What's your smog situation in Cali? A 280 Z with carbs on it won't pass smog...but if your just building for the track your fine. California doesn't mess around with stuff like this, they crush them if they catch you.
    74 260Z late
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    Registered User Stanley's Avatar
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    Might download the Motor vehicle code, possibly there's an exemption in there. So a CAT won't do it? Back in the 90's Ben Franklin would have solved that problem. Otherwise, any mods they can't see plus C.A.R.B. approved intake and exhaust mods are ok.

    Saw a late model Honda Insight last weekend that went zero to sixty in about 4 seconds - had to be an engine swap, don't think the stock 88 HP would do that. Maybe they swap the stock engine back in for emissions test.

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    a few thousand laptop batteries would do the trick to get that Honda up to 60 in 4 seconds
    brownclee likes this.
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